70sublime340
Well-Known Member
Can anyone direct me to a 34 piston in the 11-12:1 range? Prefer domed, I have looked and can't come up with anything besides sets that are $1500 or custom made. Thanks!!
340 High Compression Pistons
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70sublime340
Well-Known Member
Probably should have included they need to be forged, .030 and it is not a stroker motor.
Custom is your only route other than NOS TRW.
I have a set of the old TRW 12-1's. One looks a little beat up, not bad, but.......
I have an NOS TRW set. .030, never ran. $400 shipped. The tops have been slightly flycut for valve clearance, but the dome is untouched. They will still be around 11.5:1 compression with factory J or X heads. I probably wont ever use them. Let me know if you want some pictures. Thanks
nm9stheham
Well-Known Member
I have looked before.... the .030" size makes it harder. I looked again, and if you could go .020" over, the maybe Icon Chevy 302's would work with a minor amount of block decking and a bit for work on the tops and bushed rods.
What heads are you using? What are your options there?
What heads are you using? What are your options there?
70sublime340
Well-Known Member
Using INDy LA-X heads and the block is .020 right now was gonna take it to .030
yellow rose
Overnight Sensation
You can use the pistons in post 7 if you are using open chamber heads. If they are not open chamber, you have to mill the quench pad.
Funny thing is, that's the piston I'm using. If you are wanting max compression you'll need a positive deck height of .060 or a bit more, depending on gasket thickness and chamber volume.
Finding a machinist who will do that may be a PITA. But that's the correct way to do it. Don't mill the heads to nothing. Shorten the decks.
Funny thing is, that's the piston I'm using. If you are wanting max compression you'll need a positive deck height of .060 or a bit more, depending on gasket thickness and chamber volume.
Finding a machinist who will do that may be a PITA. But that's the correct way to do it. Don't mill the heads to nothing. Shorten the decks.
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70sublime340
Well-Known Member
My machine at will be decking the block, he has already told me that. The heads are a 62cc and open. They're basically a 68/69 X head
62 cc and Open?.....open as in ported or open as in open chambers?......the indy x head is a close chamber head.....
High compression 340 pistons are design to have a positive deck height...meaning the stick out of the bore....close chamber heads not designed to work with that type of piston...an open chamber head is....you will need to increase the thickness of the head gasket which defeats your intend of raising compression..
decking the block will only make the piston stick out further on the block...
you are going to need a dome piston that is design for a close chamber head.....
I'd suggest you clarify what a LA-X head has for a chamber. You need to know what you are using. A 68-69 X head is NOTHING like an Indy LA-X head.
nm9stheham
Well-Known Member
OK, I just was wondering if a switch to a 58 cc Magnum head was an option. That'll get you it right around 11 with, KB or JE hypers and .035 gasket. But I guess you'd have to sell the Indy-x heads and you wouldn't have forged pistons.
Those Ross pistons look great but I suspect your gonna need a bit of machining on the lower edge of the dome with those heads' chamber shape. Still a good buy. With no spark slot, it looks they are set up to be machined a bit anyway.
One of my L-2322's.
nm9stheham
Well-Known Member
And the Ross pistons have a negative deck height in a standard LA block (CH = 1.804"), so the OP may not be at the point of any problems with the decking. With and 020" decking, the Ross pistons will be approximately .002" out of the deck, so that is not all that bad. Put in .040" Cometics or .039" Felpro's and see if the piston heads can be machined to fit the X chambers. I guess that is still custom in a way but he is close and not $1500.
yellow rose
Overnight Sensation
Wait a minute. If he wants domes he needs the 2316 TRW IIRC. I guess I could go pull one and take a pic. That flat top Rob has will make 10.5:1 if you stick it out of the hole.
Better make dang sure what head you have before you drop money on pistons.
I pulled the Arias 13.5:1 Pistons out of my W2 short block and used them in my W5 short block. You just have to mill the quench pad down and be careful because you are technically moving the dome UP in the chamber. I ended up at 16.2:1 and had to massage the domes down to get it back where I wanted.
Know what you have first.
Better make dang sure what head you have before you drop money on pistons.
I pulled the Arias 13.5:1 Pistons out of my W2 short block and used them in my W5 short block. You just have to mill the quench pad down and be careful because you are technically moving the dome UP in the chamber. I ended up at 16.2:1 and had to massage the domes down to get it back where I wanted.
Know what you have first.
70sublime340
Well-Known Member
My mistake I should have looked again before posting. They're absolutely closed chamber heads.
yellow rose
Overnight Sensation
You should be able to find reasonably priced pistons in a pumpkin field for that.
70sublime340
Well-Known Member
It's looking like I'm going to have to accept the fact that the 11:1 range isn't going to happen. I know I can run trw but we are trying to save some weight. Are the close chambered heads going to hamper my piston choices considerably?
nm9stheham
Well-Known Member
Hold the phone OP.... you are so close. I'd like to ask why the high CR in the first place? If you are running a fairly radical to radical cam, then it is the right thing to have to keep dynamic CR up.
The closed chambers mean that you need to be ready to machine a domed top or have the right shape. But the Indy X chambers are not severely closed chambered, and IMHO the machining will not be severe to get the 99626's to fit. There is just a small cut to clear that angled edge of the chamber over near the spark plug, and a spark slot to add. And their compression height fits right with your decking the quench side of the chamber works with the flat on the Ross piston.....
IMHO, check with Ross to verify the pix on the Summit page, and dimensions on the quench flat area. If it looks good, see if you can buy ONE from Summit and look at the fit versus the head chamber, and take it to the local machinist. Look under the dome to see if their is meat to support a machined top. A lot of this can be done with a call to Ross.
http://www.summitracing.com/parts/ros-99626
#8---La-X and Ma-X Iron Small Block Heads
The closed chambers mean that you need to be ready to machine a domed top or have the right shape. But the Indy X chambers are not severely closed chambered, and IMHO the machining will not be severe to get the 99626's to fit. There is just a small cut to clear that angled edge of the chamber over near the spark plug, and a spark slot to add. And their compression height fits right with your decking the quench side of the chamber works with the flat on the Ross piston.....
IMHO, check with Ross to verify the pix on the Summit page, and dimensions on the quench flat area. If it looks good, see if you can buy ONE from Summit and look at the fit versus the head chamber, and take it to the local machinist. Look under the dome to see if their is meat to support a machined top. A lot of this can be done with a call to Ross.
http://www.summitracing.com/parts/ros-99626
#8---La-X and Ma-X Iron Small Block Heads
nm9stheham
Well-Known Member
And the TRWL2322 shown in post #15 looks like it could have just a bit of milling on that angled lower edge shown in the first pix and pop right into the Indy X chamber. But they are heavy....
70sublime340
Well-Known Member
My machinist recommended the high compression with an aggressive cam profile to achieve the 450hp were looking for without using a stroker kit. I know it makes more sense to stroke it and use different heads but I want to keep the stockish head outward appearance. We're aiming for more of an old school type build. Looking at the mopar muscle 340 build I don't think 450hp is out of line with the right combination
70sublime340
Well-Known Member
Also, cam has not yet been selected. We're obviously in the beginning stages of the build, only thing we know is the heads. But the order can be canceled on them if someone ha a better iron head option
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