6.5L parts in a 6.2L

[NH2112]

I just recently bought an 82 6.2L block to use as the base for a turboed engine I'm building, and would like to use as many as the parts from my cracked engine as I can. The crank and rods I'll have magnafluxed to see if they're still good, but in case I find a good deal on 6.5L parts could someone let me know which are interchangeable? I'm assuming that most parts are, but would like to know for sure so I don't waste any time or money. Thanks in advance.

[gmctd]

Late cranks, '92 up, are cut for one piece seals, may not easily interchange to early blocks with two-piece rope-type seal.
Early heads had extra water passage near corner edge - check block for similar, as you'll want correct gaskets to seal that block to the 6.5 heads. Several DP articles covered this.
You'll want the later valve rocker assemblies.
Check cylinder walls for sufficient "meat" to accept 6.5 bore. GM has always planned long-term compatibility in the truck engines.
Check bolt hole threads for all metric - '81-'82 were still a lot of inch threaded fasteners around.
Everything else is supposed to be identical, even 6.2 - 6.5 piston weight. Should make it easier to select a crank.
(Just between you and me and the fence post, Peninsular had 18:1 6.2 pistons for less than half of the 6.5 units - might behoove you to build an 18:1 6.2, eh?)
Have fun....

jd

[NH2112]

jd,

Thanks for the reply. My intention has always been to build a 6.2L, I just figured that since the newest 6.2L is 10 years old and the newest 6.5L only 3 or 4, I should be able to find good 6.5L parts a lot easier (and cheaper) than 6.2L parts. I do plan on turboing it so lower-compression pistons are definitely on the list. The block is an 82 (allegedly stronger due to a higher nickel content) but the engine I'm using for parts is an 85 C so it should have most, if not all, of the features you mention. I also have a set of recently remanned J heads but I'm not sure what year they're from (they were on an 84 K2500.) In any case, after the machine work is done all bolt holes will be chased so I'll know then which are metric and which, if any, are standard.

[gmctd]

I have the 6.2J out of my '89 cc, and keep toying with the idea of an 18:1 buildup. 20 cubic inches couldn't make all that much difference for the cost savings. Biggest layout would be the pistons, rings, and very late heads - '97 or so for the internal improvements.
VIN matches my truck, also.

jd