like it says i have a L03 heads wich ive head are the worst flowing camaro heads and ppl have told me that is i use L98 heads it will increase power by far. the guy that built my engine wich is a TBI by the way says that the 305 heads are raising my compression and killing my power said they are 64cc i believe and i need to get some 350 72cc heads. ive looked around and seen heads for 350's that are from 52cc to 74cc or whatever they go up too , whats the difference as far as the performance and drivability. back to the main question is it worth it for me to invest in some L98 heads since i dont have the money for a $1000 dollar set of heads at the moment?????

 

L-98 heads will help. low cc numbers give you more compression, and power if you can afford the high octane gas.

 

what are the motor specs?
you can get heads between 52-76cc's, and you can use a die grinder to open them up too. Those heads are definately choking your engine, so lets forget about them as being useful at all.

You want to pick a desired compression ratio that will suit your needs. Find out what's in the short block, then pick a head cc size that will net you that compression ratio.
Then find some heads that have that size, or that you can open up to that size. Preferably something that flows ok.
083 heads (L98 heads), or 081, or 416 or 601 heads all would work, for cheap. No way to know which ones are "right" for you until you know the shortblock specs (pistons, and deck height).

 

The 187s are not killing your engine. It is the weak 929 cam that is likely in it as well as the stock 305 TBI injectors and stock 305 chip. You need 350 injectors or raise the fuel pressure to about 18 psi with the 305 injectors and a 350 chip. Make sure that you are running a 350 knock sensor as well. I would optimize what you already have, rather than throwing on parts that are likely to make it slower and burn more gas. Lets face it, Swirl Ports (187s) are ample for 300+ HP in stock form.

As long as you don't try to push the envelope while pushing a 5,500 lbs Van into the wind at 65-70 mph, pulling a 4,000# boat, I have run compression as high as 10.7:1 on 91 octane and a 170* thermostat. It took a careful timing curve, but it was doable.

 

What pistons in that 350? Let's start from a true calculation of your compression and see where you stand right now. Flattops? Dished? Domed? Knowing part numbers and manufacturers would be best.

Stock L03 heads are ~58cc chambers from the factory, by the way, as are most 305 heads.

They will definitely give you higher compression on a 350 than will typical 64-76cc 350 heads. HOW high is the real question and that requires knowing what pistons are in the motor before you can even get a rough idea of your current compression ratio. High compression is a good thing for power..... until you get too high and encounter detonation which takes away all the advantages and brings other problems.

Example.... a typical 350 with flattop pistons and 64cc heads would be around 9.7:1 compression. Swap on some 58cc heads (all else held equal) and it climbs to a rather high 10.4:1. Now if you combine that high compression with a small/stock cam you might well have a "detonation monster" unless you do some very careful tuning, like Fast describes. Even then, dialing back timing to compensate for too much compression always ends up compromising power.

Knowing the cam would be the next most important thing to know. Heads and cams are the 2 components it is most critical to match correctly if you're going to have a strong running motor.

 

I have some L98 heads for sale. 90k on them, fully assembled. $100+shipping.

 

alright this is what we got. it was a basic SpeedPro rebuild kit with .030 over pistons and a set up with the cam. ( i know nothing about cams i have the box with the specs on it still though for this exact situation.) the guy said it was more like a mild cam but not wild at all. i already have the 350 computer with chip, 350 knock sensor was on block when i got it, stock crank and rods, i think there flat top pistons i might have a pic i will add if i can find it. he said with those heads its most likely about 10:1 compression, ( i ran it on 87 gas for a summer with those heads and 100k on the engine and i got like 9 miles to the gallon and ran all messed up now i get about 20 and run 93 octane) so the heads gotta go! so if anyone can give me an idea of what stockish type heads i should get or if you know anyone sellin aftermarket ones for cheap let me know. thanks for the input!!!

 

a tune would help, those heads should work better then that.

urban hunter has a good deal there...

what cam exactly is it? list off the duration @ .050", and lift.
I'm guessing it's a 204/214 cam...

 

i tried uploading the pic of the box and it wont let me it is the 204/214 and a bunch more numbers but yea, what kind of power will i get out of L98 heads and my 355 setup with this cam also? any idea?

 

That's a pretty lame cam.

With L98 heads and flat top pistons, you'll do ok. It's not the biggest mismatch in the world, but it's sure not cutting edge. Maybe 250HP at the crank say.

 

isnt it bigger than stock though???

 

Yeah, you got a scosh too much compression. Even with a stock .025" piston deck height (no decking of the block) and a rather thick .039" Fel Pro "rebuilder" head gasket you're up around 10.4:1 squeeze (assuming a typical 6cc worth of valve reliefs for a 4-eybrow flattop opiston). Too much for iron heads, a small cam and pump gas.

A set of 64cc heads (like the L-98s) will put you back down in the mid 9s and probably work a lot better with the rest of the combo.