right now i have a lightly modded LO3. this weekend im picking up a tuned port setup with everything from a 350. now my plan is to pull my motor take it apart put on 193s(LO5 heads) i think the number is 193 for it at least. i also am going to put in a LT1 cam while im at it with new springs in the heads of course. this tuned port is a MAF setup from 89. im wondering with a full exhaust headers back what kind of power numbers would i be looking at? also the 350 heads will go on with no problems correct?

 

Don't know about power numbers, but the 350 heads will bolt up to the 305, but it may lower the compression ratio. I'm pretty sure the 350 heads have larger combustion chambers than the 305 ones, so it essentially drops the compression ratio...which could be raised again with pistons or decking or something, just something to keep in mind. I actually used 305 HO heads on my 4 bolt 350 to raise the compression a bit...and those particular heads flow a bit better too.

 

I think he is putting the 305 heads on the 350, with a new cam. So up the compression. Don’t the 305 heads have much smaller valves? And flow a lot worse than l98 heads. Thus killing any gain by upping the compression.

 

The standard 305 head yes, but the HO heads were actually pretty good for flow and valve size. Valves were slightly smaller though yes. My application is not a very modded motor though also, so it works well.

 

Thanks for the info, I will pack that back in the gray matter, I never knew there was much difference in the 305 heads. What will the compression ratio be with the smaller combustion chamber 10-1?

 

Not exactly sure, I never actually got a number from the machinist or tested or anything. I would imagine is is somewhere in that range though yea. I can still run regular pump gas without issue, so it can't be ridiculously high.

 

so will my 350s flow decently well for my motor? also lowering the compression ratio what exactly will that affect?

 

Yea, the 350 heads flow well and better than most 305 heads due to the larger valves. The lower compression won't affect anything as far as having to run different gas or anything, but it affects the power I think...this is where I start losing it and will have to refer you to an engine builder. I doubt it will make enough of a difference to really matter. But if you plan on building a motor, you probably want to have everything right where it needs to be and have someone who knows the effects the changes will make describe and explain it so you know what you have.

 

I don’t think you can use 350 heads on a 305, I think the bore is two small, and the valves hit, and the combustion chamber hands over the edge of the bore. I may be wrong, (someone with more knowledge than I will chime in if I am.) Also you will drop the compression ratio to 8.3-1 to 8.5-1 or so, and that will KILL power. Only way you would want that low compression is if you were running a lot of boost.

 

ok so then i should either pick up some 081 heads instead of my crappy LO3 stock heads. or maybe pick up a whole 350 block to be better off actually.

 

corvettes with 58cc heads yielded 10.25 compression .... I've put LO-3 heads on a 90 vette 350 worked good pinged a bit but ran

 

like i said ive decided for either 081s or a 350 block with heads whichever passes me by with a better deal first wins.

 

I'de try for 083 heads to match the 350

 

yea sorry if you misunderstood but thats the block im looking to pickup. with the 083 heads.

 

So basically you just looking to drop TBI on a L-98 then like mine has?

 

again sorry i must be so confusing. no im not looking to put my TBI on an L98 motor. what im doing is buying a full TPI setup base, plenum, runners, etc etc everything needed computer ecm. then im putting an lt1 cam in my LO3 BLOCK with 081 heads on it or instead just buy an L98 block and throw an lt1 cam in it although it has very little difference in the cams.