Anyone here ~ACTUALLY sleeve a 7.3L to a 6.9L bore?

[Ford F834]

This idea is getting tossed around quite a bit on the forums. Add in a few claims that it has been done before, and it is now talked about as if it is a done deal. A valid "option" for us IDI engine builders...

But there is a serious problem. If you have pursued this very far you know what I'm talking about. The machinist I am working with has been trying for two weeks to find sleeves that thick. He says none of the main suppliers carry anything that will work. He has moved on to suppliers of custom sleeves, but warned me that it will not be cheap. He insists on a minimum of a .060" step to keep the sleeve from falling into the bore. The custom places can make pretty much anything... for a price.

So I'm curious if anyone here has actually done this. What did it cost? Where did your machinist get the sleeves? How much step did you have at the base of the cylinder? Did you sleeve to a std 4.00" 6.9L bore or some oversize piston?

At this point I am thinking the sleeving down thing is a dead end unless someone here knows otherwise from experience.

 

[The Warden]

He's not regularly active anymore, but user turbo69 did it...he took a '92 7.3L and made it into a 6.9L.

http://www.oilburners.net/forums/member.php?1307-turbo69

You might try PM'ing him and see if he answers, or do a search for his posts on here and/or on thedieselstop (he did it long enough ago that the discussion may have been on there before the migration over to OB).

Hope this gives you some ideas

 

[Ford F834]

I sent him a PM, but according to his user profile he has not been on in 5 years. Not holding my breath but we shall see. Couldn't find any kind of build thread on his "Grey Ghost" but I'll keep digging. Thanks for the link and member name.

 

[Ford F834]

Well, got my answer from turbo69...

That was one ghost I thought no one would remember...the engine in that truck was actually a 6.9l engine. It was not a 7.3. I converted the truck to a 6.9 when the motor decided to start knocking from loss of oil pressure. So I have no information for you on sleeving a motor. Honestly, it's way cheaper and easier to rebuild a 6.9 than it is to sleeve a 7.3. That's why I did it that way. No more worried about cavitation and still the same relative power output...good luck!

At least I can quit wondering how he did it since it never happened! Anybody else???

 

[rhkcommander]

well you can get oversized pistons for 6.9, is there one that could do that? I think there are at least .040 overs'

 

[The Warden]

At least I can quit wondering how he did it since it never happened! Anybody else???

You learn something new every day...I honestly thought he was the one who pioneered it.

For what it's worth, I've been one of the people who's advocated that. My reasoning is that you have the thicker cylinder walls, minimizing the risk of cavitation, and you also have the thicker/stronger head bolts. I haven't done it, and turbo69's the only one who I thought had...but, at least for the purposes of what I was thinking, I'd say find the thickest sleeves you can get pistons for and you should have as close to the same effect as possible. Or, use a 6.9L block and have the thinner head bolts...if you use studs and do a deck-plate honing with the studs in place, that should suffice; as to why a deck-plate honing is a good idea, take a look at this video:

https://www.youtube.com/watch?v=6cLjdr2GSwU

 

[hce]

I would investigate non flanged sleeves. A quick glance in the melling sleeve catalog shows promise. If the press fit fails to hold the sleeve in place a flange is not going to stop it from reeking havoc once moving in the block. Also when a non flanged sleeve is installed you do not bore the cylinder all the way to the bottom. hence leaving a ledge that the sleeve buts up against.

 

[icanfixall]

Try contacting Dart Sleeves. As for the ledge at the bottom of the parent cylinder yes.. That has to be about 1/4 inch thick. A member long ago came here asking if his lip that was left was going to be ok. He posted that he could break it off with hif finger and thumb... Nope.. that block turned into junk because some shop machinist had no idea how to sleeve any block. For me I would only do a flanged sleeve. Reason for this is they can't slip in the block like a poorly installed sleeve can. I saw this happen in my block. Also the slvves need a press fit and not super glued in the block. The glue acts like a thermal barrier to heat transfer. I might use some at the top and the bottom of the sleeve to help seal it but no more than that. The sleeves needs to be shrunk to fit with liquid nitrogen too. Figure a 2 thousands press fit too. That means the block bore is 2 thous smaller than the sleeve size. The freezing with easily shrink the sleeve to fit. Then hold the sleeve in the block with a strongback and all thread so the sleeve can't grow up out of the block. This is a possibility when the bore is not completely round. If it has a small taper the sleeve will squeeze up out of the block. A flanged sleeve is held in the block by the head and can't slip up or down like a non flanged sleeve. Most machine shops wont do a flanged sleeve because they NEED to bore the sleeve depth exact both top and bottom. Thats really a hard job. With a non flanged sleeve you bore the block and press in the sleeve leaving some extra length sticking out the top of the block. Then thats machined off when the deck is milled flat and square to the crank. Most shops just put the sleeves in a freezer to shrink them. Some will use dry ice but nobody wil use liquid nitrogen. Sticking a sleeve in the freezer of a food refrigerator is not a good idea of how to shrink a sleeve for a 2 thous press fit.

 

[hce]

Try contacting Dart Sleeves. As for the ledge at the bottom of the parent cylinder yes.. That has to be about 1/4 inch thick. A member long ago came here asking if his lip that was left was going to be ok. He posted that he could break it off with hif finger and thumb... Nope.. that block turned into junk because some shop machinist had no idea how to sleeve any block. For me I would only do a flanged sleeve. Reason for this is they can't slip in the block like a poorly installed sleeve can. I saw this happen in my block. Also the slvves need a press fit and not super glued in the block. The glue acts like a thermal barrier to heat transfer. I might use some at the top and the bottom of the sleeve to help seal it but no more than that. The sleeves needs to be shrunk to fit with liquid nitrogen too. Figure a 2 thousands press fit too. That means the block bore is 2 thous smaller than the sleeve size. The freezing with easily shrink the sleeve to fit. Then hold the sleeve in the block with a strongback and all thread so the sleeve can't grow up out of the block. This is a possibility when the bore is not completely round. If it has a small taper the sleeve will squeeze up out of the block. A flanged sleeve is held in the block by the head and can't slip up or down like a non flanged sleeve. Most machine shops wont do a flanged sleeve because they NEED to bore the sleeve depth exact both top and bottom. Thats really a hard job. With a non flanged sleeve you bore the block and press in the sleeve leaving some extra length sticking out the top of the block. Then thats machined off when the deck is milled flat and square to the crank. Most shops just put the sleeves in a freezer to shrink them. Some will use dry ice but nobody wil use liquid nitrogen. Sticking a sleeve in the freezer of a food refrigerator is not a good idea of how to shrink a sleeve for a 2 thous press fit.

How can a non flange sleeve move if it held at the bottom by the block and the head at top?

 

[icanfixall]

The non flanged sleeve can move down if the sleeve is not completely pressed down on the step at the bottom of the block.

 

[Ford F834]

I'll check into Dart Sleeves. I have been told that straight sleeves (installed with a step at the bottom) are going to be hard enough to find, let alone lipped sleeves with a step at the top. As I said earlier, my machinist says a minimum of .060" step. A 1/4 inch step would be more than the whole sleeve thickness so that isn't happening. In fact, the 7.3 cylinder wall is only about .20" thick so you're not going to get a 1/4" step. A .060" step (.120" diameter difference) should be plenty to keep the sleeve from dropping.

As far as oversize, I am trying for a .040" oversize finished bore. I know you can get .060" stuff, but I bought the rotating assembly from R&D's "Smogie" build. Shaved pistons, tri-coated, total seal gapless rings, bushed turbo rods, fully balanced etc., there is a lot of $ in that rotating assembly. I got a great deal on it, but I never could find a suitable 6.9 block and I am having doubts about the ARP fasteners with my build plans. I found a 7.3 "turbo" (C-3 casting) 1994 block and bought that. The problem is sleeving down is turning out to be less feasible (or at least way more expensive) than I originally thought. If I can't source sleeves at a reasonable price I will probably let the rotating assembly go and build my block as a 7.3 IDIT since I have a set of turbo rods and harmonic balancer. I'm not thrilled about going the other way and boring out a 7.3L, but the water jackets look brand new and if it will clean up with .020" over then a 5% reduction in cylinder wall thickness should be fine. If the block is that close to cavitation it's junk anyway. I'm pretty sure I want to run Evans waterless coolant in this thing regardless of whether I sleeve it or build it as a 7.3L.

 

[Ford F834]

The non flanged sleeve can move down if the sleeve is not completely pressed down on the step at the bottom of the block.

I have worried about this. I read a thread on FTE about a guy who had two cylinders repaired and saw a gap. He was wondering if it would be okay. I would be irate if my machinist delivered my block to me like that.

 

[hce]

The non flanged sleeve can move down if the sleeve is not completely pressed down on the step at the bottom of the block.

So incorrect installation. No different then machining the block incorrectly for a stepped sleeves.

 

[icanfixall]

I'm not sure what you mean when you say a 1/4 inch step can't be made on a 7.3 bore when sleeving... So explanation.. When the bore is machined out for the sleeve you leave about 1/4 inch of the parent bore at the bottom of the cylinder. Then the new sleeve "sitson that" and can't go any deeper in the block.. If it is bottomed correctly. If the sleeve does not sit on the bottom lip then it can and will silp down in the bore ruining the fire ring seal at the top.

 

[Ford F834]

I'm not sure what you mean when you say a 1/4 inch step can't be made on a 7.3 bore when sleeving... So explanation.. When the bore is machined out for the sleeve you leave about 1/4 inch of the parent bore at the bottom of the cylinder. Then the new sleeve "sitson that" and can't go any deeper in the block.. If it is bottomed correctly. If the sleeve does not sit on the bottom lip then it can and will silp down in the bore ruining the fire ring seal at the top.

Ah. Makes sense. I had my mind stuck on the difference in bore diameter, so I was thinking a 1/4 inch "step" had to be a typ-o. Leaving 1/4" of material at the bottom of the cylinder sounds right. I would really like for this to work out, but I'm not into paying unreasonable amounts of money forcing it to happen...