Reconditioned 37 rods

[V8COOPMAN]

I'm seeing rod bore 2.220"
minus crank journal -1.969"
______
=0.251"
-0.250"
______
=0.001" TOTAL clearance.......from your figures.

[Mark's 37]

Found the error in the math I was doing. Clearance now is .001". The spec I found says .0005-.003". Fat fingers on keys.

The question remains that the bearings are egg shaped. When I sized the bearings to get clearance on the ends, the center part of the bearing is too wide and it won't move freely. I am checking this in a vice, not on the crank itself, the side clearance isn't a problem at this stage. I am wondering if sanding the butt ends of the bearing halves where they meet could remedy this.

[Floyd]

He is not saying 0.011. He has 0.001 clearance for 4 oil films which is not enough. Back to ol' Ron who says many new bearings are too thick. That is why you have to measure everything. Also you have to learn how to measure with micrometers which takes time to get it right. First timers measuring things are always off. Ask any machinist or better still a tool and die maker who works in tenths or smaller.
Just an opinion

[Mark's 37]

Originally Posted by Floyd

He is not saying 0.011. He has 0.001 clearance for 4 oil films which is not enough. Back to ol' Ron who says many new bearings are too thick. That is why you have to measure everything. Also you have to learn how to measure with micrometers which takes time to get it right. First timers measuring things are always off. Ask any machinist or better still a tool and die maker who works in tenths or smaller.
Just an opinion

I looked up the rod bearing clearance in a Motor's Manual and the .0005-.003" spec is for the later post war flatheads. The 37 spec is .0017-.0036". Still futzing with the mics.

[GOSFAST]

Hi Mark, Federal-Mogul who mfrs the aftermarket brgs for the '37, part #9020CA, calls for a low of .0015" to a high of .003" on the clearances.

Thanks, Gary in N.Y.

P.S. I believe .0005" is going to be a little too tight and this why Ron mentioned running the rod bore dimension a .001" over the factory high limit! I agree with this number (2.021") for the finished rod size. I haven't reconditioned a high number of these rods but I would also add the ones we have done have a more "polished" finish than a conventionally resized rod. We do use much "finer" stones for these rods.

[Karl Wolf]

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Originally Posted by Mark's 37

I am concerned about that too. Looking into doing some finishing for the surface. Got some fine steel wool 800, scotch brites, fine grit polishing compound to experiment with. Got any suggestions?

I had my 29a rods redone by a machinist who did not grasp the concept of full floating bearings... They had strong cross hatch marks.

I have a small lathe, and I made a wooden mandrell the size of the big end, with allowance for 400 grit- or so- sandpaper ("hardware cloth"), torn into 3" or so- wide strips. After removing the cross hatch, I then polished the big ends with crocus cloth... I found that I did not have remove much material at all.

An important part of this is to do two rods at a time, flat sides held together. This keeps them square to the mandrell, and from getting belled at the edges.

As for clearance. I would assemble two rods on one crank throw. If they will fall independently, they will run.

Karl

[Mark's 37]

As for clearance. I would assemble two rods on one crank throw. If they will fall independently, they will run.

Karl

Karl, when you say "fall" do you mean when the rod/piston is installed on a crank journal with the new bearing, the piston/rod will fall of its own weight?

Just finished micing the rod bores again. All 8 fall into the 2.2190-5" range.

Did the same with the OD of the new rod bearings and they all are in the 2.2185-2.2230" range no matter which way it's done.

I have a set of NOS Genuine Ford Parts bearings coming tomorrow or early next week. Will compare numbers. It may mean these rods need to be redone a little larger. Don't have a lathe to try your method. Thanks.

[flatheadmurre]

The bearing clearances mentioned seems a bit high to me for a stock engine.
Basicly you need twice the clearance for oilfilm so somewhere between .001-.006
If you get to much clearance theres a chance of the pin starting pen the bearing at startup due to lack of oilfilm in the gap.
In a racer battling heat using highflow pumps and not worring about things running for years i agree on using bigger clearances.
In what way would the higher bearing clearance be hard on the rings ?

[Kurt in NJ]

Larger bearing clearances mean more oil "leaks" out of the bearing and gets thrown on the cylinder walls and piston, so the rings work harder scraping it off the cylinder walls

[Karl Wolf]

Originally Posted by Mark's 37

As for clearance. I would assemble two rods on one crank throw. If they will fall independently, they will run.

Karl

Karl, when you say "fall" do you mean when the rod/piston is installed on a crank journal with the new bearing, the piston/rod will fall of its own weight?

Just finished micing the rod bores again. All 8 fall into the 2.2190-5" range.

Did the same with the OD of the new rod bearings and they all are in the 2.2185-2.2230" range no matter which way it's done.

I have a set of NOS Genuine Ford Parts bearings coming tomorrow or early next week. Will compare numbers. It may mean these rods need to be redone a little larger. Don't have a lathe to try your method. Thanks.

My idea is that they will fall by themselves, no piston. This would mean that they aren't too tight.

I hold the opinion that when it comes to measuring with micrometers that each operator has his own style. When you mic a bore, always transfer to an outside mic. Not every one has a ball mic to measure rod bearings, you can use a rod or bolt. My point is, by the time you get through all this, there is room for error.

I measure each set of components, but only do one rod throw's oil clearances.

Some people like Plastigauge.

I use brass shim stock to measure clearances. This needs to be approached with care, do not tighten past the point where there is drag- you don't want to bend the rod. You could use paper- a dab of oil will help.

Karl

[Mark's 37]

Thanks Karl,

Just for kicks I assembled two rods and bearing on a crank pin after polishing the surfaces a bit. Locks on the crank solid at 20 foot pounds. When the set of other rod bearings come I will try again. If the same thing happens then a trip to the machine shop and possibly taking the rod bores out to 2.221"-2.222".

[Bored&Stroked]

Sounds to me like your bearings are 'egg shaped' - and quite a lot. When you mentioned that you 'sized the bearings' - how did you do that?

If you used a rubber mallet on the ends, then you went too far and now you are way too wide in the middle (due to being egg-shaped). You'll need to put the shells on a piece of hardwood, use a rubber mallet and hit them in the middle to get them back to being concentric. You should be able to easily put both halves of the bearing together and slide them in/out of the rod (with just a light film of WD40 or nothing at all). I use a rod vice and spend quite a bit of time ensuring the bearings are concentric. I also use Scotch-Brite and lacquer thinner (once they are concentric) to polish both sides of the bearings. You should be able to easily slide both halves (as a set) back and forth through the rod bore - if you can't, you have more work to do . . . or the machining is incorrect, or the parts are wrong. It sounds like you have the correct parts (bearings) - so I believe your problem is as noted above.

Here is a link to a short video I put up on YouTube to show you a bit more. I created it as part of the build process I documented on the HAMB for the 1942 Merc engine for my 32 Cabriolet. There is extensive build information on the HAMB - you might want to check it out.

Link: https://www.youtube.com/watch?v=CyVLsPdbhS8

Also, keep each "tuned set" together - as you know they are sized correctly and work with a given rod bore.

Test Assembly: You should be able to put a set of bearings on a crank rod throw, put a single rod on the throw, torque to spec and be able to easily rotate the bearings by hand around the throw. (without assembly lube - this is a 'test' only). This shows that a bearing set is not binding on the crank rod journal or the rod housing bore . . . or the fillets of the crank. Again, it should be easy and smooth to do this rotation by hand . . . if it isn't, then there is an issue that needs to be addressed.

Final Assembly: I deliberately put in all the pistons/rods on one side of the engine first - with liberal amounts of high-quality assembly lube on both sides of the bearings. (I use Redline - has worked very well on all our Bonneville and comp engines). The reason I do one side first and not both rods on the same journal is that I make sure that once again I can easily grab the rod bearings (as there is only one rod on a journal) and rotate them. I also, grab the rods and slide them back and forth (as there is play inside the piston pin area - side to side). The rods should easily slide back and forth and the bearings should be able to be easily turned by hand. This is my final check - helps me know that the clearances are good (even though I can only do this when one rod is installed . . . but I already checked the rest before assembly anyway).

I like to run about .002 to .0025 of total clearance on my rods (my engines tend to be full-race stuff, regardless of where they are driven!) - as I believe that "loose is good - tight is definitely not!".

Lastly . . . I tend to have 5 or 6 sets of bearings to work with. I've frequently found that some were just too tight, so I used the 5 or 6 sets to find the best 4 that I wanted to work with.

Hope this helps . . .

[Mark's 37]

Bored&Stroked

Thanks for making the effort to explain fitting these floating bearings. I have found information is a little scarce and varied as to what is the best way to set them up. I decided to make this part of my build a continuous thread here while I stumble through it in order to get some good advice as well as possibly provide a source of info for others. When I come to a problem like setting up floater bearings and struggle to get it right I just have to butt heads with it, make the mistakes, and push on until it works. I could find a shop that could do all this for a price but being a 78 year old engine I would rather do it myself and know it was done right. Your Youtube video was one of the first things I found and have watched it many times while doing this.

I started by attempting to mic the outside OD’s of the bearing halves at the ends and compare them to the rod bore diameter. Then put the two bearing halves together and measuring the diameter across 90 degrees from where they join together. Then using a plastic soft head hammer to narrow the ends or tapping the tops of the bearings leaving an acceptable bore to bearing clearance Again using the outside micrometer I could not get the two measurements the same. Always egg shaped in the bore one way or the other. I have also tried measuring the ID of the bearing with the dial bore gauge but not really helpful. I found this video on Youtube helpful in rod bore measuring.

https://www.youtube.com/watch?v=SuO6qvtQR_8

The micrometers and dial bore gauge I have are from Summit and clearly not the industry standard for sure. After many hours futzing with it I realized it was getting me nowhere. Measurements are too subjective and I am not a machinist with a seasoned “feel” for doing them. Having several sets of rod bearings doesn’t fit my wallet though but I have a second set of Genuine Ford Parts bearings coming next week. That will help.

As of last night, I have managed to get one bearing near fitted. Using the hammer to adjust the widths and polishing with 800 grit paper and lacquer thinner on the bearing surfaces and the rod bore I am pretty close. I set the bearing half in a vice lined with pieces of particle board tight enough to hold the bearing sides stationary but hopefully not enough to crush them. Cut some 12” strips of 800 3M wet/dry sandpaper the width of the bearing and wrapping the strips around the bearing sanding with a push/pull motion. I also went over the rod bore surfaces with 400 grit to clean them up then polished with the 800 grit. With it installed and torqued on the rod journal the rod moves freely over the bearing. It is still a little tight when I grasp the bearing and move it on the crank though so more polishing to do.

A couple questions.

Is placing the bearing half with ends down on sandpaper (800grit) on a flat surface (flywheel) to polish and remove some material to gain clearance a good idea?

How do you arrive at the bearing clearance measurement? I was considering putting plastigage on both sides of the bearing in several places and torquing them down but figured it would be more confusing than reliable.

[flatjack9]

The big end ID of the rod needs to be done in a rod hone machine to be sure it is of proper size and totally round. Don't see any way of doing this at home in a vise.

[Binx]

1. Resized rods to original spec 360 degrees.

2. Undersize crank journals/pins to next 10K spec.

3. Measure, adjust and fit new bearing with "X" clearance.

Note: If rods and crank are machined correctly, bearings will be the variable. They'll have to be measured carefully as such using precision round stock like a roller bearing needle:

https://www.google.com/search?q=meas...MC1A2qR_a0M%3A

4. The proper diameter of the bearings will need to be adjusted to slip fit both the crank and the rod.

In summary, if the round things (crank and rods) are round and the bearings are suitable size for oil clearance, then we're good.

Lonnie

[Fordors]

Originally Posted by Binx

1.


Note: If rods and crank are machined correctly, bearings will be the variable. They'll have to be measured carefully as such using precision round stock like a roller bearing needle:


Lonnie

Starrett has ball anvils available that snap on your micrometer. The .200 balls are made for .235 and .270 diameter spindles, so they may not snap on all mic's. Put it on, take reading, subtract diameter of ball.

[JWL]

I don't recall seeing a bearing situation where the ends of the halves butt together preventing proper fitment. However, if that happens it will be ok to remove material at the split. Gently.

It can take some time and much fiddling to get a perfect fit. Trying to bend or form anything to within less than .001 is not easy.

[Bored&Stroked]

Originally Posted by Mark's 37

A couple questions.

A) Is placing the bearing half with ends down on sandpaper (800grit) on a flat surface (flywheel) to polish and remove some material to gain clearance a good idea?

B) How do you arrive at the bearing clearance measurement? I was considering putting plastigage on both sides of the bearing in several places and torquing them down but figured it would be more confusing than reliable.

A) I always just gently polish the ends and make sure there are no burrs or other small pieces of bearing material on them. I've never had to remove material in this area. Typically the first problem is making sure the shells are concentric, then polishing them with Scotch-Brite. Sometimes, one just needs a few extra bearings to find ones that fit better - just the way it is.

B) How To Measure: The first big challenge is that you really do need a set of high quality 0-1", 1"-2" and 2"-3" outside mics - I have both Starrett and Lufkin mics. These are costly, but something you'll use forever. Also, you need a precision dial bore gauge - one with 3 points on it - these are very expensive (like a $1000 each - yikes).

Yes - some guys can measure with a telescoping bore mic, but it is difficult to accurately measure (and trust the measurements) with a 2 point bore mic. (I don't use these types of mics for this type of work).

Or: Have the rods checked at a machine shop that DOES have the precision dial bore gauges - so you know the exact dimensions. This is what I do on the rods - I have the larger one needed for the mains.

Calibration: Even with good quality mics, you have to know they are calibrated. I have Starrett calibration rings/rods that I use. You can't afford to be off, even by one thousandth.

General Procedure:

1) Bearing Shell Thickness: I usually use a piston pin on the ID of the bearing shell to measure the thickness. Once done, you subtract the pin diameter from the reading:

MicTheBearingThickness copy.jpg

2) Crank Journal Diameter: You'll measure the rod journal diameter with an OD mic.

3) Rod - ID of the Big End: As noted above, usually a precision 3-point bore mic is used.

4) Simple Math: Take the reading from the crank journal, add twice the bearing shell thickness and subtract this sum from the ID of the rod . . . this is your clearance.

5) Plasti-Gauge: You can validate with plasti-gauge, but this is just a general validation (ball park). In my opinion, it is impossible to get accurate measurements with it - especially with floater bearings. I typically use it on the main bearings as a cross-validation, nothing more.

You're doing a great job in learning the details of all of this - many folks just don't know what they're doing with clearances, or don't have the tools and experience to do the work. I mic everything in my engines - as every machine shop makes mistakes . . . if I'm assembling the engine, the final checks on clearances are up to me.

Full-floater rod bearings are a bit of a pain in the rear, but they work extremely well when setup correctly. Keep after it!

B&S

[Mark's 37]

The second set of rod bearings just came today. They are OEM Ford Cadmium bearings part #48-6211-Q .030". I quickly cleaned one up to measure and they are the correct diameter to fit the standard rod ID once cleaned up and made concentric. The copper/bronze(?) bearings I have been struggling with are too wide and when made concentric will not fit the rod bore. The copper/bronze bearings look very similar to what is on Speedway's online catalog.

[Bored&Stroked]

Great news! My guess is that the ones you had were oversize on their OD . . . for a rod that was honed to a larger size --> like .002, .004, etc..

Keep us posted on the build - glad you got past your roadblock and didn't just throw it together!

B&S