Talk Morgan Forums Morgan Sports Cars Morgan Three Wheeler & Super 3 Crank Pulley 'Upgrade' Kit

Was speaking to a custom bike builder about 6 months ago who have used the S&S motor as the basis of many of their builds since the motor was introduced about 10 years ago. I asked if they have any issues with cam belt failure and he indicated there was a period when S&S had an issue due to the drive gear (on the crank) and idlers, but that has since been corrected. When I asked about heat related issues with the cam belts he seemed genuinely puzzled as their high performance street machines have never seen anything like that, and they have much less airflow over the cover due to the engine position in a motorcycle chassis. When I told him about the Morgan recommended practice of adding spacers to the cover, he thought that was a very bad idea as sand/grit in the cam belt would be much more worrisome than excess heat.

I followed up with correspondence directly to S&S about the availability of a vented cover to preclude heat induced cam belt failure, and was told they do not make such a thing because it is not required. They did indicate past issues with cam drive/idler design and a batch of cam belts not made to spec. They also advised against cam cover spacers to avoid debris in the cam belt area.

Not knowing whom/what to believe, I removed the spacers which the PO had installed, as the practice of using spacers on a cover the original designers had deemed worthy of a gasket did seem silly to me, and I then drilled some holes and added covers to allow heat venting without grit ingress. So still not sure where the facts lie, but I feel better.

Bottom of cover:


Top of cover with small stainless covers over drilled vent holes:

This is a bit strange. The cam cover spacer kit is S&S PN 500-0257. I'm sure that the later vented cover is also an S&S part.

My new engine direct from S&S has the spacers fitted and a slot at the bottom of the cover as well as two nicely hidden air vents on the front.

When my cam belt broke long ago, I took the car to a chopper shop for the fix as I was very unfamiliar with the process. I brought the new belt as well as the spacer kit. Installation went well. We examined the belt and where it tore apart the belt had been blistered by heat. This did not happen due to running but when the engine stopped, and like all gas engines they have a tendency to stop at the exact same place due to compression differences. So the belt stopped at the exact same location on the crankshaft and got cooked. The spacer kit does help keep that area cooler but, more importantly, helps cool it off after running thereby saving the belt. I take off the cover during the oil changes and take a peek. I can detect that water has gotten in due to being caught out in the rain and a minor amount of dust and a minuscule amount of fibers from the belt itself. This belt has almost 30,000 miles on it and looks very good.

The S&S instructions for replacing the drive gear (Instruction 510-0319) says in item 13, "We recommend installing belt cover spacer kit (500-0257) if not already installed."

If you do a Google search for, "S&S X Wedge cam belt failure" you will find there are lots of forums listing many cam belt failures up until 2014 when the upgrade came in.

Although your cover venting holes will possibly do the job, I would be tempted to refit the spacer washers as well. Later modified covers have extra venting holes but still fit the spacers.

When I recently had my car serviced the mechanic knew nothing about the bolt working its way through the belt cover & had fitted no update kits. They have been Morgan dealers pre M3W.

Michael,

In theory this sounds plausible, but in practice I highly doubt it.

You are correct that motors tend to stop at the same degrees of rotation of the crank. The lower the number of cylinders the more precise that becomes.

I couldn't count the crank pulley teeth, but I was able to get what I think is a good count on the cam pulley teeth. I counted 38 and the crank runs at twice the speed of the cam so it has to be a 19th. I guess it really doesn't matter, but in my mind I thought it would...

The crank pulley on the S&S is 19 teeth and the belt pitch is 127 so the relationship of the crank pulley to any given spot on the belt is going to be purely random and it's very unlikely to repeat, let alone on every start/stop cycle of the motor. It takes 6.684 revs of the crank to make it once around the timing belt.

I don't disagree about the build up of heat inside the case. Even decades ago when Harley did the belt primary they had a vented cover to help reduce the heat on the belt. And that was outside the motor, not inside. Without some type of venting/cooling, I cannot believe these belts last very long on average.

I like the idea of scoops to cover the direct holes and still let air flow through the cover.

I am never afraid to be corrected on my own assumptions. The belt broke exactly at the blister point. That could have been a one time event due to a very hot engine. I have driven many miles in this and my only limitation is when my butt loses all feeling. It is then time to pull over.

Thanks! I've learned much from this site being a beta tester!

Next step... adding a small fan to the crankcase pulley to spead air over the inside of the belt casing? Would need a deeper cover, and maybe a planned air entry / exit point...

Your butt goes numb in a M3W too?

My newer Harley with the Corbin seat is quite good and I don't usually get monkey butt, but my '76 Shovelhead with the Mustang seat I can only ride an hour or so and it's numb; along with a few other items numb too......

There's no doubt that heat is a vicious thing to have with rubber around. I like the internal fan idea a lot. It may not even have to be a fan per se, but maybe like an impeller with just straight up vanes. Even half an inch of blades would circulate a lot of air around inside the cover. Is there more room up from the crank pulley; doesn't have to be on the crank to work?

Phil Bleazey where are you? How soon can you have a prototype made up and tested?