1275cc engine to 1098 gearbox

[pete/heather]

we have a 1275cc marina engine and want to fit a 1098 box but the fywheel of the 1275 has 6 holes and the 1098 4 what do we need to do to convert to the 1098 box please

[PSL184]

Very carefully redrill the missing 2 holes in the 1098 flywheel, or, buy one already machined. I think some of the suppliers sell them.....

[bmcecosse]

You first need to fit the frontplate and the backplate from the 1098 onto the 1275. Frontplate goes straight on. The backplate needs the top dowel hole opened up slightly - and the area round about the rear main bearing opened up considerably! You then fit the marina flywheel to the minor flywheel using tight fitting bolts - two holes line up. Then you carefully drill through the two flywheels using the marina flywheel as a drill jig to get the FOUR (not two) extra holes in the minor flywheel. Make sure you keep the holes as small as possible - just large enough to be a very snug fit for the bolt - no slop whatsoever. You may need to modify the starter slightly to get the bendix to clear the ring gear - check this with a test-fit on the engine before you fit it to the gearbox.

[minor_hickup]

If you replace the ring gear with a 1275 midget item there is no need to mess about with the starter. The ring gear is usually pretty chewed up anyway.

[bmcecosse]

Oooooohhh that's interesting - is the ring gear thinner on the Spridget ??

[les]

When fitting the minor flywheel to the marina crank, you will need a special adapter that fits in the centre, this will make sure the flywheel centralises properly rather than relying on the bolts!

[bmcecosse]

Can't see how such an adapter would work - at least - not with either of the 1275 cranks I have..... Where to buy such an adapter??? I agree it's not perfect to locate the fly with just the 6 bolts - hence the need for snug fitting bolts - and Loctite on the threads.....

[les]

Basically it's a spigot with two diameters each fitting the appropriate location on flywheel/crank. Owen burton used to sell them, not sure of an outlet now. Will need to find out soon.

[bmcecosse]

The cranks I have may be Ital items - a spigot adapter won't do the job on them.........

[minor_hickup]

The 1275 Spridget ring gear is identical to the 1098 except the teeth shorter giving the starter clearance. Any good specialist should be able to supply them, as well as the spigot adaptor.