Severe Use Cams

Park_W

Can anyone tell me the difference between the "severe use" cam, 311040, and the 7X cam, 309742?

Unknown

Park:

The 309742 (7X flat top cam) had a lift of .355" and a duration of 258 degrees. This became a "standard equipment" cam in '54 and one of the reasons the horsepower jumped to 170 that year.
The 311040 (Super 7X cam) had a lift of .390" and a duration of 268 degrees. This raised the hp to 180 assuming Twin-H & High-Comp (7.5:1) head.

Goin' racing?

Tim in WI.

Park_W

Tim ... thanks for the info. I had come across a '742 cam and was noting the two different listings in the parts book. If you're correct, the listings in the book are sure puzzling. In the engine section it shows the 306344A cam for the '54s, and the Severe Use section listings would lead one to think the 311040 was the one that evolved into the std cam in '54, and the 309742 was the "real" 7X." Chalk up another one for whoever works to make parts books confusing!

Unknown

Park:

The '54 Hudsons first came out with the 309742 cam. It was replaced in April of '54 with the 306344A cam but I don't know of any changes in the cam specs. The change in cam part numbers might have been done simply because the original '51-'53 cam was the 306344 and the new cam ("A") would have logically been the next series of standard cams. Possibly the part number was also changed to avoid confusion from the 7x cam designation. Maybe somebody else can clear this up for us.
The 311040 cam first came out in the Fall of '53 and was designated as a/the "Severe Usage" cam. All this info is from my old Clifford Performance stuff. Hope this helps and have a Happy 4th!

Tim in WI.

Unknown

Park...

The following URL will produce a Hudson Service Bulletin S-553 that came out 2-9-54. The Bulletin answers the question you asked.

Hudson Severe Usage Camshaft Bulletin S-553


Cheers and Happy 4th of July....

Ken Cates
aka: Heart O Texas

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Park_W

Thanks Tim and Ken for the add'l info. My "742" cam mikes at .365 lift vs. .340 for the 644A, and the 742 definitely has a "broader" nose, so is likely greater duration. Perhaps Hudson found the 742 just a little hot for production '54s, so switched to the toned down 644A.

Unknown

I ran across the change in numbers for the 54's with my current car. It is a very early 54 Hornet. At 40,000 miles it locked up the cam and ruined the timing chain. I casually mentioned this problem to Bob Kerchner who told me that the first 54 cams were recalled as they tended to lock up in the berrings. He thought it was due to the increased profile which caused a bit of a flex under load. But what ever the reason, they replaced the cam with the ..A suffix number. This eliminated the problem .

EssexAdv

Hmm... I lost my icon... Hopefully it is back now