1500cc engine

[Rob Marshall]

Help!!! Advice needed.

I have a Dolomite 1500 fitted with a rebuilt 1500cc engine which originally came from a Midget. The engine looked like it had been reconditioned well, complete with new core plugs etc. I had been told it had only done 10,000 miles since it was rebuilt.

As a precaution, I took the sump off to inspect the big ends. The engine internally was nice & clean. The bearings were not the standard size, but in excellent, unscored condition. As a precaution I fitted a set of new bearings (same size as the ones that came out) before fitting the engine to the car.

I have set up the engine timing wise on the basis that it runs well but doesn’t pink. i.e. slacken off the timing ‘till there is no pinking under heavy low rev load. The car is run on unleaded with Castrol Valvemaster. The engine does not get hotter than normal, the guage staying at just under the half way mark.

If the engine is revved from idle to 5000 revs, all is fine, but under light acceleration I get a throaty roar / knocking noise at around 2,200 – 4000 revs. Nothing happens at hard acceleration, & it will accelerate happily up to 6000 (not really recommended on a 1500, but done to test!!!) When I back off the throttle, the noise starts again.

I took the sump off with the engine in situ and took the big ends out. All perfect. So they were put back in. No difference resulted.

If I set the timing statically at 10 degrees as recommended in the book, the knock disappears, but the performace is dismal, with none of the 1500 “urgency” at light acceleration.

If I back the timing off, the rattle does disappear, but the car becomes slower than my Toledo. Any ideas guys???

[Herald Freak]

Mine did that! did it for about 3000miles then the threads stripped on a con-rod and bang.
All the castings lived and the crank was salvageable,  I got a recon crank and set of rods and all is now well,
If you still have your old engine why not treat it to a new set of rings and shells i fitted lotus twin cam con rod bolts and threadlock to increase reliability