Posted by Tridentman on 5/9/2008, 9:51 pm, in reply to "Re: Timing marks on a 73 750 us Bonnie"
96.234.105.251
I agree with what Les (L.A.B.) says reference the 'A' and 'B' markings for the 750 from its introduction until the change for "later" engines where the dash/dot system was reintroduced. Later is as Les defines it.
However a word of warning---what Les says is correct for the 750s but not in my experience for the very late 650s.
After 1972 the very few 650s that were built are real hybrids.
My 1974 T120RV for example has the 650 camshafts but is fitted with the 750 camwheels with the 'A' and 'B' markings.
Even with the keyways in the camwheels used as they came from the factory lining up the camwheel markings as per the early 750s certainly does not work!
How do I know---because I timed mine that way but then as I slowly turned the engine to set the tappets it stopped dead as valve hit piston!
I had to revert to the old method of timing the valves using a degree wheel and dial indicator. Everything was then fine.
I think on the very late (the last) 650s the factory used up old stock of 650 parts and when they ran out of this then they used 750 parts.
I guess in the factory they set the valve timing by setting the cam wheels as per "6 teeth around from the 'A' mark" etc etc.
Hope that this might help someone who has a very late 650 and gets bamboozled by this aspect (as I was for some little time before figuring it out!).
Message Thread:
« Back to thread