refacing block decks andwhat now?

[franky]

hi.doing acomplete rebuild on my 93 idi.took it inthemachine shop last year.bores are 0.30 over now and because of dissortion offblock decks andheads they are refaced now.new pistons are over deck mating surface for 0.63 mm now.how much are they supposed to be over deck and what to do when its too much.do i have to take thicker headgaskets or can i mill off these sealed power pistons?because off the long time between the shop job and the rebuild nobody nows about the amount off material thats been taken off ..not good..please help

 

[GenLightening]

Welcome! Gary (Icanfixall) should be here soon to give you all the info you'll ever need. Going .30 over on the bores of a 7.3 may not be the best thing, but I don't know how available blocks/used engines are over there.

 

[icanfixall]

I will try to help... Your posting states that the piston are .63mm above the deck.... That would be about 025 above the deck. The factory settings are 31 thousands above the deck for the pistons. Usually 20 thousands off the pistons is the maxium taken off the pistons. Any more and the top ring may be damaged because its closer to the heat from combustion. Mahle sells a low compression piston. What they did was mill the piston pin 10 thousands higher in the piston so it drops the piston that much in the cylinder. Use Felpro head gaskets. They are the thickest you can find. They are about 76 thousands thick. Hope this helps and post back for more help if needed. We can help with any questions.... PS... I reread your posting and changed what I posted to better fit what you are doing.... The heads have a minum thickness and its measured from the valve cover rail to the bottom of the head. Its between 4.795 to 4.805. The demension for the top of the block to the center line of the crank is 11.137 to 11.141 . This is a very hard demension to get because you need something to place in the main webs to measure off of. Then subtract half the diameter of the crank diameter....

 

[franky]

refaced decks

ok i made a mistake here.actual boresize is not 0.30 but 0.030 over !

 

[hesutton]

OOPPS!! Boring a 7.3 can be a risky move. These 7.3 IDI's are prone to cavitation and boring the cylinders thins them even more. If you don't have some SCA to run in the coolant you should make to you do and keep it up to *****.

As far as the pistons. If I read your post correctly, then they are past the deck by 0.63mm. If that is true, you should be OK as 0.63mm = 0.025inches (25 thousands).

Heath

 

[RLDSL]

That being the case there's no need for those nasty felpro gaskets, which would probably be hard to find there anyway ( most of that thickness is that soft goo that crumbles off and doesn't really have much substance anyway )

Much better off with a set of victor reinz head gaskets spray coated with hylomar and I'm sure you won't have any trouble at all finding either of those in Germany The reinz gaskets are much harder to damage during installation. They are the factory equipment gaskets.

 

[icanfixall]

The Felpro head gaskets don't compress much more than about 2 to 3 thousands. They have served me very well in all the differant motors I have built over the years but.... I would stand behind the Victor Reinz sprayed with Hylomar too. Someday I will try the Victor Reinz but for now I will stick with what I know works for me but... I promise I'll keep looking at your gaskets Robert... I can still learn a thing or two...