The Triumph Dolomite Club - Discussion Forum

Hello Everyone

I was wandering if someone would be able to help me with a question I have around the Sprint crank shaft pulley please.

I replaced the crankshaft pulley a little while ago due to what appeared to be distortion and wobble on the original. I am having some significant trouble with the timing on my car at the moment with it just not seemingly being correct (carb backfire etc) irrespective it seems of where I position the distributor, which is a Distributor doctor fully refurbed unit.... I have read on the forum somewhere that a TR7 pulley will fit a Sprint but it subsequently it isn't timed in the same way. And I just want to understand what pulley I actually have fitted now, and if it is a TR7 unit, how this affects how I go about setting the car up.....

In looking at my old pulley I have noticed that it has one very small line up mark/notch on the pulley itself. However the one I have on the car now has 2 notches, a large one and a smaller one. The smaller notch seemingly being the same size as the one on my old pulley. I am using the large mark at the moment but as I say I am experiencing timing issues with the car. So after reading the forum, I wandered why it had 2 notches and more importantly if this has any significance or impact on the approach taken on the car when setting the timing...... I have attached 2 pictures that hopefully will be clear enough to illustrate what I am trying to articulate....

Any views or assistance appreciated.

Thank you!

A Tr7 (or 1850) pulley will fit, but in order to get the alternator belt aligned it would need to have been turned down on a lathe to accommodate the duplex timing gear of a Sprint; both Tr7 and 1850 are simplex chain engines and the bottom pulleys have a longer 'nose' than the Sprint to make this space up..

Are the notches on the two pulleys in the same position on the circumference relative to the keyway inside the pulley? Any difference would have to be compensated for. The difference may only be a matter of degrees, so drawing around it on a piece of paper may be necessary to observe this...but if you have tested the running at the full extent of movement of the distributor, it may transpire you are simply a cog tooth out with the distributor position...

I've never been overly trusting of pulley marks (on Rover V8s they just seemed random)
As Alun says (depending on what's been removed/disturbed) you might be a tooth out on the dizzy drive or something like that?

I know it's a PITA, but I'd be tempted to fit a piston stop in plug #1... carefully (and gently) turn one direction on the crank until it stops, mark the pully based on the 0 deg timing position, turn the crank in the other direction... mark again and then true TDC should be exactly between the 2 marks. (Careful use of a protractor or timing disc should get you there) Compare that to the pulley marks you have?

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Thanks Both...

I am pretty certain that I checked the physical characteristics of the pulleys before putting the new one in, and that they seemed the same in size and 'nose' sizing. I have also looked at the fan-belt and it is straight in its position between the alternator and the crankshaft pulley, with no deviation or slant to one side when looked at from above. That would suggest that the pulley is in fact the correct size at least wouldn't it? I didn't however check the notch alignment marks on them both...!

With the new one in situ checking that the notches are in the same position is not possible without removing it is it... ? And to be honest I really didn't want to have to remove it all again unless absolutely necessary, so with what I have mentioned above is that sufficient to eliminate the possibility that a TR7 one is being used do you think?

I have checked the distributor a few times, and currently when the timing mark I am using (large notch) is set at 10 degrees BTDC, No 1 piston is near the top of its travel (checked using long screwdriver down the sparkplug tube), the cam shaft alignment marks inside the oil filler cap are aligned, the rotor arm is pointing at the dizzy housing nib, and the dizzy housing bolts are central in their locators allowing movement both ways. So with this I have assumed that I have got the distributor in correctly. I have gone back to basics several times starting with setting static timing yet it just still seems very unhappy.... hence my considering the pulley and its marks..... Everything in the circuit is new, dizzy, points, condensor, plugs, leads etc. Getting quite frustrated with it at the moment to be honest so apologies for the length of this...! It should run properly and it just wont...

I would check that the TDC mark on the pulley is in the right place, the rubber insert can allow it to slip round so it could be miles out.
Set No.1 to the real TDC using a rod/bar/screwdriver in the spark plug hole and see how the mark lines up.

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Russ Cooper
Dursley
UK

If it's a pulley with a damper (I don't remember) then this is a REALLY good point AND if the rubber is allowing movement it means the mark can't really ever be relied on... even if you correct it it could just move and be wrong again next time you look.

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I thought that the pulley on a Sprint was just one lump of metal? I have only encountered damper style pulleys on more modern cars.

My guess with timing struggles, assuming that there isn't another issue causing problems, is a jackshaft fitted incorrectly.

Nope. The Sprint pulley is definitely two pieces. If you look, there is a rubber ring which separates the two pieces to act as a damper.

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Sprintless for the first time in 35+ years. ... Still Sprintless.

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