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Discussion Starter · #1 ·
took my truck in and balance rates were
CYL 3/0.3
CYL 6/+15
All the rest/-7

maybe compression problem in cyl. 6?
these are new remans that i just installed
truck idles rough and is hard starting when warm
 

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Were they Bosch Remans?? Pensacola Remans??

16 is a big number, compression issue could be the cause. Did any of the cups comes out with the injectors specifically the #6 cylinder?
 

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Discussion Starter · #4 ·
no cups pulled, on cyl. 6 i am not positive but the factory injector washer may have stayed in the cup and i know i put 4 new ones on that side so i may have 2 in there, would this make a difference on balance readings? the other 7 stayed on the injectors when i pulled them and sat them on the bench. what is the "okay" margin for injector balance rates?
 

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Discussion Starter · #6 · (Edited)
testing was done in park at idle. i am having the mechanic do a compression check on cyl 6, if it is ok should i tear drivers side back down and check injector 6 for 2 washers? how do you check compression on these engines?
 

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take the glow plugs out and thread in the compression adapter then connect the gauge. Then remove IGN 1 fuse and have a helper crank the engine.

Watch the gauge for 6 compression cycles for each cylinder. Look to see if it slowly builds up compression, if the compression doesnt hold, or just simply record the average psi for that cylinder. IIRC GM likes them to be around 350-400psi. The biggest thing to look for though is differences between the cylinders
 

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Discussion Starter · #8 ·
whats the most common causes for low compression on LB7's? i dont really have any symptoms of a blown head gasket. if i did have 2 injector washers on that injector would it not be sealed in the cup and cause any kind of leak? thanks for the help!
 

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Discussion Starter · #10 ·
if compression is low on cyl 6, i guess i will take it apart and look for 2 washers, if only one what would be the best thing to do? take heads off?
 

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Discussion Starter · #11 ·
if for some reason i have a bent rod or something whats the best route to go, find a used engine or rebuild mine? is there any places that sell used or rebuilt complete engines that is a "good" known place to get them?
 

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Discussion Starter · #13 ·
it would b nice to do a mild build but im also on a budget right now, have to many projects going on! is there a good place to work with that carries all the parts? i am definately putting ARP studs in if its getting torn down. what else is good to do to them to make them stronger and/or last longer?
 

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The number one piece of any motor build is a good set of rods and you get what you pay for.

Crowers and Carrillos are going to be around $2600. The Crowers are a I beam design and some have been eating up wrist pin bushings. The Carrillos are great, and are an H beam design.

Then there is The DPR/Howards X Beams. These are around $2850 and are an X beam design. They have a hole EDM'd through them to force oil to the wrist pin.

All of these rods are top notch and I cant think of any that have really failed. Curtis has tested his x-beams to 1500hp IIRC. Im more partial to his rods, but all of them are great. If a rod comes out and it fails once, it will usually be off the market before long due to the fact that there are 3 great rods out there already.

While the price for a set of rods may make you run to the bathroom, remember that the market it small. There are not very many sets sold each year so the profit margin on them is slim. The inital up front cost of designing, testing and setting up the tooling is a huge cost.

Over time these prices may come down, but I doubt we will ever see a $400 set of rods for the Dmax like there is for the 350 chevy.

You will also want to have your stock pistons delipped and coated. They will be inspected for microcracks before this process. This costs between $500 and $800 depending on who you have do them. Stock delipped and coated LB7 pistons have held quite a bit of power but 800hp has been known to crack some from time to time. But since your on a budget, $2800 for a set of forged ones isnt in the works I would assume. Plus the forged ones arent very good for street use.

You will also need your head studs which are between $600 and $680. ARP2000s will work great.

Main studs are cheap and worth the investment as well.

You will also need your main and rod bearings as well and a set of "C" headgaskets.

Keying the cam and crank is also a must. This doesnt cost much.

Then there is the cost of machining and balancing which isnt much either.

If you plan to build it yourself you can do it for between $4,000 and $6,000. A used motor will be about that much, and you dont know how good of shape that motor is in.

Valvesprings are also reccommended whether you go with Guys Beehives or Curtises Dual springs.

That will get you a stout motor. There are other things you can add to boost power, such as ported heads and a different cam, but this is out of your budget.

The above motor build will probably suit you well for years to come.
 

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Discussion Starter · #15 ·
cylinder six has no compression, could it be my washer issue or maybe stuck valve?
 

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The number one piece of any motor build is a good set of rods and you get what you pay for.

Crowers and Carrillos are going to be around $2600. The Crowers are a I beam design and some have been eating up wrist pin bushings. The Carrillos are great, and are an H beam design.

Then there is The DPR/Howards X Beams. These are around $2850 and are an X beam design. They have a hole EDM'd through them to force oil to the wrist pin.

All of these rods are top notch and I cant think of any that have really failed. Curtis has tested his x-beams to 1500hp IIRC. Im more partial to his rods, but all of them are great. If a rod comes out and it fails once, it will usually be off the market before long due to the fact that there are 3 great rods out there already.

While the price for a set of rods may make you run to the bathroom, remember that the market it small. There are not very many sets sold each year so the profit margin on them is slim. The inital up front cost of designing, testing and setting up the tooling is a huge cost.

Over time these prices may come down, but I doubt we will ever see a $400 set of rods for the Dmax like there is for the 350 chevy.

You will also want to have your stock pistons delipped and coated. They will be inspected for microcracks before this process. This costs between $500 and $800 depending on who you have do them. Stock delipped and coated LB7 pistons have held quite a bit of power but 800hp has been known to crack some from time to time. But since your on a budget, $2800 for a set of forged ones isnt in the works I would assume. Plus the forged ones arent very good for street use.

You will also need your head studs which are between $600 and $680. ARP2000s will work great.

Main studs are cheap and worth the investment as well.

You will also need your main and rod bearings as well and a set of "C" headgaskets.

Keying the cam and crank is also a must. This doesnt cost much.

Then there is the cost of machining and balancing which isnt much either.

If you plan to build it yourself you can do it for between $4,000 and $6,000. A used motor will be about that much, and you dont know how good of shape that motor is in.

Valvesprings are also reccommended whether you go with Guys Beehives or Curtises Dual springs.

That will get you a stout motor. There are other things you can add to boost power, such as ported heads and a different cam, but this is out of your budget.

The above motor build will probably suit you well for years to come.
wow im impressed... sounds like you've built a motor or two!
 

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Discussion Starter · #18 ·
so whats the most common cause on LB7's if they have no compression in a cylinder.
 
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