ZZ71S

I have a zz4 with lt4 hot cam and 1.6 rockers
I am looking for some heads that will work good on the street
Looking at the AFR 180 eleminators and GM fast burns
Which of these would be the best on the street
How much HP and torque might these combos make

billla

The ZZ4 already comes with P/N 12556463 L98-type heads; some porting investment here could get you into 250+CFM intake flow.

Need more information than "work good on the street"; I assume the L98's are already doing that

ZZ71S

I am really looking for some more HP and torque
Which one of these heads would be best for street use
I would not know who to trust to port heads around here

billla

Well, as a general guideline for a 350 CID engine intake runners around 170-180 CFM are the best fit - you could go as far as 195's with the Hot Cam's .525 lift (with 1.6 rockers)

The Fast Burn heads (GMPP P/N 12464298) are 210cc intake runners, which IMHO is too big for a street 350 with a relatively mild cam like the Hot Cam.

So, I would lean towards a 180-195cc intake runner head. AFR 180's are a great choice; I would lean towards the Streets vs. Competitions or Eliminators myself.

The problem you face is that your existing heads are 58cc combustion chambers, and both of the heads you're looking at are 64cc - so you're losing about .7 points of CR with the swap.

I'd estimate about a 40HP/30TQ gain from the swap. In terms of gain/$, not sure that it would be worth the swap. There are plenty of porting companies that would massage those L98's for you.

ZZ71S

I just got done talking to AFR I can get any combustion chamber from 56 to 75 ccs in the 180s

cv67

AFR 180 is a great choice. It takes an awful lot of work to get the L98 head in the 250 range and even then you still have a 18+ yr old head
Not worth it.

64_365

AFR 180s. Lot's of magazine tests with these heads post some pretty impressive HP and torque numbers. You can port L98 heads and not get near the flow numbers AFRs make. Let's say you can find L98 heads for $200, send them to DR-Js for a $900 port job and you still won't have heads that will flow like the AFRs. Spend $340 more and be happy!

BLOWNBLUEZ06

AFR has my vote.

sly vette

Couldn't post a link but call these guys and see what they recommend.
www.katechmotors.com
Sly

willyszr1

afrs are the best bang for the buck bare none . if you are honest with them about your combo they will hook you up with the best head for you .

frenchyoliver

I like this one !!!

Katech is state of the art race engine for sure.....
Not sure they will recommend any as they do their own job anyway.

cardo0

How did you put a GEN II cam in a GEN I block without a cam retainer plate on the front of block? What did u do with the long dowel pin on the end of the LT4 cam that turns the opti dist?

cardo0

FastEddy

AFR's !! With a little more cam and go 195's.

I have 195's that were milled to give me 58cc's topping off my ZZ4 rebuild.

L98 heads are no better than 1990 truck heads, except they are alumn.

Best power making purchase you can make is good heads - spend your money there.....

FastEddy

I don't think GM's Hot cam he is using is actually for a LT4. It may be same profile though. ZZ4 does use LT4 valves, springs, and retainers in the L98 heads, I do believe.

But then again, I do remember a hole in the front of the cam that may have been for a dowel in LT4 application - and ZZ4 does use a cam retainer.......