GPM

I agree, but some of us run a bit more spring pressure and need them.

Black Baja

iTrader: (2)

If your worried about the affects of spring pressure u might want to step up to a bigger cam core. Do you have any idea how far off the lobes on #8 are compared to #1 when the valves are adjusted?

GPM

Do you have any idea how far off the lobes on #8 are compared to #1 when the valves are adjusted?
No I don't.
I do know as I moved up in spring pressure, installing a new Cloyes chain and gears it wouldn't be long and the timing would be dancing all over the place. The Milodon cured that issue, I ran them for years without any problems. I run a solid roller, at fairly high RPM.
As far as the guy who started this thread, I don't think he needs a gear drive.

SGERR828

Spring pressure has absolutely nothing to do with needing a gear drive. You would surprised how little HP is needed to turn the valve train over once the motor is fired.

Vinny P

Dont forget driving the oil pump. Thats one of the advantages of running an external crank driven oil pump.. That way, as much load as possible is eliminated from twisting the cam core and retarding valve timing on the rear cylinders. Some race engines even run a front mount distributor driven off the belt drive.

Black Baja

iTrader: (2)

Yes I know. And have you ever seen the belt for a front mount distributor? It's like a rubber band. Not much needed to turn a little plastic rotor. It does take some effort to turn the oil pump. But nothing like the forces of the valve springs. I cam can twist as much as 3 degrees from front to back... When I install a cam and use a chain I retard the cam a couple of degrees to compensate for chain stretch. They will advance when they stretch and they will stretch...

Vinny P

I didnt mean to imply that the distributor takes effort to turn, unless you are running a magneto. The advantage of running a front drive distributor, primarily for high rpm engines. is that the ignition timing wont retard as the cam twists.

SGERR828

And what are those front mount distributors mounted to? A belt drive timing set, not a gear drive. Hmmmmm...... :0)

GPM

Let us know what things look like when that Belt drive breaks at a hundred MPH. Jesel told me to expect 30 to 40 hours run time per belt in my application.

Black Baja

iTrader: (2)

I wrench on a 865 nitrous motor with a Jesel Belt one of the times when it twisted the drive shaft 3 times and pulled out of the transmission the motor reved past 11000 rpm guess what the jesel belt jumped.., the motor still ran being off a tooth believe it or not. Didn't run that bad either. If you reved it up when it would come back down to an idle it would back fire. We spent an hour at the track b4 we figured out the belt jumped a tooth. A never would have thought it but sure enough did. Thank God the piston is .200 in the hole and no valves were bent. That's my Jesel Belt story. But never had any trouble with the little rubber band running the distributor. The main reason moving the distributor to the front is it will not fit on a motor like that. I don't see a problem retarding the timing when the rpm climbs cause we do it anyhow. When the nitrous starts the timing is 0. That's the only way a motor like that will live.