Charly

Yes, it's a truck question, but please read on......

hey,

I'm thinking about putting in a 'different than stock' cam when I do the rebuild (which will be soon).

It's an 89 350 TBI, non-roller, for now I'll keep the stock manifolds and heads. I obviously want torque at or near idle and up to about 4500 at least. I realize the stock cam would be near perfect, but was wondering if I could go one step up.
I hear staying at 112* LSA is best, but I'm not sure if these 111" (one was recommended directly by Comp, but they said it was 112, there spec card says 111) cams will be OK.

Here are four that I am considering (all Comp) duration is at .050:

PN 12-304-4, 201/206, 406/406, 111

PN 12-388-4, 206/212, 425/440, 112

PN 12-249-4, 206/212, 434/444, 112

PN 12-231-2, 206/214, 432/453, 111

Stock (I hear) is about:

194/203, 395/415, unsure on LSA

Comparing 12-388-4 vs. 12-249-4, for example, would more lift with same duration be better for the lower end?

Concensus seems to be that the duration and lift of all of these will be fine with the stock chip, not sure about that LSA though.

Tranny/tcase will be NV4500 (w/ 6.34 first) and EB D20 (2.46) with 4.88s and 38s for wheeling, 35s street/winter. This will be primarily a crawler, with street duty


Your thoughts?

thanks,

Charly

iroc22

I dont think that the TBI truck cam was more than 200 dur and .400" lift. If you;re truck is goin to be primarily a crawler, then stick with the lower duration with a lower LSA. The 12-304-4 seems like the best cam for the job to me.

PaulD

Are you sure it's not a roller. If it's the stock motor, it's a roller.

iroc22

Its not a roller. Only the Caprices and F-Bods were roller.

Charly

This 350 is a truck engine, came out of a van actually. It definitely is not roller (nor is it machined for one).

So is the 111* duration gonna be Ok with a stock chip?

How crucial is staying at 112*?

iroc22

The higher the duration on the cam, the more LSA you need. The stock cam uses a LSA of 109

Charly

Thanks.

Are you referring to the stock cam in my truck 350?

Anywhere I can find a definitive list of the stock cam specs?

JuGrNuT350

Ok so the TBI 350 in my truck isn't roller?!? WTF thats the first time I've heard that? Or did they change to roller in 90??

-Timbo-

iroc22

The trucks weren't rollers until '96. They do have the block machined for roller setup though

JuGrNuT350

So if I wanted to make it a roller motor then I would need lifters, & a roller cam? Is there anything else that I would need what about the timing chain? I have a hdr. flat tappet cam right now correct?

Thanks,

-Timbo-

iroc22

yes it should be the flat tappet right now.

You will need:
the retainer spider(i think its called that)
roller lifters
lifter retainers
roller pushrods

I think the timing chain might be the same, not sure though. The above list is what u need if you want to run the stock roller setup.

Charly

My 89 truck block definitely does not have the machine work/mounts for the roller setup.

And I chose the 12-388-4 cam.

Charly

Chevyman69

On the roller thing, everyone else is correct GM trucks are flat tappet if they are a a pre 96 TBI motor. All Vortecs are roller but no truck TBI's are. My truck( the 92) is setup, I would have to drill and tap the the holes for the spider but the bosses are there to change mine to a roller cam. I am guessing a 90 is the same but since its flat tappet i would run an aftermarket roller setup, they are stronger and can handle more cam anyhow.

brharris27370

My 92 Truck L05 350 had the holes drilled and tapped for the spider. I just bought all the LT1 stuff and converted it over. HUGE difference over that whimpy stock cam. I changed the springs too since stock it had a 4500 rpm redline. Pulled very strong to 5500rpm after the change.

iroc22

I've found 350 truck engines that are roller blocks but have flat tappet cams

kevm14

It did this with no changes in programming or injector swapping?

brharris27370

More gains could have been made with a chip but it really did run great. I had an adjustable fuel pressure regulator set at about 12psi. I also set base timing to 6 degrees instead of the stock 0 degrees. Other than that it ran GREAT. My truck bone stock got 16mpg in town and 20 on the highway. When I changed gears from 3.08 to 3.42 it dropped 2 mpg across the board. After the cam installation I gained 1 mpg across the board. So with gears, headers, high flow random technology 3" cat and 3" dynomax catback with LT1 cam I only lost 1 mpg over a bone stock truck. Its powerband felt exactly like the LT1 cars that I have driven. I was just inhibited a little by the fact that the truck weighs considerably more but it was fast. Faster than my L03 Camaro with its mods.

Lowaholic

Hey all. Not to beat the proverbial horse here, but are we positive no pre-'96 truck TBIs were roller? I've got a '90 L05 in my S10 that I could've sworn for some reason was one. I've also got a '93 L03 in pieces that definitely is roller (disassembled it myself a few months ago). Anyways if the L05 isn't like i thought, I'm assuming I can carefully place the current plans for the LT4 cam in the crapper? Tell me it aint so... <IMG SRC="http://www.s-seriesforum.com/forum/images/smilies/cussing.gif">

brharris27370

If it is a truck L05 then its flat tappet and only the Caprice classic L05's were roller.