What are the suggestions and popular mild cams for an L98?
this would be for an '89 GTA with 350. 3.23 rear gears, stock converter, stock exhaust, stock heads, etc. All stock except for the cam, MAYBE add a fuel pressure regulator. One that would retain all streetability yet add a bit more HP/TQ. the engine is getting a budget rebuild and now is an opportune time to slip in a mild cam. Don't want to do any kind of computer tuning either.
What are the specs for the stock cam?
Can this car easily be converted over to a hydraulic lifter cam from the roller cam? yeah, I know the rollers are better but the aftermarket cams for a hydraulic setup are much cheaper.
What about using 1.6:1 stamped steel rockers instead? not roller rockers, just the budget stamped steel units. if they are the self aligning kind, would there be a need to use guide plates? what about new pushrods? any special springs other than standard replacements? special clearancing for the rockers?

thanks,
md

 

i could be wrong but your car should already have a hydraulic roller cam/lifter setup.
it shouldnt have mechanical lifters on it.
and i know for a fact it is roller

 

You already have a very good roller profile in your engine. The cam used in the '88-'89 305 TPI 5-speed and 350 TPI engines are the same cam, and its got 207/213 dur. @0.050", .415"/.430" lift, 117 deg. lobe sep. angle, which is more cam than on any previous or later year small block roller profile from the factory. It has more duration int/exh. than even the LT1 or LT4 factory cams.

I'd suggest you look instead at new valvesprings and 1.6 roller rockers.

BTW, you most likely have the 9-bolt Borg Warner diff, which has a 3.27 gear with the L98.

Dave

 

If it were me, I'd throw in a ZZ4 cam. Even with no other mods, it should wake that 350 up a bit....



HTH

 

I've looked on the internet for the LT1 corvette cam specs, but haven't found anything, or I've found conflicting info. Does anyone know the specs for that cam? Compared to the stock 350tpi cam?

 

the stock cam with 1.6:1 rockers gives about the specs I was looking for, maybe a hair slightly less. However, if a mild cam was used now it would be easier to add bolt ons later in addition to 1.6:1 rockers. Would just make future mods easier and more receptive. The car is going to get a new cam with the rebuild kit anyway, just need to decide on stock replacement cam or a mild one.
any more thoughts on the best choice? any recommended specs?

this 9 bolt Borg Warner rear, is this the fabled Aussie 9 bolt rear that all the ESP autocrossers drool over? I thought that was an extremely rare rear end. Or is the Aussie version slightly different? I take it the 9 bolt doesn't look the same as the 10 bolt (only 9 bolts, eh?). I have three cars with 10 bolts, seen enough of those! haven't looked at the rear end on this car, its a friends and I'm trying to find details for the rebuild. After all, I was driving the car when it spun the bearings. He just forgot to add oil.

 

the BW 9 bolt can also have a 2.77 gear ratio, thats what mine has.

 

And 3.45's if you want to be completely correct.

 

ZZ4 would be a good bet.

Your car is a factory hydraulic roller. The ZZ4 cam can be had CHEAP on Ebay, so this shouldnt really be a concern.

 

what are the specs for a ZZ4 cam?

 

If you have an original diff in your '89 GTA, with the L98 it will be the 9-bolt Aussie rear with the 3.27 gear. That was the only diff/gear ratio Pontiac used that year in that car with the L98.

ZZ4 is 208/221 roller if memory serves me correctly.

I cant see much of a gain if all you want to do is change the cam, simply for its own sake. The stock TPI induction will greatly limit the effect of anything much bigger than the stock grind anyhow. IMO, go with the 1.6 roller rockers, new timing chain and gears, and new valvesprings with your stock roller cam and you'll be good to go.

A GTA is not a light car; the stock cam is perfect for the street as it works with the stock TPI runners to create tremendous bottom and mid range torque. Putting a bigger grind in your engine won't make much gain if you do not make changes to your intake system, and at that point, ask yourself what you really intend to do with the car; do you want a solid high-torque daily driver, or more of a drag racer with higher top end?

I love all that street torque; I would not want to give any of that up in a daily driver. Just my .02.

Dave

 

I disagree, the ZZ4 will make more power across the powerband than the Stock L98 cam, Regardless of other Changes.

Considering it can be had for less than 100$ on Ebay, and the motor is being rebuilt... Why Not ?

 

I hope to go with the ZZ4 cam when I do a rebuild. Like others said, the stock 89 L98 cam is very good. 207/213 - .443"/.459" with 1.6:1 rockers, on a 117 LSA.
The ZZ4 cam is 208/221 - .474"/.510" with stock 1.5:1 RA's and a 112 LSA.
I think going to an LT1 or LT4 cam (not the HOT LT4) would be like going backwards due to the better duration on your stock cam.
Anything else seems like too much cam unless you buy new / aftermarket. (By too much, I mean to maintain stock sounding idle.)

 

The thing is, the engine is out of the car. That is the absolute best time to do a cam swap, and if you even *think* you will want to do one down the road, then make it your first priority now instead of down the road when it's 1000x harder. I'd rather swap 2 or 3 sets of heads in car than do one cam swap. Just no fun.

With that said, Bort maes a good suggestion. A ZZ4 cam will outperform the stocker by far, even with a a stock TPI and manifolds on it. And it can be had dirt cheap. And it makes lots of lift, so 1.5 rockers aren't even needed, so you can et the cam for less than you'd spend on rockers. Just get a nice set of springs and retainers to match and you'll be set.

Thats your best budget choice by far. The ZZ4 is still a tiny cam, but nevertheless has plenty of potential if you give it decent surrounding components. No lope whatsoever at idle, and only *needs* as much computer work as a stock cam anyway.

 

Very good points.

Dave

 

Hmm, I guess my chiltons lied to me, they WAY under sized it, something under 0.300" of lift. Glad to know it's not that bad.

 

Chilton's was probably referring to the lobe lift. Multiply their figure by the stock 1.52 ratio, and it should come out to the valve lift #'s posted.

Dave

 

The .443"/.459" I stated was with 1.6 rockers. Stock 1.5's put the stock 88-89 cams at .415" / .430"

Maybe the Chiltons was referring to Lobe lift? (Before being multiplied be the rockers.) Or it could be a misprint.

Does anyone know how much the 1.6:1 rockers effect duration on these cams?? About 1 to 3 degrees at .050" maybe??
Jason in GA

:hail: *** for all He's done for me.

 

Good job Dave, you beat me to it.

 

Dave

 

Thanks for clearing that up guys, I think that they were reffering to the lobe lift.

When talking about lift, is it the valve lift that is usually quoted or the cam lift? I could understand that it would be the valve lift, 'cause at the end of the day, thats what matters, but most people say "I got this awesome cam with XXXX lift" etc.....

I'm just trying to learn whats going on inside my engine, as I know just enough at the moment to get myself into trouble

 

Yeah most specs are referring to the lift at the valve with zero lash and a stock ratio rocker arm.