This convo I turning into as much fun as de-veining my old fella with a blunt scallop knife - flats work - have done and always will.

Dad raced all manner of cars at Echo Valley in Toowoomba and used flats and drove them about Toowoomba until the next race meet. No issue of burning pistons(but broke a few valves if I remember rightly...lol).

Talk to the man(as I did) and get it from the horses' mouth...lol. Ally your fears and put your worrying minds to rest - GR is the bomb!!

Pissed and Amazed

Hooroo

Rob Forsyth
Miniot!!

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Rob Forsyth
Miniot!!

Mahle forged flat tops were OK back in their day, I ran them too.
They were nowhere near as stable in shape as these, or Hypatecs- I collapsed a Mahle at Wakefield Pk last February- then drove it home....

re the Hepolite I think their cutrrent production are now either cast, or `squeeze cast'- not forged.
A Hepolite 21253 with the 2 oil drain slots is not as strong as either these, or the Hypatecs- although appearance is similar..

re dish vs flat tops see my comments above.
Many of the fast Minis (eg Greig Malaure's) do not run flat tops these days.

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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.

Any problems with boring a 998 out to +.100? No cylinder wall flex issues on a hot motor?

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Mini - The Wizardry on Wheels!

Call GR. I know he has the +100 and bigger (if memory serves)
He will tell you how they go in a hot motor... but I dont think they would have them otherwise.

Cheers,
Peter.

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Click here for the Turbo Conversion Thread!

998s (& 1098s) still have heaps of bore wall left at .100" oversize.
I used to bore them to 68.0mm, that's about .140" oversize....

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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.

Here's a Tought..one ..go.100th and see how well it drives until it goes bang...Just depending on how you would treat any rebuilt Engine untill it does go Bang. You have made that engine enjoy its self for one last time. You have paid for Pistons Rings and the Machining.

By a used 998 Block or a 1098 or 1275 Block crank/rods/pistons rings and a head possibly plus Machining

Depending on what you want to Spend I quess..You may never know you just may have the rite price for a hot 998

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

Back in 1968 I thrashed my 1220 (68.0mm bore with 1098 crank) using up to 8,500 rpm (sometimes) for 20,000 miles before I had a problem.
Problem being that a circlip broke up, and the gudgeon pin gouged the cylinder wall.
No fault of the block thickness.......

If you put the circlips in the right way round, and keep rpm down to 7000 or so, you won't have this problem.
Use Teflon buttons instead, for race motors. Overkill for street use.

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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 waited a couple of months for RE pistons to use in my bigblock engine, and they give a compression of 9.7.1 with a standardish size 940 head

i have been advised they also have no backclearance for the rings

i will now have to compromise my engine build as they do not meet the requirements i asked for.

What do you mean by back clearence?

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What did you ask for?

Daniel

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Videos - Turbocharged A-Series on Dyno & at Wakefield
Mafs waz not my strong subgeckt at skkol

Did they come with the Nippon ring set, or are you using something else?

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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.

the rings were supplied with the pistons, and are an unknown brand.

i was shown hastings rings, and they come with instructions etc..

as it was explained to me, backclearance is the rings ability to recess into the slot on the pistons, the ones on my RE pistons stick out..

i was told it would take a long time to run my motor in as the motor is very tight.

From a Perfect Circle Piston Ring Brochure:

If the engine builder desires a
clearance less than (SAE) specifications
they must machine the piston groove to
obtain desired clearance. Perfect Circle
recommends .0008” to .0015” for proper
side clearance.
Back Clearance
Back clearance is the space between the
back side of the ring and the base of the
piston. Back clearance should be kept as
little as possible without having the face of
the ring stick beyond the piston lands
when bottomed out in the groove. Perfect
Circle recommends .010” to .030” for
proper clearance.

Looks to me as though the onus is on the installer to make them fit

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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!

yeah the face of the rings stick beyond the piston lands when bottomed out in the groove.

i have been advised if the pistons are modified to make this happen, then my piston rings are likely to break.

Talk to Graham before you do anything.
He should be on deck tomorrow.

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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.