Knock Knock...

[vigman]

Crank bolt....

If your going to use this to turn the engine...PULL THE PLUGS!

That bolt is not THAT strong..

When in doubt....measure!



Vig!

 

[geekinavette]

Anybody know what the standard rod journal diameter should be?

 

[geekinavette]

Found the standard journal size

Ok I think I know what happened here.

I measured the rod journal diameter at 2.09", which means it's been machined .010" undersize, no biggie. BUT...the numbers stamped on the Clevite bearing are:

9 92
CB663P
N

I'm assuming the 9 92 is the date of manufacture? I also think these are standard size bearings (for a 2.1" diameter journal), as I remember if they were .010 oversize then there would be a -10 after the part number? Also...I don't know if it is valid to do so, but when I put the two bearing halves together and measure the ID...2.1" (plus about .002).

As hard to believe as it is...it seems that someone put standard diameter bearings on a .010 undersize crank! :eek

Thoughts?

Bill

 

[blactopballr]

good luck! i hope all works out for u nd u might take in consideration a hi-volume oil pump and new screen while u've gott it torn down

 

[vette-dude]

You are correct about the brgs. being marked. If they are .010 over they should be marked on the brg shells. Since this is a possibilty I would check the mains too while you have it apart. You will have to remove the belts in order to get the crank to drop enough to remove the main brgs and reinstall. HV pump is a good idea but use an all steel drive shaft from Milidon not the plastic one on the stock pump (around $8 to 10). Hope you got her whipped.

 

[vigman]

Tape the two bearings together

And measure the bearing ID.. that will tell you FOR SURE!

or

Get the part # ( same mfg ) for the .010 bearings

Vig!

 

[geekinavette]

They are for sure standard size bearings.

I checked one of the mains today...same story. .010 undersize journals...standard size bearings.

Bill

 

[geekinavette]

I got one of the heads off today...two exhaust valves are cracked!

I'll try to get some pics tomorrow. I've never seen that happen before.

Bill

 

[evolution]

Ohhh That sux! :eek

 

[geekinavette]

You win Vig! (heheh) This puppy's gotta come out and get the whole works.

After pulling the heads I found one of the cylinder walls is scarred up really bad. I don't know who put this thing together, but I hope they never touch a wrench again. I just hope it can be bored...it's already .020 over.

The other head also had at least two cracked exhaust valves...one of them has many cracks around the circumference of the valve. That's just NUTS! What would cause this, overheating?

Bill

 

[vigman]

From a previous post.... ( Cracked valves )

The other thing to consider here is after you shut the engine down after a hot run,
( using open/ straight pipes as an example )

The cold air in rush after shutdown will chill the valves to quickly.. causing silght heat stress ( cracks ) on a microscopic level, which over time will cause a valve to snap & drop... OUCH!

Now if your running stainless valves...it's less of a deal...

As you reduce the back pressure you give ambient air a chance to get back into the exhaust system......

Where do you think all that water comes from when you fire up on a COLD morning!

You might want to consider this....

Any exchange for preformance costs something ( as you are finding out )

Now usually this affects the Stem of the valve.

The actual face cracking MIGHT be from the valve being open ( OR ) PING city.. or nitrous
or some HI PO juice to increase the burn pressure/temp in each jug!

Is there a relationship between the loose bearings and the cracked valves?


Vig!

 

[vigman]

On further review of the play

On the exhaust valves

IF you have a HIGH lift cam
AND you got it really hot
AND revved the PI$$ out of it

The exhaust valves COOL when in contact with the head... ( heat sink)



So if they are REALLY HOT and there SLAMMIN back into the head they will crack( fracture ) around the stress area.

Would LOVE to see a pix!



Vig!

 

[geekinavette]

Hereyago Vig. (meant to post it sooner...sorry):

Same valve from more of a side-view:

I have no idea what cam is in it. When I get it out I'll see if I can identify it.

Bill

 

[vigman]

Wow

That cracks me UP ( sorry )

WOW!

Good thing your fixing it NOW~


Vig!

 

[geekinavette]

Re: Wow

That cracks me UP ( sorry )

:L Good one!

Yeah, it is good that I tore it down before one of those suckers came apart!

It does seem that "something" got into one of the cylinders. Look at these pics:

Other side of same cylinder:

And YES, I CAN feel it!

Bill

 

[vigman]

Ouch

So the little BALLS in the first pix... metal bits?

and the ridge looks like some staining as opposed a scratch.. but she does look as she was running lean ( or HOT )

Can you take a wire wheel to it and clean it up...or some 400 wet dry sand paper & oil and sand it?


SEE what did I tell you about a NEW engine..once you open things UP the problem expands exponentially ( sp... but it's early)

I'm really sorry... at this point I would junk the heads and find some aluminum ones.. by the time your thru.. it will be a push costwise
( trust me on this)

And the C-4 84 heads were NOTORIOUS for small cracks in the water jacket.


Vig!

 

[geekinavette]

Little balls? Not sure where you're seeing that. There were a few small metal bits (looked like melted aluminum) in the bottom of the pan, but that's it.

The cylinder wall is definately scratched, easily felt on both sides of the cylinder. The pattern is kinda interesting though, not sure what to make of that. I only hope that it's not more that .008" or so, so that it can be bored to 4.030".

"I told ya so I told ya so" ...yeah yeah yeah (heheheh) :L

I don't plan on trying to re-use those heads, I'm already pretty sure that at least one of 'em is cracked already. I have a set of stock heads (NOT cracked!) ready to bolt-on, at least until I can get a GOOD set.

Bill

 

[maxrevs85]

Looks like possible broken ring did the damage . I found that in mine on tear down. Also ,its time for a new crank. I wouldnt have it ground again. Crank kits are very close in price to redoing the old.

 

[vigman]

Have we done anything else yet?

Waiting for new chapter in this story!


Vig!

 

[geekinavette]

Not much Vig...I can't buy any parts until I get some work (man I HATE job hunting!)

Somebody did make a good observation based on a similar experience...the cylinder had filled up with water at some point and caused some rust, and when the piston "broke loose" that's what caused the scratches on the cylinder walls. Makes perfect sense to me. I did some closer investigating on the head chamber that matched up with that cylinder....

And that explains the water in the cylinder. I do have a good set of stock heads (but with 1.94 intake valves) to put on it (for now anyway).

So I plan on taking the block up to the in-laws, he has a machine shop in po-dunk WY and does a super good job...just as soon as I get back to work. Hopefully it can still be bored another .010 to 4.03", and if not then he's probably got a good one laying around.

I don't plan on getting too radical with the rebuild...mostly stock with the exception of the cam. I'll probably go with a Crane 2030 or 2040 grind. Several people have had good results from this cam with 2" bore throttle bodies, and a little intake/head porting. Of course then I'll need a good set of headers...some AL heads maybe...and so on and so on.