ash

Summit Racing offers a gm performance parts 350ho/330hp. When equipped with a roller cam and lifter kit will this work as a TPI set-up in my 86 Iroc? Here's the web address for the engine. http://store.summitracing.com/defaul...NAL%2D12486041

1981LT1

iTrader: (1)

I might be wrong but I don't think you can replace a flat tappet cam with a roller cam. Other than that, it looks like a great motor.

ash

Actually i Happen to know that just the opposite is true. Often times by switching to a hydraulic roller cam you will see better performance due greatly to the aggressive ramp speeds that a hydraulic roller cam will offer. Not only that, but the GMPP 350ho/330hp[http://store.summitracing.com/defaul...NAL%2D12486041] is already equipped with a hydraulic flat tappet. The only thing that I really need to know is whether or not my intake will bolt onto this engine, and if there would be any other prohibiting factors. Sorry, I guess I should have been more specific about that. Any help as far as that goes?

five7kid

iTrader: (14)

No, a factory TPI base will not fit that engine.

If you want a Vortec-headed TPI crate engine, go here: http://www.sdpc2000.com/catalog/1578...rip-Engine.htm . You'll still need aftermarket runners, 52mm TB, and headers to produce the power.

If you want a weak-kneed 350 HO with TPI, get their base only http://www.sdpc2000.com/catalog/1460...-Baseplate.htm . The 330HP HO crate engine block is set up for the factory roller cam system. It just doesn't come with a roller cam. Just putting a roller cam in won't get you the power, because the heads can't handle the lift required to get over 330 HP with TPI. Hence the upgraded heads used on the 360 HP Vortec TPI crate.

ash

Thanks, but I'm a little confused. Is the intake for use with GMPP 350ho/330hp? Also, i am well aware of the inadequacy of the stock valve springs, which is why I am going to use a set of Comp Beehive springs (pn 26918). Using these springs will allow me to go with a more aggressive roller cam without requiring extensive machining to be done to the heads. The cam I plan on using is the GMPP Hyd. Roller Hot Cam Kit (pn 12480002). This combo, along with a an Edelbrock Performer RPM AIR GAP manifold, Holley 750-cfm 0-4779 mechanical secondary carbeurator, 15/8- inch headers, and a performance exhaust system puts out 401hp/428ft-lbtq on a dyno. I figure that with a 58mm tb, Mac headers, Mac off-road pipe, Mac performance cat-back exhaust, large tube runners, and ported plenum I should see about the same results. Also, now that I think of it, do you think that a modified lt1 intake from www.lt1intake.com would fit this engine?

five7kid

iTrader: (14)

The base is for use on Vortec intake pattern heads. The crate engine includes the base.

The problem with valve lift is not limited to the springs. Although the beehives would be a great upgrade, the retainer-to-guide clearance will not be adequate for a Hot Cam installation. You need to cut the guides as well. Screw-in studs, or at least pinned studs, would also be a good idea with that much lift. That is all included in the upgraded Vortec heads used on their crate engine.

As for the modified LT1 intake, the FAQ on the link you posted includes the following:
"Will the LT1 intake fit Vortec heads?
"No, it will not fit."

I think you'll find that TPI severely cuts power vs. that carb/Air Gap combo. That's the same cam SDPC uses in their TPI Vortec crate engine, and they got 357 HP. A 58mm TB isn't going to make that much difference. However, I see they now have a "high flow" Vortec base, but I haven't heard anything more about it. Maybe the extra $40 will help make up more of the difference b/t carb & TPI.