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Question

HI I NEED SOME INFORMATION FROM YOU ALL ABOUT SHIMING SPARK PLUGS. ON A SMALL BLOCK CHEVY,DOME PISTONS,6.00 RODS AND A.F.R. 23 DEGREE HEADS 65 CC CHAMBERS.AND A .060 THICK HEAD GASKET. ON THE EVEN SIDE ONE PLUG WAS SMASHED, ON THE ODD SIDE THREE WERE SMASHED. I GOT A SHIM KIT AND I HAVE PUT THE THICKEST SHIM ON AND THE NEXT THICKEST ON PLUS THE WASHER THAT THE PLUS COME WITH. PLEASE GIVE ME SOME INFORMATION ON HOW MUCH I SHOULD SHIM THE SPARK PLUGS PLEASE. I AM GOING TO BREAK IN THE ENGINE TOMMOROW.

     &nb sp;                                                      THANK YOU,
       & nbsp;                                                                 SCOTIE

Submitted: 93 days and 16 hours ago.
Category: Chevy
Value: $13
Status: CLOSED
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Posted by Jan Andersson 93 days and 16 hours ago.

Answer


First off, I don't know the engine or this parts combo.

I thought I would offer my $.02 worth of generic advice.

You need to make sure you have teh correct lenght sparkplugs for your heads. If teh threads are proper lenght, then teh center electrodes come in different lenghts too, some protrude more than others. It has to do with the heat range of the plug as well as design.

If your plugs are too long at the threaded part, meaning the threads are exposed in the combustion chamber, it's sort of ok to shim them.. not the best way to solve it but I suppose it works.

if the center electrode is what makes it sit too deep in the chamber and shimming would leave spark plug HOLE threads exposed in the chamber, don't do it. You would have reduced support for the plug and the exposed threads would collect carbon deposits, which in turn would promote pinging/detonation.


So.. keep the threads even on the combustion side. Any exposed threads there, be it either the plug or the hole, are bad.

I will opt out and let someone else continue, hopefully someone here knows your engine combo.

93 days and 16 hours ago.

Reply

WHAT INFORMATION DO YOU NEED TO KNOW?

93 days and 16 hours ago.

Reply

SMALL BLOCK CHEVY PROBE DOME PISTONS, 6.00 RODS AIR FLOW RESHEARCH HEADS 23 DEGREE 65 CC CHAMBERS. THE PISTONS ARE HITTING THE SPARK PLUGS. ON THE EVEN SIDE 1 PLUG WAS HIT, ON THE ODD SIDE 3 WERE HIT.I AM USING THE SPARK PLUGS THAT THE HEAD MANUFACTURE CALLS FOR. SO I NEED TO KNOW HOW MUCH TO SHIM THEM SO THE PLUGS DO NOT HIT THE PISTONS.

 

SCOTIE

Posted by GNwrench 93 days and 6 hours ago.

Info Request

how thick is the biggest shim you said you have installed and they still hit? what brand and number spark plugs are you running?

93 days and 2 hours ago.

Reply

THICKEST SHIM IS 1.52 SPARK PLUG # A/C 41-629. I INDEXED A COUPLE OF PLUGS LATE LAST NIGHT, WILL THAT HELP ME WITH MY PROBLEM? ON THE TWO I INDEXWD LAST NIGHT THE THICKEST SHIM WOULD NOT ALLOW ME TO INDEX THEM CORRECTLY.

 

SCOTIE

Posted by GNwrench 93 days and 2 hours ago.

Info Request

it all depends how far in the plug was to be hitting how crunched up where the tips? or did it just bend over the tip on the end?now you built this engine?or an engine builder? and the head manufactuer told you what plugs to use was he informed of the probe domes and the 6 inch rods?ive indexed plugs before but indexing is to line up the opening of the tip with the intake valve or where ever the engine guy told you to line them up to..you usualy do not index plugs for clearence issues..

93 days and 1 hours ago.

Reply

YES I BUILD THE ENGINE AND I HAVE NEVER HAD THIS PROBLEM. AND YES THE PISTONS SMASHED THE ELECTRODE BAD!!! IT SMASHED THE ELECTRODE FLAT. YES I AM USING THE PLUGS THAT AIR FLOW RESHEARCH SHOWS IN THERE TECH SHEET. NO THE HEAD COMPANY WAS NOT INFORMED ABOUT THE PISTONS. AND YES I PUT 6.00 RODS IN IT. O.K.SINCE INDEXING WILL NOT HELP ME, WHAT SHOULD I DO TO KEEP THE PLUGS FROM HITTING THE PISTONS. NOT ALL THE PLUGS WERE HIT, 1 ON THE EVEN SIDE AND 3 ON THE ODD SIDE. I PURCHASED SOME SPARK PLUG SHIMS TO USE. SO TELL ME WHAT I CAN DO. I AM LOST, I HAVE NEVER HAD THIS PROBLEM BEFORE WITH ANY OF MY ENGINES. THE CHAMBERS ON THE HEADS ARE 65 CC.

93 days and 1 hours ago.

Reply

I AM USING .060 THICK HEAD GASKETS AND THE HEADS ARE 23 DEGREE HEADS ALUM.

Posted by GNwrench 93 days and 1 hours ago.

Info Request

how long are the plugs you are putting in that hit measure from the base of where the plug seats to the head to the tip?

93 days and 1 hours ago.

Reply

18.97 THAT IS FROM THE BASE OF THE PLUG WHERE THE WASHER WOULD GO TO WHERE THE ELECTRODE CONNECTS TO THE PLUG.

93 days and 1 hours ago.

Reply

I HAVE NOT TRYED ANY SHIMS YET UNTIL I KNOW WHAT SHIM I SHOULD USE. PROBABLY THE THICKEST SHIM.

93 days and 1 hours ago.

Reply

I FORGOT TO TELL YOU THESE HEADS ARE ANGLE PLUG HEADS IF THAT MAKES A DIFFERENCE

93 days and 1 hours ago.

Reply

ARE YOU STILL WITH ME?

Posted by GNwrench 93 days and 1 hours ago.

Info Request

i mean the lengh of from the tip to where the threads end at the base of the plug including the threads..how long is it..like 1 inch..ect....yes im with you im making dam sure we get this right we dont want to do any futher damage ok ?

93 days ago.

Reply

SIR, YES IT IS RIGHT AT 1 INCH I HAVE .045 PLUG GAP TOO. AND THANK YOU FOR YOUR HELP THUS FAR. I DO NOT WANT TO BE A PAIN IN THE NECK ON THIS ISSUE BUT I DO NOT KNOW WHAT TO DO.

 

SCOTIE

93 days ago.

Reply

THE ENGINE TURNS OVER REAL NICE BY HAND. SO NO VALVE PROBLEMS. JUST THE PLUGS ARE HITTING THE PISTONS. AND NOT ALL THE PLUGS ARE BEING HIT. IT IS WEIRD.

Posted by GNwrench 93 days ago.

Info Request

ok now take out the plugs now go to the parts store you need to look at a set of autolite 3923 and see if those measure up @1/5 inch....if not yneed a spark plug with @ 1/2 reach so it will not hit the piston top and you will be able to index them..you follow me?do you undertsand what i told you to do..and you have to do this or you will hurt the engine..

93 days ago.

Reply

SIR,

YES I UNDERSTAND. I NEED A PLUG THAT HAS A SHORTER THREADED AREA. WHAT PT.# ARE THE 1/2 REACH? AND IF YOU WERE ME WHAT PLUG WOULD YOU TRY FIRST. AND I UNDERSTAND THAT I CAN INDEX THESE PLUGS. WHERE SHOULD THE TIP OF THE ELECTRODE BE POINTING WHEN I INDEX THESE PLUGS YOU SUGGESTED?

YES I HAVE DONE ENGOUGH ENGINES TO KNOW THAT I HAD A MAJOR ISSUE, I JUST DID NOT KNOW HOW TO SOLVE THE ISSUE. THE HIGH DOME A LONG WITH THE TIGHT CHAMBERS ON THE HEAD HAS CAUSED THIS PROBLEM.

Posted by GNwrench 93 days ago.

Answer

the tip opening should be point at the intake valve..autolight 3923...try that first and measure them or bring one of your old plugs to physically see if its shorter..NGK are good..and if the parts guy there can find a a/c delco with the reach of @ 1/2 inch it should be fine

93 days ago.

Reply

WHAT I MEAN BY INDEXING IS WHERE SHOULD THE OPEN END OF THE ELECTRODE BE POINTING TO INDEX THEM PROPERLY?

93 days ago.

Reply

SHOULD THE TIP OF THE ELECTRODE BE FACING UP OR DOWN TOWARDS THE INTAKE SIDE?

Posted by GNwrench 92 days and 23 hours ago.

Info Request

the open end should be aimed at where the intake valve is in the head point the opening so that it pointing at the valve visually look and see where it would seat in the head and then point the opening there

92 days and 23 hours ago.

Reply

ABOUT TWO A CLOCK AREA? AND HOW DO I PAY YOU FOR YOUR KIND AND GOOD SERVICE TO ME. I THANK YOU FOR STAYING WITH ME AND GETTING TO THE BOTTOM OF THIS ISSUE.

 

SCOTIE

Posted by GNwrench 92 days and 23 hours ago.

Answer

just click accept.yes 2 or close to 2 oclock...any time let me know how it runs..

92 days and 23 hours ago.

Reply

BOY, A HALF INCH FROM THE TIP OF THE ELECTRODE TO THE BASE AO THE PLUG DOSE NOT LEAVE ME MANY THREADS AT ALL!! IS THAT O.K.?

Posted by GNwrench 92 days and 23 hours ago.

Answer

when you look at them there is still almost the same amount of threads its just the tip and base are a little smaller..yes they will fit fine and there is enough threads

92 days and 23 hours ago.

Reply

I AM RUNNING A COMPRESSION RATIO OF 12.0 I DO NOT WANT TO BLOW A PLUG OUT AND TEAR UP THE THREADS IN THE ALUM. HEADS

Accepted Answer

i know..the amount of threads on the shorter plug will fill all those threads up..dont worry we are not gonna let you ruin your heads..or run the lil peanut size plugs..you will be fine

Picture
Expert: GNwrench
Pos. Feedback: 99.7 %
Accepts: 
Answered: 8/22/2009

Chevy Technician

15 years GM master tech

92 days and 23 hours ago.

Reply

I HAVE PAID YOU FOR YOUR GREAT SERVICE TO ME. I THANK YOU SO VERY MUCH FOR STAYING WITH ME ON THIS ISSUE AND HELPING GET TO THE BOTTOM OF THIS PROBLEM. I WILL MOST CERTAINLY USE YOU AGAIN!!

 

THANK YOU VERY MUCH,

SCOTIE

Posted by GNwrench 92 days and 23 hours ago.

Info Request

anytime look me up by name..and drop me a line threw this post on how it runs..i love the race engines..LOL

92 days and 22 hours ago.

Reply

I JUST GOT BACK FROM THE PARTS STORE AND THE ATTENDENT WENT THROUGHT ALL THE PLUGS THEY HAD, HOWEVER THE PART NUMBERS YOU GAVE ME WERE THE SAME LENGTH AS THE ONES I HAD. SO AFTER A LOT OF EFFORT ON THE PARTS GUY REALLY TRYING HARD TO HELP ME WE CAME UP WITH A PLUG THAT YOU SAID WOULD WORK. IT IS THE 1/2 INCH LENGHT PLUG YOU MENTIONED, BUT IT WAS A AUTOLITE PART NUMBER 85 BUT IT TOOK A 13/16 SCOKET TO PUT IT ON. AND IT WAS A LITTLE HOTTER PLUG. INSTEAD OF THE 5/8. BUT ACCORDING TO WHAT YOU HAD TOLD ME ABOUT THE 1/2 INCH LONG PLUG, THE AUTOLITE 85 ARE RIGHT ON THE MONEY OF BEING 1/2 INCH LONG FROM THE BASE OF THE PLUG TO THE TIP OF THE ELECTRODE. I THOUGHT YOU MIGHT WANT TO KNOW THIS. AND IF YOU NEED TO TELL ME SOMETHING I DO NOT KNOW, PLEASE TELL ME. AND I STILL THANK YOU BECAUSE YOU PUT ME ON TRACK TO GIVE ME THE INFORMATION SO I COULD LOOK FOR WHAT I NEEDED, PLUS A GREAT EFFORT FROM THE PARTS GUY.

THANKS,

SCOTIE

Posted by GNwrench 92 days and 22 hours ago.

Info Request

ok well i would prefer a 5/8 size socket plug but..it should be ok for you to break in the engine..now i would call the head guy monday and tell him about the clearence problem and ask him what he recomends for a smaller height plug..

92 days and 22 hours ago.

Reply

YES, I WOULD RATHER HAVE A 5/8 SOCKET TOO. WHAT DO YOU MEAN BY A SMALLER HEIGHT?

92 days and 22 hours ago.

Reply

WHEN I INDEX THESE PLUGS SHOULD I TAKE OFF THE ORIGINAL WASHER THAT COMES ON THE PLUG OR SHOULD I TAKE IT OFF?

Posted by GNwrench 92 days and 22 hours ago.

Info Request

take it off

92 days and 21 hours ago.

Reply

O.K. I WILL THANK YOU. ANY OTHER ADVICE YOU MIGHT BE ABLE TO TELL ME? WHAT DID YOU MEAN BY A SMALLER HEIGHT?

Posted by GNwrench 92 days and 21 hours ago.

Info Request

i mean reach sorry mybad..been a long day...LOL..please let me know how it runs

92 days and 21 hours ago.

Reply

SORRY, BUT I STILL DO NOT UNDERSTAND ABOUT THE REACH? THE 1/2 INCH THREAD IS WHAT YOU RECOMENDED,RIGHT. WITH THE NEW PLUGS I HAVE I KNOW THEY WILL CLEAR THE PISTONS.

Posted by GNwrench 92 days and 21 hours ago.

Info Request

the reach of the plug is the distance from the base to the tip..your plugs that hit had almost 7/8 to 1 inch of REACH (the amount the plugs reach into the cylinder) we had you go to a smaller REACH of @ 1/2 so the reach would be less protuding into the cylinder to stop interference..follow me now?

92 days and 21 hours ago.

Reply

WITH LESS REACH WHAT WILL THAT DO OTHER THAN CLEAR MY PISTONS? WHAT IS THE DISADVANTAGE OF LESS REACH?

Posted by GNwrench 92 days and 21 hours ago.

Info Request

way too much less reach the plug when fire will be to far away..but the reach you have now will be fine

92 days and 21 hours ago.

Reply

O.K. I SEE. WITH THESE VERY HIGH DOME PISTONS AND A TIGHT COMBUSTION CHAMBER AND A LOW BLOCK DECK HEIGHT YOU THINK I WILL BE O.K. I THINK FROM WHAT YOU HAVE TOLD ME THE PLUS I GOT THE 1/2 LONG IS THE ONLY CHOICE I HAVE. WHAT DO YOU THINK?

Posted by GNwrench 92 days and 21 hours ago.

Info Request

i think the reach is fine like i said its fine to break it in..but i would call the head guy and ask him what he recomends to run monday

92 days and 21 hours ago.

Reply

I HAVE DONE SMALL BLOCK CHEVY'S WITH 600 H.P. TO 764 H.P. AND HAVE NEVER RAN INTO PLUGS HITTING THE PISTONS. SO I WAS JUST BLOWN AWAY WHEN THIS LITTLE 550 H.P. ENGINE STARTED HITTING THE SPARK PLUGS.I STILL DO NOT KNOW REALLY WHAT I DID DIFFERENT ON THE OTHER ENGINES I HAVE DONE UNLESS I HAVE USED HEADS WITH A LARGER COMBUSTION CHAMBER.

Posted by GNwrench 92 days and 21 hours ago.

Info Request

i bet that is it..but no worrys break it in with this plug..then call the head guy monday..you should be fine

92 days and 21 hours ago.

Reply

WELL AS FAR AS PLUG REACH , I REALLY DO NOT HAVE ANY OPTIONS, ALL THE OTHER PLUGS AT THE PART STORES WERE ALL TO LONG ON REACH.

Posted by GNwrench 92 days and 21 hours ago.

Info Request

right just check with the head guy to makesure the heat range is good for it..they do sell the reach you need in high perfromace plugs with differnt heat ranges thats why i would check with guy and make sure its the heat range he wants

92 days and 21 hours ago.

Reply

I AM THINKING THAT I WILL HAVE TO USE THESE 1/2 INCH PLUGS ALL THE TIME, BECAUSE ALL THE OTHER PLUGS WERE JUST WAY TO LONG. AS LONG AS THEY CLEAR THE PISTONS THEY SHOULD WOULD BE FINE SHOULD THEY?

92 days and 21 hours ago.

Reply

SO YOU ARE MORE CONCERNED ABOUT THE HEAT RANGE MORE THAN ANYTHING?

Posted by GNwrench 92 days and 21 hours ago.

Info Request

yes it is just the heat range i would ask the head guy about they make differnt heat ranges in the 1/2 sparkplug reach..thats my only thing that the head guy has to answer for you..thats all..but the plugs you have right now will be fine to break it in..

92 days and 21 hours ago.

Reply

WELL THE PLUGS THAT I GOT TODAY ARE 1 HOTTER THAN STOCK. AND WITH ALL THE COMPRESSION I WOULD THINK THAT WOULD BE O.K. BEING IT IS GOING TO BE A STREET ENGINE FOR A CUSTOMER OF MINE IN CANADA. WHAT DO YOU THINK. HE IS GOING TO HAVE TO RUN AS HIGH OCTANE GAS AS HE CAN GET 110 PLUS WOULD BE NICE. AND HE SAID HE COULD GET THAT GAS. I TELL MY STREET CAR CUSTOMERS THAT THAT WANT OVER KILL FOR A STREET CAR ENGINE TO GET THERE GAS FROM THERE LOCAL AIRPORT.

Posted by GNwrench 92 days and 21 hours ago.

Info Request

that sounds good..just get them plugs in and fire it up..LOL

92 days and 20 hours ago.

Reply

SO YOU THINK I AM O.K. WITH THESE PLUGS? AND THE CUSTOMER RUNNING A HIGH OCTANE GAS. IT IS A STREET CAR, HE SAYS HE DOSE NOT DRIVE IT VERY MUCH. JUST SOMETINES ON THE WEEKENDS.

 

92 days and 20 hours ago.

Reply

THE PLUGS THAT AIR FLOW RESHEARCH CALL FOR FOR THE STREET WHEN I AM BREAKING IN A ENGINE, WHEN I TAKE THE PLUGS OUT THEY ARE BLACK COLOR AND A LITTLE WET SO I WOULD THINK 1 HOTTER PLUG MIGHT JUST BE A GOOD DEAL.

Posted by GNwrench 92 days and 20 hours ago.

Info Request

yeh burn it off better

92 days and 20 hours ago.

Reply

O.K. THANK YOU SO VERY,VERY MUCH!!!!!!!!!!!!!!!1

Posted by GNwrench 92 days and 20 hours ago.

Info Request

ok

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