36 replies to this topic

[1987_ParkLane]

I would advise binning the circlips and using piston buttons. I can get these made for around £20 a set.

Cheers, I'll just give them to MED, see what they say, and what they can do.

[1987_ParkLane]

Do I got some of these pistons

minispares evolution pistons +40..

And my mate took them to MED today, and he said they are too thin to machine . So I have a few options here:

1. Get them machined myself.

2. Send them back to Mini Spares and get some other ones.

Not really sure what to do, and none of the work can really be done until the pistons are sourced . Help please, I'm really annoyed now .

[1275 SPRITE]

He said the piston crown was 6mm thick, and he measured the dish on a 1293 omega (6cc) and the dish was something like 5.2mm, but because the 998 pistons are a smaller diameter the dish would have to be deeper, therefore wouldn't be possible as the crown is too thin. ??

Please help as we are completely stuck lol.
Thanks.

[1987_ParkLane]

He said the piston crown was 6mm thick, and he measured the dish on a 1293 omega (6cc) and the dish was something like 5.2mm, but because the 998 pistons are a smaller diameter the dish would have to be deeper, therefore wouldn't be possible as the crown is too thin. ??

Please help as we are completely stuck lol.
Thanks.

Doens't look good .

[1275 SPRITE]

Doens't look good .

no it doesn't

[1987_ParkLane]

no it doesn't

Don't fancy the Omega's at £450, but if it comes to that it might just have to be .

[THE STIG]

if lowering the comp is your aim why not use pistons as they come and use a 120 thou thick cometic head gasket

although they dont list one for a 998 spoke to these guys last week and they can order a 998 head gasket in any thickness up 120thou thick from the factory in the states

http://www.performan...istributor.html

[1987_ParkLane]

if lowering the comp is your aim why not use pistons as they come and use a 120 thou thick cometic head gasket

although they dont list one for a 998 spoke to these guys last week and they can order a 998 head gasket in any thickness up 120thou thick from the factory in the states

http://www.performan...istributor.html

Hmmmm, seems like a way around it, but how reliable would that be? Don't want be changing the head gasket every two weeks lol. Also, wouldn't that be like using a decomp plate? Cheers for the reply STIG .

[THE STIG]

Hmmmm, seems like a way around it, but how reliable would that be? Don't want be changing the head gasket every two weeks lol. Also, wouldn't that be like using a decomp plate? Cheers for the reply STIG .

as reliable as any other head gasket

they make them for allsorts of high performace engines

its the same head gasket that minispeed use on there supercharger kits only theirs is for 1275>1400 cc

no is not the same as using a decompression plate as thats has 4 mating sufaces

head 1 gasket 2 decom plate 3 gasket 4 block ,theses gaskets have 2 ,head 1 gasket 2 block as made in one piece ,

Edited by THE STIG, 15 June 2009 - 08:10 PM.

[1987_ParkLane]

as reliable as any other head gasket

they make them for allsorts of high performace engines

its the same head gasket that minispeed use on there supercharger kits only theirs is for 1275>1400 cc

no is not the same as using a decompression plate as thats has 4 mating sufaces with the head gaskets ,theses gaskets have 2 as made in one piece ,

Hmmmm, very interesting, any idea how much that would lower the compression by?

[THE STIG]

as reliable as any other head gasket

they make them for allsorts of high performace engines

its the same head gasket that minispeed use on there supercharger kits only theirs is for 1275>1400 cc

no is not the same as using a decompression plate as thats has 4 mating sufaces with the head gaskets ,theses gaskets have 2 as made in one piece ,

Hmmmm, very interesting, any idea how much that would lower the compression by?

depends on all your other mesurements how many cc in pistons, how many in head , how far dont the bore are the pistons etc

but a 12o thou is enough the run a standard head and piston set up on a 1275 cc superchaged engine

so will be able to get the requried comprssion of 8.1 as can always work head chambers if needed

[1987_ParkLane]

depends on all your other mesurements how many cc in pistons, how many in head , how far dont the bore are the pistons etc

but a 12o thou is enough the run a standard head and piston set up on a 1275 cc superchaged engine

so will be able to get the requried comprssion of 8.1 as can always work head chambers if needed

Hmmm, may have to look into that option, as don't fancy the Omega's , thanks for that STIG .

[1275 SPRITE]

looks like quite a good option. Any idea on price?

[THE STIG]

looks like quite a good option. Any idea on price?

of the shelf 74mm bore, head gaskets 1275>1400cc are £75 pound are on ebay as well just put cometic head gasket in search

[1275 SPRITE]

ok thanks,
seems like a cheaper option than omega pistons. It would still be keeping all the strength in the piston crowns too.