dibbons
Well-Known Member
My 340 block was way off bank to bank. After the machining, the rebuilder still recommended two different head gaskets to further even out the remaining small deck clearance difference.
Checking deck height
- Thread starter coloradohill
- Start date
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yellow rose
Overnight Sensation
I’m confused by your numbers. How far is the quench pad out of the hole. The rest of the piston doesn’t matter at this point.
From what I see, the even side is put further than the odd side. You have to make those two equal. What’s happening in the center of the piston is really of little consequence.
BTW, I forgot to mention about piston “rock” and how easy it is to get out in the weeds in this stuff.
The only way to eliminate rock is to find some thin tape and tape off the skirts so there is near zero clearance and then measure the piston deck clearance.
If the piston is junk, and many are, or the piston is wrong for the application then you can have rock issues. You can see it on the piston above the rings.
If the piston isn’t junk or wrong, at operating temperatures the piston has very Little Rock, if my unless someone living in 1975 did the hone.
So getting ate up by piston rock is really picking the pepper out of the fly poop.
yellow rose
Overnight Sensation
Why didn’t he make both sides the same and use one head gasket?? He had the block in the mill. He should have made both sides the same.
Screw all this measurin ****. Disassemble the thing and let your machinist straighten it up. You're trying to do his job and you're handicappin yourself, because you don't have the right equipment. No offense.....You simply cannot get an accurate enough measurement doing it that way. You already know the block is crooked from the preliminary measurements you've taken, so.......take it to the shop. He'll fix it.
dibbons
Well-Known Member
Of course, that is a good question. He had his reasons and I didn't argue the case. However, unfortunately the logic behind his case of machining but not equalizing both sides at the time now escapes my degrading memory of the conversation.
coloradohill
Well-Known Member
Sorry for confusing, I’ll post a photo tomorrow but, I tried to measure where you said to. I’m not too concerned about piston rock. I am just trying to find out if it needs to be disassembled and corrected or, is it ok with .060 gaskets?
This has been balanced and I don’t want to do anything that would change that.
Thanks again as always
coloradohill
Well-Known Member
I am just trying to be involved as much as possible and like to have a good understanding of it all.
It’s how He made me
I get it man, but all of the measurements you come up with are totally irrelevant. The BLOCK is all that really matters.
If it has been balanced then all the pistons should weigh the same and the rods, big & small ends should be the same, so mix and match and you will be fine.
coloradohill
Well-Known Member
Makes sense, thanks again
yellow rose
Overnight Sensation
You assume the rods and pistons are the issue. By the OP’s numbers, it’s a block issue.
yellow rose
Overnight Sensation
Make it easy on me. Is the drivers side out of the hole .015 and .022 on the passenger side, as measured on the quench pad?
If so, you can run an .060 gasket and be ok. I’m not a fan of running with one bank .007 further out of the hole than the other. Not just the quench pad is out that far, the entire piston is.
That changes the compression ratio. By how much I’d have to do the math, but it’s enough I wouldn’t do it.
You are measuring it correctly. All it takes is a deck bridge with a dial indicator and a ratchet to turn the crank. Zero the dial indicator on the deck, position it over the QUENCH PAD of the piston and rock the piston around TDC and watch the indicator.
That kind of stuff drives me wild. It’s relatively easy to get the decks square and equal.
S'what I was tryin to say.
yellow rose
Overnight Sensation
Sometimes it's needed.
coloradohill
Well-Known Member
Yes, that’s how I measured the clearance.
So I will disassemble it ,take it to my machinist and have him square it up.
That’s what I was looking for, .006- .007 difference is more than you would allow on your build. Thank you!
coloradohill
Well-Known Member
I hear you loud and clear! Thanks again
I just like to know why things are done.
Have you ever asked someone why they are doing something and all they can say is “ I don’t know or because so and so said to”?
That drives me nuts.
Thanks again!
Oh I do it all the time myself....."just because". I just didn't want to see you go down a rabbit hole. That's all.
yellow rose
Overnight Sensation
The worst thing that could happen if he went down the rabbit hole is he’d run into me down there. It’s like I never leave that place.
famous bob
mopar misfit
^^^^^^^^^^^^^^^^^THIS ,^^^^^^^^^^^^^^ YOU COULD SWITCH A PISTON AND ROD FROM SIDE TO SIDE AND RECHECK UR MEASUREMENTS . Think the machinist should make it good if the decks are un even !!
coloradohill
Well-Known Member
Thanks, I’ll check with the machinist
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