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Rebuild for a performance oriented 6.5

So it looks like you decided against the splayed main caps?

Can't wait to see more progress.
 
n8in8or said:
So it looks like you decided against the splayed main caps?

Can't wait to see more progress.
Click to expand...


Yeah, since I found a non cracked block and the current engine seems to be holding up pretty well considering the mileage on it, I think with the better crank and stud girdle kit that it should be strong enough without spending a bunch of extra money on new caps and all the added machine work.


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Well, finally an update. The machine work has taken FOREEEEEVVVVEEEERRRRRR. Apparently he is way behind and has no help. So I have, as patiently as I can, been waiting and calling every couple weeks to keep my engine on his mind. Everything is finally done, except reconditioning the rods. The block was line bored, bored and honed with a torque plate installed, and decked. Heads were also rebuilt. I will be doing some porting and polishing once I get them back. He called today to let me know everything is cleaned and wrapped up and waiting. Minus the rods. Since the block was decked, he was going to destroke the engine slightly by offsetting the wrist pin holes on the rods. He also planned on replacing the rod bolts with ARP ones. But ARP apparently doesn't make rod bolts for 6.5s. So now we are trying to see if there is another option besides the stock rod bolts. He said they are not stretched, so they could be reused if I wanted to. But I am seeing if I can find another option instead before deciding to reuse the stock ones. I'd prefer to beef up anything I can before putting this engine together to make sure it holds up to anything I throw at it. So if anyone has another option, I'd love to hear it.
 
I've been told by others on here there's not enough clearance to offset the rods (bottom of piston would hit the counterweights on the crank). curious to know if this is in fact the case. I also remember reading that the stock rod bolts were unavailable for awhile.
 
Current practice is to use thicker head gaskets for a decked block.
Unless you are raising the RPM stock rod bolts are fine. Myself I would use new stock IF I didn't have a budget, but, I have re-used rod bolts w/o issue.
 
I can look into this problem, but one question I have, does anybody know if "all" rod bolts are the same? (except P400)
 
I have reused them as well without issue, I just thought that if there was another (reasonable) option, I would replace them with something beefier while I'm there.

I know most usually use thicker head gaskets, whether it be bc of decking or to lower compression, but I feel more comfortable using stock thickness gaskets. I have seen others run high boost and thicker gaskets and not had issues, but I like the idea of keeping the gasket stock thickness to keep the chance of a gasket blowing out at a minimum. I am keeping the stock compression as well as setting the wastegate at 30 psi (rarely sees over 20 psi sustained), so I need everything clamped together and tight as possible. I just see a thicker head gasket as another possible weak link.

Let me know what you find, Leroy. I am hoping to get everything wrapped up as soon as I can, so, not to rush you, but let me know asap [emoji4]


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I don't know how much the block was decked, but you can get pistons from Mahle that have a .010 shorter compression height. Since you overbored the engine you'll have to get pistons anyway so maybe this is a safer route to go? You won't have to worry about crank to piston clearance and they're a quality product. I put a pair in mine to reduce compression and they are nice pieces with hard anodized tops. I got mine from Leroy and he did the gapless rings at the same time. Top notch service.
 
n8in8or said:
I don't know how much the block was decked, but you can get pistons from Mahle that have a .010 shorter compression height. Since you overbored the engine you'll have to get pistons anyway so maybe this is a safer route to go? You won't have to worry about crank to piston clearance and they're a quality product. I put a pair in mine to reduce compression and they are nice pieces with hard anodized tops. I got mine from Leroy and he did the gapless rings at the same time. Top notch service.
Click to expand...


He already has the pistons that will be going in it. I considered trading my Kennedy Diesel 18:1 pistons for my brother's Mahle 18:1 pistons (mine are stock bore, his are 20 over) but I decided on keeping stock compression. I don't remember how much he said he had to take off the block, but I am thinking it was only a few thousands. So I would guess that the Mahle would still drop the compression more than I would like. I would imagine that a couple thousands of an inch wouldn't create a clearance issue, and he never said anything about it being a possible issue, but I will definitely bring that up to him first thing Monday.


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on a performance block, I would NOT machine the stock rods... decking the block would raise the compression, not lower it. if you are concerned about gasket blowout with taller gaskets, o-ring the block...
 
vstech said:
on a performance block, I would NOT machine the stock rods... decking the block would raise the compression, not lower it. if you are concerned about gasket blowout with taller gaskets, o-ring the block...
Click to expand...


Decking the block is why the thicker gaskets and rod machining was discussed....to get the compression lowered back to stock compression bc the block decking increased the compression....

Why wouldn't you machine the rods? Any rod that is reconditioned is machined. To get the big end back to the correct size, you have to machine some of the material off the cap, and then hone it back out to the correct size. The slight offsetting of the rods will not affect the rod strength any more than a normal rod reconditioning would. Which is minimal. The bigger concern when it comes to the rods, to me anyway, is bolt stretching, not weak rods from machine work. We are working on getting larger rod bolts now, which should add more than enough strength to the rods.

My biggest bottom end concerns have always been a cracked block or broken crank. I opted for a scat crank to hopefully minimize the crank breaking issue (along with probably going with a fluid dampener), the newest crack free GM cast block I had, which supposedly cured the cracking issues they had with the 97+ blocks, studs and girdle for the main caps, and hopefully larger rod bolts. My hope is that these upgrades will do the job for me. It isn't going to be a high revving, constant high boost race truck. It is simply a work truck. I want it to have power when I need it, and durability to last.


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3500_6.5 Is totally correct. I've seen somewhere around 250 -300 killed 6.5's. Cranks, blocks, head issues, head gaskets... Never saw simple rod failure.

Reconning rods is only going to help, especially if the machinist takes the time to balance while he's at it.
 
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Only took 6 months, but I finally got a Suburban full of engine parts back from the machine shop. Hopefully I can start putting it all together soon.


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I didn't do much today, but I did get everything into the shop and got the rods and pistons put together.
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