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View Full Version : sbc 350 head options

gsx97
03-22-2006, 11:28 PM
can I use stock 305 heads on a 350? also would it really affect performance?
Suicidal Racing
03-22-2006, 11:35 PM
yes u can.the intake runners are smaller then the 350 heads.witch will choke the engine in the upper rpms.depending on cam and how high your reviing it though.u will gain some compression by using them because the 305 heads are 58cc i believe.
Country Boy
03-23-2006, 08:54 AM
yes u can.the intake runners are smaller then the 350 heads.witch will choke the engine in the upper rpms.depending on cam and how high your reviing it though.u will gain some compression by using them because the 305 heads are 58cc i believe.

+1

The only gain will be the bump in compression, but the the smaller runners will negate that... Theyll choke a 350.c
GMRACER13
03-23-2006, 10:29 PM
If you do use 305 heads on a 350 block you MUST use 350 head gaskets as the 305 ones will over-hang the cylinder wall and leak compression gasses. Ask me how I know!
Suicidal Racing
03-23-2006, 10:32 PM
haha u thought they where the same bore..
GMRACER13
03-23-2006, 10:51 PM
haha u thought they where the same bore..

Not at all. Was replacing the heads on a stock 305 in a truck that had blown a head gasket and overheated. Didn't even measure the bore, just looked at the stickers under the hood that said it was a 305. I guess somewhere along the line somebody had replaced the motor with a 350. Took the heads to the machine shop and they asked me what size motor. Of course I said 305 SBC 'cause that's what was "supposed" to be in the truck. They gave me an exchange set of heads (305 SBC) and a gasket set. Went home and put the heads on and fired her up. Drove it arround the block with no other changes and said, "holy shit, this thing picked up a little power from just a new set of heads! The old heads must have had weak valve springs or something!". A day later the machine shop calls me and tells me that I dropped off a set of 350 heads and not 305 heads which is what they gave me. I told them that the heads are already on and the truck drives fine. Guy asks me if it has a little more power than it did before. I say, "Funny you should mention that, it runs much stronger". "I'll bet it does", they said, "But you'll have to replace those 305 head gaskets we gave you with 350 gaskets or else it will leak". It leaked and I replaced the gaskets and it ran well 'till it got sold. THE END!