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SAE cam timing

General engine tech -- Drag Racing to Circle Track

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Ken_Parkman
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SAE cam timing

Post by Ken_Parkman » Sun Mar 22, 2020 11:25 am

I have of all things a 62 Willys Tornado OHC engine and I have discovered there are 2 different stock cams. I'm trying to reconcile the factory cam timing specs and they do not match what I am measuring. I am assuming the specs should be per some SAE standard. I realize it is not that important, but it's a character flaw on trying to figure things out.

What would be the standard for measuring factory duration on this thing? It is a solid design with a theoretical 1.5 rocker on an OHC.

Thanks

Walter R. Malik
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Re: SAE cam timing

Post by Walter R. Malik » Sun Mar 22, 2020 11:35 am

Ken_Parkman wrote:
Sun Mar 22, 2020 11:25 am
I have of all things a 62 Willys Tornado OHC engine and I have discovered there are 2 different stock cams. I'm trying to reconcile the factory cam timing specs and they do not match what I am measuring. I am assuming the specs should be per some SAE standard. I realize it is not that important, but it's a character flaw on trying to figure things out.

What would be the standard for measuring factory duration on this thing? It is a solid design with a theoretical 1.5 rocker on an OHC.

Thanks
Most solid lifter O.E.M. cams are S.A.E. rated at the recommended valve lash or some are rated at .010".
Most hydraulics are S.A.E. rated at .004" on the closing side and .006" on the opening side; (or the other way around, I can't remember).
http://www.rmcompetition.com
Specialty engine building at its finest.

Geoff2
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Re: SAE cam timing

Post by Geoff2 » Mon Mar 23, 2020 5:25 am

Pontiac OEM cams from 1965, from a reputable source. Measured at 0.002"valve lift on the opening side & 0.008-9" on the closing side.

If you can work out how this combination was arrived at, you could probably invent the vaccine for corona virus....

Bottom line: just measure it with a degree wheel.

dannobee
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Re: SAE cam timing

Post by dannobee » Mon Mar 23, 2020 11:09 am

The SAE spec is measuring duration at 0.006" lift.

Schurkey
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Re: SAE cam timing

Post by Schurkey » Sat Mar 28, 2020 4:18 pm

Ken_Parkman wrote:
Sun Mar 22, 2020 11:25 am
I have of all things a 62 Willys Tornado OHC engine
Is that the engine where a single cam lobe operates the intake and the exhaust valve?

Ken_Parkman
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Re: SAE cam timing

Post by Ken_Parkman » Sun Mar 29, 2020 8:45 am

Yep, it's that one. The equivalent of the LSA is built into the rocker geometry, and works out to 104.5*.

Thanks for the suggestions guys. I have measured this thing every way from upside down and cannot get close to the factory valve timing specifications. It really does not matter, this is a stock restoration, I just like wasting time figuring things out.

BTW I found 2 factory cams; the early one is bigger and measures 207* @ .050", and the later one measures 183*.

The other thing is the rather impressive flow. This thing is a SOHC hemi, and I got 240 cfm with a little clean up. Not bad for 1962 with a 1.89" valve. Of course the 4 3/8" stroke might not like the rpm to make use of that flow!

Kevin Johnson
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Re: SAE cam timing

Post by Kevin Johnson » Sun Mar 29, 2020 6:11 pm

I would guess that there are significantly more than two cam patterns. You might try to find enthusiasts in Argentina with more detailed information. I think a lot would depend on the known history of the motor that you possess.

hoodeng
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Re: SAE cam timing

Post by hoodeng » Sun Mar 29, 2020 6:51 pm

Many years ago when Formula Ford took off over here [early 70"s] i lived across the road from the main open wheeler manufacturer here.

I recall a conversation at the time about the cams for the spec Kent engine not quite having design lift on them, what was discovered was that a number of the cam castings tended to be under size in the lobe area so they were ground with what fit on the stick so to speak.

I have no doubt there was a lot more to the story than the bit i heard, but that engine put out considerably more power when assembled by a skilled engine builder.

Cheers.

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Re: SAE cam timing

Post by SchmidtMotorWorks » Sun Mar 29, 2020 8:16 pm

Anyone have a picture of this valve-train?
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Schurkey
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Re: SAE cam timing

Post by Schurkey » Sun Mar 29, 2020 8:21 pm

https://www.jalopyjournal.com/forum/thr ... ne.999157/
It's larger on the JalopyJournal site than it is here.

Image

Ken_Parkman
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Re: SAE cam timing

Post by Ken_Parkman » Sun Mar 29, 2020 10:33 pm

I *think* these cams are stock, but certainly it cannot be guaranteed from the early 60's. I did uncover the service bulletin where they put bigger springs and a smaller cam in late 62. The early ones had cam and rocker problems. I found the bigger springs interesting, maybe they were being rpm'd a bunch more then the old flatheads were!

They love those things in Argentina. There were a lot of running changes, and in 73 they made a big one going to a 7 main crank and a 12 lobe cam. I've searched a lot of Argentinean YouTube and found several claiming somewhat unbelievable HP numbers with turbo versions, but I did find one guy running 9.70s in a Torino, which is an Argentinean version of a 64 Rambler American. That one does seem to be making a bunch of power.

The basic engine originated as a Graham flathead in 1935. Interesting that Graham supercharged them. They did the OHC conversion in 62 as the first mass produced North American OHC. The basic engine was still in production in 1982, at that point owned by Renault.

There was a LOT of trouble with the OHC Tornado here in North America and they flopped, gone in 65. No matter, the engine is so cool, and has the best looking factory valve cover ever - but I am biased.

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