mike40sm2

Re: camshaft help
Quote:Re: camshaft help
Quote:
Originally Posted by Apeiron
Any cam big enough to lope isn't computer compatible.

I have a 1988 tpi 350 pontiac engine the summit cam was fitted by someone else but cant i cant get it to run COULD the answer above be the problem????

I have fitted this camshaft below but having some issues with running right which I'm not sure yet if its the cam causing the problem or not???

Howards Cams 180245-10 - Howards Cams Hydraulic Roller Camshafts
Camshaft, Marine, Hydraulic Roller Tappet, Advertised Duration 278/284, Lift .500/.510, Chevy, 5.0, 5.7L, Each
Originally Posted by Apeiron
Any cam big enough to lope isn't computer compatible.
I have a tpi fitted with a 350 pontiac engine the summit cam was fitted by someone else but cant i cant get it to run could your answer above be the problem????

I have fitted this camshaft below but having some issues with running right which I'm not sure yet if its the cam causing the problem or not???

Howards Cams 180245-10 - Howards Cams Hydraulic Roller Camshafts
Camshaft, Marine, Hydraulic Roller Tappet, Advertised Duration 278/284, Lift .500/.510, Chevy, 5.0, 5.7L, Each

vetteoz

iTrader: (13)

The TWO most important numbers on that you didn't mention
Duration @ 50 225 int./231 exh.
and the LSA 110

A cam of that duration would certainly need a custom tune to run right and the LSA of 110 is at the lower end of recommended for EFI ( stock are 114+ ) .Would run nice with a carb.

A good tuner may be able to do something; otherwise given your location , install a more EFI friendly cam
Note
That is also a lot of duration for a stock(ish ) 350 engine; what other parts ( heads, etc ) do you have to support it?
You may end up with a much better working combo all round by installing a smaller computer compatible cam

mike40sm2

new cam now fitted should be ready to try starting her up this week hopfully

yaj15

iTrader: (3)

I agree with the other poster. Our early computer controlled cars aren't so friendly with respect to low lobe separation angles. With after market cams that have 112 degrees and lower lobe separation angles (lsa) you really need to start getting in to custom computer tuning.

The highest performance factory cams in the TPI cars had lobe separation angles between 117 and 114 degrees.

The wide lsa's allow for better idle quality and emissions performance. The trade off is power and torque curves that tend to be more peaky in nature than a car with a shorter lsa. With stock TPI systems though thats not really a problem because these intakes stock make power in the idle-5000rpm range anyway and most of the time you are on the street the engine is under 4,000rpm anyway.

Cars with shorter lsa's (consider 112 degrees and lower) have cams that have a rougher choppier idle because of the overlap parameters changing. These cams should also make more torque and power over a wider rpm range than a cam with wider lsa's. These cams won't also be as easy to pass a smog inspection if you still have to get that done. It can be done but you really are going to need to work with someone that knows how to tune a car with a lower lsa well enough if the car still has to pass the smog test.

To be honest once you start getting in to head and cam changes it would be very wise to get a tune specific to your application to get the best performance out of yourset up.

What are the other specs for your set up? The cam has to matched well to all the other components to get the best performance and so that you will be happy with the combination of parts that you have.