Flat Tappet cam selection for 350 Vortec HSR
 

I've got a set of SDPC Vortec heads (machined for up to .550 lift) that I intend to put on the 350 I pulled out of my IROC prior to putting it into my GTA. The short block has forged flat top pistons with a stock crank & rods. It's an old block, and I don't have the funding to convert to an aftermarket roller cam. Currently it's got a 214/224 .442/.465 112lsa Summit cam in it.

I'm undecided whether I'm going to get the SDPC Vortec TPI base, or if I'm going to go to a Stealth Ram. Let's assume for this conversation that I choose a Stealth Ram. I'd like to get opinions for what cam would be a good choice, and what horsepower/torque numbers I might expect. What I would like to achieve is 300+ RWHP and 12.XX quarter mile times. In its current form with 461 Fuelie heads, Accel TPI base & SLP runners, the motor did 250RWHP (331torque) and has run a best of 13.6 @ 101mph.

Another option is to stick with the cam I have and convert to 1.6 rockers, but to be honest, a new cam is cheaper than rockers. :lol:

Almost everybody on here that's got a Vortec HSR has a roller cam, so I'm having a hard time finding good data. What says the peanut gallery?

EDIT: Just to add some more info, I'm not looking for a max-effort cam either. I want good street manners and a good, wide, flat torque curve from the motor.

Re: Flat Tappet cam selection for 350 Vortec HSR
 

Kickin around the stealth ram idea in my head, I was thinking about the xfi268...

http://www.jegs.com/i/Comp-Cams/249/...d=#moreDetails

Note the lift is with 1.6 rockers.

Howards has a huge variety of cams, I'd probably look for something with a 114 LSA... as big as I dared.

Re: Flat Tappet cam selection for 350 Vortec HSR
 

Still learning as I go but here are some tested combos from Holley. I went with the 30142 and 30lb injectors. My heads are 200cc intakes so I thought it would be better to keep the power band up a bit higher.


355 small block Chevy, 24 lb./hr injectors, Stealth Ram intake, 58mm throttle body, 20 degree Holley heads,
Lunati 30140 cam (225/235 @ .050, .477/.507, 112 LC), 9.5:1 compression, 43 PSI fuel pressure, 405 HP @
5500 RPM, 428 ft./lbs. @ 4600 RP

355 small block Chevy, 30 lb./hr injectors, Stealth Ram intake, 58mm throttle body, 20 degree Holley heads,
Lunati 30140 cam (225/235 @ .050, .477/.507, 112 LC), 9.5:1 compression, 43 PSI fuel pressure, 405 HP @
5500 RPM, 428 ft./lbs. @ 4600 RP

355 small block Chevy, 30 lb./hr injectors, Stealth Ram intake, 58mm throttle body, 20 degree Holley heads,
Lunati 30142 cam (235/245 @ .050, .507/.534, 112 LC), 9.5:1 compression, 43 PSI fuel pressure, 418 HP @
5500 RPM, 422 ft./lbs. @ 4700 RP

Re: Flat Tappet cam selection for 350 Vortec HSR
 

That cam is way big for your combo, good luck with that.
I would have done a 228/236 on a 113 with .532 lift, still a bit big but you'll have the lift you want with your existing rockers.

Just my opinion.

Re: Flat Tappet cam selection for 350 Vortec HSR
 

I've been getting mixed opinions on my choice. https://www.thirdgen.org/forums/engi...you-think.html What do you think will be the hardest part about tuning? Just curious as to why it wont perform? Holley seems to stand behind the combo.

https://www.thirdgen.org/forums/tech...-sportman.html

https://www.thirdgen.org/forums/afte...-ii-heads.html

This guys cam is very similar in duration to mine. http://www.lt1pcmtuning.com/z28/ People all over this board too say 112 LSA is not a problem at all.

Just looking for some evidence to back up your claims. Even if its circumstancial. If the motor doesn't scream when I'm done at least I can go back and consider others suggestions.

Can someone run a desktop dyno on what I got so far? Looking at approx. 9.8:1 compression

Re: Flat Tappet cam selection for 350 Vortec HSR
 

Not sure how tunable your ECM is. As limited as the Holley 950 was, yours may be even more so, but I don't know that one way or the other.
And Holley probably didn't drive that combo, it was a dyno mule.
That other build you mention has nearly the same cam as you have now, very mild. That's why he had no issues tuning it.

After more thought, check out anybodys Vortec heads. Very few flow much better at .550 than .500 lift, so why push the valve open that far, you'll lose port velocity.
I'd do one of my cams, maybe a 223/229 on a 113 or so. It would have .472/.477 lift with your 1.5 rockers. I'd try to keep intake vs exhaust the stagger at 10 degrees or below to retain throttle response.

Just my opinion.

Re: Flat Tappet cam selection for 350 Vortec HSR
 

Since this got dug back up, I figured I'd chime back in. I wound up getting an SDPC vortec intake, so I'm sticking with TPI. I also stuck with my cam and got a set of PRW 1.6 roller tip rockers. I've got a build thread going in the engine swap forum for those who are interested.

Re: Flat Tappet cam selection for 350 Vortec HSR
 

Still haven't fired my motor yet but I have been looking around for combos with a cam like mine.

What do you guys think of the this setup?
http://www.youtube.com/watch?v=1mSb-coZHyQ

He has the lunati BMII
http://www.lunatipower.com/Product.aspx?id=1781&gid=245

This Monte had a 3000 stall. I got a 3200-3400. Why would a car that runs like this not be a good street/strip car again?

As always I appreciate any feedback.

Thanks

Re: Flat Tappet cam selection for 350 Vortec HSR
 

Just found this too. Thought I'd add it for reference.

http://www.camaros.net/forums/archiv.../t-109110.html

http://www.superchevy.com/technical/...m/viewall.html

http://www.camaroz28.com/forums/3rd-...-383-a-465179/

Re: Flat Tappet cam selection for 350 Vortec HSR
 

Try a Crane HMV278-2 113801. If you want more intake valve lift use a 1.6 rocker on the intake side. 1.5 is fine on the ex side.
1.6 in and 1.5 ex rockers gives .498" in .494" ex with this cam

You won;t know the difference between this and a hyd roller with the same .050" duration. Compression ratio can be up to 10.5:1