Does anyone know if you can still get 1100 flat top pistons?
Hepolite used to make them (18520) but I dont see them listed anywhere.
Thanks.

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Have a Nice Day.
If already having a nice day please disregard.

Graham Russell gets them made, he keeps in stock but only from +.060" up I think.
Give him a ring and ask.

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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.

GR's 1100 +0.100"

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David L


My greatest fear in life is that when I die my wife will sell my Mini and tools for the price I told her I paid for them!

have you worked out what your compression ratio would be with flattop pistons? It's simple enough to do and may save you a lot of grief if it turns out that flattops cause a compression ratio which is too high for your intended purpose(race or road). The CR is also dependent upon how much the head has been skimmed and the volume of the combustion chamber(has the head been ported and chambers modified?))

Yeah thats a good point... You need to consider the swept volume, the compressed volume of the head gasket, the combustion chamber and the area between the crown of the piston and the first compression ring.... (I deck all my blocks so that the pistons are flush,, but if thats not your thing that you also need to consider the volume between the top of the crown and the deck....

If your block and head have already been skimmed your CR may end up something silly....

**BUT** seeing as how 850man has specifically asked for flat tops,,, Id say he's already done his calc's and that is what he needs...

If the CR is too high it gets anoying, it only takes a bad batch of fuel and you need to retard the timing You also need to start looking at what spark plugs you are using too... as the CR gets higher, you start needing colder plugs other wise the fuel all detonates at once rather than being a smooth burn...

Running away now

I'm using a 295 head so I'm trying to restore compression without decking the block

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David L


My greatest fear in life is that when I die my wife will sell my Mini and tools for the price I told her I paid for them!

It appears that 998 ones are still available (Hepolite P/N 22463). You could use these and then have your rods shortened by 150 thou. This would also have the added advantage of lightening your rods - very helpful on an 1100....just a thought.

EDIT> Just to avoid any confusion, the correct way to shorten the Rods is by having the mating face ground back by 150 thou (a small skim also from the cap), Closing, Boring and Honing back to the correct size.

I'll have a similar problem at my next rebuild.. I'm already at +.060", and larger dished pistons are not available. This means I'll have to run flat tops, and somehow find a way to lower my CR since my '295 has already been decked 90 thou

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Simon

The adventures of an owner builder in the Tallarook Ranges

Don't know how much work has already been done on your head (if any) but you could look at opening your chambers? It will lower the comp. And will deshroud the valves too....

<EDIT>
Other wise you could look at running a standard BK450 (the turbo gaskets share the same part number but they have a lower compressed volume... the standard ones are 4cc) and doing things like grinding the valve seats lower into the head, using rim flow valves (cos they have dishes and lower the comp slightly), maybe even grind a little bit out of the very top of the chambers (make them deeper)... I reckon you could scab up a few extra cc's by doing all that...

Or get another head - I've got at least one maybe 2

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David L


My greatest fear in life is that when I die my wife will sell my Mini and tools for the price I told her I paid for them!

When the time comes, I reckon I'll probably just use a decompression plate. I'm kinda attached to this head (it appears to have had some very nice porting work done and performs quite nicely thank you ) and being a '295 already has a good chamber shape, so I'm loathe to take a die grinder to it

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Simon

The adventures of an owner builder in the Tallarook Ranges

You could allways machine a dish into the top of the flat top piston to get you desired comp.

The engine i am building will be for a road car with a very nice 12G202 head and 11.1 comp.

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Have a Nice Day.
If already having a nice day please disregard.

Dave,

By the looks of the photo the block has been decked? Had a similar job done but with 0.080 flat tops and both head (202) was skimed and blocked was decked. Only casualty was half the engine numbers have gone and now in a 'discussion' with person doing the blue slip inspection.

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Dave K.
1979 Moke Californian + 1981 'Coke' Moke

HI 850man
Running the small bores up to 11.4 comp is not a problem with the motor set up right running 98pulp, thats what i,m running gregs on goes really well.
Graham Russell

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"It's better to be not informed than ill-informed"

Numbers are fine .........................................................now

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David L


My greatest fear in life is that when I die my wife will sell my Mini and tools for the price I told her I paid for them!