Well over the years I have built some motors but for one reason or another I have not been able to just build one for fun. I am at a point in my life where I can afford to do it and I don't have to rely on the vehicle for daily transportation. I have found another IROC at a local used car dealer that has no motor or tranny. It was a TPI car but they took the harness and ECU out and I think it would be better off with a carb. The plan is to build a 383 for the street but I don't want it to be a pain to drive. Lumpy but not too lumpy, does that make any sence? The only thing I am having a problem deciding on is the cam. I want to keep the power brakes and don't want to have to get crazy with a high stall converter. Can that be done and still end up with a cam that make lots of power and has "that sound"?

Phil

 

It all depends on your goals, but the best thing I can suggest is call a custom cam grinder (comp cams for example) and tell them EXACTLY what you want, being extremely honest with your expectations, and see what they say.

 

the lumpy sound or lope has to do with the duration. call elliotts port works and tell him what u are looking for. he ll set u up. good place to get heads done to.

 

This is the stuff I don't understand. I know what lift, duration and LSA are but I have no idea how to read the specs and know how it's going to perform. I do know that the bigger the lift and duration the higher in the RPM range the power will be made and that is where the vacuum issue and the higher stall converter come in. Other than that, I am lost. Is there a general rule of thumb that can be used to pick out the low end, midrange and top end cams in kind of a general way. What lift and duration produce a good idle and low end power? The same for lope idle and then there's the "don't use this on the street" cam that I would like to stay away from. Thank's for the info.

Phil

 

There are alot of variables which will decide how cranky a cam is in a particular engine other than the cam specs themselves - compression ratio, cubic displacement and vacuum are a couple of them.

The duration and lobe separation are the specs you want to look at when deciding how streetable a cam will be.

A 230 degree cam with 110LSA will be quite cranky in a 305, but in a 383 it will be alot more sedate. A cranky cam in a 383 might be something like 250 degrees duration with 108 LSA, which would be basically undrivable in a 305.

For a 383 street cam in a car that isn't a daily, that will make good power and have that nice lumpy idle, while still be streetable, I would be looking around 230 degrees 110 LSA and around .500-.520" lift. Operating rev range will be from around 2000-5500 maybe 6000 if the heads and intake etc are up to the job.

Going for wider LSA will calm it down a bit, as will less duration, going more duration will make it lumpier and crankier.

Hopefully that gives you some idea of a good middle-ground for a 383 cam.

 

You can't imagine how much that helps. I knew I came to the right place. Thank's

Phil

 

Another thing to remember when looking at a cam spec sheet, is that the 383 is not really a standard size. Alot of cam manufacturers will quote cams based on a 350 engine.

The additional displacement of the 383 means more vacuum, and will dumb the cam down a bit.

So if a manufacturer lists a 222/224 .480" 112 LSA cam as having a lopey idle, good mid range and effective power band of 2000-5500, then you need to compensate for the extra cubes. So a cam like that will probably have a slight lope in the idle, good low to mid range and effective power band around 1700-5000rpm in a 383.

It works the other way too - if you were looking at a cam for a 305, you will probably need to compensate it up a notch - good mid to top end, effective range 2500-6000rpm etc.

 

sounds like fun, keep us posted with pictures of progress

 

I have built many engines and right there is your best answer!

 

I cant see it being too hard if you can put a ca18 in a datto.Has the motor got any work done to it?