5 Bearing Cam Block

CA Victoria

CA Victoria

Well-known member
Opened up a spare motor today. The serial number had been changed during a rebuild in the 50s so I did not know what year it was.

It has 5 cam bearings. Researched the topic on Plucks sight and found the changes to the ford blocks to be quite interesting, and that this is a 28 block.
I've hear a couple folks say these blocks are better for the race circuit to reduce cam whip.

Was the change from 5/3 a cost savings idea by ford ?

any thoughts on this block vs another to build for a touring motor?
 
Your 5 cam bearing 1928 engine is good as far as cam bearings, but later blocks had more reinforcing on the rear main, as well as other small changes as time went on.
 
George Riley wrote in 1931, "do not use the early block". They are weaker in the rear main area. If building for performance, use the latest block that you can get. Cam whip is minor unless you go to an extreme regrind, and use lots of spring pressure. If so, you can add supports.
 
The five cam bearing blocks that I have seen and owned, the extra two cam bearing journals did not make contact with the bearing surfaces in the block. I can see no advantage or reason for their presence.
 
Purdy Swoft said:
The five cam bearing blocks that I have seen and owned, the extra two cam bearing journals did not make contact with the bearing surfaces in the block. I can see no advantage or reason for their presence.
Click to expand...

I also have an engine like that. When Ford decided to quit the 5 bearing cam, they used up the 5 bearing blocks, but cut the 2 unused bearings smaller on the cam. This didn't make sense to me because if you already have the bearings, why not use them.
 
Eliminating the 2 intermediate cam journals was a cost saving move by Ford.
You definetly don't need them for any street driven engine.
For racing, you definetly need the added support.
Few if any have ever looked at the cam with a strobe when running in a test fixture with racing valve springs. 110 lb on the seat and a radius lifter cam.
Without the added support bearings the cam moves all over the place.

Here is a pic of the cam with the 404A grind on it I ran in my last B engine.
That cam was made from a stock B cam core.
That engine is now owned by a guy that won the Antique Nationals a couple times in the 4 banger dragster class.
 

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There are 3 different early A cams, the first had all 5 bearings ground to the same size and fit the block, then came the cam with 5 finished ground bearings but the 2 intermediate were undersize to make it easier to install in the 3-bearing block, followed by one with rough-turned intermediate journals. When all of these were used up they started using the 3 bearing shaft. As Pete says, it was a cost-saving step. I use 130 pounds on the seat on my OHV Cook, the rocker arms add to cam stress so I have installed 2 added supports.
 
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