Am I ok with this? KB107 in La block

[BillGrissom]

The shop's answer is that unless you pay for "blueprint" quality they don't machine the top of the block parallel to the bottom? Seems that would happen automatically if the block is rigidly bolted to the table of a special block surfacing machine. Perhaps metal flakes were under one end. Perhaps they used a general milling machine and it hadn't been trued. No expert, I've just watched the process on TV and youtubes. I expect that the bottom of the block is always parallel to the crankshaft centerline. Might also verify that all the pistons are uniform, like temporarily install the high ones in the low bores and see if the problem follows the piston or the bore.

 

[Swinger 340]

Have you checked the rod's? Maybe you have a bent one.

Just like checking for a bad coil on a multi-coil engine. Swap around the coils and see if you have the same fault. Swapping a rod and piston will give you a clue, if it is a rod or piston fault. Sizing the rods may be in order. Also I would check with a plastic gauge on the bearings for any slop. I know the early 340's are high on the block, so the one that is lower may be a fault in a loose bearing.

 

[Dale Davies]

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 is your +.023 above or below the deck. Normally a + deck height is below the deck surface and - is above the deck surface.
I would install all the piston/rod assemblies without rings after using a piston stop and degree wheel, so that true TDC is determined for each piston. Running mates should be able to be measured at the same time.
There is something wrong if you have the crank at TDC and measure your deck heights and find that much variance. A couple of thousandths would be acceptable but 0.043" is way to much.
What is the compressed thickness of that head gasket? DV has mentioned running the pistons 0.005" above the deck with a 0.035" compressed gasket for a tight quench promoting good mixture motion. That mixture motion promotes efficient burn and detonation tollerance. But that requires all the pistons to be the same height. Without even deck heights you will never get the engine to run its best.
You should measure each piston for deck height, each rod for center to center length and the crank throws for stroke. If 1 and 2 deck heights are very close above the deck and 5 and 6 are very close below the deck, suspect the crank and probably the machine shop if it was ground.

 

[Dale Davies]

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...

With the degree wheel and piston stop you rotate reverse rotation until it stops. Set the wheel to 0 degree. Rotate normal rotation until it stops. Read the difference and set the degree wheel half way between. Now repeat the process without moving the degree wheel.when it stops. The degree reading each way should be identical each side of zero. Now when you rotate to the 0°, 90°, 180° and 270° you are at TDC or should be. Dwell time is taken out of the picture.

 

[Bogie]

I did a quick rebuild of a 360 LA block a buddy had machined then stored (went with a 408 Crate) from a local highly regarded machine shop. So I didn’t check things as much as I should and was in a bit of a hurry need to make my truck run.

Was a bad choice

This is the result of a KB107 with positive deck height not being caught.

 

[Chadderbox70]

Ok so moving pistons around didn't change anything.

No 2. Is about .008 out of the whole no.4 is about .004 out of the hole, no 6 is about .003 and no 8 is flush.
The other side around .015 -.013 depending

So it's not as bad as my initial measurements

 

[Chadderbox70]

I did a quick rebuild of a 360 LA block a buddy had machined then stored (went with a 408 Crate) from a local highly regarded machine shop. So I didn’t check things as much as I should and was in a bit of a hurry need to make my truck run.

Was a bad choice

This is the result of a KB107 with positive deck height not being caught.

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Do you know how high it came out? Was it the factory heads ?

 

[Bogie]

Was with factory heads no idea on measurement didn’t notice till I started engine

 

[Chadderbox70]

Was with factory heads no idea on measurement didn’t notice till I started engine

Ok, Im wondering if I can't get the machine shop to deal with this, going to a thicker head gasket for extra room

Interesting your pistons collided with factory head

I need to figure out how tight this really is

 

[PRH]

At this point, I’d just get different thickness gaskets and put it together.

If you want to run “thinner” gaskets you have to make sure the chambers are at least as big as the bore.

Put the heads on the block and going in from the bottom, scribe a line into the deck that depicts the bore.
The heads need to have the chambers relieved out to the scribed line.

 

[oldkimmer]

For my own peace of mind I would swap the first 2 pistons and rods with the opposite cylinders and see if u still get the same measurements. Kim