differences from Atlas, P11, and early Commando timing cover
- Thread starter pierodn
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nortonspeed
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Re: differences from Atlas and early Commando timing cover
Early Commando timing cover (with the rev instead of later points) is identical to an Atlas timing cover.
Early Commando timing cover (with the rev instead of later points) is identical to an Atlas timing cover.
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Re: differences from Atlas and early Commando timing cover
They are not identical.
The early Commando timing cover has an oilway coming from the "pressure release" area that lines up with an oilway in the timing side crankcase going to the inlet side of the oil pump.
The Atlas timing side crankcase does not have this oilway. Excess oil pressure is "released" into the timing cover area.
They are not identical.
The early Commando timing cover has an oilway coming from the "pressure release" area that lines up with an oilway in the timing side crankcase going to the inlet side of the oil pump.
The Atlas timing side crankcase does not have this oilway. Excess oil pressure is "released" into the timing cover area.
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Re: differences from Atlas and early Commando timing cover
Also, the gear ratio is different on the 68 Commando and Atlas tach drive. Original, used or NOS 68 tach drives are difficult to find and expensive.
Mick
pierodn said:
Also, the gear ratio is different on the 68 Commando and Atlas tach drive. Original, used or NOS 68 tach drives are difficult to find and expensive.
Mick
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Re: differences from Atlas and early Commando timing cover
I have two covers, one with the tach drive mount ground off and filled, and another that has a tach drive mounting in place, but I just don't know if they're correct for the bike. Both have the designation "T2004" cast into the inner side of the case, along with what looks like the letters "WM" cast next to the opening for the tach drive. Can anyone confirm if these are the correct covers for a '68 Commando?
Or, does anyone have some reference photos of the inside and outside of a '68 Commando timing cover? Both Piero and I have the same need, which is to make certain we have the correct one for our projects.
Thanks,
Curt
I have two covers, one with the tach drive mount ground off and filled, and another that has a tach drive mounting in place, but I just don't know if they're correct for the bike. Both have the designation "T2004" cast into the inner side of the case, along with what looks like the letters "WM" cast next to the opening for the tach drive. Can anyone confirm if these are the correct covers for a '68 Commando?
Or, does anyone have some reference photos of the inside and outside of a '68 Commando timing cover? Both Piero and I have the same need, which is to make certain we have the correct one for our projects.
Thanks,
Curt
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Re: differences from Atlas and early Commando timing cover
Curt,
later today I will take a look at mine and see what it says.
Mick
Mrchips said:
Curt,
later today I will take a look at mine and see what it says.
Mick
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Re: differences from Atlas, P11, and early Commando timing c
P11 timing cover on early Commando crankcase will work but not the other way around (early Commando timing cover on P11 crankcase).
P11 timing cover on early Commando crankcase will work but not the other way around (early Commando timing cover on P11 crankcase).
htown16
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Re: differences from Atlas, P11, and early Commando timing c
As referenced above it's the oil drillings near the oil pump that are the major concern, the Atlas and early Commando are different. Be sure on the one you are using the holes in the cover match to the ones in crankcase. Otherwise, no oil to crank, big bang then much unhappiness. I was going to use an Atlas cover on a very early 68 Commando, but compared the holes in the cover to the crankcase and spotted the difference.
As referenced above it's the oil drillings near the oil pump that are the major concern, the Atlas and early Commando are different. Be sure on the one you are using the holes in the cover match to the ones in crankcase. Otherwise, no oil to crank, big bang then much unhappiness. I was going to use an Atlas cover on a very early 68 Commando, but compared the holes in the cover to the crankcase and spotted the difference.
Re: differences from Atlas, P11, and early Commando timing c
:?: :?: :?:
To avoid any confusion; it depends on where the rev counter drive is taken from. The Atlas/ early Commando it was the end of the timing cover. On later Commando was from the crankcases.
A Double speed oil pump was fitted on the Atlas from 1966 onwards which was continued on the Commando.
To add even more confusion' There appear to be a slight change in the early timing covers;
“They are not identical.
The early Commando timing cover has an oilway coming from the "pressure release" area that lines up with an oilway in the timing side crankcase going to the inlet side of the oil pump.
The Atlas timing side crankcase does not have this oilway. Excess oil pressure is "released" into the timing cover area.”
johntickle said:
:?: :?: :?:
To avoid any confusion; it depends on where the rev counter drive is taken from. The Atlas/ early Commando it was the end of the timing cover. On later Commando was from the crankcases.
A Double speed oil pump was fitted on the Atlas from 1966 onwards which was continued on the Commando.
To add even more confusion' There appear to be a slight change in the early timing covers;
“They are not identical.
The early Commando timing cover has an oilway coming from the "pressure release" area that lines up with an oilway in the timing side crankcase going to the inlet side of the oil pump.
The Atlas timing side crankcase does not have this oilway. Excess oil pressure is "released" into the timing cover area.”
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Re: differences from Atlas, P11, and early Commando timing c
The top picture is an Atlas/650SS cover the bottom picture is early Commando, my 69 Fastback was fitted with an atlas timing cover when I purchased it, a plug had been inserted into the gallery, I have since replaced it with the correct one.
The top picture is an Atlas/650SS cover the bottom picture is early Commando, my 69 Fastback was fitted with an atlas timing cover when I purchased it, a plug had been inserted into the gallery, I have since replaced it with the correct one.
Re: differences from Atlas, P11, and early Commando timing c
Please,
Could you explain the differences i cannot able to see.
Piero
possm said:
The top picture is an Atlas/650SS cover the bottom picture is early Commando, my 69 Fastback was fitted with an atlas timing cover when I purchased it, a plug had been inserted into the gallery, I have since replaced it with the correct one.
Please,
Could you explain the differences i cannot able to see.
Piero
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Re: differences from Atlas, P11, and early Commando timing c
Note the area around the pressure relief valve [3pm] "where the gasket would fit", in the bottom photo there is a gallery [hole] that feeds the pressure relief valve, this gallery is not in the early [top] cover.
Al
Note the area around the pressure relief valve [3pm] "where the gasket would fit", in the bottom photo there is a gallery [hole] that feeds the pressure relief valve, this gallery is not in the early [top] cover.
Al
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Re: differences from Atlas, P11, and early Commando timing c
Aha!
Well it appears that I also have an Atlas cover on my early '69 Commando since it is identical to the top cover in the photos. Do you suppose that since it was the transition year to a new model (Commando) that the Brits just used-up the old Atlas inventory before going to new castings?
Curt
pierodn said:
Aha!
Well it appears that I also have an Atlas cover on my early '69 Commando since it is identical to the top cover in the photos. Do you suppose that since it was the transition year to a new model (Commando) that the Brits just used-up the old Atlas inventory before going to new castings?
Curt
Re: differences from Atlas, P11, and early Commando timing c
A question, please.
The Atlas timing cover had the tacho drive fixed with the two holes in diagonal and not in vertical like in the top picture?
Maybe the top timing cover is a Mercury (or an early early Commando????) and not an Atlas?.
Piero
A question, please.
The Atlas timing cover had the tacho drive fixed with the two holes in diagonal and not in vertical like in the top picture?
Maybe the top timing cover is a Mercury (or an early early Commando????) and not an Atlas?.
Piero
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