I was wondering if someone could tell me a bit about camshaft basics. I have just picked up today 2 camshafts I have had reground by wade to try out in my sedan as the unknown cam I have in it drops off power at about 5500-6000rpm, has great torque and really pulls from 4000rpm but just not for that long. this is what has prompted the thought and I haven't found anything yet that puts it simply for the novice.

All the cams that have high durations seem to have a power range high in the rev range, What do you need in a cam to produce torque?

Get the 733a..... it was great in that lpg system. Woke it up nicely. Unless you like to pull.... I like to push

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a rule about cam, and carburetors: when in doubt, get the smaller one

Low rpm torque is better with shorter duration cams.
Mild cams are much easier to live with.

You have lobe height, lobe center seperation and lobe width as variables.

A taller lobe opens the valve further but the springs must have enough room between their coils so they don't contact (stack). They require more force is from the springs at high rpm to close the valves.

Wider lobes(more duration) give better breathing and higher rpm. The springs have to be up to the incrased rpm to prevent valve float.

Lobe centerline is more difficult. In my work with Mercruiser 3.7 liter 4 cylinder engines, it was important to have 115 degrees between the lobes. I will look up the reasons.
I ran another 4 cylinder engine of that size with 112 degrees between the lobes and it seemed ok.
The little 1200 engine will differ in its cam requirements from the larger engines.

Quote:Fit a stock A12 cam. Pulls from 3000-6000 RPM. Drops off at 5000 with the stock carburetor, but will pull hard to 6000 RPM with a larger carburetor. And still idle smooth at 600 RPM.

For a lower RPM range you can go with a shorter duration camshaft -- shorter than stock.

Increased valve lift is a ticket to more torque at full throttle. Cleanup the bowls on the cylinder head will help too, regardless of RPM.

I didnt know a series cams fit in L series dd???? You truly do learn something new each day

It won't fit.

Stock L20B cam is mild for the size of engine (same cam as was fitted to L16 SSS, where it was a 7000 RPM cam).

this link is good for explaning camshafts:

http://www.jalopyjournal.com/forum/sh ... &highlight=cam+lobe+angle

I reckon the 72 degree cam will be perfect. This is what I was going to use in an L18 in a Sunny, that cam will now go into an L20B with a 32/36 DGV in a different Sunny & be road registered (fingers crossed). Was assured by both Stewart Wilkins & Arthur Jackson, both have other 30 years experience with L series, to use this cam. Good torque can also rely on port size,too big a port size can stall the air & cause delayed acceleration, usually when your trying to keep up with traffic, & somebody jumps into the gap just as the engine comes on cam. Good luck, sounds like the cam you had was a stocker, like my L18, which stopped dead at 5300 rpm.