99A Assembly question --con rods.

B

bobscogin

Senior Member
I'm assembling a '42 Mercury 99A. The connecting rods are marked L1through L4, and R1 through R4. The rods do not have cam oiler squirt holes, and appear symmetrical in all respects, but Ford took the trouble to mark them for the left and right banks. What's the correct orientation of the marks? Thanks,

Bob
 
L should be for left bank and R would then be right bank. This would be viewed from front of the motor just like firing order and cylinders would be numbered from front to rear. Some times it relates to the piston installation as well as the oil squirts.

Someone else on this board should be able to varify this since I don't have the manuals for the late prewar engines. All I have is for 8CM types.

Kerby
 
These have floating bearings (I went through their setup a few weeks ago) The rods are symmetrical and can be installed anyway, but it's common practice to keep the numbers to the rail. As far the squirt holes are concerned the rod end play will squirt more oil on the cam and cylinders than necessary.
 
Thanks for the input. I've looked at the rods very closely, and it looks to me that the numbers could go facing in or out, and the rods could interchange from bank to bank. Curiosity drives me to want to know why they're numbered as they are and why. Logic would dictate that rods L1 and R1 goes on the first journal, L2 and R2 on the second journal, etc. but since they're symmetrical with no squirt holes I don't see how it could matter. Oh, Henry, what mysteries you've left us.

Bob
 
Ol' Ron said:
These have floating bearings (I went through their setup a few weeks ago) The rods are symmetrical and can be installed anyway, but it's common practice to keep the numbers to the rail. As far the squirt holes are concerned the rod end play will squirt more oil on the cam and cylinders than necessary.
Click to expand...

Thanks, Ron. Your comments confirm my observations. This is my first flathead build and I'd never seen rods numbered in pairs for each journal rather than by cylinder number. Could this have been because of the floating bearings? Maybe the big end I.D.s were matched in pairs by tolerance at the factory because a single floating bearing carried 2 rods.

Bob
 
Ol' Ron said:
These have floating bearings (I went through their setup a few weeks ago)
Click to expand...

Ron, any tips on the floating bearings for a flathead novice? My crank is standard and measured half thousandth to a thousand wear (low mileage fire truck). I'm using NOS Ford bearings from Joblot Automotive. Since the crank was not turned, and I'm using genuine Ford bearings, it should be a bolt up. I used a scraper to just lightly chamfer the mating edges of the bearing shells, then oiled them up good and installed the rods on the crank (on the workbench) in numbered pairs on the appropriate journals to check for binding or irregular feel. They felt smooth as silk when rotated around the journal so I guess I'm OK.

Bob
 
I outlined the method of setting up floating bearings several weeks ago on this forum. It's a mathematical problem.

I
don't have the numbers for the 99A in my head, but I do have the 21A:

The crank should be 1.998

The bearing is 110 thick X2=.220

Rod big end 2.220

All these are factory numbers.

I open the rod to 2.221 -2

Or find a .108-9 bearing.

I don't like original Ford bearings, because there are old and have a tendency to flake. The best bearings to use are USED bearings that check on size and havent flaked.
This is why we went to a full flow oil filter, to catch these flakes before they wrecked the crank. Very hi oil pressure was sand blasting the filet radius of the crank causing breakage. Racing will do that and it' How we learn.
All this is free knowledge, use it wisely. Remember your required to add to this someday.
Ron
 
I forgot, then you have to beat them round with a hammer.
And you wonder why they went to lock in bearings.
BTW the floating bearings were an aircraft design of the 20's
 
rotorwrench said:
L should be for left bank and R would then be right bank. This would be viewed from front of the motor just like firing order and cylinders would be numbered from front to rear. Some times it relates to the piston installation as well as the oil squirts.

Someone else on this board should be able to varify this since I don't have the manuals for the late prewar engines. All I have is for 8CM types.

Kerby
Click to expand...
Left and right are as viewed from the rear of the engine. Left is driver's side, right is passenger's side.
 
Ol' Ron said:
I forgot, then you have to beat them round with a hammer.
And you wonder why they went to lock in bearings.
BTW the floating bearings were an aircraft design of the 20's
Click to expand...

Going back to my previous post about trial fitting them to the crank (crank on the bench) -- After I installed / torqued them on the crank, I pounded the big ends with a hard rubber dead blow hammer. They rotated around the journals just fine before, but a little more easily after that.

Bob
 
Befor reinstalling the rods, torque them to spec and have them measured for out of round/ wear... Just like you did the crank, these are a wearing surface... Karl
 
The rods will go in any hole, but the cap must go on the rod it goes with, and on the rod right. So, it's alot simpler to have rod and cap no. R1 in no. one hole ect. You could have all no. 4 rods. rods in one engine but you must keep the right cap with the right rod. You should torque all the caps on there rods and have the large end bore checked with a dial bore guage. They usually all need recondition, there usually out of round because the bearing spins in the rod as well as the crank. Walt
 
flatjack9 said:
Left and right are as viewed from the rear of the engine. Left is driver's side, right is passenger's side.
Click to expand...

When you are numbering you go from the front of the motor. I made reference to "and just like firing order" for right and left and you usually have the motor upside down when you are installing pistons and rods anyway so you have to think about it.

Kerby
 
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