heads
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heads
I have a 1975 L-48 stock.The engine smokes when 1st started I beleive it needs valve guides. It has 81000 mi. Iwould like to give it a little more power with new heads . I was told that heads from a 305 would work? Any thoughts?
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heads
In that era of small block chevy, some of the heads may have different size combustion chambers. Years ago I had a 77 sbc and put later heads on it. It had smaller chamber heads and turned my 9 to 1 into 13 to 1. Its had lots of power but did not last long. 
Drifting
Joined: Oct 2005
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From: Angier nc
it sounds more like valve stem seals.which can be replaced without removing the heads.
305 heads will work and give you more compression due to the smaller combustion chamber.however with the smaller ports,valves, and intake/exhaust runners it will be more restrictive and lose power above 4500rpm.
find some good used(not likely) or new heads(even vortec heads if you are willing to swap intakes also)with 64cc chambers and that will bump compression up to 9.25-1 or so.
a modern cam would be a nice matching upgrade as well.
305 heads will work and give you more compression due to the smaller combustion chamber.however with the smaller ports,valves, and intake/exhaust runners it will be more restrictive and lose power above 4500rpm.
find some good used(not likely) or new heads(even vortec heads if you are willing to swap intakes also)with 64cc chambers and that will bump compression up to 9.25-1 or so.
a modern cam would be a nice matching upgrade as well.
Melting Slicks
Joined: Feb 2006
Posts: 2,753
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From: backwoods upstate ny
350 block with 305 heads is common combo used by ''street stock'' circle track racers who are rulebook challenged to stock, cast iron heads...early 305 heads are preferred to the later ones that have restricted ''swirl'' intake ports... ''HO'' 305 heads may give too much compression on some 350's for pump gas.
