Early IDI's; thin blocks and piston squirters

[bike-maker]

Pretty sure I'm going to end up buying a 84 F250 with 6.9/4 speed. Truck is rough but runs good; I'll probably part it out and use the engine for my truck.
I'm curious at what point the 6.9's switched from having the pressed in piston squirters, and which blocks were prone to cracking around the block heater.
I remember the 83 engines as the ones that had lower compression, but I could be wrong there.
Dug through all the FAQ's and tech articles, but didn't find the info I was after.
I wanted to stud my current engine and upgrade the cam, but it's making more sense to just start with a second engine.
Just not sure if the 84 is a good candidate...

 

[TahoeTom]

I am not too good at this interweb stuff so I will tell you the long way to a good article. Find enginebuildermag.com and do a search for International 6.9. Pretty thorough article with photos of changes made. There are two casting numbers, early and late. The number is on the drivers side of the block partially behind the motor mount. Early # 1805440C1. Late # 1807996C1. I looked at mine, still on engine stand, and could only see the first half of the number, but a 7 instead of a 5 should verify if early or late.

 

[TahoeTom]

Found some more info. Looks like bolt in piston cooling nozzles were introduced with engine serial #237016

 

[Knuckledragger]

I rebuilt my 85 and it still had pressed in oil squirters. It is a hassle getting them out and in, but the aiming is pretty self evident. I did not have the template and had to make a couple of special tools, but the engine is running just fine. It is worth the trouble taking them out anyway, I found three that were plugged with ---I don't know what. I think it was old gasket material. Same in the oil cooler.

 

[The Warden]

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Hope this helps some

 

[Knuckledragger]

My silver truck has serial number 201380. It was manufactured in Norfolk, VA in about July of 1985. I'm guessing the late '85 through mid 87 (when the engines changed to 7.3) all had the bolt in oil nozzles.

 

[bike-maker]

The engine seems to run strong. And I don't think it has that many miles on it.
I'm not planning on a full rebuild. Hopefully I can just do rings and bearings, head studs, reground cam, and run it. You never really know until you tear them apart.
From what I've gathered so far, it will have the standard compression ratio, press in squirters, and the older style oil cooler.
Main thing I haven't figured out is whether it's one of the crack prone blocks.
Don't know the engine serial number yet.

 

[The Warden]

You'll have to get the block number to know for sure, but FWIW my '84 has the "A" engine with the different compression ratio. OTOH my truck was built in August 1983, and was likely one of the first '84 diesels off the line, so if the one you're looking at is a later build, it should have the "B" engine