LT4 cam in a L31?

[1fastsilverado]

could i get theLT4cam kit with rockers lifters and retainers and springs from summit to work in a L31 motor? or if not what cams can i use that wont need a big computer tune.

[19doug90]

the whole point in switching cams is to get more lift and more duration.

So not only will the stock computer not have enough air anywhere, it wont have it at the rpms you need.

it'll never run the way it should without tuning

i would kill to be able to throw a cam in my yukon right now but i dont have the 800 dollars for tuning/datalogging equipment nor the time to be tuning it.

[91chevZ71]

LT4 HOT? fuggedabout it being a DD without tuning.
LT4 production? I've "heard" and "read" it runs OK on the 96-99 L31's. FW it's F'n W. gotta tune it, man

[91chevZ71]

the production LT4 was 10.5 C/R, IIRC. something to think about, possibly.

[Pauly]

10.8:1 for the LT4, LT1 was 10.5:1.

I just did some reading on a stock Vortec 350 in a TBI truck with the LT4 roller cam and it made 255 rwhp and 315 rwtq. Not bad IMO.

The LT4 Hotcam with 218°/228° on a 112°LSA will be boggy in the lower rpms and will need a higher stall torque converter to retain drivabilty. With ported heads this cam HAS made 302 rwhp on a Vortec 350 and over 330rwhp on a 383.

The stock 1996 LT4 Vette camshaft with 203°/210° on a 115° has .476"/.480" lift with 1.6:1 rockers or .446"/.50" lift with 1.5's. I would drop in a production LT4 Vette cam with 1.5 rockers and get a tune for it.

I would swap ANY cam without getting a tune, but thats just my opinion.
peace
Pauly

[1fastsilverado]

what about ZZ4 cam?

[Pauly]

ZZ4 cam will work as well, but it does have a huge duration split. 208°/221°. This cam will have a more agressive idle than the LT4 Vette production cam.
Fuel economy would be better with the LT4 cam.
the ZZ4 cam has lift that is out of range of stock L31 heads. its lift is .474"/.510" on a 112°LSA. You will need to machine the valve guides down or use 01-04 LS6 Vette or 26918 Comp Cams Beehive springs with 787-16 Comp Cams NON Gen 3 retainers to have the ability to run 0.550" of lift on virgin Vortec heads.

The4 ZZ4 cam will require MORE tuning(for teh lack of a better term)than the stock LT4 cam.

The LT4 cam is designed to feed a 330sae net hp engine (around 360 hp in actuality) and the ZZ4 cam is designed to make 355 hp in a ZZ4 350. The ZZ4 engine is really just a 10:1 350 with L98 aluminum heads. The ZZ4 needs more cam to make the power than the LT4 does beacsue the LT4 has much more advanced heads.

The production LT4 cam will have a stable idle due to its 115°LSA


peace
PAuly