 1.7 Pistons, 90 mm high compression |
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| Downunderman |
 Oct 4 2018, 04:55 PM
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#1
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Senior Member  Group: Members Posts: 852 Joined: 31-May 03 From: Sydney, Australia Member No.: 766 Region Association: Australia and New Zealand  |
I asked this in the paddock so might as well ask here too. Who makes forged pistons for a 1.7 with a compression ratio about 10.5:1? I need to source some for my historic racer engine. TIA. Howie.
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| bdstone914 |
Oct 4 2018, 07:28 PM
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#2
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bdstone914 Group: Members Posts: 4,522 Joined: 8-November 03 From: Riverside CA Member No.: 1,319 |
JE Pistons will make anything. You would need to provide the specs.
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| Downunderman |
Oct 4 2018, 07:56 PM
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#3
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Senior Member Group: Members Posts: 852 Joined: 31-May 03 From: Sydney, Australia Member No.: 766 Region Association: Australia and New Zealand |
I know but if they have made some for someone else it will be a bit easier. I have asked them but haven't heard back yet. Same with Wiseco.
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| VaccaRabite |
Oct 5 2018, 02:40 PM
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#4
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En Garde! Group: Admin Posts: 13,444 Joined: 15-December 03 From: Dallastown, PA Member No.: 1,435 Region Association: MidAtlantic Region |
Are you not allowed to use base rings between the case and cylinders? Running no head gasket and then adjusting cylinder height should get you where you need to be for CR. If you needed to you could also deck the case and forgo the base shims.
Getting custom made pistons is $$$. |
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| Downunderman |
Oct 5 2018, 05:10 PM
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#5
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Senior Member Group: Members Posts: 852 Joined: 31-May 03 From: Sydney, Australia Member No.: 766 Region Association: Australia and New Zealand |
I thought of that but run into valve clearance issues. JE doesnt have an off the shelf option.
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| ChrisFoley |
Oct 6 2018, 07:17 AM
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#6
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I am Tangerine Racing Group: Members Posts: 7,925 Joined: 29-January 03 From: Bolton, CT Member No.: 209 Region Association: None 
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QUOTE(Downunderman @ Oct 5 2018, 07:10 PM)  I thought of that but run into valve clearance issues. JE doesnt have an off the shelf option. I use Wiseco forged pistons modeled after the domed stock pistons. Cutting eyebrows into pistons isn't that difficult. The hardest part is locating them properly. For that I mock up the engine with no valves in the heads. Then with each piston at the top of it's stroke I use a transfer punch to mark both valve center positions on each piston. After that, mount the pistons at the valve angle on a milling machine and use an appropriate diameter end mill to cut the pockets. Each piston requires a unique pocket pattern, unless you cheat and use a large single pocket for both valves. For that you just traverse an end mill large enough for the intake valve across the piston. Using an off the shelf piston that has a single valve pocket as an example can eliminate the effort of mocking up and marking each piston at some expense of compression ratio. It is valuable to understand that the closest approach between valve and piston does not occur at TDC. Pocket depth should allow at least .080" clearance at the closest approach. |
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| Downunderman |
Oct 6 2018, 12:48 PM
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#7
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Senior Member Group: Members Posts: 852 Joined: 31-May 03 From: Sydney, Australia Member No.: 766 Region Association: Australia and New Zealand |
Thanks Chris. I was trying to avoid all that but if not so be it. Do you have the Wiseco part number for the pistons?
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