i have a 95 chevy 6.5 that had a cracked head. im going to buy a bare casting, but i was wondering if anyone had the most basic instructions to remove and re install the valves in the new head. any trick to it?

any help would be appriciated, thanks!

 

you have to surface valve faces so it best just to take to the machine shop unless your freind has valve grinder.

 

Check the valvesprings, or have them checked, make sure you don’t install weak parts on a new head. A Chiltons or Haynes manual might be a wise investment, give you a well laid out source of info to start from, add tips and tricks to that.

 

As a minimum, you will need to lap the valves.

If reusing your old ones, make sure the stems are true. Easily checked on a piece of glass. Roll the stem on the glass and if the valve head wobbles, your stem is out of true. An out of true valve stem can prematurely wear a valve guide.

 

ok thanks for the info, i found out what was happening, cracked head between valves in #8, going to buy a bare casting and go from there.

best place to buy one?

 

Unfortunately, cracked valve bridges are common on the GM castings.

There's not a lot you can do to prevent it either; if your heads aren't cracked, they eventually will be. It has to do with the thickness of the valve bridge and the proximity of the coolant passages. Get 'em bad enough and they enter the water jacket.

There is a "fix" which involves inserting a "sleeve" into the water jacket, but I'd honestly rather not waste my time and money. Lots are driving around on them though so it is an option, if you can find a machine shop that does that kind of thing.

The best castings are the redesigned GEP heads (deals with aforementioned casting deficiencies), only problem is they don't sell them separately from the entire engine assembly. You might get lucky buying a surplus military engine (IE: GEP), but you're taking your chances there too.

But, get a Navistar cast block (that's who casts the heads and blocks for the GEP Optimizers) and you're laughing all the way to the bank plus you get another Navistar head and block to go with it. A military "take off" head will also be assembled and ready to drop on your block. Get a Navistar military takeout in good shape and you can drop the whole assembly in and drive for another 200-400,000 fairly worry free. But you also have the hassle of trying to find and buy a good military take out.

Maybe try "Teds Trucks" for a Navistar head. IIRC, he had a bunch of "rejects" from his last batch of military engines. I think they were mostly because of bad cylinder bores (rust, pitting etc). He might be persuaded to sell a head or two for a decent price instead of scrapping them. Dunno either way, you'd have to call him I guess.

My GEP engine is great for piece of mind. I'd hook my 35 footer up to it and tramp all the way across the continent tomorrow and not worry about it cracking or failing one bit. The injection pump however.......

Other than those options, you're taking your chances with any "new" casting. No way to tell who is selling you a "boat casting" although I'd venture to say almost everyone is. Those "China castings" are hit and miss; depends on who imports them and what kind of QC they have done on them.

Some of the China foundries have even caught on to the whole "GEP Optimizer thing" and started casting the Navistar "Diamonds" in their parts to pass them off as the real deal, so no help there. There's no shame in some of those dirty buggers!

Not a lot of money to be made recasting new parts for these old hacks so repop parts are pretty suspect these days.

Maybe try the local GM parts department and see what they offer for heads. The replacement 6.5's they sell are actually GEP engines (optimizers) sourced from GEP, so they might have heads from GEP also. Be prepared to pay through the nose though.

But be aware; even the General is using made in China replacement parts now.

Heck, they even use China parts on their brand new rigs......one can only hope the QC is more stringent on those bits......