I got the spark plugs that were suggested by Edelbrock for the Performer heads and they keep backing out after a while. Especially if I rev up to about 5500+rpms... which happens every damn time I race! I get about 1 or 2 that seem to back out so they rattle around in the hole...not necessarily in any particular cylinder either. I tighten them pretty tightly and they eventually back out... what gives?!? I'm about ready to use some red loc-tite!

Lately I've been getting rather fed up with my Edelbrock stuff...

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1984 z28 w/ a 357 cu in. monster engine which is looking like the posterchild for Edelbrock with the exception of the Holley 750vac... all the suspension stuff... 9-bolt posi disk is in...

-=ICON Motorsports=-

 

My first instinct was to say the different metals expand at a different rate but it seems that it would take it a while to do this. Maybe a month or so of heating up and cooling down.

Have you checked to see if the threads are alright and not stripped a little? If everything looks alright and it still does this try some loc-tite like you said. couldn't hurt.

 

you should definetly put some anti-sieze on the threads, I'm sure those are aluminum heads.

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'86 IROC 5-speed
305 LG4
edelbrock performer rpm intake
edelbrock 600 cfm carb
msd pro billet hei distributer
'95 3.23 rearend
hotchkis rear suspension
PST front polygraphite suspension

 

Edelbrock sucks.

With that said...

Thats probably the problem right there. What kinda plugs are they telling you to use?

 

No other comment neccesary



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"American made baby. 100% American iron. The muscle among the masses. My hero. Yep, you can take your ergonomically designed, space age, computer controlled, 4 door, cup holding map lighted split double wishbone split fold down retractable cargo covered moon roof piece of transportation and keep it. For I have felt the thunder. And I know the difference!"
JSP Motorsports
ICON Motorsports

 

Yes they are aluminum heads... I was only joking about the loc-tite... and Jester I'm not pulling them and going with another brand

With that said, I'll have to look tonight on a plug to get the exact name, but it is a RC Champion plug I thing... Like RY 134 or something with 2 metal washers on it. I have them gapped at 0.40".

It mainly happens after I do a high RPM run on the motor...

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1984 z28 w/ a 357 cu in. monster engine which is looking like the posterchild for Edelbrock with the exception of the Holley 750vac... all the suspension stuff... 9-bolt posi disk is in...

-=ICON Motorsports=-

 

R what? Champion??? Yuck. At least it seems they are gasketed.

Try a different brand, and see if you can measure the thread length while you are in there so maybe I can tell you if the common vette plugs will work or not. I cant think of any good reason plugs would back out, doesnt make much sense.

 

The only things I can come up with are the static compression is very high and/or someone made a suggestion that the two metals expand/contract at different rates... I can only imagine what will happen when I do a 125 shot for the first time! I foresee all 8 plugs shooting out of the block by the end of the 1/4

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1984 z28 w/ a 357 cu in. monster engine which is looking like the posterchild for Edelbrock with the exception of the Holley 750vac... all the suspension stuff... 9-bolt posi disk is in...

-=ICON Motorsports=-

 

High compression? Materials?

I have vette aluminum heads on a car running 10.3:1 that cranks 195psi when I checked it two weeks ago, and it doesnt back out the plugs. Something else is going on.

Just curious, are the spark plug holes heli-coiled?

 

I kind of counted "materials" out because it happens after a run usually. The holes are the stock holes that came on the heads from the box to my engine.