wanted +80 hi comp pistons

[Rocket Racer]

just on the off chance someone has some and would part with them, ideally 10.5:1 for a race engine
pm me please

[Rocket Racer]

just on the off chance someone has some and would part with them, ideally 10.5:1 for a race engine
pm me please

in absence of responses and to progress the build; will be resleeving and fitting some std forged MC 10.5:1 from baxters in the US. Should be a lot lighter than +80's except the cost of resleeving. Do have a set of +80 GPM 8.5:1 which I'll probably never use .

[muskrat]

G'day RR.
I'd like to buy your +80's to offset the cost of your re-sleeve. PM me with a price.
Cheers

[RDfella]

Two things bother me about this amount of oversize. I seem to recall that when I bored my GF to + .060" there wasn't much left of the cyl wall below the flange. Seems to me at + .080" that part of the cylinder, if it doesn't actually disappear, will be very prone to breaking off.
Also, there's the question of how much material is left above the flange and whether that's weakened enough to cause the cylinder above to break away from the flange. Boring for a liner would clearly regain strength below the flange, but can it be expected to help the barrels above to remain with the flange? And if that isn't bad enough, we're expecting it all to stay together with high comp pistons and some hard riding. In another sphere, I'd be calling for a 'thick block' but do these exist for A10's, or are they all the same thickness?

[Rocket Racer]

Two things bother me about this amount of oversize. I seem to recall that when I bored my GF to + .060" there wasn't much left of the cyl wall below the flange. Seems to me at + .080" that part of the cylinder, if it doesn't actually disappear, will be very prone to breaking off.
Also, there's the question of how much material is left above the flange and whether that's weakened enough to cause the cylinder above to break away from the flange. Boring for a liner would clearly regain strength below the flange, but can it be expected to help the barrels above to remain with the flange? And if that isn't bad enough, we're expecting it all to stay together with high comp pistons and some hard riding. In another sphere, I'd be calling for a 'thick block' but do these exist for A10's, or are they all the same thickness?

I have in my possession a fin donor barrel; large fin thin flange that by the state of the pistons had been run very hard in the US for some time with 10.5:1 at +100 ! the flanges lifted so it did fail but not at +80. My concerns are more weight related and lack of compression. At +60 my race engine routinely ran up to 7500 although with the six speed in I now try to keep it to 6500. I would have no qualms about fitting +80 to a road engine balanced for these. the capacity increase is useful. A resleeve will likewise weaken the barrel. A sleeve od according to feked is 2.877" or 73.07mm now thats boring to +120! so the flanges are up to it and is done to all barrel types

[Rocket Racer]

G'day RR.
I'd like to buy your +80's to offset the cost of your re-sleeve. PM me with a price.
Cheers

will do, thanks

[muskrat]

G'day RD.
I understand your concerns. My A7SS only bored to +40 lifted a few barrels but that was at 14:1 and 7500-8000 rpm. I fixed that by through bolting head to cases.
Both my A7 plunger and A10 Cafe are through bolted but with a lot lower comp ratio.
Cheers

[berger]

hi musky, when you say lifted do you mean smashed the casting at the base or pulled the threads in studs or nuts?

[Rocket Racer]

I was recently looking for a7 barrels and a mate had a small collection with broken flanges (lifted)and on one a crack right across the pushrod tunnel. The thin flange a7 barrels don't appear to be that suitable for high compression as std. On any thin flange barrel I would personally not run high compression without through bolting mods like Muskrats.
I have more confidence in the thick flange barrels however.
8.5:1 +80 should be fine on an a10 barrel if used reasonably.  A resleeve makes the flange to barrel attachment thinner than a +80 piston will

[muskrat]

G'day berger.
The barrels broke all the way around just above the flange.
The A7 plunger inherited the racers top end when I converted it to the A10 Cafe. So it is through bolted even though it's low (7.5:1) comp.
Cheers