Vortec cam upgrade

[chevy355s10]

been blowing thru the thousands of threads that popped up on google and have a cam question.

They keep talking about the HT383 cam being a perfect upgrade for a stock vortec 350 without changing springs and such. I will be running a carb,good intake, longtubes,and 2-1/4" duals with flowmaster knockoffs.
has anyone done this? how did you like it. cam specs are as follows
1.5 rocker
intake @.050 196*
I: .431"
exhaust @.050 206*
E:.451"
LSA 109*

 

[rich weyand]

What are the "advertised durations"; this will be a larger number, from the time the valve first opens to the time it is completely shut. That combined with the .050 durations will tell you how fast the ramp is, which gives you some idea if it is a modern grind or old school grind.

 

[chevy355s10]

288/308

 

[rich weyand]

When you subtract the .050 durations from the advertised durations, you get 92/102, which is a very slow ramp. The reason it matters is that the .050 durations affect how much you can flow, which is horsepower. The advertised durations tell you when the intake valve finally closes (late!) and when the exhaust valve first opens (early!). Late intake closure reduces the dynamic compression at low rpms and costs you torque, early exhaust opening dumps the charge early so you don't get everything out of it, costing you torque at low rpms as well as fuel mileage.

A modern cam has ramps of 40-50 degrees. Most old school cams are 70-80. 92/102 is way slow.

Look at Comp Cams 12-238-2, for example. (which would be a good choice, BTW, though you would have to change springs, I think)

Or look at 12-300-4, which would be a stump puller. No springs change.

 

[chevy355s10]

the cam that my engine came with and the cam im asking about,are both hyd rollers. I would prefer a roller,just for ease of mind. that being said, isnt there some kinda weird rule you have to take into account when figuring ramps of a roller cam?

 

[rich weyand]

Ah. Can't help you there. I have zip experience with rollers.

 

[kleedus]

I got the ht 383 cam for my vortec swap in my 90 crew cab.

the motor is built the same as the gmpp ht383e using the ht 383 cam.

but I have not got it running yet so I cant say how it runs

 

[chevy355s10]

I know its literally the same cam they use in the ramjet 350. the only difference between a vortec 350 and a ramjet 350 is this cam and the different fuel injection. seeing as ill be using a carbed intake,headers and this cam...it should be at least the same numbers as this...
http://www.hotrod.com/techarticles/engine/113_0307_gm_performance_parts_ramjet_350_crate_engine/