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Sun Jul 06, 2025 9:28 am

2387 flanged crank engine which will have 12 to 15# boost.
Lathed #1 barrel to 0 deck and cut the rest to the same length.
Appears CB (or Autolinea) milled the decks off the parting line not the crank centerline.

Opinions on running it this way?
Compression isn't affected enough to worry about, but the bores are not parallel with the stroke.
I just don't know if it is off enough to make a realistic difference.
I would have to ship the case 1/2 way across the USA to get it corrected.
My equipment isn't big enough to do it right.

Sun Jul 06, 2025 11:02 am

I usually figure if I am under .005” on the different deck heights, I am doing pretty good. I would probably just rock it the way it is since correcting it will be questionable and expensive.

Brian

Sun Jul 06, 2025 11:15 am

Brian_e wrote: I usually figure if I am under .005” on the different deck heights, I am doing pretty good. I would probably just rock it the way it is since correcting it will be questionable and expensive.

Brian

Yep probably negligible, my OCD doesn't like it, but if I got the math correct arcsin(0.0899mm /112mm) = 0.04546 degrees.

Sun Jul 06, 2025 11:17 am

BTW, I love your engine stand adapter.

Sun Jul 06, 2025 12:19 pm

Alexander_Monday wrote: BTW, I love your engine stand adapter.

Thanks!

Brian

Sun Jul 06, 2025 10:26 pm

simple .
your 0.10 compression difference .
cc your heads ,take 0.7cc out of 2 of the combustion chambers #1 and 4 .done

Sun Jul 06, 2025 10:34 pm

Close enough to work,
for what your doing.
The piston rock will be more than the cylinder tilt, and boost makes rings seat anyway.
But it is near the limit of what I'd call acceptable for a production engine(.001" per 1), and not good enough to be a blueprinted engine by my standards. (.0005" per 1)

I am sure there is a milling machine in your city, or ten,
tho making friends with whoever owns it can be hit or miss.
(I think you could figure out how to run one and set it up easy, if you are halfway to mastering a lathe)

IMO, trimming four cylinders the same is MORE harder and more time consuming than decking a case, well, assuming I make somebody else clean up the mess at least. I'm kinda tired of cleaning engine blocks. It was fun the first few thousand times, but now it's work

Mon Jul 07, 2025 5:37 am

My lathe is a combo, but the mill part is far from big enough for a case.
Cutting the barrels the same isn't too difficult with the mandrels I made and a DRO.
Main thing with a hobby lathe is making sure to keep the tailpiece aligned, the head stays put once shimmed.

Mon Jul 07, 2025 8:45 am

Look at dat shit ^^^^^^^

Tue Jul 08, 2025 8:25 am

Dont take this wrong But this is important step during mock up .and a good reminder for others .
if you are using a dial indicator and getting your piston to top of its travel .use the same piston and cylinder on every case bore - does not matter what the measurement is its a number . record them all . now you have the data to make decisions before the machining begins .
again since you have trimmed the cylinders and i will assume the cylinder tops are at the same height and you are at zero deck , cc your heads and just soften 2 of the combustion chambers .
good luck

Tue Jul 08, 2025 11:25 am

I checked the barrel lengths to be sure they were the same and that the head mating surfaces were even before I cut them down.
I checked the head mating surfaces for even again after cutting them down.
I used a test indicator for TDC which has more precision than my dial indicators, although a dial indicator would have been ok.
I checked CB H beam rod length, main & pin diameter and eccentricity with and without bearings and end & total weight and pin fit after CB balanced them.
The Wiseco pistons are all consistent on pin compression height, although I did have to balance them.
I picked the best rod bearings (all but 3 of 16 measured consistent at 0.06220" 90 degree from parting line) from a full set of King CR 803XPN SBC small journal bearings and cut those down to width using mandrels I 3D printed since the Mahle bearings I got were inconsistent and undersized.
I have a spreadsheet of measurements starting with case main diameters 90 degree and 15 degree to parting line with and without bearings, crank mains & rods diameter, ring gaps, etc etc etc, I even put the crank in the lathe and checked runout.
I built my own cam doctor and profiled all the lobes, unfortunately that was before I decided to go to 2387 and am waiting on Jones Cams to grind another custom cam so will profile it and do all the other measurements.
I could go on, but point is that this time I am striving to build this one the best that I can.

(BTW, if someone decides to use Mike Jones for a custom cam, be aware it is a very long wait and his communication is lacking at best)

Tue Jul 08, 2025 1:03 pm

Alexander_Monday wrote:
BTW, if someone decides to use Mike Jones for a custom cam, be aware it is a very long wait and his communication is lacking at best

This is good to know. Thanks for passing it along, and let us know how it ends up.

Brian

Tue Jul 08, 2025 2:23 pm

The profiles of the first cam he sent me look pretty good.
More aggressive opening ramps than the FK profiles but rounder nose and less aggressive closing ramp to set the valves back down at about the same rate as the FK profiles do.

Tue Jul 08, 2025 3:37 pm

- sorry i live in a world of diagnose, find fault and repair . and hopefully assisting you in your question of centerline /deck height error cause and correction
I apologize i misread your info , 2 PISTONS ARE POSITIVE .0035" ABOVE THE CYLINDER as per your reading of +0.0035"

will have to assume at some point you missed something , which is ok and still its correctable . choices are now.
- re machine case to correct centerline then replace and cut 4 new cylinders. ( most expensive )
- cut 2 pistons and rebalance ( free just your labor )
or shim all cylinder and soften 2 chambers , i have made shims down to .003" , simple and you can as well looks like you are capable ( cheap and simple )

will go with first statement .
'''I checked the barrel lengths to be sure they were the same and that the head mating surfaces were even before I cut them down. ""

-- ok ill stop here i will assume at this point not all 4 positions were checked for piston deck height, only 1 .
because at this point the difference of positive + .0035 " would of been discovered and cylinder trimming would not of been the next step

Tue Jul 08, 2025 5:20 pm

Yes, I made an assumption that they (CB or Autolinea) would have machined the decks off the crank centerline not the case parting line.

Wed Jul 09, 2025 5:44 am

This was an aftermarket case, about .004 taper of crank centerline to case split.
Checked it on a surface plate, I shimmed case to get decks parallel to crank.
If you have an indicator stand and test indicator and a power tool table like a table saw, or other flat surface, you can check other parts as well, pics show comparison only just to make sure all are the same, pin heights can be checked this way also, quick and easy.

Sat Jul 12, 2025 1:52 pm

jim martin wrote: cut 2 pistons and rebalance ( free just your labor )

Done, now all are 0.000" and 386.2g (+- my inexpensive tools tolerances)

Sat Jul 12, 2025 3:02 pm

Great ! Nice job .
Check that off the list