should this be about 65-66mm??

if so then i just found out my car has already been bored 20thou over!!

i think i am going to go 40 thou anyway whilst im building my g13b engine and subframe.

STD bore of 1098 is 64.6mm near enough, ignoring 2nd decimal point...
so,
+.020" is about 65.1mm,
+.040" is about 65.6mm.
+.060" is about 66.1mm.

Ain't no real substitute for cubic inches, or cubic centimetres either!

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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.

just measured it again with one of those special ruler thingys and it is exactly 65.6mm

looks like its 40" thou over....

So don't stuff about- bore the sucker to +.060"! 1152cc approx.

Later... (if you find some pistons, as they are like rocking horse dung here in Oz now) you can bore it to 68.0mm and use Imp pistons, for 1218cc or so.

<edit> Notch the block & add a 12G940 head and it'll fly! Mine did...

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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.

ok, where can i get a set of those imp pistons to go to a 1218???

NZ or UK.

Have a trawl of this Imp site and check the links there..
http://www.imps4ever.info/tech/supply.html


<edit> you can also try JP Pistons www.jp.com.au
or Panjay, in Mona Vale- 9997 3252.

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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.

boost more

I'm looking at doing this engine build as well, as my 998 block is running +0.060" and is in need of a rebuild. So far I haven't had much joy sourcing genuine Imp pistons at a reasonable price. A supplier in NZ wanted $800NZ per set, and Thorntons in the UK are asking 45 quid per piston. That equates to $450AUS roughly for a set of 4, then you've got to get them out here and possibly pay duty on them. I don't think you'll find better prices anywhere else much. Panjay's can't help, I tried them on drminis' advice but no good.

If you do go ahead with this build, you will have to offset the bores by 0.025" on cylinders 1 to 3, and 0.015" on cylinder no.4, even then there's a chance that you might break into an oilway on no.4 cylinder. You will also have to deck the block by about 0.135" or so to get the piston up to the top of the block at TDC. You'd best check out David Vizard's book "Tuning the A-series engine" for details. If it's only a temporary engine while you're building a g13b, you might be better off to just go to +0.060".[/quote]

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Who's MadMax?

I wonder if Hypatec make them? Maybe not, but it's worth asking.
Check with Ken Nelson at www.miniauto.com.au


JP Pistons have them listed, but I dunno if they have stock.

If you are real desperate, my bro' has some S/H Imp ones but I dunno how worn they would be- they're still in an Imp block!
Let me know if you're interested.

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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.

One of the suppliers in UK I contacted said he could supply a s/h set of Imp pistons too Kev, but I think I'd rather put new pistons into a new bore if ya know what I mean - especially if you've gotta pay for s/h psitons and then import 'em from UK. If the pistons your bro' has are in good nick and not too worn I 'd be interested in them. That is ifboost_morrre doesn't want them - this is his thread after all.

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Who's MadMax?

Dave,
I just got off the phone to bro' `Imp Man' Geoff, he has a bunch of motors lying around and I've offered to help strip 'em in the next few weeks.

Nothing wrong with pre-loved' pistons, if they're not worn.
The +.040" Mahle flat tops in my 1310 came out of my Cooper S which had worn bores, the pistons were fine so I put a new set of rings on and bored a 1275 block to suit. That was 45,000 miles ago and it's still going like sh!te off a shovel. It still gets revved past 7500.

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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.

Cool,

Thanks heaps Kev, no great rush though - I've got plenty to do on the body before I get too worried about getting the motor rebuilt. Repairs to A panels, outer sills, battery box, and part of the spare wheel well needed for starters. Then a complete respray might be in order.

I'll strip the 1098 for the crank in the school hols though, it'll give my young bloke something to do.

Sorry to hi-jack your thread boost_morre, you want these pistons or no?

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Who's MadMax?

Kev, put me down for a "possible" set of imps....

I got a spare 998 block here just itching for the 1100 Crank to go in.......

What sort of dish do they have ? if i left it "undecked" (just enough to true it up) would it have less than, say, 8:1 compression with a 12G202 head ?

Or while I've got the block apart, should i just pocket and stick that thumping great 12G940 head on ?

WIll probably get another "russell" cam maybe with a little less inlet duration and maybe a little more exhaust, as well as hopfully making a larger exhaust manifold ........

thinking, thinking, thinking.......
J

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All Imp pistons were flat top, flycut for the inclined valves. No big deal.
2 types sold here, std Imp and Imp GT. Only diff I can see is the GT had thicker wall gudgeon pins. Both types have the gudgeon pin offset so watch how you fit them..
Deck height is about .140" or so less than a 1098 one, so if you are building a N/A motor mill a chunk off the block. I guess for turbo you could leave 'em down the bore a bit.

When I built mine back in `68 I notched the block and ran a 12G940 (1100S) head, with a 544 cam and twin HS4s. The thing screamed- 8500 was no big deal. Until I broke a piston circlip.... bore got scored big time, and the fun came to an end.
<edit> Fit teflon (PTFE) buttons instead of circlips if you're gonna rev it hard..

I then fitted a 1275 motor in, but it just didn't go the same.

I'd just use stock 1100S valve sizes- or maybe fit S inlets. Stocko exhausts.

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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.

I've got a 12G295 head here Kazjim, that I could be talked into parting with if you're interested. It has not been used since it was recoed. Inlet valves are std. and exhausts are 1 mm oversize but seats are not unleaded. I paid $550, so I'd want that much for it. Let me know if you're interested. I'm only selling it 'cause I bought a leaded one off another ausmini member.

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Who's MadMax?

Hay Kev I'll take a set of those pistons...Next Time Morris need's to done over again I'm going to need them You know we had the engine out and I should have got you to Pocket the Block and then put on a 940

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Stop Licking the Dog...I Don't Care Who Started It