Am I ok with this? KB107 in La block

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Chadderbox70

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I have a 360 La block. (Factory crank and rods , resized and balanced)

I have begun installing my kb107 pistons and I notice the first one number 1 is almost flush with the deck.
The number 2 piston actually sticks up.
(I'm not exactly sure my written numbers on them are accurate with a feeler gauge at home)

Should I do the others to see more, or quit right here, I called the machine shop and they told me ,I can pay more to have it resurfaced again, just depends on how blue printed I want it to be.

Second question is if I am out of the hole , am I am to use my fel pro 1008 head gaskets with the factory J open chamber heads?


Thanks

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So one is .023 above and one is .020 below deck? Is that right? Either the block needs decking OR the crank needs indexing. Or both. You need better tools than feeler gauges though to make an accurate measurement. A degree wheel, an over the cylinder piston stop and a depth micrometer would be the absolute minimum.
 
I would temporarily install the other 2 on that bank and see if the block is machined non parallel to the crank centerline.
 
stupid question, but have you checked to see if the connecting rods and pistons are all the same length/height? Part quality these days has been a nightmare.
 
Answer: D All the above,
Question did they clean up the deck and if so how much did they take off?
 
Yikes! I'd install all of the pistons (less rings) to see where they all sit, and what the problem could be. The hints above give you the possibilities.....none of which are easy fixes.
 
I'd also double check bearing clearances, most to rule out an issue there.
Dial indicator is the way to go for checking these types of numbers too. Like others have said, feeler gauge can be tough to get a good check with.
Also be sure to try and 'rock' the pistons a bit, or at least tap them lightly with a soft-faced hammer to make sure they're all rocked 'the same', since piston-to-bore clearance can let things move around a bit.
 
Most shops around here install the two end pistons on each side to get a good idea of squareness. Remember too, to take your measurements from the non thrust sides of the pistons. That's the front and rear. Otherwise, it might be possible to pick up some slop in the wrist pins. Especially if you assemble with no rings. It's possible either way.
 
Phreakish said:
I'd also double check bearing clearances, most to rule out an issue there.
Dial indicator is the way to go for checking these types of numbers too. Like others have said, feeler gauge can be tough to get a good check with.
Also be sure to try and 'rock' the pistons a bit, or at least tap them lightly with a soft-faced hammer to make sure they're all rocked 'the same', since piston-to-bore clearance can let things move around a bit.
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A dial indicator is good, but I prefer the depth micrometer. It can be much more accurate. It can also be used to measure positive deck clearance with one foot off of the piston head with feeler gauges between that foot and the deck. In that instance, feeler gauges are very accurate.
 
RustyRatRod said:
A dial indicator is good, but I prefer the depth micrometer. It can be much more accurate. It can also be used to measure positive deck clearance with one foot off of the piston head with feeler gauges between that foot and the deck. In that instance, feeler gauges are very accurate.
Click to expand...

I was sloppy with my wording. A dial indicator could mean several things, and I envisioned it setup just like a depth mic. A depth mic (which has a dial indicator, LOL) would definitely be the easiest/quickest!
 
RustyRatRod said:
Most shops around here install the two end pistons on each side to get a good idea of squareness. Remember too, to take your measurements from the non thrust sides of the pistons. That's the front and rear. Otherwise, it might be possible to pick up some slop in the wrist pins. Especially if you assemble with no rings. It's possible either way.
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Beat me to it lol. Installing the middle pistons is a waste of time since block deck surfaces typically aren't wavy.

I made the mistake of only checking the height of one piston back when I put together a 360 LA with KB107s and Magnum heads. You likely have one deck taller than the other, hopefully not by as much as your quick and dirty measurements show because .040" difference is quite a bit. Square decking based off the crankshaft centerline is the way to fix all of that but not all machine shops have that capability and it's more costly. Confirming how much difference there is between the two sides then having the taller deck milled down to match will still be a big benefit.

I believe the "depth mic" is also called a "deck bridge".
 
Phreakish said:
I was sloppy with my wording. A dial indicator could mean several things, and I envisioned it setup just like a depth mic. A depth mic (which has a dial indicator, LOL) would definitely be the easiest/quickest!
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I didn't say it, but I was including it in my list. Whenever I say degree wheel, I always "assume" everything else. I should have included the dial indicator there. It's totally necessary.
 
MopaR&D said:
Beat me to it lol. Installing the middle pistons is a waste of time since block deck surfaces typically aren't wavy.

I made the mistake of only checking the height of one piston back when I put together a 360 LA with KB107s and Magnum heads. You likely have one deck taller than the other, hopefully not by as much as your quick and dirty measurements show because .040" difference is quite a bit. Square decking based off the crankshaft centerline is the way to fix all of that but not all machine shops have that capability and it's more costly. Confirming how much difference there is between the two sides then having the taller deck milled down to match will still be a big benefit.
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Right. Wavy usually doesn't happen, but unlevel does and the pistons in the corners method will pick that up.
 
Chadderbox70 said:
Second question is if I am out of the hole , am I am to use my fel pro 1008 head gaskets with the factory J open chamber heads?


Thanks
Click to expand...


OK, there are plenty of suggestions for the difference in deck height. I have nothing to add there. But to address your second question: Yes you can. Factory 340 high compression pistons (68-71) came out of the hole .015-.025 and they cleared the open chamber X and J heads even with thin steel shim head gaskets. Those pistons are the reason why Edelbrock offers their 340 aluminum heads in a large chamber version which is just the regular RPM head machined the diameter of the cylinder some .060 inch - just to clear pistons with a positive deck height.
 
Yes it appears to me that one sticks out that much and the other is below that much.
65 Cuda 340 said:
OK, there are plenty of suggestions for the difference in deck height. I have nothing to add there. But to address your second question: Yes you can. Factory 340 high compression pistons (68-71) came out of the hole .015-.025 and they cleared the open chamber X and J heads even with thin steel shim head gaskets. Those pistons are the reason why Edelbrock offers their 340 aluminum heads in a large chamber version which is just the regular RPM head machined the diameter of the cylinder some .060 inch - just to clear pistons with a positive deck height.
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Thank you! The shop that took my j heads and installed 2.02 valves for me machined them a bit they are shiny and straight. I have no way of knowing how much they took off and if it's still safe.
 
What you got is the beginning of a fucked up mess. You need to find a quality engine builder that has 20 + years of experience in mopar and no dumb *** kids working in the shop. Everything in an engine needs to be measured and fit together. For the machine shop to tell you that more money solves the problem is bulls ****, find a better shop.
 
Just eyeballin it, you can be off many degrees trying to find TDC, due to the dwell time. That's why a piston stop and degree wheel are so important here. Without those tools, all you have are assumptions, regardless of how "accurate" you think you are.
 
RustyRatRod said:
Just eyeballin it, you can be off many degrees trying to find TDC, due to the dwell time. That's why a piston stop and degree wheel are so important here. Without those tools, all you have are assumptions, regardless of how "accurate" you think you are.
Click to expand...

The deck bridge/depth mic will also get it there as it will precisely show where the piston height maxes out. It won't show exact TDC because there are (at least) a few degrees of crank rotation where the piston dwells at the top of its stroke but for this kind of measurement it's the easiest and most straightforward method, IMO

Is there a way for a machinist to accurately measure and correct deck height without the machine/fixture for square decking, or without installing pistons and rods and checking where they sit at TDC? I'm imagining a set of big calipers going from the main bearing bore up to the deck but I feel like that wouldn't be very reliable...
 
If a man had a nice machined shaft sized to the mains, one could check with machinist rules and straight edges to see if it was stupid off.
Set all the pistons on a surface plate and see if they all match. etc.
 
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