Sluggish engine, help, please

["Slack Alice" Simon]

I spent yesterday changing my rattly engine with a slightly dodgy clutch, for a much smoother one with a fierce "on or off" clutch.

The "new" engine has no go, struggles to get to 35 mph.

Fuel pump, carb, dynamo and dizzy, and exhaust and gearbox are all the same.

Pistons are new in slightly worn bores, the engine doesn't feel tight on the handle.

The heads are different, this one is standard low comp, the other was the last low comp, a little better c/r.

The only thing I can come up with is the cam gear is a tooth out, though I checked before re-assembly.   Two small circles meshing with a dot - maybe the dot is wrong, maybe the gears are tight, though they are not noisy.

This engine was like this before I changed the pistons - I thought the sluggishness was due to special oil control rings adding too much friction.

Any ideas, please?

I'm probably spending tomorrow putting the old engine back in, I just KNOW the clutch will go half way up Prescott on Wednesday!

[David Stepney]

I understand that, some while ago, there were replacement timimng gears available that didn't have the markings in quite the right place. As a result engines tended to run sluggishly. I don't know how to tell genuine Austin parts from the aftermarket ones, but, if you have another set of gears, it might be worth trying that first.

[Stuart Giles]

Your timing gears may not have been a pair from the factory, which could well result in the cam timing being out if you just line up the timing marks.

I always check the cam timing with a disc and dial guage, but you can get an idea of whether the cam timing is ok by checking the inlet tappet as the motor comes up to TDC on the starting handle.



As you can see from the factory chart above, the inlet valve shouldn't be coming off the seat before the piston reaches TDC.

[Ian Williams]

Simple to check, the inlet and exhaust valve should be rocking ( In opening as Ex closes ) when at TDC.

[AustinWood]

Ignition retarded?