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Warning on used 6.2/6.5 Blocks

Missy Good Wench

Missy Good Wench

Wild Blonde from Cloud Mt
Messages
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65
Location
Newberg Oregon
BLOCK WARNING

Recently I have posted a lot on a 6.5 rebuild
Yesterday afternoon I found out during the assembly of rods and pistons into the block that one deck had been cut before I got the block.
The Block was a used bare block from a rebuilder supplier.

My machine shop decked both sides to clean them.
The practice is common and requires the use of a .010" thicker gasket.

The issue is this, many of the used blocks for 6.5's can be 17 years old and who knows whats been done to them in these years.

I now have a $600 finely machine door stop. With .030 piston protrusion on one side there is nothing any reputable mechanic can do at this point with this block.

When buying a block, be sure to get it in writing that the block is machinable and that your $$$ will be refunded if cracked and or the decks are unserviceable (Been machines once before and now needing more.

The only check is to stuff in a crank with front and back mains then a rod and piston assembly on both sides. Measure the protrusion of the piston above the deck on both side.

Stock should be near flush with piston at TDC.

My block has one side thats .015" above and one thats .030 above
The .015 will work fine with the .010 OS gasket the other wont.

Just be wise and look sharp folks.

MGW
 
Last edited:
That sucks! I'm no mechanic but can't you use a thicker gasket? I hear of guy's using thicker head gaskets to decrease compression.
 
One shot through on these blocks.

There is a .010 thicker gasket available from Felpro.
This will allow up to about .015 to be cut off the decks.

Mine has one deck that has been cut twice. Once by me and once some tim in the past.

Thats the end of it. Pistons could be cut and the assembly reballanced but that is just a mess and no way to build a full time runner.

To coin a phrase, for you Star Trek Fans "Its Dead Jim"

MGW
 
Sorry to hear that,that sucks big time.
I guess that block supplier takes no responsebillity for failing to mention one deck had been cut? But then,how do you prove it now.
 
Oh crapola, Missy. That's a kick in the keester. I hope that you can scrounge around for another block and continue this build. I'm pullin' for you.

If it makes you feel any better, I once spent WEEKS fully porting a set of GM SBC heads only to find out they were cracked all to heck....

They're now tire chocks. :rolleyes5:

Keep the faith.
 
Rodd said:
That sucks! I'm no mechanic but can't you use a thicker gasket? I hear of guy's using thicker head gaskets to decrease compression.
Click to expand...

Yeah-I remember milling heads on the flathead Ford V-8 back in the day. sometimes the valves would hit the head, so we would use 2 head gaskets to cure the problem. Of course these things did not have 400 PSI of compression either, so we got away with it ( damn kids) . With that in mind, I think a thicker head gasket thicker than.010 would be weak. Oh and by the way, Bones' saying was " It's worse than that! He's dead Jim".
 
Sorry to hear of your misfortune... I am going to take the heads off of my block this week. Im sure mine has never been touched though, only 90k miles and looks all original...
 
I was always under the impression that these engines were throw aways like the 3208s anyway so this is good info. Thanks for updating. Sorry to hear.
 
I can't remember but there was a thread either here or on the old site but I think it was here about the AM general blocks if that helps. I'm outta my league on this .
 
Missy Good Wench said:
BLOCK WARNING

Recently I have posted a lot on a 6.5 rebuild
Yesterday afternoon I found out during the assembly of rods and pistons into the block that one deck had been cut before I got the block.
The Block was a used bare block from a rebuilder supplier.

My machine shop decked both sides to clean them.
The practice is common and requires the use of a .010" thicker gasket.

The issue is this, many of the used blocks for 6.5's can be 17 years old and who knows whats been done to them in these years.

I now have a $600 finely machine door stop. With .030 piston protrusion on one side there is nothing any reputable mechanic can do at this point with this block.

When buying a block, be sure to get it in writing that the block is machinable and that your $$$ will be refunded if cracked and or the decks are unserviceable (Been machines once before and now needing more.

The only check is to stuff in a crank with front and back mains then a rod and piston assembly on both sides. Measure the protrusion of the piston above the deck on both side.

Stock should be near flush with piston at TDC.

My block has one side thats .015" above and one thats .030 above
The .015 will work fine with the .010 OS gasket the other wont.

Just be wise and look sharp folks.

MGW
Click to expand...


JUST a question, can you machine the .015 deck to .030 so they are both the same deck height and then machine the pistons down .025. Which leaves you with .005 above each deck height. Use the plus .010 head gaskets.

I know how to make a Jig that lets you machine your own pistons on a lathe. Balance the pistons yourself. This may be a cheaper way to fix this mistake than buying another block.
 
The valve train may start to complain, I dont know yet.

The plan for the fix right now is a RED 6.2 Block.

yupp gonna stuff the 6.2 Red beast in there with the needed 6.5 parts to make it all bolt up and run with the DS4.

The only mod needed is to run a pressure line for oil to the turbo.

The reluctor (crank timing gear) and the 6.5 ballancer will need to go on too. (shorter snout)

The heads for the 6.5 will work fine.

Yessssssss Red it is. May paint it RED too.

MGW
 
Missy, the easy solution for the turbo oil line is to put this at the stock oil pressure sensor hole:

1/8"NPT close nipple
1/8"NPT T

Insert OPS into one of the holes in the T
Get a longer hose made up for the turbo and install in the other hole in the T.

That's how Diesel Depot does it with their 6.2 as 6.5 motors.
 
Missy Good Wench said:
The valve train may start to complain, I dont know yet.


MGW
Click to expand...

The distances we are talking about (assuming true deck height of zero, we are taking away .020 net from that, 030 machined off the block and add back the .010 gasket) won't make much difference in the valve train. I am sure the loss of .025 from the pistons would not be that big a deal either. I know this will work, I have had to fix (save) a lot of things in 40 plus years of working on equipment.
 
OK here is the latest.
The build is back on due to the discovery of "COMETIC" head gaskets

These guys offer a MLS head gasket for the 6.5
These can be had almost any way you want from stock at .045" thick to ????

I am ordering a .070 Gasket (this is compressed to running thickness)
All specs from them are running thickness and not as packaged.

This little discovery solved a load of Issues.

My RH Cyls have .035" of projection (Deck + .035")

The normal 6.5 will have the piston at the deck level and a .040" gasket thickness when assembled.

I have +.015" on the LH side and using the Felpro + 010 gasket will give .035" clearance between the piston and the head.

(These numbers are the best that can be extrapolated with the info available)

Now with the +.035 on the RH side the .070 gasket will also give .035" clearance from piston to head.

The location of all important parts (Valvetrain) will be very close if not spot on.

The issue though with these engines is still to be sure what you have before plunking down the $$$$$$$$$$$$$$$ and turning any shavings in the machine shop.

MGW
 
The cometic Gaskets??
Most certainly you could.

I personally would not be in favor of $125 PER Gasket when a set of Felpro Gaskets at about $27 each will do fine.

The nice part (and advantage) of the Cometic gaskets is that it will allow an otherwise unusable block to be saved from the scrap heap.

MGW
 
Hmmmm.......with that much solid copper between head and block, seems like that side would run cooler than the side with composite gasket..............
 
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