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#1 tom

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Posted 11 September 2004 - 01:16 AM

Well, I bought a 998cc, the registration doc says 998cc, but today, I fiddled with the car, cleaned out the carb, rockers, spark plugs, etc.

I took her out for a spin (with no bonnet!), it was a little damp, but not very.

Well, she goes like a rocket now, so much so, that I span her! :saywhat:

Never done that before. It was a corner that I have driven round 1000's of times before. She's so fast that I'm beginning to wonder if it really is a 998cc lump in that engine bay. I know that the engine has been changed for a A+ unit, but I assumed that it was a 998cc, but could it be a 1098 or a 1275? how can I tell?

#2 Al*

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Posted 11 September 2004 - 03:29 AM

If it's a 998 the first three digits of the engine serial number will be 99H

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#3 Guess-Works.com

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Posted 11 September 2004 - 06:35 AM

If it still has the engine number !!

If it's an A+, then it'll be either a 998 or 1275, They stopped doing 1098's long before then..

If find the following method right 99% of the time... The head is the indicator... if two of the thormostat housing bolts are inline front to back, then it's a small bore ( 998 ) if inline left to right large bore ( 1275 )... the 1% error is achieved when you get a largebore head on a smallbore engine, which is a known performance improvement but requires the engine to be pocketted otherwise the valves would smack into the top of the block.

Picture looking at the top of the head, with the front of the head at the bottom

Posted Image

Beyond that the only way to actually find out the cc is to whip the head off, and measure the bore and stroke.

Use the old PI * radius squared * stroke * 4 formula to get the CC

#4 Dan

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Posted 11 September 2004 - 09:32 AM

On A-Plus blocks, 998 were yellow and 1275 were red. If it is unchanged of course. There were some 1098 A-Plus engines fitted to the last of the Clubby Estates but they're really very rare and I doubt you'll have one. But you might do. Measure the height of the block from the sump gasket to the head gasket. The 1275 block is 3/8" taller, but I can't give you the measurement you need 'till a little later today. Also the crankcase ventilation arrangements are different. The 998 having a very simple system with one breather on the rear of the block below the exhaust manifold.
And the 998 has removable tappet chest covers, while the 1275 (A-Plus) has solid cast tappet galleries.
There are more core plugs on the 1275 block. Above the flywheel housing there are two on the 1275 and one on the 998 (kind of behind the steady bar).

I'll be back with that measurement.

#5 TimS

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Posted 11 September 2004 - 11:05 AM

what is the engine number if its still on it of course

#6 tom

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Posted 11 September 2004 - 12:29 PM

I've got a 99H engine number, so it's a 998!

Oh well, it just seems rather quick, maybe it has some gnarly cams, or something.

Anyway, thanks for the help.




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