Cam Timing???? Help Please

I have two NOS Isky roller cams for my engine. Both are very similar, but have differences. Can someone explain the differences and what those differences mean. Both cams have 505 lift at the valve. The difference is in the opening & closing times of the valves.

Cam 1 (Isky RR505A):
int opens @37, closes at @73
exh opens @73, closes @37

Cam 2 (Isky RR505C)
int opens @52, closes @88
exh opens @88, closes @ 52

Is one better at something than the other?

Thanks

 

Generally if the valves open and close at an earlier time, there will be more low and mid range torque, but could sacrifice some on the high end. I think your cam 1 would have more low to mid range power than cam 2 and cam 2 may have a bit more at the high end. I'm no expert however.

Nick

 

Cam #2 more radical....has 140 degrees overlap
Cam #1 110 degree overlap

 

Tell us about the rest of the motor...

 

This is correct...

 

The 505C is a high rpm race cam. If you have heads and rest of the engine to support a power curve that starts at 6000 rpm, and that is the use you have in mind, go for it. I had my 505C reground to a little more realistic numbers for a Packard motor.

 

Call Isky and ask them. They are very easy to talk with and have been very helpful to me.

 

Cam #1 has 290* duration and cam #2 has 320* duration. Cam #1 would be more of a torque cam and cam#2 would be a serious rpm cam. Bump the rocker ratio up to 1.6 on the second grind wich would make the lift come out to roughly 540 and that would be a good rpm piece>>>>.

 

I was about to say the same thing.

I run a pretty mild cam that I run a little bit on the slow side (don't ask for numbers please its a Pk'n'Bner thing). Made a 7K mill with a 52-5500 cam.

Given options I would probably start with the slower cam and if it proved to be too much cam swap in the faster one.

 

You need to tell us a bit more about the entire motor package, transmission, rear end ratio, intake/carb, exhaust, car weight and what you want to do with it. The second cam is much more radical than the first -- total duration and overlap is quite a bit bigger.

Without knowing the answers to the above questions, we're just throwing sausages down an alley . . . hoping they hit something

 

You damn c-bus boys go about *** all wrong. And I figured he should just put the big cam in... big cams make more power, right? And Nothing sound better than an over-cammed motor struggling to stay alive on the street.

 

If you wanna get technical about this give me the #s at .050 and the valve lash. I'll enter the data into my trustee computer and we'll see what will make the power>>>>.

 

OK, thanks for the input. I am not sure I will use either one. Both seem to be kinda radical for my needs. The engine will be a 1958 410 MEL (Edsel), 10.0 comp, cleaned up heads (these baby's already have huge ports), single 4 barrel, C-6 ******, vertex mag, headers and 3:70 gears. The engine will put into my 1959 Ford Ranchero and will be used as a tow truck for my AA/F Coupe.

 

Given your application, you're probably making a wise choice to put something a little less radical in the car -- especially since this is a tow vehicle where you need lots of low-end torque. You probably need a cam with .450 - .475 net lift and about 220 - 230 degrees @ .050 duration. That is just a wild *** guess - as I don't know the available cam profiles for your motor.

 

Agreed. Smaller cam is a better choice of the 2, but probably not ideal.

 

These Isky roller cams really are good for wall art only. They are from the late 60's or early 70's with very gentle ramps because the spring technology was not there in that day to have a high lift cam like modern roller cams have or even flat tappet cams do today. The RR505B version of this cam had 258° degrees Duration at 0.050" lift with only 0.505" lift like the A & C versions!!!! Any modern day hydraulic flat tappet cam will far out perform any of these cams especially for your intended application of a street motor for towing. Even the origianl stock cam would be better than one of these on the street with and automatic trans. Something in the range of 0.475"-0.520" lift and duration @ 0.050" lift of 204°-220° is good for a towing cam. 204°-213° is considered a light towing cam and 214°-220° would be considered a heavy towing cam.

Roger

 

#1 for a good daily driver
#2 for raising Hell!

 

Thanks guys, This helps. I do have another NOS Isky FT cam for this engine. How about this one.

Isky E-6 FT
Int opens @ 35and closes @ 35
Exh opens @ 75 and closes @ 75

I want it to provide good reliable low end pulling power. Of course I also want it to sound bad *** at idle. I could have any of these cams re-ground, or even the stock one re-ground. The idea of running a roller cam sounds cool, but are they reliable for my application? What do you guys recommend? FT, RR, or hyd? What would be a good powerful, but reliable grind and who should I use?

Thanks for all you ideas.

Beep

 

I forgot, the E-6 FT cam has 407 lift