LMM: Well it finallly blew, and Now it Runs!
- Thread starter slowlmm
- Start date
any chance of it being back together for the socal diesel dyno day???
with alot of hope i May be driving it there. gotta make sure every thing is perffect been takeing alot of extra time specing every thing to make sure its all the way it should be. but it wont be on the rollers for sure.
Just one of thoes things that would be cool to have on the dining room table. My wife love that kind of stuff.
Phil
Time to take it apart again, Main's had 2 thou clearance and Guy recommended bringing them up to 3. We ran out of plastiguage too
You can do it after,Its just the order Gm specs tells you to do it in were you can block the crank and tq the new cam bolt to 173ft lbs.
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clearance
I just sent the mains on mine at .0028 and the rods will be right at .003. Just a little tide bit the Johnboy have seen on are motors with head studs. When you tq the mains with a tq plate and head gasket the cylinders run out of round by just over .004!!!! I would never put in head studs without honing the block with a tq plate. With the cylinder moving that much with normal piston to cylinder wall clearance YOU WILL HAVE TROUBLE! Pistons will try to hang as a worst case or you will get oil to the top side from bad ring seal. Jeff
I just sent the mains on mine at .0028 and the rods will be right at .003. Just a little tide bit the Johnboy have seen on are motors with head studs. When you tq the mains with a tq plate and head gasket the cylinders run out of round by just over .004!!!! I would never put in head studs without honing the block with a tq plate. With the cylinder moving that much with normal piston to cylinder wall clearance YOU WILL HAVE TROUBLE! Pistons will try to hang as a worst case or you will get oil to the top side from bad ring seal. Jeff
No way would I run the clearences that tight. I like recommend .0025 to .003 on the mains and crank.
Stock
Those are GM specs for a production engine. I beleive a performance engine needs more clearence. I have .0027 on my rods and .0028 on my mains. No oil pressure issues even at hot idle.
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You, nwpadmax, and myself have all seen what happens to the bore when heads studs are installed with a torque plate. I think is safe to assume that this is not a fluke and very common in the Dmax engine. The block that nwpadmax and found this in where LB7s yours is a LBZ so it looks like both blocks are prone to this.
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On a daily driver/ racer truck like Tommy's truck I like running as close to factory spec as I can, To get that lose of a clearence on your bearing you guys are sanding away on those bearings. I can see running the piston to cylinder wall clearence at .00350 on 1-6 then .004 on 7 and 8 On the main bearings .00175 is what mine is at I had a typo earlier and on the rod bearings .0015, For some of you guys that are not driving your trucks daily and just sled pull or run now glow plugs and really not a truck that you use everyday you can get away with being that lose, Just my 2 cents might not be worth much but I like to stay as close to GM spec as I can,But each to ther own.I hold 32 psi of oil pressure at idle with the truck warmed up at forst start up i'm at roughly 65psi and warm driving down the road I get around 58 psi not into if I hammer down i'm in the 60 to 65 area.In my mind running those specs that lose is like running Ross piston and needing all that cylinder wall clearence they call for why beat it up if you dont need to.
To me it is not about daily driver or race truck. It is about output. When your talking an engine with double the output of stock you need more clearence. More pressure, and more heat needs more oil. The spec I post are in the GM spec for the most part just the upper end. They are with in the GM service limit.
As far as piston clearence I would make them all the same. I dont like to use different sizes. I like to keep it simple.
Seeing how much these blocks move is an eye opener. You should see what happens when you install main studs and side bolts
Also I hooked the glowplugs back up. Rough starts get old in a hurry.
I know all of Gm specs I have posted almost every spec on the site in the vin chech tsb and gm spec area, The piston clearence specs came from Guys he likes .00350 on 1-6 then .004 on 7 and 8, I don't want to start a nothing on here but each to his own, I can understand with running the bearing looser in a all out race setup I have had many race motors, But i'm not going to run my rods and mains that lose if I dont have to what works for you or others is ok after break in yor going to be looser anyways.Mybe Guy or someone else might come in and give us there 2 cents also to help us all out.
