[72cat]

Alec wanted to know about upgrading his cat economically, and quite a discussion got going, we have most of what was mentioned already on our cougar but two things puzzle me, having spent the last couple of days in the company of V8 buffs, my head is reeling with talk of cams and diffs. Someone please explain this to me, patiently and in english, I know what the cam does, I do not understand the 'degrees', what is better and why. What is the diff ratio, how do I find out what ratio we have. I have asked and been given 'those' looks. When Logan talks about his cam being RPM, what does that mean, and what would he get as a 'badass' cam.
Help guys, I just need to understand to 'understand'.

Dayle

 

[clevelandcougar]

The degrees or duration of a camshaft tell you how long the cam will hold the valves open. Duration is measured by Advertised duration, or duration at .050 inches of lift. The more duration there is on the cam the longer the valves will be open. Lots of duration means more power, but this power is achieved at high Revolutions Per Minute(RPM), a cam with lots of duration is NOT good for the street.
In my opinion a good street cam has around 205 to 220 degrees of duration @ .050 inches of lift.
Logans cam, which you called an RPM, is made by Edelbrock.
RPM is just the name they gave the cam. Edelbrock makes two cams different cam one called the Performer, and one called the Performer RPM. The Performer RPM has a little more duration, and makes a little more power.

 

[72cat]

Thanks Cody, we were given a spare cam by the PO, he said it was a 360degree??, if its an old cam, and he has put an edelbrock performer intake cover on, maybe he changed the cam as well?. Anyway to tell straight out what cam we have in, without opening up anything, or is that just wishful thinking.

 

[clevelandcougar]

I do not believe that there is any way to tell how "big" your cam is with out pulling it out of the block. You would have to find the grind number or part number, then reference it with the manufacturer.
Good Luck
Cody

 

[72cat]

Thanks Cody, think I will just phone the PO and find out what he put in, might be a lot simpler. Now on to that Diff question, anyone able to help me on that one??????

 

[Cougar72]

Anyway to tell straight out what cam we have in, without opening up anything, or is that just wishful thinking.

Why dont you want to open up anything? Thats the fun part
Go out and get you hands dirty, get some grease under your fingernails:1poke: I dont know about this diff. stuff either so I'm reading carefully.
-kyle-

 

[72cat]

I know thats the fun part, but she's at the body shop [still] and I can't do anything on her till she comes home, then I won't want to anything but drive her for awhile, then maybe will open her up and see whats going on. We have just bought a Ranchero, 302, not quite sure what year yet, about 1970 I think. Now we will definately be getting our hands dirty on that engine, already bought the whole gasket kit etc. She goes okay but could do with a good overhaul.

 

[Alex]

Whose "Alec"?

 

[72cat]

Sorry, meant Alex.

 

[72cat]

Test?

cougman test

??

 

[MunchE]

Diff ratio I would assume you mean your gear ratio...

You can either decode the codes on your door tag, or check for a little metal tag hanging off of the pumpkin on the axle.

My car is a god awful 2.80 ratio.

I need to get my 3.77's.

 

[72cat]

My axle code on the door tag is 2, which is 2.75:1, I think. Spoke to a gear guy here today and he said I must find out what size rear end the cat has, posi I presume, any ideas on how to find that out, then he basically told me I did not have a hope in hell of finding another diff here in SA that would be the right fit [2nd hand] and it would cost 1000's to get one and so on. Kinda turned me right off even looking for one.