Three Questions

[kconnair]

Apparently the engine in my truck is a later replacement 660 block - probably a 1990 vintage. Seems to have later heads (stamped rockers, small valves, etc.).

1) Would these later heads have the slightly changed injector angle that the 6.5 heads had?

2) Should I change to some of the earlier pre-cups (I have plenty) to get the best possible mix of mileage and power - I rarely would tow more than 5,000 lbs, and usually around 3,700.

3) Would the DSG block girdle be a good idea (no cracks on the mains at this time)

Thanks,

Kevin.

[oilburnertoo]

post the date code behind the pass cyl head just above the bell hsng flange, and some one can decipher it for you as to what year it was cast in.

[kconnair]

Date code is D120 on the block...

The bearings are Moraine 200's.... Dated 1989

Regardless of the year of the block, (it's hard to tell what would have found it's way into the goodwrench supply stream) the engine was originally built and sold sometime between 1989 and 1991. I am trying to figure out the heads, pre-cups, and if I should invest in the DSG block girdle...

Thanks,

Kevin.

[Slim shady]

The diesel page had a great article on the precups. Here is a link for that.

http://www.thedieselpage.com/features/65fueleconomy.htm[/url]

The diesel page is the usualy the best for any type of information on the GM diesel. Thanks to the members.

Slim

1995 Chevy 2500,4x4, 5 spd, 6.2 .040 over, 18:1 ceramic coated pistons, Ported 6.5 turbo heads,6.5 high pop injectors, Gm-8 turbo ported turbine housing, custom intercooler, gm dual thermo, 130 gph water pump, 3 to 3.5 turbo down pipe to 4 inch exhaust. Custom electronic adjustable waste gate (got the idea from the Honda guys, Thanks), custom frame mount FSD cooler.

[john8662]

what's the casting number off the cylinder head? It should be located on the inside of the valve cover mounting area in the middle.

J

[kconnair]

I decided to get the girdle as a measure of insurance... to go with the new balancer and gear drive.

The two things I am still wondering about were 1) the cylinder heads (Casting 14077162 - date codes C070 & C060) and 2) whether or not to change the pre-cups to the earlier style.... I read the article when it came out, and that is why I am asking the question. I am looking for some opinions regarding using the earlier pre-cups to improve the mileage while still getting more power with the turbo on the engine.

New question... Why would GM assemble my crank with standard bearings, but use an .013 for the rear main? Did GM make a habit of salvaging cranks for the resale engines? Did they cobble together the cast-offs from the primary assembly line? Now I will need to put in a crank kit or have mine turned .5mm under if I want to change the bearings before I put it back together :confused: :mad: What a Pain.

Thanks,

Kevin

[Slim shady]

Whe I rebuilt my 6.2 to replace my 6.5 that failed (block cracks) I ran into the same thing.

The bearings are under and over size based on Millimeter not thousands as we are used to measuring them.

I measured my crank, the rods and mains were all the same size even with the upper bearing half being .013 and the lower bearing half being .026 mm undersized. I spoke with a number of engine rebuilders here since I have never had this problem before. They advised me that GM used this process to "line bore their blocks", the plus and minus in the upper and lower bearings actually was done to save a machining process.

The engine rebuilder offered to line bore my block and put in bearings but it was actually cheaper to buy the GM bearings and replace them as they were originally assembled.

The after market bearings can be had in the .010 mm undersized this amounts to a little over .001 inches I beleive. I might be wrong it has been awhile and I am not about to do the conversion. Depending on the combination you have it may be cheaper to get the GM bearings if you want to be precise and not mess with line boring your block.


Slim