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Discussion Starter · #1 ·
just went to put the plugs in on my afr 305 bbc chevy heads and its a no go. Is there a weird thread on these heads, as far as i knew any bbc, sbc, etc. spark plug would atleast thread in.
 

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camaropwr,

I had no trouble with my 315 cnc heads. AFAIK, they use .750" reach, 5/8" hex head gasketed plugs, along with a little anti-sieze on the threads. Do all the cylinders have this problem?

John
 

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Discussion Starter · #6 ·
i originally tried the ngk v power 7 out of my old heads. it looks like the threads in the heads are messud up. all the threads looked good, so i never figured it would be a problem. heads are on the motor right now, i might try to chase one of them and see how hard or easily the chaser goes down.
 

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pack the flutes of the chaser with grease, it will help pick up the shavings.

Are these heads new?
 

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Discussion Starter · #8 ·
yes there are new, i ran the chaser down all the holes(with grease), and it looks like i caught all the alluminum. i opened the exhaust valve on each cylinder and blew air into the cylinder and out the spark plug hole. it looks like they had a bad tap or atleast a bug on it, when they tapped these. anyways, the chaser cleaned the heads up, so it looks like i avoided a small tragedy. im guessin that if a little chip of aluminum made it into the cylinder, it probably wouldn't hurt anytning being softer than the rings and cylinder wall? lesson here, definatley run a spark plug down each hole before bolting them on.
 

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Crank the engine over about a dozen times with ALL the plugs out before you continue. Aluminum chips will blow out the holes. You leave out the 8 plugs to stop chips from blowing into the intake and other cylinders and becoming trapped.

Harry P Hunter
 

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i feel your pain-years ago i learned to test fit plugs in heads, esp. alumn. b4 install-i had to pull the headers to fix the one i had trouble with
 
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