Freshening up my Ramjet 502

[chevynut]

If you really want to make bragging rite power, even at high altitude, why not just blow it?

The car is already built and I'm not looking for a 200+ HP gain. The intake stuff is fabricated. I'm not taking that step now. The next one will be supercharged.

[chevynut]

Actually I find cam choice has too many personal preferences and variables associated with it and its about like trying to advise someone what to look for in a wife.

That's the way it was in the 60's when people didn't understand cam design. Now it's more of a science than an art. Get up to speed.

[Rick_L]

If cam selection is so straightforward, why are there 73 posts in this thread with you asking a LOT of questions? Just sayin'.

[chevynut]

The real issue I'm trying to address here is I've read several places where people say the stock 502 cam is "small" and it's been said here too. It never sounded "small" to me and it's "bigger" than a lot of them being sold for street performance.

So with that in mind, it looks like there's still room to improve the cam specs and gain some performance, cheap, especially considering my altitude. I probably won't do it for a 10-20 HP or 10-20 ft-lb torque gain...that's only 2-3%. As I said, I want to see around 550 HP and 600 TQ if I do it at all.

The valve springs and valves are some of the best sold by GM, probably made by others. The aluminum heads are made by Edelbrock. I shouldn't necessarily have to change lifters, pushrods, valves, or springs to use a bigger cam based on what I've researched, but some of that isn't very clear. I don't want to unnecessarily overload the components with too heavy springs for 6000 RPM. I am planning to change to roller tip rockers anyhow since they apparently fit under my valve covers. I just think they have to be better than stock.

I'm not too hung up on doing this, but now is the time to decide and I want to make the right decision so I don't regret it later....either way.

[chevynut]

If cam selection is so straightforward, why are there 73 posts in this thread with you asking a LOT of questions? Just sayin'.

Probably because I don't understand all the parameters, but there are those who do. Apparently it's nobody here.

[markm]

That's the way it was in the 60's when people didn't understand cam design. Now it's more of a science than an art. Get up to speed.

I have bought cams for my 55,56,4 Camaros and 1 Corvette and am happy with performance on all of them, besides I am not the one posing the questions. Too bad you don't have automatic so we could talk torque convertors and stall speeds.

[Rick_L]

My recommendation to you is that you have a bunch of comments and have done some other research. Make a decision and get on with it. The only way you are going to get any better on this is to actually do it and get the experience. Then you can decide whether you made the right call and can use that to either modify what you have or apply your experience to the next one.

I learned a long time ago that once you get anywhere near the right cam, all the other similar choices really don't matter. There's not a whole lot of power in nit picking camshaft decisions.

[chevynut]

Here's what I think I've learned....

Increasing duration doesn't increase torque, it just shifts the torque curve upward.
Increasing lift increases torque, and helps at high altitude.
.050" duration doesn't really tell how "lopey" the cam is at idle.
79 degrees overlap is a lot.
.050" overlap and overlap based on advertised duration differs a lot.
A wide LSA increases engine vacuum and decreases overlap for better idle.
Big engines perform better with a narrow LSA (if max power is the goal).
A narrow LSA moves torque downward in RPM and increases maximum torque but narrows the torque band.
A wide LSA moves torque upward, decreases torque, and widens the band.


So regardless of what I end up doing with my 502, I've learned a lot. Maybe I should have started a new thread on "Cam Design" instead of putting this all here.

[hutchenc]

Ahh the pitfalls of asking a question like this on a forum. I'm no expert, but I know that picking a cam for our altitude isn't the same as doing it at sea level and that is lost on most people because they don't live at altitude.

So, like I said, pick up the phone and talk to someone who does know. When I had Mike Jones spec out my cam, he increased the lobe lift on the intake for precisely the same reason Chris Straub said...a bigger intake charge because we have much less air density up here. He also lowered the exhaust lobe lift and slowed the lobe down a bit in terms of duration.

Not many off the shelf grinds are going to be optimized for altitude. Probably not one actually.

The other thing, outside of a custom ground cam that I would consider is simply running a higher ratio rocker arm to increase the lift. You mentioned changing those anyhow...why not go to a 1.8:1 while you're at it and maybe leave the cam alone altogether? Not the perfect solution, but inexpensive and pretty easy.

[Troy]

Just go get a 3/4 race cam and be done with it!!!! LOL