I got my new engine in on Sat and it's been running luverly for the last few days, felt like a new car.... apart from a few little niggles.

One of which was at idle it seemed to be going a little fast then gradually slowing to a more modest pace. When I returned home tonight I took a look at the carb and noticed it looked there was an overstretched part of the throttle return spring that was just gradually pulling it forward, so wiggled it a bit.....

But oh dear! it popped off and the engine went up to full revs! I pulled it back and went round to turn the ignition off. just as I was turning the ignition off the engine revved again (I couldn't have hooked it on properly!) so I suddenly stopped the engine at high revs!

Now the engines stuck, the flywheel won't move more than a few notches either way!

WHAT HAVE I DONE?

Jeepers!

I wonder if, in your panic, you first turned the ignition key to 'crank' and this engaged and stuck the starter motor pinion in the flywheel teeth? In which case, shove it into 2nd gear, release the handbrake, and rock the car back and forth. Hopefully you'll hear a 'click' as it releases.

I can't see how shutting it off at full revs could have caused any particular damage; the engine would have had to be run like this for some time before anything major would have happened, I'd have thought.

Er, when you say 'new' engine, do you mean fully reconditioned and yet to be run-in? If so, oops, I could be wrong about the above...

Didn't really panic as such, just did it really quick! The starter motor just clicks and doesn't turn the flywheel! But isn't that because the flywheel only moves a little?

Only 'new' as in new in and cleaned down, painted tinwork and everything moving as it should. The engine was running before I got it and I was going backwards and forwards around town... but never really revved it that much in any gear!

Thanks! shall be poking various things in the morning!

What happens when you try and turn the engine over with the crank handle?

Ok, if it IS a stuck starter (and I hope it is...) then put the car into 2nd or 3rd gear on a level surface, handbrake off, get a mate at one end and you at t'other, and push in turn - rock the car as far as possible back and forth repeatedly. Get some vigorous shakin' goin' on.

Take the plugs out and try again.

Imo, is it stuck fast or can you turn it round so far and then so far the other way? I recently tried an unknown engine which turned over by hand and then on the starter motor for a few seconds but then got stuck at one particular point. Since I've got the heads off, it's apparant that whatever crud may have been in or around the engine had found it's way to the bottom of one of the cylinders and then due to the horizontal nature of the engine, pushed it all to top dead centre, thereby stopping the cylinder from moving any further.

I've removed it now so when I put the cylinders back on, all should be well.

Is the gear from the starter motor engaged wit the teeth on the flywheel ?

If so try some shock treatment to free it... That wil be a large hammer then!

I've just had the starter motor and the rocker covers off and all the valve gear looks as it should! So crud it could be? It sure had a good shake down! The cylinders seem to be stuck in the fully extended position. Is that top dead centre?

I would have already started to take the heads off if it wasn't in the street in the blazing sun! Miles away from shady Mum and Dads drive and my shed of bits and bobs!

It depends on how far you can turn the flywheel. It might be just one cylinder with crud in which case you should be able to turn it almost all the way round then round the opposite way to the same point or if there's crud in both then you'll only be able to turn it a little.

There's only one way to find out for sure!!

No the flywheel only moves a few notches back and forth!