6.2 vs. 6.5 heads question

[JHG]

I have a low mileage 6.2 engine í my 81 K5 (have not started it yet, is converting from 350).

Recently I bought a 1996 6.5 TD with broken crank (bought it cheap, wanted turbo parts, serpentine system and starter). I was wondering if it would be better to use the 6.5 heads on my 6.2 or if I should stick to the 6.2 heads?

 

[Mikey von]

The heads will interchange. No problems there. There were some changes in injector angles, but nothing that cannot easily be overcome.

 

[Mikey von]

Now are 6.5 heads better than 6.2l heads? Not sure. 6.5L precups are better for power, that is known. Some 6.2l exhaust valves are bigger, but may experience crack issues. There was a change in the rocker setup, I don't remember which is preferred (I have roller rockers). I would look at both and take the one that has less cracks. Put the 6.5l precups in what ever you choose.

 

[JHG]

Thanks for the replies. I will look at the precus, maybe it will be worth buying newer than 1996-1997 precups but I heard they are best for performance.

 

[izzy1776]

I just bought new heads for my 6.5 from SSDieselSupply and they state they are good for both the 6.2 and 6.5.

http://www.ssdieselsupply.com/p129_brand_new_6.5_diesel_cylinder_head.html

I don't see any reason that stock 6.5 heads wouldn't fit as well.

 

[diesel4me]

Geesh,385 bucks for brand new,I guess having heads resurfaced and a valve job done locally is a thing of the past.....

Not many auto machine shops left here really,few would touch a pair of heads for less than 500 bucks now..and many of the remaining shops do not have a good reputation...some that are "good" are so back logged with work they tend to rush thru things,dont keep their machines in good condition,etc..

 

[black dawg]

What are the plans for this engine? the 6.5 precups will add power (but cost some mpg) over the early 6.2 cups.

The best running (power and cold starting) NA 6.2 that I had, used 6.5 heads with a precup that I never could ID. mpg was only 16

 

[JHG]

What are the plans for this engine? the 6.5 precups will add power (but cost some mpg) over the early 6.2 cups.

The best running (power and cold starting) NA 6.2 that I had, used 6.5 heads with a precup that I never could ID. mpg was only 16

This Truck is used for traveling mostly on snow. I changed from gas to diesel so it will be cheaper to travel and also so I wont have to brings as much fuel with me.

So getting good mpg is something I want but I also want to be able to start the truck when its really cold outside (I have been thinking about buying a diesel preheater from Webasto for that). Of course I want as much power as possible without loosing to many mpg.

The 6.2 heads are low mileage (5000 miles) but the 6.5 ones come from a high mileage truck (+200 thousand miles).