Engine Rebuild Questions...

I don't get why everything in these engines are so overbuilt yet they use plastic for the oil squirters lol.

I am about to load the block up to get the cylinder bore taper measured to majke sure I am within spec.
 
After thinking about it, would it be a good idea to have metal oil squitters machined? I have a friend who works at a precision machine/grinding shop that I bet he could whip some up. If I did what grade steel would ya'll recomend? Or would it be pointless?
 
I'm told the plastic squirters tend to fail more often than people think. I've heard of people going to metal one's but don't know if they are worth the extra hassle/cost.
 
Ok I got my block back from the machine shop.

#1 measured 4.018"
#2 4.018"
#3 4.019"
#4 4.018"
#5 4.017"
#6 4.019"

Those are the bore measurements at the top and bottom of each cylinder bore. The guy who measured them did so without a torque plate bolted up to the block if that makes a difference?

Also though he haid every single cylinder measured .005" bigger in the middle of the cylinder than it did on the top, could that because he did the measurements without a torque plate?

With those numbers can I just put new rings on the stock pistons or does it need to be bored?
 
TTT

Also from lookin' around the forums it seems .005"-.007" piston to wall clearance is recomended for hot street trucks.

Is that cylinder bore-piston diameter= piston to wall clearance?
Or is it (cylinder bore- piston diameter) divided by 2= piston to wal clearance?

So would it be .005"-.007" total (each side of the piston having half of that clearance) or is it .005"-.007" on each side of the piston?
 
Muddin_dude06 said:
Ok I got my block back from the machine shop.

#1 measured 4.018"
#2 4.018"
#3 4.019"
#4 4.018"
#5 4.017"
#6 4.019"

Those are the bore measurements at the top and bottom of each cylinder bore. The guy who measured them did so without a torque plate bolted up to the block if that makes a difference?

Also though he haid every single cylinder measured .005" bigger in the middle of the cylinder than it did on the top, could that because he did the measurements without a torque plate?

With those numbers can I just put new rings on the stock pistons or does it need to be bored?
Click to expand...

That is how a cylinder wears. It is normal to see wider measurements on the sides of the cylinder.
 
The green plastic ones appear to be what I bought for my rebuild project. Cummins part# 3937214- which are the exact same dimensions as the black ones I pulled out of the 90 motor I am using. I don't think it would be worthwhile at all to try to get metal oil squirters. These appear to be a fiberglass embedded plastic. The most likely thing that would cause them to break off is taking in/out the crank. I am sure they are high temp, otherwise people would notice them being distorted when they go to take them out.
 
Does anyone know if I can just get by with fresh rings on factory pistons with those measurements on my cylinders?
 
I am also reusing old pistons on my build- haven't even put it together yet, but I don't forsee it being a problem at all. I just had my machine shop check the bores and pistons for size, honed the cylinder walls to deglaze them, and I'm throwing new rings on the pistons and going. I did have the skirts dry-lube coated, and the tops ceramic coated.
Just don't try to get new rings to seat on a bore that hasn't been deglazed- supposedly they won't.
 
Yeah I want to reuse my factory pistons with just fresh rings. When the guy who measured my cylinders did them he ran a dingle-ball honer through all of them before taking his measurements.

Are .010" oversized rings avaible? I can just trim the rings down for the appropiate ring end gap.
 
Muddin_dude06 said:
TTT

Also from lookin' around the forums it seems .005"-.007" piston to wall clearance is recomended for hot street trucks.

Is that cylinder bore-piston diameter= piston to wall clearance?
Or is it (cylinder bore- piston diameter) divided by 2= piston to wal clearance?

So would it be .005"-.007" total (each side of the piston having half of that clearance) or is it .005"-.007" on each side of the piston?
Click to expand...

If i remember right, it's "X" amount piston to wall clearance total. The factory spec I think was up to 0.006" on my 01 in the service manual. With 140,000 on the ticker it was right at 0.006" so I had them hone it to 0.008" before I ppumped it for alittle more room to account for the higher heat and rpms for pulling. It has some blowby until warmed up, then it's fine. With 0.008" piston to wall clearance, factory rings will be right at the maximum allowed end gaps.
 
So right now my piston to bore is

.007
.007"
.008"
.007"
.006"
.008"

Should this be ok for a 400-450rwhp daily driver that will be towing quite frequently? I don't want to have a blow-by monster and I don't want to HAVE to change the oil every 2500-3000miles because of soot contamination either.

This is such a damn headache :bang
 
Muddin_dude06 said:
So right now my piston to bore is

.007
.007"
.008"
.007"
.006"
.008"

Should this be ok for a 400-450rwhp daily driver that will be towing quite frequently? I don't want to have a blow-by monster and I don't want to HAVE to change the oil every 2500-3000miles because of soot contamination either.

This is such a damn headache :bang
Click to expand...

The factory bore is 4.020,how did you measure clearance.
 
I am just subtracting what my pistons measure from what the engine guy measured my bore at. The book I looked at with the engine guy and wha I have seen online says the factory bore should be 4.015"?
 
Muddin_dude06 said:
I am just subtracting what my pistons measure from what the engine guy measured my bore at. The book I looked at with the engine guy and wha I have seen online says the factory bore should be 4.015"?
Click to expand...

Cummins says 4.020 but I have always measured a few thou short,your bores seem fine wall clearance is usally 004 to 005 in a stock engine,are you measuring the skirt of the piston at the bottom.
 
Well I borrowed a Haynes manual and it says 4.0203" ?

I am starting to feel a little better about my cylinders being ok since it seems some places say 4.015" and others say 4.02", I am inbetween that.
 
Hey I am about to have my valves done on the head, the machine shop was able to save it with one oversized valve seat pressed in.

Is there anything to be done to the valve angles or seat diameter that can be done to improve flow/valve cooling?
 
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