Installing connecting rods with motor in truck?

BoostnLLY

Member
Jan 4, 2020
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Hello guys,

I’m getting to a point were the stock rods on my LLY are going to be a limiting factor as horsepower is increasing. I’ve read that, that range can be a measly 550-600hp .

After some searching I wasn’t able to find duramax specific answers so My question is, can a set of Mahle rods or equivalent match up/compatible with stock pistons? Is it possible for just the rods to be installed while the motor is in the truck?

The body of the truck underneath isn’t in southern rust free condition but has been POR-15’d and makes me reluctant in spending more money on it just based on that but I justify the build as “The work truck” and want more and more power.

If I absolutely have to pull the motor, I think I’m going to gather parts for an LBZ build


Alex
 

Chevy1925

don't know sh!t about IFS
Staff member
Oct 21, 2009
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i dont see it happening. i mean, if you are dead set on it? you probably could but it would be a royal bitch to do. youd have more time involved than pulling the engine.

biggest hurdle is getting the wrist pin out without removing the piston from the cylinder bore. the moment the piston comes out, you have to install it from the top with a ring compressor. you MIGHT be able to hand push rings into the piston and slowly work it back into the cylinder but your hands will hate you after just one.

you also have to drop the trans to get the 2 rear most upper pan bolts out (behind the belhousing of the trans) and the front cover has to come off too. all youd have left is engine mounts and wiring to pull the engine from there. Everything else has to come off anyhow
 

jlawles2

Well-known member
Jan 28, 2010
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Danbury, TX
Its not possible to change the pistons without 10X more headache than its worth. Plan on pulling the engine and removing the heads. While you have the heads off, have them checked. Mine needed 16 of 32 valve guides at 160k. Also while you have the heads off, if you have not already done so, upgrade the head gaskets, and install studs.
 

jlawles2

Well-known member
Jan 28, 2010
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Danbury, TX
Dont forget you will most likely need to remove the flex plate to pull the upper pan also. I got extremely lucky and found a socket that would fit the head of the bolts and allow me to remove and retorque them.
 

Bdsankey

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Feb 1, 2018
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Dont forget you will most likely need to remove the flex plate to pull the upper pan also. I got extremely lucky and found a socket that would fit the head of the bolts and allow me to remove and retorque them.

Flexplate bolts, rod bolts, crank bolt, cam bolt, and main bolts are are single use by GM (IIRC the side main bolts are reusable).
 

BoostnLLY

Member
Jan 4, 2020
35
0
6
Well I just ordered PPE manifolds, Up Pipes and DHD Y bridge Kit. Looking at fuel next. I guess if it blows up I’m going LBZ and transferring parts. I don’t want to pull this motor the chassis sucks. Thanks for input