I was wondering if there was any significant gains or losses with putting 305 heads on a 350. Did a search, and couldn't find much. Would like to here what you guys have to say.

 

Your compression will be raised. This can give you a little more performance but the 305 heads sport smaller valves and definetly should be ported to achieve max performance. Extensively ported 305 heads are a common performance mod on here.

 

I am currently running 58cc 081's on my L98 roller.

I can say for sure, it has more power than it did before
I started the rebuild. Compression is raised a tad, but not
signifigant. I havent noticed any power-loss due to the
smaller head.. It seems a tad more peppy.

Depending on head choice, It might not be desirable
to machine/port them. 416's & the 081's seem to be
the most popular to mod & best flowing head of the $.
But, there are better flowing heads out there.

I successfully passed emissions with a 280 cam and
305 081 heads on a 350 with a stock tune in a L98 car.
So, the ECM likes it.. Though it is a tad lean.

Good luck

 

put in some 1.94 valves and have the seats redone and the chamber hoged out

 

Something you might like to know: take the 350 head gasket and lay it on the 305 head, and look at the head gasket compression ring and how close it is to the water passage in the head itself. What I am saying is that if the motor overheats you run a good chance of haveing to change the head gaskets.

good luck