Hi,

Anyone use the Mummert Y-292S cam, I was curious if it had a super lopey idle and what the rpm at idle was? Also if it had much power on the bottom end. I'm using a C4 with a 2500 stall converter and 373 gears, I can sacrifice a little bottom end, as long as I get the super lopey idle. Maybe some history with an Isky or another brand of cam that is big and has a super lopey idle?  

Thanks Ed                                                                                                                     

with 240* @ .050 and 108 separation, it'll be lopey. You'll be giving up a lot of bottom end. How are you going to use the car? Call John see what he has to say.


Lawrenceville, GA

Sanman,

         It would work better in a bigger motor, more low end. Do what Charlie told you, call Mummert. You should have done heads, headers, Maybe a Blue Thunder and a 10:1 motor to use that much bumpstick.  

Frank/Rebop

Bristol, In ( by Elkhart) 

Hi,

The motor is a 292 .040 over, balanced, 9.4 compression, gasket matched ECZ-G heads, 1.54 rockers, ARP head bolts and main studs, Blue Thunder intake, Holley 570 Street Avenger, 7 psi fuel pump, MSD distributor, coil, 6AL box, headers and 2.5 exhaust, with this combo, that cam is too big? Not a daily driver, just for fun now and then.

Ed

I think it will be much too big for that combo.  It will probably sound great at idle but I doubt it will perform well.  You will need to up the compression as Frank says.  This means race fuel, blended fuel, or octane booster.  You will need to have your heads ported.  Gasket matching will not be enough.  Call John.  Get a cam that will sound good and perform with your combo.  We don't need the chevy guys to see a great sounding Y that can't get out of it's own way.

I have a video on youtube of mine idling.  The recorded sound quality isn't great; it's much better in person.  It has some lope to it.  My cam is 226 @ .050 and 112 lobe separation.

http://www.youtube.com/watch?v=qnwVX2uWE4Q

If you can hold off a couple months and make it to Columbus you will be able to hear quite a few of the different cams available, see them perform and learn about the combos.

I think the 284 or possibly 270 will be better suited.  The 270 is slightly smaller than mine but it has a smaller lobe separation which will tend to make it more lopey when eveything else is the same.

Lawrenceville, GA

That Y292S cam is definitely marginal in your instance but your saving grace is the 2500 stall and the 3.73 gears.  Because of the borderline nature of this cam in this particular application, it must be degreed in to prevent the possibility that it’s being installed in any kind of retarded position.  With a new chain in place, you’ll want to install this camshaft at the 4°-6° advanced position or at 102°-104° intake lobe centerline.  Even with all this done, low end performance will still be lacking.

Lorena, Texas (South of Waco)

Hi,

So if I want the super lopey idle, I need to use a cam that is too big, installed at 102-104 and it will still lose some bottom end. If I go with a smaller cam I will get the bottom end back but loose the super lopey idle. Catch - 22. The true roller sets seem to be out of stock at this time, can a stock timing set be modified to degree the cam? Could I use a carbide end mill to cut a new keyway in the lower gear of a stock timing set?

Thanks Ed

Ed:

It would probably be easier to make some offset cam keys than to re-machine keyways.  IMHO.

John

John - "The Hoosier Hurricane"

Ed, any way you do it you are going to have the idle you want with that cam. Advancing it will just make it slightly more driveable on the street.


Lawrenceville, GA

It’s not necessary to run a big cam to get that lopey idle.  Big cams tend to sound racier because of the increase in the amount of overlap that occurs due to the increase of duration for both the intake and exhausts which in turn creates a later closer exhaust event and earlier opening intake event.  That lopey idle on a small or stock camshaft can be achieved by having the camshaft ground with a reduced lobe centerline without necessarily increasing the duration.  Reducing that lobe centerline will give the idle your desired ‘chop’ by increasing the amount of overlap at the expense of some fuel dilution at low rpms and a reduction in manifold vacuum.  The Isky E4 comes with a 108° lobe centerline and has a nice rumble but reducing this to 106° would increase this to more of a 'chop'.

For cutting new keyway slots in timing gears, I'll use a 'broach' which is a stepped cutter that I use in conjunction with an arbor press.  The use of an end mill would have the size of the slot longer than it needs to be due to not have square corners.

Lorena, Texas (South of Waco)