68matic wrote:
this is where i got my impression that 998s were the longest lasting
the 1100s had a bitta trouble
by Paul Gibson,
http://coopers.itgo.com/Restore1.htmlThe most reliable engine is the 998 cc. This is well-proven and will outlast the body in most cases. The 1100 cc has a bigger stroke than a 1275 cc. This causes the pistons to wear out and break the rings around the 60,000 mile mark and high-quality pistons with a small piston to bore clearance of 2 tho. should be installed. These engines gave good horsepower and were reliable except for that problem.
The 1275 engine suffered badly from harmonics. Originally so bad it used to tear the centre main clean out of the block and BMC had to make a heavier block to fix the problem. This didn't fix the harmonics as the crankshaft tends to whip in the middle because of the weight difference on either end.
These days, 99.9% of 1098s would have been rebored and different pistons fitted anyway.
Look at 1098 Sprites- they didn't have much of a piston problem, same basic motor.
Or the Morris 1100- they built squillions of them, they didn't give much trouble back then.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.
