Need a little input from all you cam guru's. New engine build and I have 3 cams to choose from. Build so far, 272 bored to 292, 5cc domed pistons, G heads w/ported exhaust ports, Block & heads resurfaced just to make everything straight, Rollmaster timing chain set, 'B' intake w/600 cfm carb (may go to 3x2 later), 57 exhaust manifolds or Reds headers, T5 trans & 3.50 rear in a 57 Custom 300. I was told the compression could be close to 9.7/1. Not really looking to race it, just looking for that "saturday nite cruise" lope when you pull in somewhere. But I'm sure I'll blow the cobwebs out occasionally. Here are my choices:

Isky RPM 300 Adv Duration = 270, Duration @ 050 = 228, Lift = .448, Lobe sep = 112

Mummert Y270s Adv Duration = 272, Duration @ 050 = 224, Lift = .440, Lobe sep = 108

CompCam Adv Duration = 264in 268ex, Duration @ 050 = 234in 238ex., Lift = .528in .536ex, Lobe sep = 110

Whatever cam I run I would like to run it 2° advanced to keep the power curve on the lower rpm side. I already know that the CompCam will have to be run straight up because of piston/valve clearance. Opinions,

Thanks,   Dan

Dan      Kingman Az.      86409

I'm coming up with compression closer to 9.07:1 and since the block is only cleaned up, it's probably much lower. Consider zeroing the deck while you have it apart.

I wouldn't consider myself a cam guru but I think either the Isky or Mummert will do the job. I also think they'll be fine straight up. Since only the exhaust has been ported, I probably wouldn't use the Comp, plus the piston and valve guide clearance issues.



Lawrenceville, GA

I'm no cam guru either, but I've been warned against over-camming and over-carbureting... the two most common mistakes of novice hotrodders.



My engine is similar to yours... 292 .040 over, zero decked, 113 heads shaved to 67cc chambers, flat pistons, stock t-bird exhaust/2" all the way back, B-intake. This is 9:1 SCR with composition gaskets. Stock ford-o-matic.



I ran a Holley 4160 600cfm for a while, but I like the response from a 465 better. I chose a Mummert Y265 cam and I couldn't be happier... plenty of torque, good match for the ford-o. Very cool rumble at idle & around town, but a mean snarl when I punch it. Very tractable and predictable power, from parades to back road blitzes. I wasn't looking for huge top end power, but I got what I wanted.

Skygager.

Do you know what the intake manifold vacuum is at idle with the car in drive? I am kind of curious. You are so right about too much cam and a Ford O Matic not playing well together. Pete

Dan.  Without knowing exactly where the camshaft is installed, the head combustion chamber cc or the distance the pistons are sitting in the hole, some assumptions must be made.  But beyond that, here are the numbers I used with the Isky 270° cam installed at 2° advanced.  Static compression ratio is 8.89:1 while dynamic compression ratio (DCR) is 7.04:1.

 

 

With the Mummert 272 cam installed at the same 2° advance, DCR increases to 7.20:1.

With the Comp Cam 264 (Int) cam installed at 2° advance, DCR increases again to 7.31:1.

 

In regards to piston to valve clearance, advancing the camshaft brings the intake valve closer to the piston while retarding the camshaft brings the exhaust valve closer to the piston.  Until you mock up the engine and do a physical check, you’ll not know where you stand on piston to valve clearances.  The amount the decks and heads are milled will be a player here.  But looking at the Comp Cam specs, it will tolerate a moderate amount of cam advance even with some heavy milling on decks and heads.

Lorena, Texas (South of Waco)

Ted, I went out and did some more measuring on my set-up. Deck height was 0.014 "in the hole". The clearances on the CompCam were: 2* advanced I had 0.040 piston/intake valve clearance. Straight up it measured 0.160 piston/intake valve clearance. I always figured low compression would be my limiting factor in running the CompCam. Talking with CompCam people they said it was "right on the edge" of being too big. Of the other two cams which one do you think will run the best? I was leaning towards the Isky, installed 2* advanced, if I cant run the CompCam & have it run good.

Thanks,  Dan

Dan      Kingman Az.      86409

Dan.  Your valve to piston clearances don’t jive for the difference a 2° change in cam timing makes.  The general rule of thumb is 0.025” change in valve to piston clearance with each 4° change in cam timing.  Are you checking the V/P clearance with head gaskets in place and with valve lash or no head gaskets and zero lash?  Might be worth rechecking your V/P clearances.

 

But beyond all that, then the next choice in camshafts would be the Mummert 272 mainly for its 108° lobe centerline which works with a majority of the street driven Y exhaust systems.  And don’t limit yourself to just 2° advance as you may be happier with 4-5° advance and especially if the timing chain set is new.

Lorena, Texas (South of Waco)

Ted, Im checking the clearance with head gasket installed & valve clearance adjusted to spec. I'll go back & reck it this morning. Interesting information on the Mummert cam, you've got me thinking. What kind of performance would could be expected with running the Mummert cam 4* advanced? Would that combination be better than running the CompCam straight up? Thanks for the information.

Dan      Kingman Az.      86409

I used the Mummert 272 advanced 4* and am very happy with the results. (292, .060" over 301 Y)

55 Vicky & customline

58 Rack Dump, 55 F350 yard truck, 57 F100

59 & 61 P 400's, 58 F100 custom cab, 69 F100, 79 F150, 82 F600 ramp truck, 90 mustang conv 7 up, 94 Mustang, Should I continue?

Bill, what intake & carb are you running with this? How much vacuum is it pulling? Flat top pistons?

Thanks

Dan      Kingman Az.      86409