Hi, I'm having some technical issues with my 270 engine in the machine shop. I'm curious if parts are interchangeable with a 248 and if so where does it state that the parts are interchangeable? I have a service book for the 100-400 series trucks and cant find if anything is interchangeable. Am new to engine rebuilding James
Here are pages that detail engine specifications - I am not a GMC Knowledgeable person, I found these doing a search and thought they might be useful, covers a lot of information regarding engine specs, casting numbers, etc....courtesy oldgmctrucks.com right click on image, open in a new tab, then magnify..
The GMC Heads page has some good details regarding head casting numbers and the model year.
Hopefully a GMC expert will be along shortly to provide more information...
Last edited by Dusty53; 05/10/20222:11 AM.
Ron - - Dusty53 1954 Chevy 3604 In the Gallery Forum "You can't dance with the Devil and then wonder why you're still in Hell." "They will forget what you've said, and they will forget what you have done but they will never forget the way you made them feel."
That info shows what is different between the designations, I can't see them tooling up for different con rods and heads. Even other parts that may need a change are likely done by machining them to different dimensions. You have to love those odd fractional dimensions of that era, like the Bore and Strokes.
Kicking self for selling off my Taskforce trucks. Still looking for an LCF or conventional big bolt in decent shape.
As of 10-26-2022, A 55.2 Taskforce long bed now the work begins
Gmc 270 and 248 use the same rods. Some of the early gmc rods used a different big end bearing. The main difference is the small end changed in about 53 they went from a .990 to a .1050 small end. What is the casting number on the rods you have ?
