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Rebuild for a performance oriented 6.5

What do you mean? The sprockets only go on one way but you can adjust the cam timing by just installing the chain (or gears in my case) a tooth off or wherever it needs to be. My plan will be to line the dots up like its supposed to be, check the centerline (the spec he gave me to base it off of) and then move it a tooth if it needs it and then go from there until I get it where it needs to be.


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I'll try to get a video or lots of pictures when I do it. Maybe it will make more sense with visuals rather than my possibly poor explanation.


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Can't do it that way unless the cam is way off and that probably isn't the case . I used offset keys from a small block Chevy and I think I moved it maybe 4 degrees .
 
How can you not do it that way? That is how it will be done. That is how it is done on the Fords. I guess if it can't be adjusted to make it within his spec by doing it that way on the 6.5, then I will be working on fine tuning it by working on the key. But for the Fords, the instructions simply say to make the cam one tooth off and that sets it correctly.


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Jumping 1 tooth is 10* on a 6.5 Iirc. Hefty increment. Buy offsetting keys for cam and crank ahead of time. Are you going Leroys gear drive, and if so what the tooth to degree count compared to the old dsg.

Advancing the cam is huge on a vacuum creating gas engines. Boosted diesel?

If you haven't tried it, please do- but be willing to run it, then tear it down and go to stock for direct comparison. Been there & done that.

All that playing around is what got me to running dsg gears and having my cam cut out of new stock instead of a cut down regrind. I'm in the huge lift and duration crowd. Of coarse, when it went wrong, I stuck many a rod into asphalt. Haha, I miss the excitement sometimes.
 
I am not sure on the tooth to degree count, I was just going to say that I could easily figure up the amount it would change per tooth by counting the gear teeth. Anyone know the stock cam specs? This cam is supposed to be set between 110-112 icl. So if I know the stock spec, it wouldn't be hard to figure out what moving it a tooth would do.

My wheel I ordered from summit, of course, wasn't in stock at their Ohio store (probably bc I bragged about being able to get it so quick), so it was shipped out from Georgia. So it won't be here until tomorrow, so I didn't get to mess with it at all this weekend.




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And I am running the stock cam now. As of right now there isn't really going to be any other changes with the new engine vs the old other than possibly redoing the exhaust manifolds. But all the other performance parts are just being transferred from the old engine to the new. So I think that I will be able to tell if the cam itself makes much of a difference or not.


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So I was looking at the marine cam specs and if it the same as the stock cam intake centerline, then it is 101*. So if I am lucky and one tooth on the gear drive is 10*, then that would put me right where I need to be.


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10° is getting awfully close to valve/piston clearance issues. Add in more lift/duration, chain stretch and it could be a recipe for catastrophic consequences. I would do a trial assembly with some clearance indicator atop the piston valve reliefs, turn it over by hand several times and then disassemble and inspect it. Most gasser adjustable cam sprocket and chain sets have keyways for -2°, 0, and +2°. With offset keys you can get another 6-8° either way. And IDI diesel is a whole lot different than a wedge or hemi head gasser for valve/piston clearances. Just be careful that the new cam and its centerline indexing doesn't make your new engine an experimental guinea pig grenade.
 
I'll definitely be doing a dry fit and test. I would imagine that the fords run a similar stock cam, so I would guess clearances would be ok. But "imagine" and "guess" aren't exactly words I like to use when putting together a brand new engine that already has too much time and money in it. So I'll be checking, and double checking, and triple checking, and double checking my triple checking to make sure nothing bad is going to happen. And then still cross my fingers when I go to fire it up for the first time....


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I looked on Leroys web pics. 46 tooth so 7.826 degrees per tooth.

The chain sets are 36 tooth so 10 degrees each, but not way would I run close on a chain set again. The first 2 times I smacked valves into Pistons from a little to advanced timing and chain slack.

Clay your piston tops. It's the smartest $ you'll spend if you are running close. A couple sets of head gaskets are cheap. Don't mess around with old valve springs when it's that close. Valve float is hard, but not flutter on a quick ratio lifting cam- and since yours is a recut...
 
Just wanted to remind you that the injection pump has a adjustment limit in all this as well. If you jump a tooth on the chain, IMO from the extreme sprocket keyway and key wear on my 1992 project, your valves will be ok. However as the cam is bolted to the IP drive gear you can run out of adjustment for the IP. I couldn't advance the pump enough to start the engine without ether and even then it took a few tries.

Someone can jump in and say what the slots allow for IP degree adjustment.
 
Easier breaking is possible, but as long as it's 3 or 4 degree max per keyway, he should be ok. Just make sure there is no slop. If he is trying to run over 100,000 miles then, yeah they will strip or snap. Performance is not longevity.

3500 hasn't told a lot about his cam, or set up- so I didn't pry. But maybe should. If you don't want to share details-it's ok. But what I've caught so far:

Regrind cam, so not as much lift and duration as stock so he is trying to shorten the power band. In doing so it becomes more important to move the range of that power band up or down in rpm to match acceleration rate and gearing. The rule of thumb is 1 degree per 100 rpm. So a 10 degree advance would move his peak torque down 1000 rpm. Colder burn on startup, and intake valve hitting piston is only concearns here.

This helps a lot keeping IP output in lower rpm so high fuel rate is easier. If still running the hx35/40 then a quick spool is going to be required to maximize the stump puller build. It will also help cool the valves better to beat egt. He just looses the top 250 rpm from the engine.

The opposite-a 10 degree retard will cost the lower end but help the easier flow top end rpm and maximize fuel savings if boost is back down to half its peak and a little more egt as the burn gets to the exhaust valves a bit more. Or if he is pouring on the coal at high rpm and able to ramp boost to the peak, like a little fuel kicker (propane or meth wmi) can push his torque curve up closer to the horsepower curve. The danger here is burning valves, increased egt, exhaust valve hit piston.

If we see you hooking up to a tractor sled, I guess we know.:D
 
WarWagon said:
Just wanted to remind you that the injection pump has a adjustment limit in all this as well. If you jump a tooth on the chain, IMO from the extreme sprocket keyway and key wear on my 1992 project, your valves will be ok. However as the cam is bolted to the IP drive gear you can run out of adjustment for the IP. I couldn't advance the pump enough to start the engine without ether and even then it took a few tries.

Someone can jump in and say what the slots allow for IP degree adjustment.
Click to expand...
Yes, in his instructions that came with the cam (which is the instructions for the fords), it reminds you to adjust the ip to compensate for the other adjustment made. Basically it is just a matter of moving the ip to cam timing the same as you move the crank to cam timing, only opposite. So a one tooth adjustment for the crank is just a one tooth adjustment for the ip. If I have to use new keys to adjust the timing, hopefully there will be enough adjustment with the ip itself to make up the difference.


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