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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| 1100 flat top pistons https://www.ausmini.com/forums/viewtopic.php?f=5&t=59045 |
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| Author: | 850man [ Tue Nov 24, 2009 8:55 pm ] |
| Post subject: | 1100 flat top pistons |
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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| Author: | drmini in aust [ Tue Nov 24, 2009 9:35 pm ] |
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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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| Author: | Wombat [ Tue Nov 24, 2009 10:55 pm ] |
| Post subject: | |
GR's 1100 +0.100" 
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| Author: | mini7boy [ Wed Nov 25, 2009 12:18 pm ] |
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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?)) |
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| Author: | Phat Kat [ Wed Nov 25, 2009 12:45 pm ] |
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mini7boy wrote: 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 
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| Author: | Wombat [ Wed Nov 25, 2009 1:14 pm ] |
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I'm using a 295 head so I'm trying to restore compression without decking the block 
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| Author: | GT mowog [ Wed Nov 25, 2009 2:37 pm ] |
| Post subject: | Re: 1100 flat top pistons |
850man wrote: 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. 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. |
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| Author: | sgc [ Wed Nov 25, 2009 2:47 pm ] |
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Wombat wrote: I'm using a 295 head so I'm trying to restore compression without decking the block
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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| Author: | Phat Kat [ Wed Nov 25, 2009 2:59 pm ] |
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sgc wrote: Wombat wrote: I'm using a 295 head so I'm trying to restore compression without decking the block 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 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... |
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| Author: | Wombat [ Wed Nov 25, 2009 3:17 pm ] |
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Or get another head - I've got at least one maybe 2 |
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| Author: | sgc [ Wed Nov 25, 2009 4:32 pm ] |
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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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| Author: | 850man [ Wed Nov 25, 2009 5:44 pm ] |
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sgc wrote: Wombat wrote: I'm using a 295 head so I'm trying to restore compression without decking the block 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 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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| Author: | miniDave [ Wed Nov 25, 2009 7:35 pm ] |
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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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| Author: | GR [ Wed Nov 25, 2009 7:43 pm ] |
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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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| Author: | Wombat [ Wed Nov 25, 2009 8:20 pm ] |
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miniDave wrote: 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. Numbers are fine .........................................................now
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