Has anyone in here used the aluminum L98 heads on a 305 before? The newer d-port styles?

yep. i've got the 113 heads on mine with a backcut on the valves and mild bowl blending. times in sig, still no REAL tuning yet.

I forget the casting number, but I am using Ported ZZ4 heads on my 305 (312 but whose counting) TBI. It has produced 420 HP on the engine dyno.

Thats impressive from both of you!

well, we are the two fast n/a 305 guys on the boards. like i said, mine has little to no real tuning yet, haven't even looked at my plugs and the time in my sig is the 2nd pass ever made, and the engine only has 250miles since refreshed. based on ET and weight i'm making ~415fwhp and based on mph i'm making ~390. so i figure ~400fwhp is a decent guess. i hoping to dip into the 11's n/a once i get her all tuned up, get the chassis/suspension where i want it and get some cooler air come my way.
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while i'm not sure of the exact casting number for the zz4 specific heads, the 113 heads and zz4 heads are supposedly the same casting, just with different numbers.

hey Fast, how much porting was done on those heads? could you imagine if we teamed up what we could do! my cam, c/r and your heads...that'd be sweet!

MW- I think the differences in our engines are Carb vs. TBI , L98 vs. ZZ4, Solid vs Roller.

Actually, I wonder what your combo would do with my heads and my cam.

Comp Xtreme EFI retrofit roller P# 280XFI-HR13
Advertised -280*/288* Duration
.050--------230*/236* Duration
Lift(1.6:1)--.576"/.570"
LSA---------113*
ICL---------108*

I wonder how it would fare with a 750 DP on top instead of the 670 CFM BBC TBI unit.

I am also pondering trying a different intake than the standard Performer RPM.

I have also heard that the ZZ4 heads flow a little better than stock 113 aluminum heads, but cannot confirm this statement.

A good amount of porting was done on them in my garage and GM valves meant for a Fast-Burn head were installed at a local machine shop. I decided to relieve the area at the top of the bore to unshroud the 2.00-1.55 valve combo.

holy jeebus that's alot of lift! yeah, while i've got more duration, i'm running a BUNCH less lift. and the fact that it's a solid flat tappet...

238*/248* @ .050
.480"/.500" lift 1.52 ratio pro-magnum's
114* lsa

and i've got a 650 double pumper, though i've also got a 750 main body that i think would probably help on the track, but hasn't got near the driveability as the smaller main body. i believe the booster signal is too weak and therefor creating a very strang bog at part throttle cruise. if i stomp on it from a dead stop it works great and procedes to blow the tires off. i'm sure the combonation of the two combos would produce some pretty impressive numbers.

How would L98 iron heads work on a 305?? My friend has a set that are ported..but other than that stock..as far as valve sizes..etc..

My comp cam is designed for use with 1.6:1 rockers, which is what I have on it.

I wonder how it would run with a done up Q-Jet on it. I know of some guys in the F.A.S.T. drag racing series running 10s and 11s with them. They will pull in over 900 cfm @ WOT, retain the small primares for good part-throttle, and have the Air Valve on the secondary side.
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The chambers are too large to get good compression.

honestly, i've seriously considered going to a Q-jet, but would be impractical for the blow-through turbo system i'm building and would be a waste of money. so i'm sticking with the double pumper. though i know the NHRA/IHRA STOCK/SUPER STOCK guys are running some SERIOUSLY impressive numbers and are limited to a Q-Jet. they are just so dang expensive for a good one.

as far as the iron l98 heads, they have a 64 cc combustion chamber and while the static compression will be less, the overhang of the larger combustion chambers on the small bore could cause hotspots promoting detontation. i say, try to get some 113 castings or do up a set of 416's, 081's or 601's. all three of those are GREAT iron 305 heads to start with. do some porting and put in some larger valves and you're on your way to having a quick little 305.

If I were doing an Iron head 305, I would use the 601s, they have the old closed chamber setup, not the open chamber smog heads. They are worth 20-30 ft/lbs throughout the powerband vs. the open chambers according to David Vizard.

14101128...86-87...350..........Aluminum, 58cc, angle plug


how do these heads compare to the 113 castings?

they are decent though they don't flow as well as the 113's do on the exhaust side due to the 113's upgraded D-shaped exhaust port. with work, they flow just as well.

got a link on porting? showing the specific problem areas on the 113's and 128's. Im a little weary on tearing up a good set of heads..but i do have a spare set of 416's to practice on.

search for Sitting Bull's threads on home porting. also, get the book "how to port small block chevy heads".

Well..my cousin bought the aluminum L98's..the D-port style..used but they have been freshly rebuilt...for $400. We are installing a Summit TPI cam (Edelbrock Performer basically), and an Edelbrock intake..with the stock rebuilt Q-jet. The car is a 87 SS...it has Dynomax LT's and h-pipe..nice true duals. That exhaust is on it now..the only mod..and it was a huge difference over the stock manifolds and y-pipe!!!! For a heavy car it goes well now. I will let you guys know how it works out. He went with the small cam due to the computer and stock carb in the 87's.

Here ya go, it's in my sig

Do you use the same style intake, for the 87 up, on the 113 heads?

no, you'll use the 55-86 style intake. this may be a good time to upgrade to a holley street dominator intake p/n 300-36, which is what i'm running. i'd like to see you run more cam though. also, because aluminum dissapates heat so well, run a Fel-Pro .015" steal shim head gasket to keep c/r up. that's what i'm running c/r ~10.2:1 and is totally pump gas friendly, even with 18* initial and 36* total all in by 3000rpm.

So the TPI on the Vettes were the old bolt pattern? I assumed the L98 heads all had the same pattern...hmm..interesting. He had to stay with something mild to not mess with the Monte's stock carb and computer...from what the guys in the Monte SS forums said. I'm sure he could have went a little larger but for the price this cam was a steal..and should be better than the stock one at least. He has flat tops now and 9.5:1 stock....so no idea what it will be now...same CC size on the heads of course...but these have been decked some I guess.

well if they've been milled, then the compression is going to be bumped anyhow. may want to measure the combustion chamber and see what kinda volume you got going there to calc. correct c/r, and to see what size gasket you can run. you can run a higher static c/r though with aluminum heads and would be a good idea to try to run right around 10:1.

yes, all the vettes used the older style bolt pattern up through 1991, 1992 they got the lt1.

your nuts! thats teh cam i want to run on a 383 HSR/LT1 intake motor that will do low low 12's at 115mph. i wouldnt even think to run that on a 305. that 305 must rev to the moooon with that big roller

FYI: 115mph is good for 11.6's

In TBI form it made 421 FWHP @ 6,600 RPM and 390 ft/lbs @ 4,500 with over 300 TQ from only 2,400 rpm. Pulls 14-15 in/hg of vacuum @ 750 RPM unloaded.

Pulled 410 @ 6,500/ 385 ft/lbs @ 4,750 with a Q-Jet and LG4 intake.

With Sequential TPI it didn't make 325.

YouTube - 400 FWHP TBI 312

lol true, on good tire and proper suspension it should. i probly wont be, ill still be running my stiff road suspension with et streets. wont be cuttin the best 60s so low 12's is good for me

hows the power brakes with that setup. is 15inch good enough to run power brakes?

well, considering that a stock motor pulls about 16-17in/Hg...yeah, it's pretty dang good. it's when you get to around 6-8in/hg that you'll run into problems with power brakes. cams ground on 112-114 lsa's build good vacuum (and just happen to really love boost and/or nitrous!)

mine is ~14in/Hg

14 in/hg is plenty for powerbrakes, but if you drive in alot of traffic you need a vacuum reserve canister. Neither of my trucks have vacuum power brakes so my brakes work just fine. Both have hydroboost run off of the powersteering pump. Was an easy conversion for both my G20 and S15 Jimmy as both vehicles were factory equiped later in their respective production years. Pulled a setup from my 1992 G20 donor van for the 1983 G20 and a different setup from the 1994 GMC Jimmy that my 4.3 CPI came from. The 305 is going in place of the CPI 4.3 in my 1987 GMC Jimmy.

that's gonna be a fun little ride!

If I can keep the stock S-series transfer case and 7 1/2" ring gear 10 bolt in it. It already has 3.73s in both ends.

good luck with that. you guys got some great combos working there in nice cars!

hey thanks Orr89RocZ! it means alot comin' from you bro!

So what does it take to put the aluminum L98 heads on a 305 block, milling the heads down to get the combustion chambers to "match" the bore ??

I have a 305 short block in the garage, the LO3, tried getting hold of the TPI heads to see if there really is a THAT much difference between the TBI or TPI heads (from what I've understood now, one had may flow better at higher rpm other one at lower ?)

But if I could get hold of a set of L98 aluminum heads, I would definately go for those



Holy **** (after looking at the video), Fast355, that's your 312 ??? How many people do you get asking you how much bored over/and or stroked that "350 of yours" is ?