Crank and Rod questions

[mr_clean]

Two questions here.

1. On the connecting rod, a couple of them have a coppery color under the bearings... I've never seen that before and was wondering if it indicated anything about the rods...

2. On the crank journal, there is some discoloration/streaking and a minor scratch that I can barely catch my fingernail on... Can I clean this up myself or do I need to have the crank re-ground?

I'm basically just trying to freshen up this engine to get me by for a couple of years while I look into a 383, so I didn't want to put a bunch of money into it, but I do want it dependable... It will be basically a stock 350 with flat top pistons...

Thanks!!!
Scott

 

[AkMudr]

I'm not an expert but it looks like it ran low on oil at one point in time and got hot, REAL hot. I recently pulled my main cap to do my rear main and they were still shiny even at 125k miles. I would say get it reground but thats just me.

 

[mr_clean]

I was wondering if it might have gotten hot...
There was a ton of crud built up around the exhaust crossovers on the heads also...

The last crank journal is the only one with that streaking and a scratch. All others seem fine and they all mic out to within tolerances...

Any ideas how much a crank grinding should cost?

 

[big83chevy4x4]

local machine shops here charge 75-90 to send them out for crank work.

 

[4X4HIGH]

There are several reasons why you could have copper showing on the rod bearings.

(1) The rod may not be sized properly and the bearing to crank clearance is too tight.

(2) The rod may be bent. (looks like this may be the problem since it looks to be on 1 edge only)

(3) Dirt passing through the crank and bearing can cause a scratch which will show copper.

(4) Detonation. If the rod bearing is copper on the upper half, (rod not cap) but not the lower half (cap) it is definately detonation. When looking at the mains it would be opposite, copper on the lower (cap) but not the block.

At my shop i charge $50.00 to polish the crank or $95.00 to regrind it. If the crank is on size then a repolish should do the trick, the scratch won't hurt anything so long as there are no high spots, the polishing will make sure of that. I would definately have a machine shop check the rods for sizing.

 

[mr_clean]

Exactly the information I was looking for. Thanks!!!

So it sounds like this engine had problems, so I probably should look into full block prep, crank polishing/grinding, recondition rods, head jobs...

adding this all up plus master rebuild kit is it just better to get a GM crate for $1,300 and call it good... I really didn't want to put that much into this... Maybe I should look into building the stroker now...

Man, this project keeps getting pushed farther and farther out...

 

[Greg72]

"Never ask the barber if you need a haircut".....or in this case, never ask the machinist if you need engine work!!!



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[mr_clean]

hahaha, exactly my fear of taking it all to a machine shop...
I can almost hear them telling me that I have a .043 taper in the #1 cylinder...
It's been a while since I had any machine work done, so I don't know who to go to now...
My $400 budget rebuild is doubling before my eyes...
Oh well, that would be on par with everything else for the Jimmy...

 

[4X4HIGH]

"Never ask the barber if you need a haircut".....or in this case, never ask the machinist if you need engine work!!!



.

Hey, what are you saying here? I think you got away cheap on your engine rebuild, what maybe several dinners plus parts?

 

[Greg72]

Hey, what are you saying here? I think you got away cheap on your engine rebuild, what maybe several dinners plus parts?

Flipoff? FLIPOFF!!!

Oh, my feelings are hurt. And just for the record, the only part I didn't like about the engine build was the "smell".....


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[1-ton]

You would be surprised what you can get away with on a Chevy engine. I did the same thing you are looking to do with an extra small block I had laying around, and it went 70,000 miles. It could have gone more, but I wanted to put a better engine I had into it.


All I did was emery cloth the crank (real good), install new rod bolts on the rods (had them inspected for stretch and twist at a machine shop first), ball-hone the cylinder walls, new oil pump, install a new set of the cheapest rings & pistons I could find, and had the heads freshened up at a machine shop. I would say the whole thing cost me about $600 with complete gasket set and all.

 

[diesel4me]

Not uncommon....

Its not uncommon to see bearings with copper showing,many high mileage motors that have been overheated or run low on oil have this happen--and many small blocks I've taken apart had copper showing only on the frontmost bearings near the timing cover--the first main gets the most wear on vehicles with A/C and the fact the drive belts are adding to the side loads on it..

Your crank might be "tapered" or the rod might be tweaked,seeing how most of the wear is on only one side--putting new bearings on that crank or rod without correcting the problem will only lead to early failure--it would be best to at least have the crank checked for size and taper,and reground if needed,or polished to get the scratches smoothed out if its within spec--a "crank kit" with matching bearings might be cheaper than having to old one turned(about 175 bucks last time I bought one "exchanged" with the core)...Its a toss up to whether its worth doing,depending on how far you rebuild the rest of the motor(honing,rings,pistons,cam,lifters,etc-)--it dont take long before you have spent as much as a "Mr.Goodwrench" crate motor costs...

 

[ben427]

Ya know, if your gonna do pistons and everything, summits has Eagle 383 kits for 909.00 bucks. Its not online yet but its in the catalogue.