188 Case Diesel piston drop at 8 degrees BTDC.

[mEl]

Gentlemen, a couple of you on here have gone through the rebuilds in these engines pretty thoroughly. Have any one of you taken the time to determine the piston position down the wall at 8*. I may be in a situation where that info would be helpful. I know it is an unusual request but hoping! My own 530 had an engine replaced and it was from a crawler which had the timing marks in a hole up right behind the starter and they did not change the flywheel so I have no timing references and I am involved with a 630 with a similar issue. I guess that's what happens when you get called in on the end of these projects.

 

[WilBury]

Sorry for the delay, don't check often enough...

I made some measurements and notes before I tore down my 188D trying to nail down piston clearance. The valve train was so beat up tho, I could only use it for general info. I did ask my rebuilder for some numbers. I'll read thru his sheet and try to decipher my own notes as well. Will get back to you.
So how are you measuring where the piston is now, valve drop? Head off? Are you looking to just get it close?

 

[WilBury]

First glances suggest about .019" movement between 8 BTDC and TDC

 

[used red MN]

Gentlemen, a couple of you on here have gone through the rebuilds in these engines pretty thoroughly. Have any one of you taken the time to determine the piston position down the wall at 8*. I may be in a situation where that info would be helpful. I know it is an unusual request but hoping! My own 530 had an engine replaced and it was from a crawler which had the timing marks in a hole up right behind the starter and they did not change the flywheel so I have no timing references and I am involved with a 630 with a similar issue. I guess that's what happens when you get called in on the end of these projects.

I am sure those measurements would be helpful but here is another option and maybe you’re well aware of this. If this engine is direct injection and the injectors point down at the top of the piston here is what you can do. Remove the number 1 or 4 injector whichever is easiest. I believe this engine may have pencil injectors, obtain a rod the diameter of the injector. You are going to fabricate a piston stop. So the rod will be as long as the thickness of the head plus what is needed to project down into the combustion bowl of the pistons. Where it stops the piston is not critical just so it is long enough to do it. Then fabricate something to hold it in position such as by the injector hold down bolt. Wherever you monitor the timing you will turn the engine the normal direction until the piston is stopped by your fixture. Then mark the flywheel or pulley whichever. Then turn the engine backwards until the piston again stops against the fixture. Make another mark. Halfway between the two marks is exactly TDC.
Editing to add: If you are using the flywheel and there is no access to the area to measure between the two mark made this will prove to be difficult. A piece of tin bent at the end with a 1/4 measured of on it would maybe be able to help you measure back from each mark scribing a mark every 1/4”. This is assuming the vie hole is the normal inch to 1 1/2” normally seen for this purpose.

 

[WilBury]

There are some calculators online to convert degrees to piston travel but they want rod length.

 

[WilBury]

Got the the rod length, workin' on it...

 

[WilBury]

Tried 3 or 4 online calcul;ators and they all come up with .026" piston travel between TDC and 8 degrees. That's with 4 1/8" stroke and 7.0034" average rod length center to center.

 

[WilBury]

Took the Conn Rod data from this doc, page 38

https://www.yumpu.com/en/document/read/11476371/connecting-rod-manual-april-2006

 

[WilBury]

For comparison, the calculators say
7 degrees - .01990"
8 degrees - .02596"
9 degrees - .03283"

I like used red's method for finding TDC. That and this should get you out of a bind. Pretty darned close anyway. I still can't believe we're telling you anything about this engine, LOL!