This, is why you pull the clean out plugs on a crank!

[RalphM]

This is a 4 inch mark crank that I pulled out of a 1940 engine. It was set up for racing, running full floaters. Bearings look pretty toasted and you can see why.
I stuck a Q tip in the right side and pulled out a lot of crap.

[Tinker]

Certainly not a clean block either... i'm guessing

[Bored&Stroked]

I'd say that engine has had a bit of water/rust in it! Good that you decided to clean it out!

[RalphM]

Crank measures .020 under on the mains and .017 under on rods.
These are the bearings

[supereal]

Ay our shop we grind lots of crankshafts. The plugs have to come out so the oil passages can be cleaned thoroughly to remove years of deposits.

[Bored&Stroked]

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Originally Posted by supereal

Ay our shop we grind lots of crankshafts. The plugs have to come out so the oil passages can be cleaned thoroughly to remove years of deposits.

Exactly! And then on these cranks, tap the holes for screw-in plugs (especially the larger Merc cranks).

[Bored&Stroked]

Originally Posted by RalphM

Crank measures .020 under on the mains and .017 under on rods.
These are the bearings

I'm sure it will need to go to .030 and .030. Before you grind it, make sure you have both the rod and main bearings in hand -- and hopefully the block you might put it in. The only real way to size the mains is with the block and bearings you're going to run . . . as clearances tend to vary a bit, so I always do it the right way on my race engines. Also, "loose" is better than tight! LOL

[Bored&Stroked]

What size are the rod journals???

[rotorwrench]

The crank pin bores are a last chance filter of sorts on a lot of old engines. The centrifugal forces will usually hold the particles in the throw end of each crank pin. They sort of get stuck there in a sludge mix of crud. Eventually, they can get like that if too much crud deposits in there. That would generally be a sign of poor maintenance or not properly warming the vehicle up during operation. Little old ladies that only drove to the post office or store and back for all of a 5 minute ride had engines just full of sludge like that.

[RalphM]

Originally Posted by Bored&Stroked

What size are the rod journals???

Measured 2.121”,
My book says standard is 2.138”.

I have some NOS .030 over full floating rod bearings.

[JSeery]

Not sure what was going on with this engine, but I have seen engines run on salvage yard oil. They drain the oil from old junked cars and reuse it! I rebuilt a 460 that I later learned had been through this. The inside was a mess, it was unbelievable what all needed replaced!! So do a lot of checking, even on parts or surfaces that you would suspect on a normal rebuild.

[RalphM]

In the 80’s my sister had about a 8 year old Oldsmobile. It had a popping through carb, I suspect that it had an issue with the valve train so I pulled the valve cover, and there was a perfect mold of sludge in the shape of the valve cover. Once I got it all cleaned out I found a broken pushrod. The car was a cheap runner so I cleaned the sludge out of the other side as well as drain the oil and ran Diesel through it a couple times. Then put oil back in it. She ran it for a while before she finally got rid of it. In 40+ years of working on cars I’ve never seen another one with that much sludge buildup.

[Bored&Stroked]

Originally Posted by RalphM

Measured 2.121”,
My book says standard is 2.138”.

I have some NOS .030 over full floating rod bearings.

Sounds like it is using the 29A rods - which you already have. So, it would not be a problem in going the route of full-floater. The other approach is to switch over to the 8BA 49-53 rods (regular insert bearings) - they are cheap and much easier to install (don't have to do all the hand fitment work you have to do with floaters).

There is nothing wrong with full-floaters (I use them in my traditional stroker builds - with 91A/21A rods), just that most folks don't take the time to correctly fit them to the crank/rods. I like Ole' Ron's idea of opening up the big-end of the rods a bit (like .001) to make them a bit "loose" - as loose is fast in my book! (Of course I build high-end race-type engines). If you have any questions on full-floater fitment, feel free to PM me (if you've never done it before).

Good luck and STAY WARM - was about 10 degrees this AM . . . probably about 20 degrees warmer than your world! LOL

[RalphM]

Thanks,
Not bad now, but supposed to get cold this weekend, -35 by Saturday.

Yes,full floating rods.
So what would the finish measurement on the big end of rod be?
Or is it better to measure rod bearing thickness to determine these clearances?

[Bored&Stroked]

I don't have the spec off hand, but just lookup the current ID of the big, end - have them hone the ID to .001 larger than spec. If they are resizing the rods, then they're going to hone them anyway. Also, make sure they know the ID is a bearing surface - you want a highly polished surface. If they don't know how to do that - find somebody else. I would always have the rods checked anyway - chances are they'll need to be resized.

You can figure out what your rod journals need to be by doing a bit of mic work - starting with the ID of the rod (using a precision 3-point bore gauge), then add the bearing thickness, then add another .002 or so. You'll probably find that you'll want the crank grinder to make the journal size about .001 smaller than they're used too. You want to end up with .0025 or so of total rod journal clearance. After all this, you'll probably have to hand fit the rod bearings anyway - using a rubber mallet, scotchbrite and lacquer thinner. You want to make sure the bearing shells actually FLOAT - in the rod and on the journal. You can't just drop them in and go - that can be a fatal mistake.

On the mains, buy the bearings FIRST - then have them install them in your block (torqued to spec) and then use a precision 3 point dial-bore gauge (they better have one!) to measure the exact ID of the bearings, then you want to have them grind the mains for a final clearance of about .0025 to .00275 or so.

By having the actual main bearings and grinding the crank to FIT THEM (for each main), you'll end up with the right clearances. I've seen many cases where the main bearings fluctuate a bit and I can't get the correct clearances without doing it this way (which is always the best way anyway). We don't have the luxury in our Flathead world of ordering bearings that are .001+- the standard sizes.

[v8fordman]

I'm wondering how do you guys get the plugs out of the rod journal ends? I've tried different ways, but this would be interesting to hear from different people. What size plugs or thread size do you tap the holes when putting them back in?

[RalphM]

After today I’ll be off till the day after Christmas. I’m going to pull those plugs and I’ll take some pictures and post them on here. I’ll see if I can try a couple different methods.

[rotorwrench]

I use an appropriate size thread tap and tap some threads in there. I have a matching threaded fitting for my slide hammer to pull them.

[bobss396]

Originally Posted by RalphM

In the 80’s my sister had about a 8 year old Oldsmobile. It had a popping through carb, I suspect that it had an issue with the valve train so I pulled the valve cover, and there was a perfect mold of sludge in the shape of the valve cover. Once I got it all cleaned out I found a broken pushrod. The car was a cheap runner so I cleaned the sludge out of the other side as well as drain the oil and ran Diesel through it a couple times. Then put oil back in it. She ran it for a while before she finally got rid of it. In 40+ years of working on cars I’ve never seen another one with that much sludge buildup.

My sister was famous for killing cars. The problem was that she only put like 1000 miles a year on her cars at the time. Short trips and she drives like someone's grandma.

[KiWinUS]

Same as rotowrench but many are peened in some fashion if so I use die grinder to remove peened area first.

[RalphM]

So I got a chance to attack this today. The first one took a little while trying to figure out the best method. I tried just tapping with a 1/2-13 tap, And putting a bolt in and trying to catch the head of the bolt with a slide hammer hook. It did not work. Then I took a 1/2-13 Bolt and welded it to an adapter on the end of my slide hammer. Also I beveled the hole with a drill bit to cut the swaged portion out. The first one came right out!
A lot of crud hidden in that hole!
Two others were really quick this way. But one still remains.
I drilled it out a little bigger and tried a 9/16 tap and it was a disaster. So I’m gonna have to sit back and think about this one.
The last two pictures show the hole after the plug was removed, I used to pick to pull some of the crud out of the hole.

[RalphM]

Here’s the bad and the ugly.

[Desoto291Hemi]

RalphM,
Back in the mid 80,s I was working in a shop and a Thunderbird came in.
It belonged to a young woman I knew as it turned out.
She had 80,000 miles on it and had never changed the oil.
When she finally did,,,a few days later it spun a rod bearing .
When I removed the valve covers,,,there was a perfect mold of it in wax.
She had used Quaker state all the time,,,,not the oils fault she didn’t change it !

Tommy

[Tony, NY]

Quaker State was (is) a paraffin base oil. Some stories out there of high buildup even with regular changes.

[rotorwrench]

Most oils refined for lubrication purposes are from wells that are higher in paraffin levels. Pennsylvania crude was known to he high in Kerosene or paraffin levels but may have depleted somewhat in the modern era. Paraffin can come from other mineral resources as well. Jet fuel is the most common use for Kerosene now days.

Broken tap removal tools are available or metal disintegration can be employed. A lot of machine shops carry such MDM equipment.

[RalphM]

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Success!
I removed the broken 9/16 -24 tap, Drilled out a little bigger and put in a 9/16-18 tap and while running the tap in and out it just came out!
Now it’s off to the hot tank, but I think I’ll run some wire, and pipe cleaners through first.

[Mart]

I've not done many, but on the 4" French crank in old Rusty I drilled a small hole in the plug and used a coarse threaded self tapping screw to pull them out. I welded the small holes and reused the plugs after, making sure the hole was well peened.

Mart.

[Ross F-1]

Originally Posted by Mart

I've not done many, but on the 4" French crank in old Rusty I drilled a small hole in the plug and used a coarse threaded self tapping screw to pull them out. I welded the small holes and reused the plugs after, making sure the hole was well peened.

Mart.

My rebuilder does it that way, except he doesn't even drill the starter hole. I saw him do a whole crank in less than 5 minutes. He uses an air drill, and a bolt down the middle of an old socket. Practice makes perfect, he probably does 30 flatheads a year.