i have a LO3 motor in my 92 rs backed by the t5. now i know everyone is gonna tell me to go 350, but right now its not in my budget. i was wondering what would happen if i took off the stock heads on my motor and put a set of 083 centerbolt heads on, 64cc combustion chamber, 1.94 and 1.5 valves i believe, and not sure of the flow numbers, but i do plan on takin them to a machine shop to have work done to them. i also understand that these are better heads for a 350 but if i have them decked would that bring them down enough to be close to my stock compression? i know flowing better is only gonna help torque but i do plan on going with a bigger cam later on too. im just lookin for some opinions on wakin my motor up a lil, and right now its basically stock except for a msd ignition that ima take off, (bought the car with it already on there). plans for the future would be: headers/full exhaust, cam, intake, and obviously the heads. i do plan on getting a 350 someday and even stroking it to a 383, so im not lookin to dump alot of money into this motor for the parts i wouldnt wanna use on a 350, just want it to be fun to drive now until i can afford better stuff. thanks in advance for advice and opinions.

 

If you plan on or have already bought the 083's, set them off in the corner of the garage until you build your 350.

In order to see any benefit, you would need to do cam and exhaust at a minimum, and probably intake.. Shaving the heads now for the 305 would make them too small for the 350 or 383 later.

 

^ What he said. All things considered, it would be better to wait.

If you can't wait, then definitely have bowl porting work done on your heads and get a good 3-angle valve job. I wouldn't resurface them more than 0.010". Use the thin gaskets.
If you can, add some good headers at the same time and it will more than make up for any small loss from the compression drop. As long as you don't go to big on camshaft duration, the lower compression shouldn't be an issue.

 

i was planning on having them ported at the very least, and a valve job, also better springs installed and i was thinkin of doin an ls1 cam, nothing extreme for now, just lookin to make it breathe a lil better. the engine is prolly pretty tired, car has over 200k on it and i dont know if its been rebuilt or not. it runs pretty good, doesnt smoke or anything aside of a little miss at idle. and im in no real hurry to get the heads on, i was planning on collecting a few parts first. also i already have the heads, i figured if nothing else i planned on a 350 later and they are good heads, picked em up for 150 and they look like they have been on a motor long enough to break it in (interestingly enough the guy i got them from said he took them off to replace them with a set of camel humps lol.) anyways i appreciate the info, i wouldnt have put them on without the cam, but i might have held of on the headers and exhaust for a while. guess ill wait until i have everything i want first, and later on ill pick up a short block or a bare block 350 and start building it. even when i do that though i will be on a pretty tight budget, so if there is any tricks to make power for cheap on a motor like that, please dont be afraid to post your ideas. thanks again

 

An LS1 cam won't fit in a Gen I 305 or 350. LT1, yes, but not LS1.

 

my bad, i knew it was one or the other, but thats the cam i wanna go with, cheap and ill prolly just get a used one from a junk yard.