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after rebuild, engine won't start, stalls as if too much advance


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hi all,

 

I have performed a rebuild of my engine recently. It is now back in the engine bay but won't start : starter runs, and when engine seems to catch up it stalls as if it had too much advance and explosion occurred before TDC

I have double checked ignition timing and it seems good (to me but I may be wrong)

Here is a link to how it behaves : https://youtu.be/rd-hfZhAzwk

any idea of what could be the problem ?

thanks

 

Philippe

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HI Phillipe,

the posts above sound about right.

 

Take off the rocker cover and get #1 piston valves both in the up position (Piston at TDC).

 

Use whatever method to ensure the piston is actually at TDC.

 

Mark the crank pulley - you may well find the mark you are using at the moment is 180' out.

 

Annoyingly it is possible to fit the crank pulley belt guides out by many many degrees

 

Roger

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Yes Roger, I had exactly this on my 4A when acquired in 1970 with the result that the hole in the rear half of the fan pulley did not line up with the pointer on the crank case when the engine was at true dead centre with no 1 piston on the compression

stroke. I found it was actually 120 degrees out. I never understood why the ST engineers did not poka-yoke this assembly so the

two pulley halves could only fit together in one orientation.

 

Tim

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thank you for all the prompt answers. So timing should be the problem

As I have only changed the rod bearings, rings, and worked on the head, I am pretty confident the pulley mark is good when at TDC

any way I could have misplaced the distributor gear ? I'll recheck everything

 

thanks

 

Philippe

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  • 2 weeks later...

Good news.

 

When I did mine I waited what ever time/miles the book said before re-torquing the head bolts again.

The head gasket failed (gas into water cooling system.)

For the next one I re-torqued it after a few runs around the place in the TR. Well before the recommended mileage.

Has worked OK ever since.

Dunno what the the experts recommend, might get a few comments on which is the best policy.

 

To get at all the head bolts the tappets have to come off again. (sigh) It is the way of things.

Edited by littlejim
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The success of the head gasket seal depends upon how assiduous the liner heights have been worked and should stand being run in it's original configuration until the head gasket is again retorqued.

Bearing in mind the original suggestions were based upon a then new engine not as we have now with 50 and 60 year old units you can understand how the liners may have moved or the seal is marginal. On race engines I normally retorque after about 200 miles after which the engine is ready to race, I don't see a problem doing it this way and have successful head seals.

 

Mick Richards

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