Lotus Elan and Lotus Elan Plus 2 Forums

1/4 unc, short ones are 1/2", long ones are 3/4".

Recently replaced mine with Allen bolts while engine was out and sink was being refitted. Making the getting of the sump on/off easier should lower the likely good of it leaking....

As mentioned there are two lengths - it's proper practice to use longer ones in the aluminum (USA spelling!) front cover and rear crankshaft seal carrier in an attempt to stop thread stripping.
All of the original untouched Ford and Lotus engines I have stripped have longer bolts into the aluminum covers than the ones into the cast iron of the cylinder block.

There are a few blind holes and over length setscrews may have been fitted in the non blind hole in the block flange. Orginally they were all the same length for the 6 bolt crank sump

If you have a 4 bolt sump the rear two screws were longer if I recall correctly.

regards
Rohan

As a matter of course on an engine rebuild I Helicoil both front cover and oil seal carrier, and fit screws long enough to ensure full thread is engaged.
Reason, I?ve seen too many 4 bolt oil seal carriers with stripped threads, clearly due to an attempt to stop a leak by over tightening, then the situation just get worse.
Ron

Thanks. Is 6 lbs the right torque?

rgh0 wrote:There are a few blind holes and over length setscrews may have been fitted in the non blind hole in the block flange. Orginally they were all the same length for the 6 bolt crank sump

If you have a 4 bolt sump the rear two screws were longer if I recall correctly.

regards
Rohan

That's strange - I wonder why the Lotus Twincam parts book specifies two different set-screw types for the 6-bolt sump : one set for the "rear retainer and front cover", and one type for the "block" alongside the same year and Lotus designation?
Agreed there are two longer bolts at the back on a 4 bolt sump.

Rear sump bolts on 4 bolts crank longer ?, yes just slightly about 2 inches!!!