Re: Raising compression on a 318
[Re: derekeh]
#176908
12/28/08 02:09 AM
12/28/08 02:09 AM
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Joined: Jan 2003
Posts: 2,001
s. e. pa.
calrobb2000
top fuel
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top fuel
Joined: Jan 2003
Posts: 2,001
s. e. pa.
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hi yes definatly go to the 302 heads and shave at least .020 off , more than .020 and you will also have to cut the intake face also . use the thinest head gasket you an find. usig taller pistons would also be good . 
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Re: Raising compression on a 318
[Re: derekeh]
#176914
12/28/08 12:04 PM
12/28/08 12:04 PM
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Joined: Nov 2003
Posts: 36,041
Lincoln Nebraska
RapidRobert
Circle Track
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Circle Track
Joined: Nov 2003
Posts: 36,041
Lincoln Nebraska
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If you do end up altering the short block & ch pistons make your selection(piston/gasket/heads) which will give you proper quench if not as said thinner gaskets/302 heads(or magnums) is about all you can do & you might adv the cam. I'm in the same position my 360 build is .110" in the hole so I might continue to look for a 3.79 crank or a 4" er if the pistons will stand enough milling but thats not looking too promising or maybe a custom cometic head(& intake) gasket(s)
live every 24 hour block of time like it's your last day on earth
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Re: Raising compression on a 318
[Re: dulcich]
#176916
12/29/08 09:12 AM
12/29/08 09:12 AM
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Joined: Jan 2003
Posts: 16,123
Grand Haven, MI
patrick
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 16,123
Grand Haven, MI
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Quote:
With the 302 heads and .024 gaskets you will be about 8.8:1.
I wouldn't spend the coin on rebuilding another set of heads, and would just run it as-is. Even with this set-up the pistons are always going to be a mile down in the hole.
Put headers, small cam, and two-plane intake on it and don't worry about the compression if you can't swap the pistons for now. Finding the heads and getting them rebuilt and swapped is way, way, more work and time and money than swapping pistons, and the 302's aren't any good for flow without a lot of port work and bigger valves anyway.
The best thing to do is re-piston and then add some good heads as time and money allows.
-dulcich
pistons to use would be KB167's...some other options would be to tear the motor down and get the block decked about .050 or so....
another option would be to get some enginequest 318B magnum style heads. they have about 5cc smaller chambers than the open chamber 318 heads, and with the thin head gasket should put you at 8.5-8.8:1.....you can get a set of new heads assembled with springs good for .5" lift for about $650/pr, which is a better deal than rebuilding some 302's...
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Re: Raising compression on a 318
[Re: derekeh]
#176920
12/30/08 09:06 AM
12/30/08 09:06 AM
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Joined: Jan 2003
Posts: 16,123
Grand Haven, MI
patrick
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 16,123
Grand Haven, MI
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Quote:
Ill probably just leave the engine alone then. Someone just gave me the 302 heads and I was looking for a cheap way to get the compression up. My idea was a home porting job on the heads and getting bigger valves put in. But if its not worth doing Ill just leave the engine as is. It has a bigger than stock cam but Ive been unable to find out what kind it is 
well, the bummer with this is by the time you buy new oversize 2.02 or 1.88/1.60 valves and re-cut the heads for them, you're probably in to it for ~$350-400 or so, plus probably another $100 for springs/retainers. and you still have heads that flow ~150/100 int/ex. then you have your time for porting, and these heads, done by a professional porter will likely max out at about 230/135 int/ex, (probably less by someone like us w/o access to a flow bench or a lot of experience), which is about the same (or slightly worse) flow than as-cast enginequest mag heads, for about the same $$ as new, assembled EQ heads.
if you wanted to do heads on the cheap, if you can find a set of used magnums, do a valve job, maybe open up the pushrod pinch a skoash, and put some GM3100 springs and retainers on them, or find some junkyard 2.2L retainers and a good 1.4" diameter spring on them, and probably save about $200-300 over a new set of enginequests.
but the "cheapest" way to up compression is to either mill your existing heads, or if your engine is fresh enough, get some KB167's in the same overbore as your motor, do a quickie hone, and toss them in...
1976 Spinnaker White Plymouth Duster, /6 A833OD
1986 Silver/Twilight Blue Chrysler 5th Ave HotRod **SOLD!***
2011 Toxic Orange Dodge Charger R/T
2017 Grand Cherokee Overland
2014 Jeep Cherokee Latitude (holy crap, my daughter is driving)
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