Norton Dominator timing cover fit problems. Recess for oil pump seal too shallow?

Hi:

A question for all you Norton veterans.....

I have a 1962 Norton Dominator 650SS that after many trials and tribulations is now running absolutely magnificently! Thank you to everyone on this forum who has helped me get to this point!

The engine was rebuilt and now that I have run the engine in and put some 1000 + miles on it, I want to check the timing chains. Which of course means removing the timing cover. I had a few problems during orignal assembly that maybe you have some experience with. Maybe there was something I was missing last time around that I can avoid this time?

The issue is that when I originally offered up the timing cover during assembly, the cover was not mating correctly. Evidently there was a high spot somewhere. After much head scratching I determined that the problem was the rubber oil pump seal, (which protrudes from the oil pump and fits into a timing cover recess when the timing cover if fitted. The seal was too tall for the apparently too shallow recess in the riming cover. I believe the cover to be original, (vertical tachometer mount to the cam shaft, not canted forward as I think some later ones were) produced in Birmingham, the production number of my bike equates to late 1961 manufacture.

I ended up cutting the seal down. A reasonable seal to the timing cover gasket was only obtained with loads of Holymar sealant and uncomfortably well tightened down allen screws. I checked oil pressure after assembly and all works well, but it still feels liks a bit of a bodge. Maybe I can do a better job this time around? Or maybe I'm just a bit OCD?

Has anyone had a similar problem? I hear rumours that some people run a "thick" timing cover gasket.

Kind Regards,

James

Britstuff said:

After much head scratching I determined that the problem was the rubber oil pump seal, (which protrudes from the oil pump and fits into a timing cover recess when the timing cover if fitted. The seal was too tall for the apparently too shallow recess in the riming cover.

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The pump seal should be under a certain amount of compression (0.010") to seal against oil pressure, however, did you fit an oil pump gasket between the pump and crankcase as that wasn't introduced until later (early Commando)?
Edit: Also check there are no unnecessary shims between the pump and pump spigot.

Dear L.A.B:

I do not remember any shims. I like to think I would of removed them if there were any.

I most certainly did fit an oil pump gasket between the pump and crankcase. That would explain at least part of my problem!

Thank you very much!

Kind Regards,

James

Plus one on LAB'S comment. Usually the problem is the opposite, the seal doesn't crush enough and you have to shim it out. Are you using the correct conical shaped oil pump seal and not the later 850 one? Also the early engines use a thinner timing cover gasket than do the later engines that use a gasket under the pump. I've had timing covers off many times. It's not unusual for them to weep a bit until they've been snugged down a few times. FWIW I think the vertical tach drive is for the later engines. The early engines had an angled tach drive and an unarmoured cable. This set up worked because the early engines had a slight "kink" in the exhaust that allowed the cable to clear.

Dear Bodger:

I double checked regarding what pump seal I am using, (Norvil have some helpful photographs). Definitely using the correct one.

Thank you for the correction regarding the dating timing covers.

Kind Regards,

James

L.A.B. said:

The pump seal should be under a certain amount of compression (0.010") to seal against oil pressure, however, did you fit an oil pump gasket between the pump and crankcase as that wasn't introduced until later (early Commando)?
Edit: Also check there are no unnecessary shims between the pump and pump spigot.

Click to expand...

Wow wild, I have an early 650 as well, '62, and had/have the exact same problem. I also fit the gasket behind the pump!

Simply love this forum.

seanalex said:

Wow wild, I have an early 650 as well, '62, and had/have the exact same problem. I also fit the gasket behind the pump!

Simply love this forum.

Click to expand...

Might work ok if you used the later, thicker, Commando timing cover gasket. Might confuse the heck out of a later owner.

Just had a similar discussion with another mechanic this morning. We have never taken a Norton apart that had a gasket between pump and engine case, but every kit has a gasket in them. I put a very light sealant coat and NO gasket, IMHO