My logbook states that my engine is a 1250cc. The previous owner said it was a 1100 bored out, but I haven't been able to confirm this. Anybody know how it is acheived?

Also I'm looking to trace previous owners of my Coupe reg no. UNE 77S.

Thanks

Griff

An 1100 (actually 1098) has the longest stroke of all the A series engines. It's actually a long stroke 998. That means that increasing the bore size gives the biggest capacity increase but even so you don't get anywhere near 1250 without using Hillman Imp pistons.

It goes like this,

std bore 1098
+0.020" 1115
+0.040" 1132
+0.060" 1150

You then have to use Imp pistons which means re-pitching the bores and machining 0.135" off the top of the block as they have a lower compression height.

std imp 1215
+0.020" 1233
+0.040" 1251


I suspect there may be an error on your log book. I would imagine that most people would simply fit the 1275 motor rather than going to all the trouble and expense of modifying a 1098 to 1250.

Well an 1100 is really 1098cc and a +.060" rebore (the biggest 'std' size) would give you 1150.
Vizard suggests you could use +.040" Imp pistons to get 1251cc, but I've never come across anyone that's done it, I would think the bore walls could be rather thin by then!

Oops, crossed posts with John, at least I agreed

Yeh, he beat you by a minute . Thanks anyway

Story of my life really..always coming second

What's your engine number? That should give a basepoint.

My Coupe is in a mates garage at the mo, and he lives 50 miles away (he wouldn't know an engine number from a spark plug, so it's no good asking him). I'm visiting next week so I'll find out then.

According to the log book it says.. 113181, which seems a bit short for a mini engine.

With an engine number like that it could be an offset bored 1098 - at 1250cc, engine numbers like that are usually machinist numbers after work has been done.

I'd have expected to see 10A or 12H at the start of the number otherwise