Valve pocket size intake/exhaust

[ChargerST]

I ordered custom pistons from Autotec and specified 4 left and 4 right pistons. Gave them my valve sizes (2.19 and 1.75) and got these pistons. Looks like the exhaust valve pocket is radially oversized (same size as the intake valve pocket) making it a symmetrical piston - not really what I had in mind.
Is there any disadvantage of having that much clearance? Quench pad on the piston looks larger than on the head anyways.
See Trick Flow chamber for comparison.

 

[493 Mike]

Well you gave up extra compression. Were you looking for a specific compression ratio? I don't believe I am familiar with Autotec. Who are they?
Mike

 

[Curiousyellow71]

The owner of Je pistons sold the company and then had a noncompete for a couple years and then started autotec and racetec...who specialize in custom pistons. I wouldn't be happy either with a huge eye brow for the exhaust. The quench pad I think is fine...but I am surprised they did that...I think I'd call them..its got to be a misunderstanding...looks like they understood you wanting to put the same piston in both banks instead of Lh and Rh. It's a CNC piston they can build it in any manor... it's just a program change they are a small company...you have a shot of them making it right. Probably 3 cc lost maybe? Just a guess?

 

[ChargerST]

Autotec is the 4032 version of the racetec pistons (which are 2618 aluminum alloy). Yeah, rather strange why they did that since the order form clearly stated 4 RH and 4 LH. I had also specified that the intake valve pocket should be radiused which they didn't do either. The pistons are at a friend's place so I wasn't able to cc them to see if the inverted dome and valve pockets have the ordered -17cc or not.

 

[wyrmrider]

looks like you ordered lefts and rights
what uses and source on that 1.75 exhaust?
why are the valves so low- do you need a top cut? (or not) ask someone with experience on YOUR heads
is this a blower piston?
is the plug side tepped down or level with the quench side? old eyes can't tell
if so it might actually help
what angles or radius seat?
think of the head flows (I and ex) together with the piston

 

[ChargerST]

looks like you ordered lefts and rights
what uses and source on that 1.75 exhaust?
why are the valves so low- do you need a top cut? (or not) ask someone with experience on YOUR heads
is this a blower piston?
is the plug side tepped down or level with the quench side? old eyes can't tell
if so it might actually help
what angles or radius seat?
think of the head flows (I and ex) together with the piston

Not a blower piston. I ordered a piston with -17cc to give me 10.6:1 compression ratio @ .005 down the hole.
Not sure what you mean by the valves being so low. Heads including valves are ootb Trick Flow 240s.
Not a stepped dish - plug side is level with quench pad.
btw. heads info incl. part number were given to Autotec together with the cam info (.620" lift).

 

[Curiousyellow71]

If your cc's are what you want for your scr it's likely not going to effect how it runs at all. I understand why your surprised with your end result..because typically it should be the way you ordered it...that's usually the idea behind "custom". But when I've look at the autotec pistons in the mopar section it didn't really look like they offered as many custom options for the pistons as I thought they would? But it's been a few months since I've looked at their pistons. It seems like certain parts of the piston like CH and pin size, they are custom, but dish's and domes, valve releifs they have a list to pick from...yes custom made...just maybe not as custom as the concept of being exactly the way you want it. That's just what I gathered from looking through the site. When I was looking I didn't see a piston custom option to get what I was after so I moved on. But best talk to them and ask if you have a question.
I may be overlooking something.. looks like a symmetrical piston? I would think the quench pad should be as big as possible on the piston. It doesn't look like when they cut the fly cuts deeper they were smoothed out and radiused? Is that what you see? Hard to tell in the picture.

 

[wyrmrider]

so run the .028 mr gasket and you are good to go the tighter quench will offset the additional compression

I would not sweat the larger valve pocket
if it were smaller the dish would have to be deeper
thinner head
all tradeoffs

what's the valve job on those heads
top cuts
3 angle or multi angle and does it make a difference
ask around from those who have flowed those heads

 

[Curiousyellow71]

The owner of Je pistons sold the company and then had a noncompete for a couple years and then started autotec and racetec...who specialize in custom pistons. I wouldn't be happy either with a huge eye brow for the exhaust. The quench pad I think is fine...but I am surprised they did that...I think I'd call them..its got to be a misunderstanding...looks like they understood you wanting to put the same piston in both banks instead of Lh and Rh. It's a CNC piston they can build it in any manor... it's just a program change they are a small company...you have a shot of them making it right. Probably 3 cc lost maybe? Just a guess?

Just thought I'd mention when I wrote this I thought I was looking at a dome piston on my phone..Lol. I should of looked harder. I'd polish up the fly cut machining a bit and run it.

 

[33 IMP]

How big is your stroker? I have what looks like an identical Ross custom piston, made for a 4 5/8 B1 motor.