948cc Engine Rebuild

Post by **MacQuigley** » Wed Nov 25, 2009 10:34 pm

Im finally getting the old 948 engine back together but I think I have a problem and I cant identify it.

I finished putting the timing gear back on this evening but when I put the camshaft nut back on the engine seems to bind when I turn the crank.

I cant really see any reason for it! There doesnt seem to be anything in the wrong place or not set up correct. If I back off the nut until its a little mre than finger tight it seems fine.

I cant find any torque settings for this nut. Haynes say tighten securely and the original workshop manuel simply say's tighten.

Any one out there any suggestions?

Post by **ssnjimb** » Thu Nov 26, 2009 11:16 am

Seems there is a tight spot.

Did you turn the crank by hand before putting the cam in.

Seems silly but are all the bearings inserted correctly was the crank reground.

Jamie

Post by **MacQuigley** » Thu Nov 26, 2009 2:18 pm

With just the crank in place and tightened down, it roteted with no binding whatsoever.

Once the pistons went in it did "bind" (not really a bind, but it was a little harder to turn over) a bit as the 4 pistons leveld off in the bores ie at the point where the friction would be at its greatest. Id expect this, especially as Ive put in new rings and would assume that there would be some friction at this point

It was only when I put the camshaft retaining nut on that I had a problem.

This is my very first solo engine rebuild and the last one if did with my father was a 1098 oh about 25 years ago. So I am a little unsure and the last think I want to do is put the engine back only to find Ive put it back together wrongly.

Post by **MarkyB** » Thu Nov 26, 2009 8:58 pm

Have you fitted a duplex chain?

Post by **MacQuigley** » Thu Nov 26, 2009 10:01 pm

Well I found the problem. Tge new camshaft thrust plate I fitted is 10-12th thicker than the original. Thats enough, that when I tighteded the camshaft nut the timing gear was tightening against the thrust plate.

Swaped the new plate for the old and all is well.

Unfortunatly when I was taking the timing gear back off I dropped the crank gear and broke two teeth! So I now have an excuse to fit duplex gear (is that how to turn a negative into a positive!).

If I dont get this engine back in the car soon its going to end up costing me a fortune!

Post by **MarkyB** » Fri Nov 27, 2009 9:12 am

When I read

dropped the crank gear and broke two teeth

I thought you'd dropped it on your mouth

.

Don't forget the lower bolts have to be replaced with countersunk screws or the chain will bind against them, which is what I'd thought was causing the problem.

Post by **MacQuigley** » Sat Nov 28, 2009 12:05 am

I wish it had been my teeth Id broke! At least Id have been able to get the engine rebuild finished!

Mind you that would have cost more than the new parts.

But good point about the duplex gear as I decided to order a duplex set seeing as I was having to replace the crank pully. It's probably going to be my luck that the set Ive ordered doesnt come with counter sunk screws.

Post by **Declan_Burns** » Sat Nov 28, 2009 7:54 am

I have a duplex kit in my garage which has not yet been fitted. I bought it from ESM and the countersunk screws are included-just checked.

Post by **MacQuigley** » Sat Nov 28, 2009 9:46 am

I had a look at the parts I ordered on the Bull Motif website last night and it looks like the screws are included in their kit to.

With luck it will arrive today and I can get on with the engine. If not its back to body work repairs.

Post by **bmcecosse** » Wed Dec 02, 2009 6:13 pm

I'm only up the road in Stonehouse -so if you get stuck - let me know!

Morris Minor Owners Club

948cc Engine Rebuild

948cc Engine Rebuild

948cc Engine rebuild