Help: Need Engine Machining and Tolerance specs from the "builders"

[Leadfoot]

My friend (who builds many competition motors) works at a shop that just bought additional bobweight and torque plates for Duramax's.

The have two motors they are building and are looking for input. I told them I would ask the "community".

What are guys using for Piston to wall clearance (I know it varies by type of piston used so that is requested as well).
Main bearing clearance, rod bearing clearance
What types of bearings (assuming it may vary by intended use, so that is requested as well)
I know some guys are opening the guides on the exhaust valves (how much)
Piston protrusion do's/don'ts
Minimum piston to head clearances
They are keying the cam and crank but they asked how many are keying all three locations on the crank or just the balancer and first gear?
Any other input on machining or building is welcome as well.

Thanks!

 

[Leadfoot]

Secret Squirrel Stuff

 

[S Phinney]

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[S Phinney]

Piston protrusion not more than. 012
Rods. 0025-.003
Mains. 003-.0035
Piston/wall coated cast
.0035 or manufactures recommended
C gaskets
Quince. 030 performance build

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[S Phinney]

Key only first two gears
H bearings

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[super diesel]

Weld the water pump shaft (front and back). Pin the shaft and gear of the oil pump (it can spin the gear). One extra thing I did was to also open the oil squirters from .063 to .085 (you don't need to go this big but I wanted the extra cooling and oil up there and thats almost twice the flow amount if running the same pressures). I'm sure there replacing the valve springs, but one thing to keep in mind if using the stock spring is that after about 30K or so they loose about 1/2 there strength. Go with good valve springs. Plus the rocker shaft needs better bolts. I used just simple grade 8 bolts.

 

[Sledheadxp800r]

Mahle forged piston to wall clearance?

 

[jneal]

Mahle forged piston to wall clearance?

.008 ptw

 

[TheBac]

I just used the OEM clearances, specs and torque values. So far, so good.

 

[jneal]

We have always keyed all 3 locations on the crankshaft. Damper, reluctor, crank gear. All with one stepped keyway.

 

[S Phinney]

There is nothing the natter with keying the Crank gear but it isn't going to break the pin that's there. If youve ever taken one off you will understand why.
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[jneal]

I've removed many crank gears, I've also seen them spun.

 

[Sledheadxp800r]

There is nothing the natter with keying the Crank gear but it isn't going to break the pin that's there. If youve ever taken one off you will understand why.
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You really trust those tiny ass pins? If that thing was to schear off? I just don't like the thought of the entire engine relaying on that little pin.

 

[xtremebikr04]

I had all 3 locations keyed on mine. Not worth the chance not to. Its already apart so do it right the first time:thumb:

 

[S Phinney]

Sixty Five thousand miles on my build and no problems with that little five mm pin. Several premier builders dont key that one. I would agree that in a extreme HP application it should be done. Most builds don't see mid 800s if that.

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[Sledheadxp800r]

Sixty Five thousand miles on my build and no problems with that little five mm pin. Several premier builders dont key that one. I would agree that in a extreme HP application it should be done. Most builds don't see mid 800s if that.

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Im hoping to see well over 800 with my puller this spring. So everything wil be keyed. I just can't see running without it.

 

[ripmf666]

Im hoping to see well over 800 with my puller this spring. So everything wil be keyed. I just can't see running without it.

Good luck getting that gear off. You will need a lot of heat and I would buy a new gear then.

 

[x MadMAX DIESEL]

Good luck getting that gear off. You will need a lot of heat and I would buy a new gear then.

I'm using my stock gear.

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[Stingpuller]

Motor

I would key all three also. You can get the gear off with a press and you don't need any heat.

 

[super diesel]

I would key all three also. You can get the gear off with a press and you don't need any heat.

X2. I just took 2 pieces of cold rolled 1" thick flat stock steel that were 3" wide and 12" long each, put them together in a vice (side by side and bored a hole about .025 bigger than the journal behind the gear in the two halves where they mated together). I then put them on either side of the crank under the gear, held them together with clamps and pressed the crank down off of it. One big, BANG, and then the crank dropped out pretty easy. Put something slightly under the end to catch the crank from dropping to the floor. There see? Clear as mud.