How To: Ford CMP "Blitz" miscellany

[Tony Smith]

Originally Posted by Jacques Reed

Good Day,

I just received the prototype engine and transmission data plate from the laser engraver and I am very happy with the results. I liaised closely with him to make it as close to original as possible.
Cheers,

I made some of these up a few years back: http://www.mapleleafup.net/forums/showthread.php?t=4818

I noted at the time that there is a variation in spark plug gap .025 and .030 on different plates. Never got a response on why the difference.

[Jacques Reed]

Originally Posted by Tony Smith

I made some of these up a few years back: http://www.mapleleafup.net/forums/showthread.php?t=4818

I noted at the time that there is a variation in spark plug gap .025 and .030 on different plates. Never got a response on why the difference.

Tony,

I found in the attached pages from the British War Department "Special Pattern Vehicles" Two types of spark plugs are specified. Champion J-9 and Champion H-10 both with different 0.025" and 0.030" gaps respectively.

It also appears that at some time the plug type was changed in the parts lists.
Both a 1940 parts list and a 1943 parts list show part No. 52-12405 C as the earlier part and 01T 12405 a later part to be supplied when 52-12405 C is depleted. 01T 12405 is also specified in the 1943 parts list as a Champion #H-9.

"J" plugs have a 3/8" reach with the 0.025" gap
"H" plugs have a 7/16" reach with the 0.030" gap

Not sure why but for some reason they changed the type of spark plug to be used.

Cheers,

[Jacques Reed]

Good Day,

Recently I was asked by a fellow restorer for the dimensions of the splash plate in front of the battery on a Cab 13.

In the course of drawing it up I noticed two variations of the same plate.

One has a rectangular opening to clear the running board support adaptor and the other a 45 degree opening to clear it.
The first one also has a semi circular hole at the chassis rail and the other has the plate pressed out at that location.

I am sure both are original. the one with the semi circular hole came from a an early 1943 cab and the one with the pressing came from a late 44 built vehicle.
A design change for some reason? I could not find any reference to the part in an F-15A Parts List. Not in the running boards, battery, cab, or miscellaneous sections. If anyone can point me in the right place please let me know.

Have posted the drawing here of the earlier one which may be of use to someone. They do go missing, as I found out with my first truck.
Hope this is of some interest.

Cheers,

[David Herbert]

The changes are I think just driven by better production practice.

The punch that makes the hole with the 45 degree step will last longer than the original design, require a bit less force and reduce the need to clamp the plate to avoid distortion.

The pressed bit in the top left corner will require less force than the punched notch and support the extreme top left corner of the plate much better. Again the tooling will last longer.

It is possible that there was more than one source of this piece so it could be that one factory was better at production engineering than the other rather than an evolution thing.

David

[Jacques Reed]

Hi David,

Very good points from a manufacturing perspective. Sharp corners in openings are always to be avoided for stress concentration so I can see why the 45 degree cut was used instead of the 90 degree corner at that position.

I know which one would be easier to replicate unless one has a 20 tonne press!

Cheers,

[Mike Cecil]

I would suggest that all the holes were punched at once with a double-action press: first action clamps the plate flat in the die, second punches all the holes in one action. The die set for the earlier plate with the notched half-round opening along the top edge would be easier to manufacture than the die set with a forming punch to force the bulged shape in that location.



In any event, punching 1/8th MS plate would need to have the plate clamped to avoid distortion and to ensure the plate strips from the punches as the die set's punches are withdrawn. I also suspect each plate was dipped in a drawing/cutting compound prior to placing into the die.


I suppose the other question is the country of origin: Canadian or Australian manufacture? Both from the same country, or one from each?



Mike

[Jacques Reed]

Originally Posted by Mike Cecil

I suppose the other question is the country of origin: Canadian or Australian manufacture? Both from the same country, or one from each?

Mike

Hi Mike,

Both plates came off Australian assembled vehicles. Both seem to have never been touched before I removed them. Still, 75 years of paint, mud, and gunk can hide a lot of things.

The other question to ask is what is the purpose of the hole/pressing on the two plates?

From the photo it appears the only reason is to clear the front running board support adaptor bolt. The pressed one actually touches the adaptor at the pressing so was it a secondary reason to perhaps stop the splash plate from vibrating? I guess only the original designers know.

Cheers,