Diamond block details...

[Special Coupe Frank]

I thought it might be helpful to share some photos of detail features of a Diamond engine that I am working on.

First group of Photos are of markings on the block, cast and stamped.

Casting date code is for June 9, 1935.

Does anyone know the significance of the " 8 <> 5 " stamped above #4 Exhaust port ?

Also, is there any significance to the " X "stamped in the deck, above the water inlet ?

[Special Coupe Frank]

Next Group of photos, the Valves.

Note that there are valve seat inserts on the Exhaust valves.

[Jim Brierley]

All of the stampings were done later, probably by a rebuilder? Diamond blocks had hard-seats from the factory.

[Special Coupe Frank]

Jim,

Thanks for your reply... in reviewing Vince Falter's article and other threads about the diamond block, I was under the impression that the hardened seats were a production upgrade for later production, but I haven't found a date for the change yet?

I don't know the history of this block; boss above the water inlet bears the stamping:
RC 55086 'star', in the later Ford font, with a "vertical" 6.

It apparently did visit the machine shop at some point for new babbitt and crankwork: the Mains are .010 under and the Rods are .040 under.

The bores are still stock, with the factory Ford pistons, original Ford valves, etc.

Frank

[Tom Wesenberg]

My diamond block doesn't have separate valve seats. I don't recall the casting date.

[Synchro909]

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No hardened seats in my diamond block either. No idea of the munufactured date.

[colin1928]

I have seen at least 1/2 dozen diamond blocks of the years they all had valve seat inserts

[Ron in Quincy]

On the West Coast there were 2 Ford Plants that produced "Diamond Blocks"; the number stamped in the pad was RF**** = Richmond Ford and LB**** = Long Beach Ford.

These blocks were "New" with hard seats in the exhaust, new valves, pistons, and "A" crankshafts, and new "C" camshafts ; the lift on the intake lobes was .021 and the exhaust lobes were .029; a book I have says to set the clearance on the intake cold at .011 to .013 and the exhaust cold at .018 to .021; these cams were copper coated between the lobes. The last block I checked had a "C" cam that had even a higher lift on the lobes , I recall the exhaust was in the .030 plus range . I do not recall any other stampings except the raised diamond cast above the timing cover.

Ron

[Jim Brierley]

Ford made 3 Model B cams over the years. With .302" lobe lift, one with .315" lift and one with .335" lift

[Special Coupe Frank]

Does anyone know what the "RC" signifies ?

Originally Posted by forever4

There are also many "RC***" numbered diamond blocks.

Also, many diamond blocks do not have hardened seats. Mostly the later ones do.

Here are the correct cam specs for Model A and B camshafts:

Model A Ford Garage ~ Model A & B Camshaft Specifications
www.fordgarage.com/pages/camshaftspecs.htm

[CarlG]

My "diamond" block had hard seats both intake and exhaust. All evidence is that the hard seats were added during the last rebuild before I got the vehicle. And not very well, I might add, as the exhaust seats came loose on #3 & 4.

[Tom Wesenberg]

Originally Posted by CarlG

My "diamond" block had hard seats both intake and exhaust. All evidence is that the hard seats were added during the last rebuild before I got the vehicle. And not very well, I might add, as the exhaust seats came loose on #3 & 4.

That's why I always say don't install seats unless there is a real need for them. They should never come loose if installed correctly, but I've seen some come loose, and I've also seen factory seats come loose from aluminum heads. Of course with an aluminum head or block you have to install seats.