am wanting to install a jm-18-20 cam in my 330 th350 cutlass to give it better bottom thump, it has the 23/2600 stall converter now and am also replacing the valve springs that with the kit? somewhere around 100 lbs, am I going to be ok with this? really getting over my head some but want the thump idel and more torque but will never use it as am done with racing just trying to go back to my days lumpy idle good sound hard shifting. thanks folks, ....jim

 

Jim,
Not to knowledge-able on cam selection but would comment that hard shifts would be achieved through transmission valve body work and real torque through the use of a big block. If you want some driving satisfaction with the car you have probably getting some throaty dual exhausts are the most bang for the buck, pipes as straight as possible.

 

my olds has 2 1/2 pipes w/flowmasters, th350 trans w/2300 stall, 355 posi, 255/60r15, was hoping that the above named cam would be a good one/ what would need to be changed?, valve springs, rocker arms, push rods, if so which ones would be needed? would like to run roller rocker's, would do you think?....jim

 

ANYBODY?

 

Again, I can't comment on that particular cam and don't feel qualified on cams in general. I do know that roller rockers aren't used unless the cam lift profiles are much greater than .500. If that cam has a profile like that then perhaps roller rockers would be needed. Not sure.

 

I cannot speak for anyone else, but, I have not replied, because this is not a language that I understand.

Norm

 

JOE P CAN YOU HELP?

 

JM-18-200.4880.496260°/266°216°226°112°1000-5000
$149.00 StreetHL-230
555-H
555-HCRSK-247-SPSK-245-DTR-252
TR-499ARK
SAR110-140
I assume by "bottom thump" you mean a cam with a rough idle? This is not the one you are looking for.

 

I hate when my motors get a bottom thump.
Especially if there's a rod sticking out of the side of the block.

 

But it is a good cam for a SB street car with his set up. It won't idle like a W31 though just a slight lope. You might be better served with the JM 20-22 cam w/ a true 9.5-10:1cr.

 

thank you wireman, Ive decited to go with an eangle cam, 512/524 lift,104 lobe separtion, 274/280, duration, lots of low end torque, 1500 to 5000 range,roller rockers, guide plate's and push rods.

 

Keep in mind most recommended rpm ranges are for the long stroke Olds engines. That cam will be a little rougher in a SB short stroke Olds. What captjim preaches is true, most have a tendency to over cam the SB. That cam sounds good though for your setup. Post it up on YouTube when your done, so we can hear the music...

 

IT WILL BE DONE ABOUT MID JAN AND YOU ARE WAY OVER MY HEAD AS TO UTUBE, MAYBE ONE OF THE SONS CAN HELP,

 

I certainly am not a cam expert or probably even a good novice but with the specs on that cam, I wonder how much low end torque you are really going to get. It seems pretty radical. I bet it will have one heck of a lope. It looks like you have the gears and the stall for it.

 

Make sure you get the correct lifter bank angle.

 

I had that same cam in my 350, the JM 18-20. VERY mild. But I know why. When I checked it in the engine it had almost 10 less degrees of duration @ .050 than it was supposed to. Also had less lift. I was not overly impressed.

Engle is NOT the only cam choice for ANY Olds. There a lot of good cam companies out there that will grind you one or already have the cam you need.

If it's the wrong cam for your application then it's the wrong cam period, no matter who's it is.

 

YOU ARE RIGHT, IVE DECITED TO GO WITH MONDELLO'S 22-25-10 CAM IN A 1975 350 WITH 65 330 HEADS, WITH OTHER SLIGHT MOD'S.

 

I understand what the terms lift and duration are but how would one measure those dimensions of a cam in the car, or out of the car for that matter?

 

Dan
You use a degree wheel and a couple of dial indicators. Usually done when you are putting the engine together. What they call dialing in the cam or sometimes called degreeing the cam.

Gene

 

Lift can be measured with calipers. The diameter of the base circle (heel) at its shortest point, subtracted from base circle to the highest point of the lobe.

All specs are checked, using a lathe or similar fixture, and degree wheel, the same way as its done in the engine. No problem for a competent shop.

Norm

 

Thanks guys, after posting my question and reading your replies I realize I had known about that. I guess that is showing my age (not sure what is going faster, my body or my mind).

 

I thought you were asking, for the benefit of the new guys.

Norm

 

I am embarrassed in two ways now. First, for being a dummy and asking a question that I already knew the answer to out of plain forgetfulness and second for not watching out for the people here on the sites. DOH!