Rebuild for a performance oriented 6.5

[3500_6.5]

I figured instead of adding more to my original thread in the build, I would start a new one for the new engine.

Quick background for anyone who hasn't read the original thread. And if, like me, you use Tapatalk and can't see signatures. The truck is a 2000 k3500 crew cab dually currently with around 250,000 miles on the original engine. Over the last year I have done bolt on performance upgrades to this engine. Figured I would use the engine in the truck for all of this as it took a lot of trial and error with parts to get it to perform how I want. The plan has always been to get a second 6.5 engine and then build that to handle what I have done to this engine for the long haul.

Basically what I have now is: modified marine db2 pump rebuilt and modified by Unique Diesel, marine injectors from Unique, hx35/40 hybrid built by Unique set at 30 psi, head studs, 1.6 roller rockers from Leroy Diesel, Walbro lift pump from Leroy, pre filter from Leroy, in tank sock filter removed, I replaced the factory ffm with my own ffm with a filter and base from Leroy, and it is intercooled. That is pretty much all the "performance" things I have done to it. So on to the new engine build....

I currently have a 6.5 out of another 2000 k3500 that was wrecked that I am going to be using for the build. After almost two years, I finally got it completely pulled out of the truck a few months back. Disassembly started this past week with an hour here and there and then finally had a whole morning to finish it up today. Good news! It appears to be 100% crack free. I haven't put any crack detector on it yet, but there are no oil lines or obvious cracks anywhere in the block as of now. I've always been able to tell pretty quick once the crank is out and the oil is cleaned up so I'm hoping this is a good sign. More good news is that I should be able to save some money on machine work and Pistons as I can still see the cross hatches in all 8 cylinders. But once I get it to the machine shop, we'll know for sure. So as of now, we are off to a great start!


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[3500_6.5]

The donor engine

The tear down

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[3500_6.5]

Hopefully tomorrow I can get it nice and clean, check for cracks with the spray, and then hopefully get it to the machine shop early next week.


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[tanman_2006]

No cracks in #8?

Otherwise looking forward to the build!

 

[3500_6.5]

As of right now I have found zero cracks in any of the "prone" spots. So fingers crossed that it stays that way.


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[Burning oil]

What a mess! I hate that part, but its so nice when its all cleaned up and painted.

 

[3500_6.5]

Dropped the block and heads off at the machine shop today. Talk to him about a few things I was planning. I told him I was thinking about using gapless rings and he advised against it. He preferred factory rings and said he has seen more bad than good come from gapless rings. I think any benefit from them would be minor anyway, and I trust the guy, so I'll probably just be going with stock rings. I also mentioned putting a bigger exhaust valve in and his only concern was taking material out between the valves where they were already prone to cracking. I told him that people have done it and he said he would do it if I wanted, but he was not sure if it would be worth the risk of putting cracks in the head down the road and having to pull them to repair/replace them. So I am on the fence on that.

I will be dropping off my main stud girdle kit and head studs as well for machining. He said since I am not using stock bolts for the main caps or for the heads, the added clamping force can cause distortion. So he will be using a torque plate with the head studs to bore it and also line bore it with the main stud girdle kit installed to insure precise machining. He said the distortion may not be much on a 6.5 bc it is a thicker block, but he said on small blocks they will easily distort the cylinders out of spec so he wants to make sure to take any "chances" off the table for the machining and assembly. Which I like. Better to be overly cautious with the build than not and then possibly have an unnecessary issue down the road. I want it to have the power I want and the reliability I need along with that power.


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[chevyCowboy]

Where did you get the girdle kit

 

[3500_6.5]

Kennedy Diesel


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[Burning oil]

I'd like to know what harm he's seen with gapless.

 

[Will L.]

Same here. Several friends in the top fuel circuit that all run them and put some good numbers from it, life and more power. From there they run them in their dd's with high mileage and no problems. Ive seen some holes burned in too of pistons and the gapless rings were still perfect.

If he has pics of failed gapless rings please get them posted up.

 

[Burning oil]

Love mine so far (only 5000 miles)

 

[Twisted Steel Performance]

Carbon causing sticking over the long term would be a guess, diesels will be a bit different from gassers over time...

 

[3500_6.5]

Carbon causing sticking over the long term would be a guess, diesels will be a bit different from gassers over time...

Yeah, it sounded like cylinder scuffing and premature ring failure (compared to stock rings) was the issue he had seen with them. I would imagine high performance applications (drag racing and even high hp street applications) wouldn't worry about a shorter ring life as those engines are typically rebuilt more often anyway so the more important thing is power. His experience with them may have only been with gas engines, I didn't get into it that far with him. I just know that as soon as I mentioned them he shook his head and said he would never run them and would only recommend the factory rings. Next time I am there I can ask him to explain a little more about why he doesn't like the gapless rings and can pass the info on.

On another note, just ordered my scat crank, head studs and a better replacement hose for the factory always leaky turbo oil drain tube/hose from Leroy. Hopefully the next couple weeks will be lots of productive machine work and getting everything in order for the re assembly. Only thing that I am still really up in the air about at this point is the cam. Still have no idea if I want to stick with the stock cam or try something different. Exhaust work is another question at this point, but that won't be worried about until the engine is back and together.


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[tanman_2006]

On the exhaust valves do they make inserts to help with cracking?

 

[3500_6.5]

He said he can put hardened seats in, but he said that he would be cutting into, or very close to, the water jacket, especially if I put larger valves in. He said he can do it if I want, but that will only make the actual head material even less between the valves so the chance of cracking between the valve seats would be even higher. The heads I am using are aftermarket heads that are supposed to be made of better material and resist cracking better....but my aftermarket block was also supposed to be better and it had cracks all over it.


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[Burning oil]

P400 have hard inserts FWIW.

 

[3500_6.5]

Yeah, I looked at them and quickly looked away lol. Would be very nice to have a set, but they are too rich for me for this build. I didn't ask how much it would cost to put hardened seats in the heads I have now, maybe I'll check when I drop the rest of the parts off next week.


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[WarWagon]

With the cleaner oil I have seen with the gapless and ZERO blowby... And strongest of all: After 21K of my abuse w/o issues... I have scuffed cylinders/pistons in the 6.5 on conventional rings. One is supposed to file fit the gapless rings to the cylinder. OOPS - never bothered to do that and got lucky.

With as dirty as the 6.5/6.2 engines run the oil with normal rings I suggest you can get your money back from the gapless ring cost by extending your oil changes. (Leroy has good prices on them.) When I was running it 550 miles a day I had to change the oil once a week at 3K and was pushing the limits of the oil at that with conventional rings. (1993 Manual says change oil at 2500 miles for HD use.) It looks like I could run the gapless to 5K w/o issues if I put that many miles on it in a year in her retirement.

 

[3500_6.5]

Got my crank and head studs from Leroy this week. Dropped those, along with the stud girdle kit and rods off to the machine shop on Friday. Block got bead blasted and cleaned up and still no signs of cracks so I think we are good to go. Heads have also been cleaned and checked for cracks, and everything checked out. Hopefully now that I dropped the rest of the parts off, the machining will get done this week.


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