Still trying to pick a cam for my L98. I have a list of a few that i'm considering.The only difference between them is the duration. The lift is pretty near the same on each cam. My question is how does the duration affect the performance? I know it has to do with the powerband of the motor, but exactly how? Less duration makes more low end, or vice versa? Here's two of the cams I'm looking at:

Comp 210/220 .480/.480 112lsa
LPE 214/224 .476/.496 112lsa

Any advice or suggestions welcome!

 

Hey,
more duration moves the effective powerband up higher. Less would have more low end.
I would go with the first one for a tpi. I ran that same cam and had good results. Its the 08-302-8 right?

 

Yeah. Thats the one! How did the car run with that cam? How did it sound? I love the lopey idle....but who doesn't? You see, I'm worried about having all of my power down low and not enough on the top end. Did you have this problem? I only have 3.27's in the rear, so this should solve some of that if the problem does come up. I'd like it to be hard off the line, but pull through 4500-5000 too. Let me know what you think. Thanx.

 

Just some info on that combo.
It was a 2 bolt 357 10.2:1 cr
Aluminum L98 heads with LT4 valvespings
Stock TPI components, slightly ported base and plenum
Comp 08-302-8 cam
1.6 rr's making around .512 lift
Edelbrock TES headers
19# 305 injectors
Performance Resource chip for a 305 with 19# injectors
stock auto and conveter with 3.73 gears

I never got the most out of this setup as I could, it hydro-locked in a flood.
I had a best time of 13.7 @ 101 on street radials.
It had a noticable idle, some lump, you could tell, no race cam though.
It idled great, had great vacum
The cam is rated to 5200 rpm, it seemed to run out of steam around 5500. Had a strong low end too.
So if you want great low end and still pull thru 5k, this is a good cam.
Can't think of anything else, feel free to ask about anything though.

 

Cool. Thanx. You think you would have been able to pull a 13.30 out of it? Thats what Im looking for.

 

Oh deffinatley. the 13.7 was on street tires, on a 2.05 60'. Stock torque converter and suspension. If I could have run a 1.7 or so 60' with slicks and the converter I have now, that would have been at least a 13.4, probobly better. then theres the "not so good" tuning and restrictive TES headers.
I could see a low 13 at over 103 with everything right.

 

Can you remember what pressure you ran the 19 lb'ers at ? What do you think of the PR chip ? Also, what is hdryo-locked ?

thx,
RP.

 

It's been a few years since I ran that engine, but if I racall, it was around 48 psi.
The PR chip was OK. I bought it when I ran a TPI 305, it didn't help performance at all on that engine, it did run better with it though. On the 357, I couldn't even run the stock 305 chip, so I continued to use the PR chip, it seemed to work fine. The extra fuel programmed into the chip helped to feed the larger engine.
Hydro-locked is when the engine sux a bunch of water in through the intake. Since water is much, much harder to compress than air, usually something goes in the engine. In my case, in bent a rod real good and siezed that piston in the bore. I also think it cracked one of the heads too.

 

I've decided on the 08-302-8 cam. Now I need springs. Which did you run? Comp reccomended the 941's, but I've heard they don't like to last too long. Any recomendations? Thanx

 

Water is Incompressable, actually.

 

Incomressible, even worse!
Nasty, I ran the GM LT4 springs. They are around $35-$40, maybe less depending on where you get them. I got them for $40 through my engine builder, and that includes his markup. Check Scoggin Dickey.
Never had a problem with them at all, don't remember any valve float at higher rpm's either. They fit in the stock spring pockets too if I recall.

 

SWEET! How's this sound to you guys...?

Comp Cams 08-302-8
LT4 Springs
1.6 Roller Rockers that will boost the lift to .512
Slightly ported/polished iron L98 heads
Accel large tube runners
ported base and plenum
KB Hypereutectic pistons
Hooker shorty headers with exhaust cutout
Rebuilt 700 R4 with shift kit
2800 stall converter
Maybe a little N20 later on down the road.

Any commments and suggestions are welcomed. They're actually invited!!

 

Just my 2$-- WHY-- go with 1.6 rocker's- when you are putting in a new cam?? 1.6's are a pain to deal with and unless you know your rocker design and setup you will have wear and alignment issues. just get a cam with the spec's you want at the stock ratio! by the way my cars idles at 700 nice lope and great response, i think its the 305-8(see sig) i am glad i did not go any smaller. size does matter later Mike

 

Sounds like a decent combo nasty bird, should yeild what your looking for.

I would Probrably Skip the aftermarket Runners, and Siamese the base deeply Myself, But The validity of that is still up in the air.

There was someone who was going to make a run on a siamsed base this weekend, I forget who it was. That should help us see How well it actually works in "normal" applications.

 

Also, Make sure to get screw-in Studs and the valve guides cut down to accommodate the Lift.

I don't see any reason not to use 1.6 Rockers providing these two steps are taken.

 

Thanx fellas. I'm using the aftermarket runners only because I got them with the motor. As for the rr's, thats something later on down the road. I couldn't find a cam with the exact specs I want. The 302 is it, but it just doesn't have the lift. So I'll solve that with the 1.6's if I want to later on.

What are the specs on the 305 cam? It's not in your sig

 

Sounds real good Nasty, should put you where you want to be.
Bort, why would he want to siamese the base with stock runners? I can't see it helping unless he had fully siamesed runners. would it make a difference to join the runners after they are already separated?
I'd gut the base and get some large tube runners and possibly port them too.