Crankshaft Main Bearing Cap Needed

F

Flathead 1930

Junior Member
Yesterday was a bad luck day! I had purchased a 1950 Mercury Flathead engine that was to have only 500 + or - miles on it after rebuild. The engine came in a 1931 Ford project car. I removed the oil pan for cleaning, painting and was in the process of replacing the gaskets. I did not like the looks of the upper rear main gasket and decided to loosen the main bearing caps and replace. When I got to the center bearing one of the bolts were broken and the cap was also broken. I am very lucky I removed the pan and checked the internals. I have been searching for a new center main cap with no luck. The casting identification is: 7RA-6339. What would be a good source to secure this cap? The next problem is to remove the broken bolt from the block. I will have the engine machine shop line bore the block and bearing caps and I hope he can remove the broken bolt.
Thanks for any help or advise!
Ray

To view the 1931 Ford and click on the hot rod picture
www.rayscorvette.com
 
Flathead 1930, I think I'd go into that motor a little further to figure out "whys" instead of the "whats". Personally, I couldn't sleep at night until I knew "why".

Lonnie
 
Hi Ray, I would think with all the "bad" blocks around the country it should be real easy to get a few caps to try.

Couple "tips":

Check the torque on the main fasteners, check the "webbing" above the center main where the main threads are located for any cracks (look very closely), and lastly, you really need to check the "balance" on the rotating ***'y!

Would also inspect cap and block at parting line for any "chatter" marks(detonation, pinging, etc).

We now use studded mains in almost all the Flathead builds, keep numerous sets on hand from ARP.

Could be likely the torque was not correct and the bolt worked itself out or the fasteners are just N.G anymore?

Thanks, Gary in N.Y.

P.S. "Happy Holidays" to everyone here!
 
Re: Crankshaft Main Bearing Cap Needed
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Everything on the block, crankshaft and bearings seems to be fine except I need to get the broken bolt out of the block. The break in the cap has the same color or shade uniformly on both halves. I expect the problem was bolt failure. I believe that the bolts are original and when inspecting the broken section of the bolt one area is dark in color/shade and the other half or section seem to have a fresh look that is lighter in color/shade. I am planning on taking the block and parts to an engine builder that I have used in the past. I plan to have him clean and inspect the block, line bore after (I have secured the center bearing cap) and then balance the engine. Thanks for all the help and Happy Holidays to everyone!

Ray
 
All those 8BA center caps are all the same, the bolt holes are in the center of the cap, the front cap has an off set to the bolt holes. BUT, each cap is made for it's own engine and should be line bore to fit another engine. BUT, some caps are pretty close and people have got by with just putting them on. A guy had that same trouble last summer with a 59AB engine, broke the center main cap and bolt. I gave him a couple of caps and bolts, he put one on and platic gauged it .002 clearance and the engine turned good and it running fine. I'll go up in my storage barn tommrow and dig out a cap and bolts. Walt
 
You guys are GREAT! I should have three or four center caps in the mail. Hopefully one will match up and we can get the flathead back together and move on to another part of the hotrod project. I have contacted the engine machine shop that has done all my engine work in the past and will be taking it to his shop as soon as the bearing caps arrive.
If you would like to see the broken bolt and cap, please click on the link below and scroll to the bottom of the page: www.rayscorvette.com

Merry Christmas to all!

Ray
 
You should be able to drill the broken bolt by brazing or welding the old cap & use it as a guide to drill the bolt.You could slip a piece of tube that just fits the hole in the cap & fits drill size you need. Use a straight tapered E-Z out as they work better than the cork screw type.
 
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Quick up-date on the main bearing cap. First, thanks to all that have helped with providing me with great information and the center bearing caps needed. I met with the machinist today and he stated that the thrid cap he tried was "Perfect" no machining needed. He also stated that there was no damage to the block and the crankshaft looked great and balanced. Now for the bad news. One of the camshaft bearings was not installed correctly and had some damage and the cam seemed to be a Ford cam that had been reground. He has recommended that I replace the camshaft. I now need to determine what would be the best cam shaft for my driving style and application. The 1930 Coupe has a 1967 Ford Toploader transmission with a wide ratio connected to a 1970 Ford positraction 8" with 3.55 gears. The engine is a 1950 Mercury with the 4" crankshaft, aluminum 400 Offenhauser heads and an Edlebrock three-deuce set up.

Question 1. What would be the recommend camshaft for street use and a good sound or lope?
Question 2. What would be a good rear tire size? I believe that the wide ratio transmission may cause problems when starting out in first gear.

Thanks again for all the help!
Ray
 
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The 77B is a good cam, but not much differant than a stock one, for the same price you could get a Max#1. I always recommend the L-100 and that would run the A just right.
 
Is that toploader a 4 speed or a 3 speed? If 4, then the wide ratio transmission has a 2.78 First Gear Ratio. That will be fine with a 3.55 rear axle ratio. I don't know anything about the 3 speed stuff
 
Ray
The same thing happened to me on my merc flathead, was lucky enough to find a perfect match main cap that worked. I installed a main cap support from Speedway for a little extra insurance.
 
I Finlay got the 1950 Mercury flathead back from the engine shop! Thanks to everyone that has provided me with help and the main bearing caps! I now have a good selection of main caps, (complete set and center caps) if anyone is in need of caps for the price of shipping, I only ask that the caps you do not use get passed on to another person in need; email me at: ray63@rochester.rr.com

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rebuilt%201950%20merc.jpg

You guys are GREAT!
Ray
 
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