i am trying to figure out which plug fit my alumunium heads they are of of a vette. when my mechinic put it back together he put the old 305 plugs back in.i took them out and they are carboned bad .so i went and got ac rapidfires for a 88 vette alum. heads.they are quit a bit longer from thread to thread.maybe the old plugs were to short and that would explain performance problem.g-tch said 15.22 96 mph in quarter.this is a 305 with heads mentioned already accel runners and intake,ported plenum,crappy 2.73 gear,roller rockers,(downfall stock chip)edelbrock control arms,panhard rod,strut bar,headers,gutted convertor,flowmasterexhuast.please tell me the right plugs and tell me bad performance was from the old plugs.sorry for long post

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[This message has been edited by bdiroc (edited June 27, 2001).]

 

The aluminum head plugs are a totally different deal than iron head plugs. I dont know the rapidfire #, but the regular AC Delco number is FR3LS.

 

thank you i will try and crossreference the #'s

 

acfr5ls
904
mr43lts
#8 in rapid fire

 

L98 "Corvette Aluminum" heads use a tapered seat 14mm thread with a 3/4" reach.

Try a slightly hotter plug if you foul up as you say. Don't go too hot, or you risk detonation.

Stay away from gimmick plugs...no rapid fires or Bosch Plus-4's etc etc. Go with a good quality standard plug design, and no platinums in our cars.

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86 Trans Am WS6 Black with tinted windows, ZZ4, Mini-ram, true duals, LT4 HotCam, AFR 195 heads.
***Too many other mods to mention***

"In the future, cities will become deserts,
roads will become battlefields, and the hope of mankind
will appear as a stranger" The Road Warrior

 

thanks for replys .put plugs in now she runns worse.just now checking fuel pressure,timing .remember dont buy edelbrock headers like me unless you want to change plugs with a wrench from top and bottom .i thought it was easy with factor stuff, butnow it suxs.i guess i will have to take air pump off so i have room,also i just burnt accell 300 racing sleeve wires that were $100. (now i now what all of you guys were talking about)thank god there lifetime warranty i will have to send them back the rest of life thanks brett