Jesel timing belt

[Ed McLawhorn Jr.]

Encounter something today new on super stock motor. Installed new replacement jesel belt (sbc # 30990) on existing belt system with heads off, degreed cam and everything seemed ok. Installed heads and rocker shafts. Adjusted valves and now have 3 degrees rotation in crank with out cam moving. Upon inspection, the belt is tight, but the teeth are not fitting correctly in grooves on cam gear. Its like the belt teeth are slightly smaller contour than the cam gear. I only noticed this after adjusting valves and the old belt did not have this issue. Has anyone else seen this before. I bought it during winter and just getting around to installing. thanks.

[Jim Johnston/6022]

I had the same issue a couple of years ago. Called Jesel and they said block must have been align honed and i could order a shorter belt. The fact i tried 2 different old belts and an old complete comp.cam belt system and they all happened to be tight did not change his mind. I put it together with it being a couple of degrees weird and it has been ok and no drama.
Jim & Ken Johnston GT/QA

[Ed McLawhorn Jr.]

Originally Posted by Jim Johnston/6022

I had the same issue a couple of years ago. Called Jesel and they said block must have been align honed and i could order a shorter belt. The fact i tried 2 different old belts and an old complete comp.cam belt system and they all happened to be tight did not change his mind. I put it together with it being a couple of degrees weird and it has been ok and no drama.
Jim & Ken Johnston GT/QA

Exactly Jim, I don't believe a shorter belt is the answer. The belt is tight, but sliding in cam gear groove between the cam gear teeth and only became evident with spring pressure.

[BillK]

Ed,
I have seen this several times on modern street engines and every time it has been the belt made improperly and a different brand belt fixed the problem. I know in your case you are stuck with Jesel for the belt but I think at the very least I would ask them to send you another belt and see if the teeth are made correctly. I sure as heck would not want to run it if the belt does not properly match the sprocket.

Just my opinion

[SBillinson]

There may be a gauge available to check the pitch and other dimensions, similar to a thread gauge.

You could instead make a template out of aluminum to fit the gear and then compare it to your belt. Take a photo and send it to Jesel if the two don't seat correctly.

Easier still would be to take a photo of the top gear with the belt on.

Most Jesel belt drives don't have an idler. I've never understood why. I imagine the belt would stretch or create slack between the leading and trailing sides, especially with a lot of spring pressure. Has your spring pressure changed significantly?

[Ed McLawhorn Jr.]

Originally Posted by BillK

Ed,
I have seen this several times on modern street engines and every time it has been the belt made improperly and a different brand belt fixed the problem. I know in your case you are stuck with Jesel for the belt but I think at the very least I would ask them to send you another belt and see if the teeth are made correctly. I sure as heck would not want to run it if the belt does not properly match the sprocket.

Just my opinion

Thanks Bill. As a follow up, I called jesel yesterday and the tech guy told me that 2-4 degrees was accepted and expected. Not sure I still like it. I called a friend who builds motors for a living and he told me he had been seeing this for some time. I don't believe another new belt will be better. He just keep the belt up against cam gear in correct rotation for cam degree.

[Ed McLawhorn Jr.]

Originally Posted by SBillinson

Has your spring pressure changed significantly?

Not really...I did move seat pressure up 15lbs, but not enough to cause this issue. Thanks.

[57 Vette]

This is one of the many reasons I had Alan at SDPC Race Shop install a Milodon Gear Drive System on my 582 Head Hunter engine. I would never put a rubber band on any engine I own. I have been running gear drives on all of my engines since 1975.

[Jim Johnston/6022]

My son Ken and myself run a 55 chev. 265. It has been a modified production street car super stock ect.since 1960s. The 180/200 single 4 barrel got hit for 5 hp (80#) a couple of years ago. We had the proper 2x4 carbs and found a tunnel ram-went with same long block to 1956 225-230 to G/T. Had experience helping with late brother (R J) late friend Rick Pike with 265/225. Still working on manifold as it is way to big for small engine. Just sold street1967 chevy two wagon to pro mod racer and fabricator Roy Lazic. Should be interesting to see what he does with it.
Cheers Jim