Chevrolet Repair Questions? Ask a Mechanic for Answers ASAP
Thanks for that information. I'll be back in a little while with a reply
Hi, I am a professional certified mechanic, with an engineering background, and 35+ years experience. I will do my best to assist you. Also keep in mind I don't know if you are a pro or a novice, so feel free to add any additional info at any time.
Hot engines in a 4x4 are tough sometimes, because hot engines typically loose low end torque, 4WD vehicles thrive on low end torque, so you can kill the torque you need. The standard trans will be good because you can rev it a bit. What kills you in a 4wd is a situation like rock crawling, where you have to pull to a hill, rock or other obstacle and grunt it from a dead stop in a strain where the hot cam and free flowing heads are not on power band yet, it can be tough. A stock engine would likely outperform a hot engine here, but once the hot engine gets revved up just a bit it comes alive big time. So that grunt spot is your biggest concern along with breaking parts. The heads, you don’t need aluminum, although you can opt for them. It is easy to make 500+ HP with the iron World Products Motown 220 heads. BotXXXXX XXXXXne is they are a lot cheaper, and they will resist damage from overheating a lot better than an aluminum head will, especially on a 4x4. I like to use them a lot on 4x4's and hot street cars, they rock, and the make tons of power. A good cam is a Comp roller, in particular is part number XR294HR. I would look at the Speed Pro LW2605F pistons. If you use a 5.7 inch rod, and a 72cc head combustion chamber will give you about 9.2 to 1, and a 64cc head will give you just under 10.0 to 1 which is about a max on pump gas. In that grunt situation I described, you need fairly low compression, high compression will cause detonation. Once again once it rev’s up it is on. If your injection has a knock sensor capable of controlling the ignition, you can get away with more compression. You need to use a lot of high strength parts, bearings, rod bolts, good oil pump, big radiator and more. Anyway this setup will produce over 500 HP at 5700 rpm's ,and over 500 foot pounds of torque at 4700 rpm's. Go over all of this and if you have any more questions at all, I am here to help. Good luck with it, have a great day, and Thanks for using Just Answer.
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What you have to understand is the basics of making more power, big ports, big valves. hot cams, and free flowing induction system all kill low end power, it is inherent to any of these types of modifications. Once the engine revs up a bit it goes, but down low it suffers. Modifications like more cubic inches, and more compression do build low end power, but the high flow heads, big cams, and free flowing induction systems that are needed to make big power numbers are going to kill low end power. The only way to have lots of power, in the low revving range and when the engine is screaming, is with a supercharger. It has power from idle to top end, but they are pricy. Aluminum heads generally are used more for weight savings than anything, this is helpful on drag cars, but on trucks it isn’t of much use. It is true that aluminum heads will tolerate a super small bit more compression because they absorb heat a little faster, but the unspoken side effect is any heat lost from the combustion chamber is horse power lost. It is a small loss, just like the amount of extra compression you can add is small, in fact very small, but both are real. Aluminum heads expand and contract a lot more than cast iron heads, and this movement along with their tendency to allow head gaskets to blow easier is pretty undesirable in a 4x4 engine. It is all a balance, gain some here loose some here, when you modify an engine. Like I said the only way to not loose low end power is to use a supercharger. You would honestly most likely be happier in a 4x4 with closer to 375 HP, it would have lots more low end pull. Still I understand the need for speed, I have it bad myself. Go over all of this and if you have any more questions at all, I am here to help. Good luck with it, have a great day, and Thanks for using Just Answer.
A choppy idle is a sign of a significantly big cam, so you have to be real carefull because of the 4wd. What type of head do you have, are they Vortec? do you know the casting number I can ID them for you. As far as the heads, the ones I recommended to you are hot heads are necessary to make the power you originally said you wanted. So that was the best recommendation for the power level you were looking for. The twist is the heads are not optimal for low end torque, but their detrimental effect is minimal with a better cam, and their power developing benefit is significant above about 2800 RPM's, so they would work on a 4wd. A big hot cam is about the worst thing for low end power. To have the best of both worlds, good power, and not badly killing the low end torque, look at the Edelbrock Rollin Thunder 2209 cam, it is a great cam for a 4WD and it is a cam that is even used in a lot of hot rods. Go over all of this and if you have any more questions at all, I am here to help. Good luck with it, have a great day, and Thanks for using Just Answer.
Take a look at the link HERE, check out the S/R Torquer. The link shows 4 different World product heads. The stock Vortec 350 heads are a great choice too, check into them.
The cam is a retrofit, it's end play is controlled by the stock thrust plate between the timing gear and cam. All factory roller 350 blocks had this thrust plate. I am sure Edelbrock offers the cam as a kit, but it will work with stock high quality lifters, & pushrods. Check Jegs, or Summit for good prices on the cam and other pieces you need. Let me know if you need any more help. Go over all of this and if you have any more questions at all, I am here to help. Good luck with it, have a great day, and Thanks for using Just Answer.
The Crane Cams 109671 is a good cam, but extra duration it has will have some negative effects on your engine at low speeds, but positive effects once the engine revs up. If you have power brakes the Crane Cams 109671 will noticeably degrade the power brakes. You will still have decent brakes but they will be significantly less powerful. If you have power brakes, I would consider installing an electric vacuum pump, and reservoir to provide the brake booster with adequate vacuum, because of the loss of vacuum from the engine. The other negative effect is less low end HP, and torque. Cams basically program the engine when to produce power, and you have to pick an RPM range that you will make max power in. The more you move towards max power at higher speeds, the less power you have down low. The Crane Cams 109671 will work great as long as you can keep the engine speed up under heavy load. Below 2200 RPM's under heavy load it will start to be a real dog. In the higher RPM range it is very strong, and will produce outstanding power. This cam really starts working at about 3000 RPM'sCrane is closed tonight, I normally contact the cam manufacturer for spring recommendations. You need crane 10535 lifters, I would use stock push rods, and for rocker arms the field is wide open. Stock rockers work fine. The type at the link HERE are entry level performance roller tip, and the rockers HERE are the best, XXXXX XXXXX Pay attention to stud size when you order rocker arms, and use the corresponding stud size in the heads. Aluminum rocker arms are pretty popular, but I have seen too many premature failures with them, aluminum fatigues pretty fast. They can be great, but I tend to go with steel if I have my choice. Go over all of this, if you have any more questions at all, I am here to help. Good luck with it, have a great day, and Thanks for using Just Answer.
Those heads will be a great match for all the other parts, they start doing good things about 1800 to 2000 RPMS, and really start moving from there. Below that they work well. When making engine modifications it is real important to make sure all parts complement each other, and the heads go real good with the cam you like, and that makes it a balanced package. They have 2.02 intake & 1.60 exhaust valves.
World's SR Torquer provides up to 30HP over stock heads. The S/R Tourquer cylinder head is the preferred performance alternative to expensive OEM castings or junkyard rebuilds. These heads are designed with extra-thick decks and walls for improved reliability as well as equipped with hardened steel exhaust seats that are compatible with today’s unleaded gasolines. They also come with screw-in rocker arm studs for extra durability. Needless to say, the S/R Torquer is substantially more durable than OEM castings. They feature a a larger 2.02 Intake Valve and a 1.6 Exhaust Valve.
Remember the angle plug issue here that we talked about after I recommended them. The Motown 220 heads will work great with the cam you chose. I deal with all types of people, and some wouldn’t want anything to do with a setup like this, while others want even hotter parts. I always try to help them figure out what a setup will run like before they spend the money. This will be a hot package, it will pass everything but a gas pump, as I often say. So it will very run hard with an explosive type powerband. Good luck with it, have a great day, and Thanks for using Just Answer.
That last line "available with a straight plug" that would make them work for you as far as the plug. An angle plug was the only hangup with existing headers. One last thing is I would get with your piston manufacturer, and check on your specific piston part number, and see what the compression ratio will be with a 64cc head. If that is good to go, then if you want to go big, I say do it. Different flat top pistons will produce different comp ratios, it is always better to know before you buy the heads.
When I first recommended that Comp XR294HR cam we were talking about 450+ HP then I turned it back some, because I realized it was for a 4x4 truck. Mainly because of the complications that comes with a real hot engine. The Crane Cams 109671, you asked about is milder than a Comp Cam XR294HR, a Crane 109671 and would run better, as far as drivability, and fuel consumption compared to the Comp Cam XR294HR, but the XR294HR would turn on harder as the RPM's climb. So the Crane 109671is overall milder.
I still think you should consider the Edelbrock Rollin Thunder 2209. It would use significantly less fuel, be stronger at lower speeds, and still turn on strong, but the other two cams will out power it starting in the midrange and especially in the top end. A cam basically programs an engine when to make the power. Go over all of this and if you have any more questions at all, I am here to help. Good luck with it, have a great day, and Thanks for using Just Answer.
Pulling a boat up a steep ramp is a pretty tough spot, in that situation I would really want the Edelbrock Rollin Thunder 2209, it is just so good for that situation. Still in 4x4 in low range, getting into the gas a bit to make it roll you could do it with the cam you like. I have built so many engines, and I am not trying to drive it into the ground, but I keep thinking of the Edelbrock Rollin Thunder 2209, especially when you talk about boat ramps, and big boats. If you are going to be on a boat ramp, don’t use the Comp Cam. If you have any more questions hit me tomorrow.
I would absolutely go with a dual plane like an Edelbrock 2101, A hot dual plane helps the low end, and midrange. While still allowing the engine to rev and make a lot of power. If you went with a single plane intake with the other pieces you have a boat ramp with a larger boat would be virtually out of the question. Cams are the most influential part that programs the RPM range, the intake is the next most influential part. If it was a 3000 pound car with low gears, I would go with a single plane, but it would be a real boat ramp killer for a truck that was going to be used to pull anything large. As far as the ignition an HEI is what I would use without a doubt. It is one piece, only needs one wire, totally self contained, and works super good. You can spend a lot more and build a complex system, but for a hot street engine an HEI is so functional and works so good from a performance point of view. The 1987 and newer blocks are setup for a thrust plate behind the upper timing gear, it controls the cams end play. With this setup you don’t need any type of button to deal with backlash. Go over all of this and if you have any more questions at all, I am here to help. Good luck with it, have a great day, and Thanks for using Just Answer.
I would put a fuel pressure gauge on it to start and make sure it isn’t loosing fuel pressure when the engine is done, so to speak. You could have a simple fuel delivery problem, especially if it is an LS6 they are pulling like crazy at 5,000. If it an LS1 it can benefit greatly from an LS6 cam and heads, you can get a huge performance gain with stock parts. As far as changing the injectors, they might be the limiting factor, so be ready for that. I know you want to keep them, still if you need more volume, it could be a must. If the fuel flow the injectors are producing is to low, sometimes a reprogram of the computer will add sufficient fuel flow to get away from larger injectors. That being said I don’t like to run injectors above 85 to 90% of their rated flow, that is an area you want to stay out of, it is plagued with problems. These engines will make lots of power, it is pretty easy to get 400 HP out of them and still have a relatively smooth running engine. If that is your goal, look into the stock LS6 parts. You also need to positively ID your engine it will make a lot of difference, knowing what you have will dictate to a degree what parts you need to reach your performance goal. Go over all of this and if you have any more questions at all, I am here to help. Good luck with it, have a great day, and Thanks for using Just Answer.
Great cam, it shouldn’t need any more injector below 6,000 RPM's with 400HP. One key here is most people don’t realize that injector flow can be manipulated, this can also avoid the necessity of having “tuning” performed electronically. If you have the stock LS1 injectors, they are technically rated at 24 PPH (pounds per hour) & (22 PPH in a 99 or 00 model). The most common thing to do if you need more injector is to raise the fuel pressure to about 60 pounds, with an AFPR (adjustable fuel pressure regulator) Then the same 24 PPH injector flows 29PPH @ 60 PSI, and the 22PPH injector flows about 26.2PPH @ 60 PSI. So the trick is to bring the pressure up, then retune the engine if needed. To make 400 HP, you need a fuel delivery rate of 27.8 PPH at the injectors, if you drive the at 90% of their max rated capacity. So I would ID your injectors, this way you can know what they are, and if you need to replace them. If you need larger injectors ebay is one of the best places to shop for them. Manipulating the fuel pressure with an AFPR, sometimes prevents the need for electronic tuning. That is a trick a lot of people miss, really important, because even electronic tuning needs “tweaking” many times. Go over all of this and if you have any more questions at all, I am here to help. Good luck with it, have a great day, and Thanks for using Just Answer.
18 volts in a 12 volt system is just dangerous for all the electrical parts. This high voltage makes failure likely especially with electronic parts. Your alternator will be involved, but the real issue will be it's regulation, and control. Regulators will tend to runaway if they loose their ground, it could also just be failing to regulate properly. Most newer alternators have internal regulation, so the normal fix is to install a rebuilt alternator. This is something you should deal with without delay, it can cause a lot of damage. Go over all of this and if you have any more questions at all, I am here to help. Good luck with it, have a great day, and Thanks for using Just Answer.
Both those cams will work great, the smaller of the two does have a little better drivability characteristics, but the larger has better power output, especially in the upper midrange and top end. The smaller cam will run and feel more like a stock cam in smoothness. The larger cam will start showing it's size, and you would be able to hear it a little. Because they are rollers and the roller allows steep ramps, the duration stays short on both of these compared to earlier non roller cams, this adds a lot of drivability to them, even on the larger cam. If you are a bit of a HP fiend the larger is the choice. If you want smooth and still pretty hot go with the smaller. I have seen the XR265HR pass tough CA smog tests, you cant tell them in CA you are running it or it while passing the tests will fail because of an after market part.
Your stock injectors should do with factory heads, with a mild, or what I would call a normal port job. With a MAX port cut and the larger cam you would be getting near where you would need larger injector’s. For the throttle body, I would look at the Edelbrock 3868 it's 80mm, it's a direct bolt on, so no mods are needed to make it fit. One last thing is my resistance to change the injectors unless needed is because of all the time and programming it takes to dial them in. Good luck with it, have a great day, and Thanks for using Just Answer.
The MAF, and O2 sensors can tune the engine a bit on their own, and you can install an adjustable fuel pressure regulator too. The MAF tells the computer the amount of air the engine is taking in, and that is critical when you modify the engine to have the engine mix the fuel at correct ratios, then the O2 sensor tells the computer, if the mix is correct, sort of a check, and recheck, and when it is working good it is sweet.Adjustable pressure regulators have been hard to get from time to time for this setup. Still with a little digging they can normally be found, these help you adjust the injector output. If you do have to get into a custom computer tune, find someone who is really good. 90% of the "tuners" are not qualified, and don’t fully understand what they are doing. A lot of them can screw around with an engine until it runs good, that isn’t what you need. There are very few are true pros that tune. That is one reason I am so resistant to getting into the computer unless it is a must. Good luck with it, have a great day, and Thanks for using Just Answer.
I made an error and posted the wrong post here so I deleted it, I will follow up shortly.
Your oil pressure looks good, I wouldn’t worry about that. If you ever need to get to the pump it is under the front timing cover, and the Melling 10296 high volume pump is the way to go.
If you decide to get it tuned that is when I would go with bigger injectors. Holding out with the stock injectors when you can get away with it is an effort to not have to tune it. But once you use larger injectors it lets the flood gates open unless you tune it, so tunning is a must once you go big on the injectors. Now on injectors you can easily spend 2K, so some shopping is a good approach. As far as size in the 30LB range is where you want to be, say nothing larger than a 36 LB injector for your setup. I would shop on ebay and find a deal. Right now you can get a new set of 36 lb injectors for about $350 at the link HERE. If you have time you might do a lot better. Injectors are starting to show up at automotive swap meets too. Good luck with it, have a great day, and Thanks for using Just Answer.
Aftermarket intake manifolds are pretty expensive, they do allow an engine to make a little more power at higher RPM's but it is some of the most expensive power you can buy. For an all out super street/drag type engine I would say get one. Otherwise they don’t offer a whole lot, especially for the money. Cold air intake system, look at the SLP setup for the 2000 Z28. Hand made ducts used with a K&N type filter are real popular, the kits are a lot easier. Good luck with it, have a great day, and Thanks for using Just Answer.
The SLP has an improved cover/lid that allows for extra flow, and more importantly a reduction in turbulence. There isn’t a huge gain, but it is a very popular upgrade. For a bolt on it's a good upgrade. Add a K&N filter and it is a great setup. Good luck with it, have a great day, and Thanks for using Just Answer.
The Volant Cold air intakes are more aggressive and further away from stock. The SLP unit corrects the turbulence and removes the silencers/baffles the stock lid has. The Volant Cold air intake is sensitive to rain, you really don’t want to drive it in the rain the engine will swallow some of it. It's more of a non rainy day street strip aggressive setup. Good luck with it, have a great day, and Thanks for using Just Answer.
The 21045 has a hose coming off of the drivers side of the unit, and the 21044 doesn’t have the hose. I believe the list the 21045 for your application. Good luck with it, have a great day, and Thanks for using Just Answer.
The lifters are held and stabilized by a holder, I have a pic for you that shows one, click on the link HERE, a photo says a thousand words. Let me know if you have any more questions about it. Good luck with it, have a great day, and Thanks for using Just Answer.
That is sort of a tough call, let me explain. The engine is going to be a little loose from wear, because of the miles. But probably not excessively loose. When you build a really hot performance engine, they are built a little loose. It prevents bearing bind, and if a piston gets really hot, and expands rapidly, if it is a little loose, the engine wont seize up. So there are some advantages to the engine being a little loose. 2 qts of oil in 5K miles with a leak isn’t much oil consumption. If you are concerned about the rings, do a leakdown test, it will let you know if the rings are doing well. All that being said you probably still have some miles left in it even with new hot parts. Of course the text book answer is rebuild it, more so to check it than anything else. I have seen dozens of these engines with this many miles on them do well after some hot rod parts install. For street use, with some occasional pounding if you have good oil pressure, and the leakdown test shows good it, should be good for many miles to come. If you want to spend time at the drag strip and seriously pound it, rebuild it. Go over all of this and if you have any more questions at all, I am here to help. Good luck with it, have a great day, and Thanks for using Just Answer.
Ok, I watched the video. I agree that a leak-down test is absolute in that it will absolutely let you know if there is a leak, and where it is coming from. I already know that I am pulling the heads to have them ported and rebuilt. in doing so, I will obviously be eliminating any valve wear and head gasket leakage. With that being said, if I just want to test the integrity of the rings, wouldn't a compression test produce the same feedback? if there is any crank case leakage, the pistons rings of the cylinder will obviously be at fault?
The answer is no, absolutely not. A compression test depends on the engines compression ratio, throttle position, condition and speed of starter motor, and even things like the battery's strength. Other factors like the cams profile will change the compression figures. The major point here is the leakdown test is not dependent on other factors, and is the best indication of the piston, and ring seal in the cylinder. Good luck with it, have a great day, and Thanks for using Just Answer.
There are a lot of different ways, some harder than others. The best way, or I will say at least my favorite way is to pull all the plugs, and get #1 up to TDC on the compression stroke. Then use the firing order, every 1/4 turn of the crankshaft in the normal direction of rotation, the engine progresses to the next cylinder in the firing order. This method saves a lot of time, and works perfectly. Go over all of this and if you have any more questions at all, I am here to help. Good luck with it, have a great day, and Thanks for using Just Answer.
On the older style small block Chevy engines the factory stamped steel rocker arms really left a lot to be desired, and I never hesitate to get rid of them. But the LS series of small blocks come with some really decent rocker arms. When it comes down to if you really need roller rockers, on an LS series street engine you don’t get a lot of benefit from rollers. You can use higher ratio rockers to get a little more valve lift from a cam. Lift doesn’t upset idle quality, or an engines intake vacuum and adds power. The rockers with the roller tip are nice, the roller tip is way more useful than the roller fulcrum on a street engine. Now on a race engine, or a super high RPM street engine I would say to go with roller fulcrum and roller tip rocker arms. On a race engine I would use aluminum roller rockers to reduce valve train mass. Aluminum fatigues on a street engine when you use it as a material on rocker arms, so I would stay away from aluminum rocker arms. There are some good stainless steel, roller tip, brass fulcrum rockers that are pretty inexpensive, I will post a link HERE for those, they are 1.8 ratio I believe. Going from 1.7 to 1.8 ratio increases valve lift about 12%. Go over all of this and if you have any more questions at all, I am here to help. Good luck with it, have a great day, and Thanks for using Just Answer.
You can remove the engine out the top if you have a lot of jacks, and some huge jack stands that will go up 25 to 30 inches. The main problem in pulling the engine out the top is the engine can only come up a few inches, and when it is up as far as it can go, and you try to pull it forward, the oil pan hits the crossmember. It isn’t a little hit, you need a lot of additional room. Basically the engine is locked into place because of its shape. To get it out the top, you go through all the normal removal procedures and get the front cradle resting on some type of support, and as opposed to lifting the body off, lift it with jacks and place it on the tall jack stands. Then you can lift the engine pull it forward, up then out. It is probably more work that removing the body, but it doesn’t require a lift. Next you should watch a link I know of, it really shows a lot about the process. This is some good info, the link HERE. Go over all of this and if you have any more questions at all, I am here to help. Good luck with it, have a great day, and Thanks for using Just Answer.
If the distributor is off by a tooth, it will be something you can spot with a timing light., the timing will be off. I would double check the firing order too if it is popping. What type of injection system did you go with, it is probably in need of tuning because of the modifications. If you want a larger throttle body, you need to install it before you get it all worked out, or you will have to retune it again. More airflow with the increased displacment, and other mods is a good idea, it would increase performance, but it isnt 100% necassary, your call there. Getting into the tuning you need a way to measure the fuel mixture to dial it in, you will probably need to get it to a tech that is a tuner to get that dialed in. If your local laws allow it, a Holley 3310 carb is a good option, it is a bolt on and go thing on an Edelbrock performer intake, it would make a lot of power, still it isn’t injection.
That type injection setup is called a SD (speed density) injection system. It basically operates off of pre programmed parameters, like a specific displacement, cam profile, and the flow of the intake and exhaust system. An SD system works amazingly well on a stock engine, but when you modify it, especially if you significantly modify it, it cant react to the changes in flow and displacement effectively. It is basically a dumb system that counts on pre programmed parameters, only the O2 sensor will give it mixture feedback, and that isn’t enough for it to dial itself in. If you had a MAF that measured airflow, you would have a better chance of the computer being able to react, still even with a MAF you would likely need some retuning. I tuned a 1994 impala SS a few months ago and it has a 383 installed. It had a MAF, and it still needed tuning. Those a real slick setup because the computer allows you to tell the program the engine displacement, and injector size, and it sets the base parameters, then the MAF, MAP, and O2 control the final mix. The SD system needs to have the same tuning done, and it has to be precise or it wont run like it should. Sorry about that news, still it is something you have to deal with or it wont run good. If you have any more questions at all, I am here to help. Good luck with it, have a great day, and Thanks for using Just Answer.
A larger throttle body will make a little more power, so that is an option. Do you need it for the engine to run good, no you don’t. It is just that it would make a little more power with a little more airflow. As far as a tuner, it depends a lot on where you are located. I would get on the internet, and look for tuner resources in your area. They need a dyno, and AF ratio measurement equipment, then computer tuning equipment. Be sure to explain in detail your setup to the tuner, so he can tell you if he can tune your setup
I am pretty sure the 7.4L throttle body looks similar, but wont bolt up. I wouldn’t go to the trouble of modifying to fit it, tune it, and then change it later, it is just a lot to do. There is an adapter that bolts to the stock intake,and allows a Holley carb to bolt on. It is a good alternative especially for a temporary fix. It isn’t injection but it is always nice to have options. I will post a link for that adapter HERE. The factory intake manifold is a big hindrance to performance. Something keeps screaming out to me to talk you into using an Edelbrock performer intake manifold, and a Holley 3310 carb. It would make significantly more power than anything you can do using your stock intake. It doesn’t need to be electronically tuned, and it will scream when you floor it. Did I mention it will haul butt, LOL. So I am going to say, no on the 7.4L throttle body, look at a factory sized throttle body, or aftermarket bolt on performance throttle body. Or use the adapter and a carb (use a Holley 1850 carb) , or the Holley 3310, and a performer intake. I will warn you if you bolt the performer and Holley 3310 on you probably wouldn’t take it off for any reason, they do work that good, also no electronic tuning issues, this part s a god send. If you have any more questions at all, I am here to help. Good luck with it, have a great day, and Thanks for using Just Answer.
You can use your factory pump, if you use a bypass type regulator with a return line, you would use your factory return line with this setup. It isn’t considered to be the bast way to go, I normally don’t recommend setting it up like this, but it will work. I will post a link HERE where you can get a good regulator with the functions you need.
Holley carbs, VS Edelbrock, that is a deep subject, I could write 20 pages on that one, LOL. You mentioned backfiring and Holley's. Anyone that tells you that doesn’t have a clue about Holley’s. They use a rubber diaphragm in the power valve, if it is ancient, and rotted, a backfire can rupture it, but these diaphragms are tough. Think of the rubber diaphragm in an old mechanical fuel pump, same basic thing. Normally when you hear horror story’s about Holley’s, it is an old Holley, that has been taken apart 5 times by people who don’t know a lot about what they are doing. Or a Holley that has been sit up, had a low quality kit installed in, or otherwise screwed with, like bad modifications. Ebelbrock carburetors are copy’s of the Carter carburetor designed in the 60's and used on production vehicles. They were designed to be cheap smooth, and didn’t need to be highly tunable, or precise. The big down side to the design is the fact that the front and back barrels have venturis and other characteristics that are non symmetrical, it makes it almost impossible to make a super precise mixture especially wide open. They are at their worse wide open. Holley’s were designed from the ground up for performance. Most designs have virtually identical barrels, and are almost infinitely tunable. They were not designed to be the least expensive to produce carb like the Carter design, but to be the best. Holley’s produce a more precise mixture, and even wide open still produce precise mixtures. Holley’s offer tunable vacuum secondary’s, or mechanical secondary’s with secondary accelerator pumps, the carter design is light years behind in this area. What this Holley design selection does is to allow a specific type carburetor, IE vacuum or mechanical secondary’s, and a huge range of sizes to give an engine what it needs. That and providing precise mixtures is the key to their success/power. Carter/edelbrock carbs are crude in comparison, and less expensive to produce, they are great on grocery getters, there is a small range of sizes, you basically get what they give you secondary actuation, non precise wide open mixture, and more. Carters do what they were designed to do, and they do it well, but they have severe limitations by design. If you go to a drag strip and look at winning competitive race cars they all use Holley’s, or Holley clones, because they are superior by design.
There is a lot of opinion when dealing with carbs, but if you stick with the facts you are better off. I can give you the name of 3 shops that claim quadrajet carbs are the best performance carbs when they build them, but you don’t see them winning any races. The street isn’t a race track, but the performance of a Holley still shines through. Holley’s are great on the street. Chevy chose them is the late 60's, on all of their hottest factory performance engines, for good reason. One last thing is I have taken Edelbrock carbs off that were tuned well, and bolted on Holley’s and have seen HUGE power increases. It isn’t that Edelbrock carbs are bad, they just don’t have the advantages of a carb like a Holley. OK, that is my sermon for this Sunday, let us all pray for the Edelbrock carbs. LOL, seriously If you are trying to make power Holley’s do it, are rock solid, and do it right. If you had a bad experience, buy a new one it should/will destroy any Edelbrock craving. I do love Edelbrock intakes, on their carbs they wanted to be different, and they are. I had better get out of here now.
Oh, you can pump through your old pump if you disconnect the wires. It will freewheel, and create a slight restriction. I don’t recommend it, but I have seen it done over and over. As the old pump turns it will produce electricity, the wires have to be taped. If you connect the wires it will virtually lock the pump and create an extreme restriction, keep them separate, and tape or heat shrink them. If you leave the old pump in use a strong electric pump mounted as near the fuel tank, and as low as possible. You asked about the feed line, it should be larger in diameter. Open both lines any turn on the key to a second to confirm, use a piece of hose on the line and put the end in a can, so you wont have gas everywhere. If you have any more questions at all, I am here to help. Good luck with it, have a great day, and Thanks for using Just Answer.
Holley's are great, I will set you up some links. I will get the links and post them here for you as soon as I gather them up, it wont be too long.
In my opinion, if you are going to rev above 5800 RPM's regularly, they are worth it. Otherwise a stock HEI coil works good. The HEI produces a really hot spark stock, but they start loosing it above 6K RPM's. Depending on your needs you might want to look into an MSD 6AL or similar MSD ignition control box, the CD (capacitive discharge) based ignitions are hard to beat at high RPM's. Now granted that high RPM window isn’t a place that you stay, or maybe even visit very often, and an engine will let you know if it needs more spark by how it runs, so you might want to run it, and if it acts up at high RPM's go hotter on the spark. Go over all of this and if you have any more questions at all, I am here to help. Good luck with it, have a great day, and Thanks for using Just Answer.
You need to be sure an earlier sending unit will fit the tank as far as the size. The EFI high pressure pump modules sending unit will work it is just the pump that is the problem. There are in tank pumps like GM used inside the tank on some carbureted applications that you might consider. Or you can just replace the internal pump with a straight piece of tubing, and use an external electric pump. I always like to use a sock type filter on the end of the new pickup tube. These sock filters were used for decades in carbureted vehicles, and slide right on standard tube sizes. They keep a lot of debris out of the fuel system. Good luck with it, have a great day, and Thanks for using Just Answer.
If I remember correctly the line size is 5/16 on that pickup tube when you pull the pump off in the tank. If you get a universal piece of tubing like a parts store sells in steel, they are normally preflared, just cut the ends off. Anyway get the next size larger and it should slide over the existing tube just fine. My favorite way to secure it to solder it, it is fool proof and permanent. Other options are to slide fuel line over the two pieces and clamp them, or use a gas resistant epoxy. Sliding the oversize tube over the existing tube makes it rigid where no other support is needed. Cars like an E and B body Mopars with a 426 Hemi, or 440 sixpac used a 3/8 fuel pickup filter sock. Otherwise a 3/8 sock can be tough to find.Fuel filter, your stock one will probably do, it is small and not meant for lower pressure. The Z car filter is carburetor friendly, huge so it holds a lot of debris before it causes a problem, and has a fine filter element, it is hard to beat. If your stock filter shows any sign of restriction issues, switch it out for the z car filter. Go over all of this and if you have any more questions at all, I am here to help. Good luck with it, have a great day, and Thanks for using Just Answer.
Just a super, super thin film of rtv is good insurance. Not necessary, anywhere but the corners, but if there is any micro defect in fit, the gasket, or one of the machined surfaces, the sealer can help prevent problems. Just don’t use any on the bottom of the carb, or the top of the carb gasket. More important than the torque is tighten it evenly, it is easy to break the carb base, if you get medieval with one or two nut's. Holley says 60 to 80 INCH pounds, in a crisscross pattern. Take your time here, I have seen so many get broken, it is easier than you think. Use studs in the intake and then nuts to secure the carb.
There is no real need for sealer, but you can use a little between the intake and gasket if you like, use none between the carb and the base gasket. A new Holley carb will come with a base gasket. The problem with ordering a base gasket it the shipping will cost twice what the gasket does. It is a good item to pick up locally. A Holley 108-10, 108-12, or 108-58 will do. Also Mr gasket makes good carburetor base gaskets too.
The tube sizes are metric, 5/16 is tight, but works, and 3/8 is a little loose and works fine. I would rather stretch to fit, as opposed to using loose fitting line and clamping. Either works still I like the tight fit. You have to remember we are just dealing with 10 to 14 PSI, simple hose clamps with good fuel line will hold over 100 PSI. Also the Z car filter is optional if you are not comfortable with the fit. You can opt for a universal filter that is to spec with your fuel line if you feel better with that type of setup. The z car filters flow enough fuel to make about 600 HP, after that they are too small then I use two in parallel, I personally love them, still your call. Also by running the 14 PSI to the front, then regulating it down just before the carb, you can get away with a smaller line and get the same flow, than if it was lower pressure all the way. Good luck with it, have a great day, and Thanks for using Just Answer.
Could you have gotten the polarity backwards when you powered it up, a brushed DC motor will run fine backwards, and it wouldn’t pump running backwards. Otherwise possibly the discharge hose might have blown off inside the tank. It seems like twilight zone stuff, but it is just got to be something basic, aggravating agreed, because it wont pump. So take a look at the polarity.
I like the K&N filters, if you don’t have to drive down dirt roads. The dirty little secret is all the high flow filters don’t do as good of a job filtering dust and dirt as the old school paper filters in extreme situations, like constant dirt road driving. Most people don’t need to deal with dirt roads, still it is nice to know this. As far as a filter for the valve cover, I have a link for you, it is valve cover gasket wonderland at K&N. Some universal filters have an optional opening in their base that can be connected to the valve cover, and allow filtered air to be drawn in by the valve cover, without a separate filter.
Lot or Q's are no problem, I appreciate the good ratings. I have been doing this so long It is just second nature for me. Back to the PCV system. You only need one filter on one valve cover, it actually works better that way. You basically are evacuating the crankcase of any gasses that get past the pistons and rings. A single vent on one valve cover lets in some fresh air, to help keep the air inside the engine from being stagnant with fumes. Applying vacuum to one side and letting filtered air in the other side provides a type of cross draft ventilation through the engine. Even with systems that are set up differently, if you introduce a little fresh air, and a little vacuum, it keeps it all cleared out.
Compression fittings would be a good choice. I just brought up solder, because it would be my go to for this modification. I thought of pros and cons of both setups, and I cant find fault with either. So with that in mind I would say use either method, whatever works best for you, and you will have a reliable setup
In a high vibration locations that are very thermally active (engine/trans) compression fittings with a compressed ferrule are pretty taboo, they have a bad reputation, but they are easy to use. Double flare is generally is technically noticeably better. Think of the number of times you see a double flare and then a compression/ferrule fitting in an automotive application. The twist is the gas tank gets away from all the vibrations of the engine and trans, so you should be able to get away with a compression/ferrule fitting.
Are you thinking about restrictors that go in the center of the intake gaskets, they are used there to decrease exhaust flow in the exhaust cross over on the intake.
The rear most port on each side, they are cooling system crossover ports. These ports, are not used on a 350 Chevy, as long as they are sealed you are good to go. I have seen the exhaust restrictors drop out and seat in the water cross over ports I am thinking that is what might have happened, because why restrict a port that doesn’t flow. Anyway beyond that I do like the rubber end gaskets, over a large bead of RTV, I use them any time I can. Both work, the rubber end gaskets have less of a chance of a problem. Mainly because they are already formed, the RTV can get deformed before it hardens, and leak.