How much of a differance would stock l98 heads make on my car?
 

I still have the tbi heads and was wondering how much hp I would pick up from swaping them. Im thinking about buying a set of used iron l98 heads and was wondering if it was worth it.

The swap would ONLY be worth it if they were ported before installation. The Stock L98 heads flow like crap to begin with, 195cfm before they begin to port stall. Of course with a new set of heads, that cam would have to go. I would recommend somthing in the range of 215* duration and .460 lift with your setup.

Look for a gain of about 30hp or so.

I'm not a big fan of putting 350-style heads on the small bore 305. It just doesn't give me a warm-and-fuzzy. Others have done it with decent results, but I've not had good luck with it.

I'd save your money for a complete 350 long block. It will make a MUCH bigger difference than putting L-98 heads on a 305.

drhtryhrt
 

Look for a set of 305 TPI heads and have them cleaned up, hot tanked, checked for cracks...Have the valves and valve guides checked for wear and replace them if you have to. Have new valve seals put on. Have the valves backcut with a 3 or 5 angle "valvejob" and have the heads "pocket ported". If you have more money, i'm thinking i would have the exhaust port opened up/ported also. I wouldn't spend more than $500-700 but with that kind of money, i think you could get some nice power out of the so called "stock, crappy" heads

Another option is to buy a set of 305 heads that are already ported...intake and exhaust full port work, 7/16" studs, new springs.. There is a guy on this message board namd Dan Burke. His screen name is ws6transam . He's a pretty well known Michigan member and he has these heads...His 3500+ pound ws6 84 trans am ran 14.0 last year at 101+ MPH with these heads which he ported himself(He's a logical guy who did some research and reading about airflow and port work), a small comp cam(218/224 .480 lift i think), headers, cat back, 3.73 gear....good combination! look him up and tell him I sent ya. I have a feeling he would let the heads go for a nice price! later man

305 TBI and TPI heads have 58cc combustion chambers, while the 350 f-body TPI heads have 64cc combustion chambers. You'll lose compression and that will negate any gain in airflow.
I dont think the f-body heads flow 195 cfm stock, its probably more like 175. The corvette heads flow 195 cfm.

Plus, as said above, the money you'd spend on a set of heads for the 305 would be much better spent on a 350 engine.

Go to the link at the bottom of my sig and do your own 305 heads. Your total cost will come out to around $400. That includes EVERYTHING you need to port and polish the heads AND the cost of all machining and all new hardware.

And these have been flowbenched and shown to flow just like a set of L31 Vortecs.

You just can't beat that with a stick :D :bow: :p