Re: stock stroke- forged pistons with scj valve reliefs brands that make them ?

dfree383 March 27th 2014, 7:45 pm

Carl wrote:
dfree383 wrote:Mark at Probe will add the reliefs if you ask and it's not an issue with the crown. I've added them myself to a set and have had no issues with the pistons.

Getting some domes made isn't a problem with any of the manufactures. A coupe of them have them on file but they are custom pieces. With a few you would need to make a mold.

Yes, Probe will add them. Having OEM reliefs added to their SCJ dish piston as we speak, but they probably won't even get into the top of the dish. Just need a small notch at the edge.

When you added reliefs to your pistons, what depth did you make them? What was the crown thickness before cutting? What was the crown thickness at the thinnest point after cutting? How big of a cam were you running and what was the V/P clearance? I know Diamond's reliefs are .190 deep on their "shelf" piston.

they are the same depth as the production reliefs. I don't recall the thickness numbers, but it was nothing that is a problem.

As far as lift, I've had .850 lift rollers in the engine with 2.30 intake valves, piston to valve was fine.

466cj March 28th 2014, 4:21 am

I'd do the probe flat tops as Dfree recommended. If you use a .041 gasket, zero deck pistons, .060 over 460 and a 72cc chamber you will be just hitting 12:1 CR. That is figuring 5cc's for both valve reliefs. If you mill down the heads to 65cc's you would be at 13:1 CR. If the valve relief is bigger you will need to reduce the chamber by that amount.

Better off with the Probe SRS piston anyway as it has a 1/16" ring package and for a drag race only deal you want a low tension ring package as there is HP to be had. Put the money saved into rings and a vacuum pump.

nuclearcobra March 29th 2014, 11:08 am

I bought the scj from Lem and he also had diamond make some flat tops with the one relief for my 472 , if I remember they were about 720 , I went with flat tops because I built this around spraying the crap outta it to see if 8.99 or better is possible on spray. The heads aren't ported at all but Charlie did backcut the intake valves on them. So far I ran a best of 9.98 all motor in a 2660lb mustang with a slipping old c6 and a used converter I got from here. I'm getting ready to put in a new rollerized c6 and getting the converter stalled for it. So I'm happy so far with outta the box heads , flat tops and a flat tappet cam , your Maverick is gonna fly Very Happy

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