1965 gt350R model Camshaft

[68countrysedan]

Per the Shelby American Performance Catalog - August 1966

GT 350 Racing Camshaft Kit

Specifications: (Figures reflect actual valve movements, not cam lobe readings. Timing is measured at the valve with .001" lift.)

Intake opens 29 degrees BTDC

Intake closes 75 degrees ABDC

Intake duration 284 degrees

Exhaust opens 75 degrees BBDC

Exhaust closes 29 degrees ATDC

Exhaust duration 284 degrees

Valve lift .445"

Intake tappet clearance (hot) 0.018"

Exhaust tappet clearance (hot) 0.020"

Part number: S1CR-6250-2

Shipping Weight: 14 lbs.

[gt350hr]

  Those specifications always puzzled me. The cam is smaller than the original K code cam. This may have been one made for a 260 which did not have valve reliefs in the piston and that would limit duration and lift to eliminate valve contact. By my calculations that cam would not need a valve relief. The lobe profile might be the original 390 Police Interceptor lobe design Ford used.

[68countrysedan]

Those specifications always puzzled me. The cam is smaller than the original K code cam. This may have been one made for a 260 which did not have valve reliefs in the piston and that would limit duration and lift to eliminate valve contact. By my calculations that cam would not need a valve relief. The lobe profile might be the original 390 Police Interceptor lobe design Ford used.

Interesting. I am also wondering if the original cams in the limited production GT350R were "limited" production Engle cams. Since the catalog listing is a year later, cam specs may have been revised because the cams would be used in a wider selection of Windsor engines.

FWIW Catalog discription includes:  "The grind is particularly suitable for use with a hi-riser manifold (#S1MK-9423-A) and the 715 C.F.M carburetor (#S1MK-9510-A) from Shelby-American."

"USED ON: 221, 260 and 289 CID engines. . . . ."

[SeanSide]

Randy you are right. I noticed the lift is lower on the S1CR-6250-D at .445" vs the .478" on the C30Z-6250-C. It seems a  document i found talking about the S1CR cam has a paragraph about a description based on "a customer" upgrading his "base trim" 289, and suggesting that customer to upgrade to the cobra hi-rise manifold (S1MK-9423-A) and 715cfm carb (S1MK-9510-A).

Could it be, that shelby had a batch of "Engle cams .445"" ready to install just before the advent of the K-code cars (planed from years of knowledge and experience racing the 289 cobras and such), and when they got the the K-code engine, they didn't use the Engle cams because the K-code camshaft and piston combination ended up being a better design than anticipated, allowing more lift? And they sold the S1CR over the counter to customers as "performance upgrades"

[SeanSide]

In other words:
- What do you think is the camshaft in Ken Miles' prototype GT350R mustang?

https://www.mecum.com/lots/SC0520-414695/1965-shelby-gt350r-prototype/

https://youtu.be/xNI22OocHLE

Indoor:
https://youtu.be/4r7qwFeDLMc

C3OZ K-code cam to compare:
https://youtu.be/PyrTi1pUz_E

(ignore the straight pipe sound and it seems similar when comparing the indoor and c30z videos, but i might be crazy)

[trotrof1]

 R Model, side exhaust, big valve heads, SA equipped mods, compared to stock K Code. Yes sir, very different animals.

[gt350hr]

    To my knowledge the only man still alive from the SAI engine shop is Ryan Falconer in AZ. He "might" remember what they put in the engines. I'm positive different ones were  used during the year (65) in an effort to make more power. "I" do not believe any R Model engine had the C3OZ-C cam OR the .445 lift cam from my experience.

[shelbydoug]

    To my knowledge the only man still alive from the SAI engine shop is Ryan Falconer in AZ. He "might" remember what they put in the engines. I'm positive different ones were  used during the year (65) in an effort to make more power. "I" do not believe any R Model engine had the C3OZ-C cam OR the .445 lift cam from my experience.

I still see Falconer & Dunn Boss 302 Weber intakes advertised that he said they never made.

[gt350hr]

  That is why I said might.

[SeanSide]

I emailed Ryan Falconer and he replied "sorry i do not remember".

[98SVT - was 06GT]

The lobe profile might be the original 390 Police Interceptor lobe design Ford used.

A friend worked at a cam regrinder in LA. I've still got a 289 cam he put the Dontov 30-30 cam profile on. He made a lot of them and installed them in cheap shortblocks he sold to Mustang guys (yeah same guy who later had the Chinese knock off parts for his ebay biz).

[Helmantel]

One issue with the specs for these old mechanical lifter cams is that you never know how they measured them and what lash they took into account. For the Hipo cam for example, I've seen durations of both 310 and 290 degrees and ~.470" lift (lobe lift x 1.6, probably) and ~.450" lift (actual valve lift)

[gt350hr]

     There is a very noticeable difference if you plot (or cam doctor)the two cams and overlay them. The .445 cam has less duration than a C3OZ-C cam , besides the lower lift. The .445 lift cam was almost certainly for a 260 engine that did not have valve reliefs in the piston. New information has possibly linked it to a Potvin camshaft but the jury is still out.