Priya

I'm building a Vortec/TPI 350 motor. I have Arizona Speed and Marine large runners and planning on using 24 lb injectors. With the 64 CC Vortec combustion chambers my motor will have 10:1 compression ratio. After a lot of reading and looking at other people's builds I had planned on using the Iskenderian roller cam below:

Intake .485 lift, 217 degrees duration at .050
Exhaust .505 lift, 225 degrees duration at .050
Lobe separation angle 112 degrees, 44.5 degrees overlap, 8.00:1 dynamic compression ratio

The heads I'm looking at buying come with valves, springs, etc. and have a max lift of .480 inches. As budget is a concern I'm looking at the flat tappet cam below as it doesn't exceed the max lift of the heads and won't require me to adapt my 79 350 to a roller cam.

Intake .477 lift, 224 degrees duration at .050
Exhaust .480 lift, 230 degrees duration at .050
Lobe separation angle 114 degrees, 45 degrees overlap, 7.90:1 dynamic compression ratio.
Manufacturer's note: "Best cam for modified 350 TPI with improved chip, injectors, plenum, runners and exhaust."

As I've never tuned a fuel injected motor I'm hoping to use a stock 350 TPI tune on my EBL or at least not have to deviate too much from stock to get the motor running properly. There's quite a bit more duration on the second cam than on my first choice. Will this be too much duration for a good quality idle and driveability? Will the second cam require a greater amount of tuning from the stock settings than the first cam?

Orr89RocZ

iTrader: (20)

Tuned well it will work fine but why not work the heads over and put the correct springs in?

Abubaca

iTrader: (3)

I agree with Orr. ...not that much extra work really. ..and that first Isky cam looks awesome for TPI.

Priya

Cost is the reason. Not only will I not have to rework the heads, I won't need to convert my flat tappet 350 to roller lifters.

Orr89RocZ

iTrader: (20)

Also a roller cam is a very good idea, as there have been alot of flat tappet cam failures

Priya

I'd prefer the roller cam, but I'm thinking that's going to cost quite a bit more than the flat tappet cam. Also, I'm confused by what I've read is required to convert to a roller cam.

BadSS

What exhaust system are you running? Depending on what it is will determine the amount of split you need for the exhaust.

Priya

That's yet to be determined. I wanted to go with headers but my husband says I better stick to the factory rams horn cast iron manifolds as headers often leak which will cause havoc with the fuel injection. After that a dual exhaust no catylitic converters, perhaps an X or H pipe before the quiet mufflers.

Orr89RocZ

iTrader: (20)

Its all in the gasket and bolting if it leaks or not. Bolts do back out sometimes but the right gasket seals well and wont have an issue

TTOP350

iTrader: (8)

Do you have the 79 350 rebuilt or could you just sell that and step up to a -87-96ish roller shortblock? That's the road i'd go.

Priya

I hadn't really thought of that. The L82 350 does have 4 bolt mains and a forged crank though so its got that going for it. I'll give it some thought.

TTOP350

iTrader: (8)

That is nice to have but for the engine speeds and power level of a modified TPI, you really don't need 4bolt or forged crank. Just food for thought.

BadSS

I'm going to guess this isn't going in a third gen. True dual exhaust and dual mufflers are tough to run on them.

That said, as others have alluded to, I used to have all kinds of issues with header leaks until I started running these cheap lock washers. Use a quality gasket, tighten them after the first few heat cycles, and you're done.

http://www.speedwaymotors.com/High-C...t-12,1180.html

I'd advise deciding on the exhaust before buying the cam. Also, you really need to check the heads to see for yourself how much lift you can run. Most information leads you to believe the stock Vortecs can run as much as .480" lift, but the few that I've had my hands on were maxed out around .465". I'd guess it has something to do with the type retainers being used. I'd sure hate it if you bought a .480 lift cam and it not have proper clearance.

Priya

The heads I'm looking at aren't factory Vortecs, they're an aftermarket Vortec (EQ) with thicker casting and advertised .480 max lift.

BadSS

Good deal. Are you planning on porting the Vortec base? They're fairly restrictive as cast (don't flow much better than a stock TPI). The reason I ask about that and the exhaust system is that'll determine how much intake duration you'll need to run and the split on the exhaust.

Priya

No plans on porting the Vortec base. And assume factory cast iron rams horns with dual exhaust, no cats and an H pipe.

BadSS

With the true duals and unported Vortec TPI intake, I’d go with a custom from Comp using the lobes below cut on a 112 lobe spread – which is very similar to your first choice cam from Isky.

Call Comp direct – they’ll do a custom grind at no additional charge to THEIR normal price, but it is a little higher than an off the shelf grind through Summit.

Lobe...Adv….050”….020”---- Tappet Lift ----- Lift 1.5..1.6
5085… 262….218 ….131----.315 .060 .047-------.473 .504
5443… 268….224 ….137----.318 .070 .056-------.477 .509

Priya

Can retrofit roller lifters from a different manufacturer such as below be used with the Iskenderian roller cam? The only Iskenderian roller lifters I see are $974 U.S. - prohibitively expensive.

https://www.summitracing.com/int/parts/hrs-91164n

BadSS

Yes, you can run different roller lifters.

With the Vortecs and TPI,,, going with the hydraulic roller, assuming similar vacuum, changing springs to compensate for the additional (yet "reasonable for daily driving") lift needed to make any real difference will give you about 15-20HP over the rather maxed out flat tappet recommendation made earlier.

You don't have to spend a lot of money to go fast, but certainly the more money you spend the faster it SHOULD go. There's definitely a point of diminishing returns per dollar but at what point depends on you and what you want. For example, a set of long tube headers would give more average HP and TQ over a wider RPM band than the difference in an aggressive flat tappet hydraulic compared to a hydraulic roller for a lot less.

Priya

Thanks BadSS, very helpful!