Need help with my pistons

[RaiderGT]

So I bought a set of diamante pistons for my build. Ordered for a 1992 diamante, SOHC and checked the Beck/Arnley part number against threads on this site and turbo dodge and ebay to absolutely make sure they were the correct 10:1. Ordered from rock auto in 50mm oversize. I took the to my builder and we put them in the block and compared them and everything looked good. He called me to day to say he is concerned about the valve reliefs not matching up. What do you guys think?

http://i.imgur.com/Pk9Wc41.jpg

http://i.imgur.com/nZiGy6c.jpg

http://i.imgur.com/pWu9Wt7.jpg

[lightbulb010]

I'm pretty sure the 10:1 pistons make an interference motor so the reliefs don't really matter anyway. I would run them. The intake valve relief is what makes the stock pistons weak. Very little metal between the relief and the top ringland.

[Spiritman]

I also bought diamante pistons from the rock and they were wrong. ended up getting some from lordco.

[RaiderGT]

In what way were they wrong?

[lightbulb010]

I don't see those pistons causing a problem. It looks like the quench pad is shaped wrong for the combustion chamber but not by much. If you can still return them and get pistons with the right quench pad it would be more ideal if you want to be anal. If it were me and it would cost me more money to get the "right" pistons I would just run these. I doubt you would ever notice the difference from the quench pad. With that being said, I would measure everything else to make sure they are what they're supposed to be and that the crown is the only place where the company changed the design.

I'm curious as to what Spiritman might have to say. I almost ordered those same pistons for my current engine but decided I could spend the money elsewhere and didn't want the compression bump. I would only have been using them for the added strength I'm guessing these have due to what I mentioned in my previous post about the intake valve relief.

[masterjr33]

bolt a head down. with some silly putty. rotate the engine.

[RaiderGT]

I don't see those pistons causing a problem. It looks like the quench pad is shaped wrong for the combustion chamber but not by much. If you can still return them and get pistons with the right quench pad it would be more ideal if you want to be anal. If it were me and it would cost me more money to get the "right" pistons I would just run these. I doubt you would ever notice the difference from the quench pad. With that being said, I would measure everything else to make sure they are what they're supposed to be and that the crown is the only place where the company changed the design.

I'm curious as to what Spiritman might have to say. I almost ordered those same pistons for my current engine but decided I could spend the money elsewhere and didn't want the compression bump. I would only have been using them for the added strength I'm guessing these have due to what I mentioned in my previous post about the intake valve relief.

Thanks. These were the last six they had and the only ones I have been able to find so far in the correct oversize. Everything else I have found that has been advertised as diamante pistons have been of the stock compression ratio.

- - - Updated - - -


bolt a head down. with some silly putty. rotate the engine.

Wouldn't the timing components need to be in place so the valves are open when they should be?

[masterjr33]

that would be implied with the spin it over comment.


BUT

not if you just want to check for worse case. is it interference now?

[RaiderGT]

that would be implied with the spin it over comment.


BUT

not if you just want to check for worse case. is it interference now?

Everything I have read says it become interference with the 10:1. I don't have the motor infront of me currently as I am on travel.

[Ondonti]

It will be interference. The valve reliefs need to be very very deep to avoid contact.
The OEM diamante reliefs make zero sense, don't line up, etc. I see a slight dish which would prevent your overbore from increasing compression beyond 10:1.

Jumping timing is not a common thing for the 12v. Never seen or heard of a 12v diamante that had bent valves or holed pistons.

Side view of the pistons showing the ringland thickness would be more important to me. The bottom too!

[RaiderGT]

Well it's back together at this point anyway. Checked each piston on the compression stroke and everything spins like it should. Machinist said everything else was fine.