How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Mike S. Your Own Question
Mike S.
Mike S., Chevy Mechanic
Category: Chevy
Satisfied Customers: 6819
Experience:  ASE Certified Master Technician
20625509
Type Your Chevy Question Here...
Mike S. is online now
A new question is answered every 9 seconds

Hp chevy bb will only run @ 40 degree timing at idle machine

Customer Question

hp chevy bb will only run @ 40 degree timing at idle machine shop engine dont have any spec
Submitted: 1 year ago.
Category: Chevy
Expert:  Lou P. replied 1 year ago.

Hello. It sounds like the balancer is bad or inaccurate for the engine. Can you give me some backstory on what was done to the engine before this happened ?

Customer: replied 1 year ago.
new balancer ck tdc mark to tdc #1 piston
Expert:  Lou P. replied 1 year ago.

Ok , so why did you replace the balancer ? Because of this ? How did this occur ? New engine ? And where is your number 1 plug located at ? And are you sure you have the correct number one cylinder with your timing light ?

Customer: replied 1 year ago.
only thing that makes sense to me is timing chain off mark didnt build engine
Expert:  Lou P. replied 1 year ago.

That could very well be , that's why I asked more info on the engine

Expert:  Lou P. replied 1 year ago.

I suggest removing the spark plug for cylinder 1. Insert a long stick or 1/4" extension and crank the engine by hand until the extension stops moving to truly fint tdc and then see where the timing mark is at.

Customer: replied 1 year ago.
allready did that 0 the #1 piston is tdc this aint my first rodeo
Customer: replied 1 year ago.
even if the cam is degreed it still shoud not hae that much advance
Expert:  Lou P. replied 1 year ago.

Hey man I am just trying to help you out. Why it would need to be 40 advanced to run we both know ain't right. I will opt out and see if another expert can help. I'm not sure where to go from here. My apologies. Lou

Expert:  Gary replied 1 year ago.

new expert here

a few questions for you when set to 40 degree's the engine will idle good and drive and perform just fine and shut off without dieseling and crank right back up no problem ? no pinging ?

Customer: replied 1 year ago.
new engine not driven starts rough idle no run on when shut off restarts when warm
Expert:  Gary replied 1 year ago.

starts rough like the timing is too far advanced ?

and when set to 0 it will not run at all ?

Customer: replied 1 year ago.
no
Expert:  Gary replied 1 year ago.

it really bothers me you need it at 40 degrees for it to run

the balancer is correct and the distributor is set in correctly

are you 100 % sure the valve are adjusted correctly ? ( i just want to be sure we are not compensating with the timing for an issue like tight valves )

what type distributor are you running ?

Customer: replied 1 year ago.
msd pro billet with factory installed heavy springs no back fire dont think valves to tight
Expert:  Gary replied 1 year ago.

double check the valves if they are good do you have any access to a basic HEI distributor you can put in this engine and see if it will run when set at 0 degrees ?

Customer: replied 1 year ago.
Customer: replied 1 year ago.
whats your theory on distributor
Expert:  Gary replied 1 year ago.

you have tried another distributor and it will run at 0 and allow you to set the timing and it will start up ?

it is either defective or somehow is retarding the timing when it should not be as you need to advance that one 40 degrees for it to run

is it tricked out somehow ? brand new ? used ?

Customer: replied 1 year ago.
have not switched dist yet this is a mystery engine from some machine shop think chain off marks
Expert:  Gary replied 1 year ago.

i would try to switch out a basic HEI and see what it does before you pull the timing cover

if its fine with the HEI the distributor is the problem

if it still does the same thing and the valve's are adjusted correctly then the chain has to be off then pull the cover and see if it has a cam sprocket with different marks on it v/s the stock marks

if so either change it back to a stock double roller or try to set this one back to stock marks

Customer: replied 1 year ago.
thanks going on vacation get back with you next week
Expert:  Gary replied 1 year ago.

sure thing

you can always get me back through this post for FREE anytime with any follow up with this question anytime even after you rate us here at Justanswer !

Customer: replied 1 year ago.
i disagree with dist theory spark delivered 40 degree before piston comes up to tdc time light dont lie
Expert:  Gary replied 1 year ago.

40 degrees does not lie correct you don't have to agree or disagree with the theory at all either way

bot***** *****ne is this engine needs 40 degrees for it to run either physically or from the distributor itself

is it actually needing 40 degrees to run or is the distributor itself doing this ? we do not know

try another distributor to be sure

you are in the process of eliminating things at this point

if an HEI put in the engine and it does the same thing then pull the timing cover

Customer: replied 1 year ago.
back from vacation switched dist with stock gm hei pulled ft cover marks aligned when 1cyl tdc ck valve adjustment half turn after push rod play removed still idles best at 40 degress but still runs rough no back fire and no starter kick back please help thanks
Expert:  Gary replied 1 year ago.

at this point with an HEI only running best at 40 degree's you need to pull the timing cover and see if the timing chain is set degree'd or not

Customer: replied 1 year ago.
already pulled cover 1cyl tdc marks aligined
Expert:  Gary replied 1 year ago.

lets see if any other experts have any ideas

another expert will reply back to you

Customer: replied 1 year ago.
also did compression ck between 125-150 i know rings have not seated yet but seems low to me
Expert:  Mike S. replied 1 year ago.

is this a timing light that has the adjustment dial on it to measure advance?

Customer: replied 1 year ago.
no old school t light
Expert:  Mike S. replied 1 year ago.

How did you set the distributor in?

Expert:  Mike S. replied 1 year ago.

I think you are a tooth off.

Customer: replied 1 year ago.
i can move dist from 0 to 60 degress
Expert:  Mike S. replied 1 year ago.

60 degrees at idle? There is only 180 degrees total and if you divide that by 8 for each cylinder that only leaves 22.5 degrees before the spark from the rotor would be jumping to the next distributor cap tower. That is why I asked you how you set the distributor in?

Customer: replied 1 year ago.
it will idle at 30 - 60 retard past 30 engine stalls
Expert:  Mike S. replied 1 year ago.

Try it this way. Remove the distributor. Turn the engine over and find when the #1 piston is coming up on tdc compression stroke again, then set the timing mark on the damper and timing mark at 0. Then set the distributor down in until it meshes with the cam gear and note where the #1 is on the cap and point it toward either the #1 cylinder like I like to do or point it straight forward like some other people like to do, then pull the distributor back out until the gear is free from the camshaft gear, so you can now turn the distributor until the rotor now faces just before where #1 was on the cap. Remember as you drop the distributor in the rotor will move as the gears mesh so it may take a few times. Then reach down and turn the oil pump with either a screwdriver or a special tool so the distributor can be dropped in exactly where you want it.

Then once the oil pump is turned the distributor will drop completely in and the rotor will be facing #1 and also the armature will be ready to fire also. Most people forget that last step.

Expert:  Mike S. replied 1 year ago.

Here is what I am talking about.

Expert:  Mike S. replied 1 year ago.

Then static time the engine in order to get it started then time it with the timing light.

Expert:  Mike S. replied 1 year ago.

To static time,

First of all you will need a test plug.

Get the #1 piston up on TDC on its compression stroke and align up with the timing mark, whatever base timing should be. Now remove the distributor cap and make sure the rotor is facing toward or at least close to #1 tower on the cap. Put cap back on. Make a test plug and remove the spark plug wire from #1 spark plug and insert the test plug into the end of the wire and ground the clip. Loosen the distributor hold-down bolt just enough so you can turn the distributor by hand. Now turn the ignition key to run, watch the test spark plug and quickly turn the distributor back and forth across where the rotor was facing #1 on the cap tower and look for a spark. Once you find where it sparks, stop. Tighten down the distributor a little, start the engine then time the engine.

Expert:  Mike S. replied 1 year ago.

Test plug

Expert:  Mike S. replied 1 year ago.

You can make a test plug with a new spark plug and some wire, a mini hose clamp and an alligator clip. First open the spark plug gap to around 0.075” and strip both ends of a 16 gauge wire about 4 foot in length. Attach the mini hose clamp around the threads of the spark plug cause that is a ground and secure it with the mini hose clamp with the bare wire end in between to make a good connection. Next, take the other end of wire and secure to an alligator clip.

Now, you have a test plug. Remove any spark plug boot you want and insert your test plug onto the spark plug wire end you just pulled off and ground the alligator clip. Lay the spark plug in some shade somewhere under that hood and then crank the engine and look for spark. It should crackle with sound and should be blue but red is ok, orange is a little weak. If it can jump that 0.075” gap you should have no problem igniting an engine.

Expert:  Mike S. replied 1 year ago.

There, that should do it.

Customer: replied 1 year ago.
that makes no sense to me 2 different dist engine runs can move dist to timing is 0 or move 60
Customer: replied 1 year ago.
nothing wrong with 2 dist same result
Expert:  Mike S. replied 1 year ago.

What makes no sense, that the distributor can be in wrong?

I asked you how you set it in and you didn't answer.

I assumed then you didn't know how to set one in properly.

Expert:  Mike S. replied 1 year ago.

When you removed the one distributor and set the other one in, I know it didn't just drop right in. You had to turn the oil pump.

I asked you how you dropped it in.

Expert:  Mike S. replied 1 year ago.

Ok, let's try another question.

I don't recall you ever saying what year this engine was

Is there a vacuum advance? If so, do you have the vacuum line going to ported or non-ported vacuum?

In other words, is there vacuum advance at idle or not? If not, try vacuum advance at idle so you can set the base timing back some.

If this isn't the case, I still think you need to either set the distributor down in correctly or at least tell me exactly how you did set it down so I know not to suspect that anymore.

Customer: replied 1 year ago.
had to move oil pump rod dist seated flush with intake do you have the story on this engine from the other 2 mech that gave up
Customer: replied 1 year ago.
never seen this in 30 yrs of working on engines
Customer: replied 1 year ago.
6in of vacum compression 130-150 pro comp alum heads 11-1 compression says 600 horse
Customer: replied 1 year ago.
1st dist msd pro billet mech advance 2nd dist gm factory hei vac not hooked up
Expert:  Mike S. replied 1 year ago.

Yes, I read all of those other conversations.

Here is what I think is going on. You are a tooth off on setting the distributor in and what this is causing is the rotor may be facing #1 but the armature isn't facing where it is firing, so it is so far advanced it is firing at the next tower on the cap.

6 inches of vacuum where? At the intake manifold?

6 inches is really low.

Hook up the vacuum advance for the distributor to vacuum advance at idle.

Expert:  Mike S. replied 1 year ago.

No vacuum advance? So this has a computer?

Expert:  Mike S. replied 1 year ago.

Is this fuel injected? What year is this engine or at least close to what year?

Customer: replied 1 year ago.
this is a hp 70s 454 block 850 demon carb bore and stroked to 500 something
Expert:  Mike S. replied 1 year ago.

try this. Move all of the spark plug wires on the cap one turn retarded and see what the timing mark is at now when it idles the best.

Customer: replied 1 year ago.
moving the wires or turning dist create the same result
Customer: replied 1 year ago.
the factory hei came out of a well running hp small block and cap was marked with firing order

Related Chevy Questions