63 Corvette Mystery Motor
- Thread starter oldskydog
- Start date
Ok guys, I need some help for those that have some Mystery Motor info stuffed away.
We have been in the process of rebuilding the engine. In the process we were looking at the cam and checking all parts, heads, block etc. The guy that is doing the engine rebalancing, etc, noticed something usual about the camshaft when he put it on the table.
What he noticed was the MM cam has a completely different cam lobe positioning for the standard firing order. We put an NOS Z-11 Eonic cam I have beside it for comparison.
Take a look and see how radically different they are.
Now, we have not yet determined the firing order, but will, meanwhile for this cam to operate properly it cannot be done with the crank the engine was made with, the 0- Z-11 crank. I have 2 of those cranks and brought one over to make sure they were the same and they are. Back to the cam, it is impossible for this cam to work with the correct crank.
I have called Rusty Symmes and John Mounce and neither have ever heard of a cam like this.
In full disclosure, this cam was installed at a rebuild sometime in the 1980's and was never run, possible it was just put in with no thought if it was correct or not.
My opinion is it was an experimental cam Chevy made, had the cam blank made with the cam lobes in these locations and then ground, no telling where a corresponding crank would be.
Meanwhile, here are a few photos so you can compare. The MM cam is on the right. Thanks for any info.
P.S. I'm going to call Bill Howell, the engineer that was primary under Dick Keinath the Chief Engineer on the project, he and I talked for about an hour 8 months ago. Hopefully he might remember if they made such a cam/crank combination.
I guess that's why they call it a Mystery Motor
We have been in the process of rebuilding the engine. In the process we were looking at the cam and checking all parts, heads, block etc. The guy that is doing the engine rebalancing, etc, noticed something usual about the camshaft when he put it on the table.
What he noticed was the MM cam has a completely different cam lobe positioning for the standard firing order. We put an NOS Z-11 Eonic cam I have beside it for comparison.
Take a look and see how radically different they are.
Now, we have not yet determined the firing order, but will, meanwhile for this cam to operate properly it cannot be done with the crank the engine was made with, the 0- Z-11 crank. I have 2 of those cranks and brought one over to make sure they were the same and they are. Back to the cam, it is impossible for this cam to work with the correct crank.
I have called Rusty Symmes and John Mounce and neither have ever heard of a cam like this.
In full disclosure, this cam was installed at a rebuild sometime in the 1980's and was never run, possible it was just put in with no thought if it was correct or not.
My opinion is it was an experimental cam Chevy made, had the cam blank made with the cam lobes in these locations and then ground, no telling where a corresponding crank would be.
Meanwhile, here are a few photos so you can compare. The MM cam is on the right. Thanks for any info.
P.S. I'm going to call Bill Howell, the engineer that was primary under Dick Keinath the Chief Engineer on the project, he and I talked for about an hour 8 months ago. Hopefully he might remember if they made such a cam/crank combination.
I guess that's why they call it a Mystery Motor
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Pat,
I'm amazed with: number one,..... all the incredibly rare and unique items you have in the stable. Number two, is your ability to ferret out pieces of Chevrolet history that is all but forgotten. I'm looking forward to following this and all your other great and rare Chevrolet projects.
Dennis...
I'm amazed with: number one,..... all the incredibly rare and unique items you have in the stable. Number two, is your ability to ferret out pieces of Chevrolet history that is all but forgotten. I'm looking forward to following this and all your other great and rare Chevrolet projects.
Dennis...
OK, let me share my brilliance(not). Working with 409's and not big block engines as much, it is incredibly obvious that on a 409 the valve positions are Intake, Exhaust, Exhaust, Intake, etc. big block and MM engines are Intake, Exhaust, Intake, Exhaust, etc.
a real DUH moment. Still more info to come as we get this thing together.
a real DUH moment. Still more info to come as we get this thing together.
Ok, here is the latest cam info on the mystery motor.
I have 2 of the "0" cams and I have no idea which one to use, both look fine. I called Rusty and discussed with him. He said somewhere in the back of his mind he remembers Crane had made one but could not remember details. He is using one of the original cams. So, I picked up the phone and called Crane. After talking to lots of real nice people, none of which knew anything about what I was talking about, "what's a Mystery Motor" sent me to the "gray haired" guy Allen. I left a message for him.
Very promptly the next day he calls to discuss my story. After sharing all of it, he slightly laughed and said yes they did a cam, but it was so long ago and after all their trials and tribulations, computer system changes, etc, that they would not have retained anything. We talked more, about cams, heat treating, etc. I hung up the phone and began thinking about what to do next.
Next day Allen calls back. He says guess what?, I was walking by our tech guys and mentioned our conversation, he said all of a sudden one of the "gray haired" tech guys said, "oh, I have that file right here, I printed the profile sheet and kept it because I thought it was so cool"...that was 2004!
Seems the project was the Junior Johnson, Holley Farms NASCAR car that was being restored!
Allen also told me he found a blank shaft, a that was made and not ground for that project and they would be glad to make a cam.!!!! WHAAATTT ARE THE ODDS!!!
Below is what I clipped from his email to me yesterday:
"We will build you an mechanical roller camshaft from an 8620 steel billet “round lobe” cam core. (The original flat tappet “cast iron” camshaft core for this engine no longer exist.) We will have to grind the lobes and journals to match your special interim engine between a 409 and a 396 Chevy designs.
Our records show that the GM Mystery cam wasn’t a slouch for its day. Advertised duration was around 284° / 292°, with the duration @ .050” tappet lift at 250° / 253°, the lobe lift were in the .320” range +/- .002”, which would bring the valve lift to around .560” with a 1.75:1 rocker arm ratio. The power range would be estimated to be 3800 to 7000 RPM in its original racing form. We can figure out the details as what profile you will require, this isn’t a problem, it’s all custom made anyway."
Very exciting to fine this cam core.
Now, I told him since I am the camshaft genius that I am, I would feel better if I sent you the cams, I have to just make sure.
One thing he instructed me to do was ship it securely and insured!
He told me of instances where cams were sent in the cardboard tubes only to arrive broken in half. So, we are making a wooden crate to hold the tubes with the cams.
On the pistons, we have measured each hole and have sent pistons and measurements along with the combustion chamber info to Ross and they are about 6 weeks out, but that's fine.
That's all for now, thanks for listening. Getting closer!!!
I have 2 of the "0" cams and I have no idea which one to use, both look fine. I called Rusty and discussed with him. He said somewhere in the back of his mind he remembers Crane had made one but could not remember details. He is using one of the original cams. So, I picked up the phone and called Crane. After talking to lots of real nice people, none of which knew anything about what I was talking about, "what's a Mystery Motor" sent me to the "gray haired" guy Allen. I left a message for him.
Very promptly the next day he calls to discuss my story. After sharing all of it, he slightly laughed and said yes they did a cam, but it was so long ago and after all their trials and tribulations, computer system changes, etc, that they would not have retained anything. We talked more, about cams, heat treating, etc. I hung up the phone and began thinking about what to do next.
Next day Allen calls back. He says guess what?, I was walking by our tech guys and mentioned our conversation, he said all of a sudden one of the "gray haired" tech guys said, "oh, I have that file right here, I printed the profile sheet and kept it because I thought it was so cool"...that was 2004!
Seems the project was the Junior Johnson, Holley Farms NASCAR car that was being restored!
Allen also told me he found a blank shaft, a that was made and not ground for that project and they would be glad to make a cam.!!!! WHAAATTT ARE THE ODDS!!!
Below is what I clipped from his email to me yesterday:
"We will build you an mechanical roller camshaft from an 8620 steel billet “round lobe” cam core. (The original flat tappet “cast iron” camshaft core for this engine no longer exist.) We will have to grind the lobes and journals to match your special interim engine between a 409 and a 396 Chevy designs.
Our records show that the GM Mystery cam wasn’t a slouch for its day. Advertised duration was around 284° / 292°, with the duration @ .050” tappet lift at 250° / 253°, the lobe lift were in the .320” range +/- .002”, which would bring the valve lift to around .560” with a 1.75:1 rocker arm ratio. The power range would be estimated to be 3800 to 7000 RPM in its original racing form. We can figure out the details as what profile you will require, this isn’t a problem, it’s all custom made anyway."
Very exciting to fine this cam core.
Now, I told him since I am the camshaft genius that I am
, I would feel better if I sent you the cams, I have to just make sure. One thing he instructed me to do was ship it securely and insured!
He told me of instances where cams were sent in the cardboard tubes only to arrive broken in half. So, we are making a wooden crate to hold the tubes with the cams.
On the pistons, we have measured each hole and have sent pistons and measurements along with the combustion chamber info to Ross and they are about 6 weeks out, but that's fine.
That's all for now, thanks for listening. Getting closer!!!
So cool thanks for sharing with us Pat...........
Amazing what happens when you find the right old gray haired guy.
Cool stuff Pat.
Cool stuff Pat.
Guess I need to remove and repackage a certain item I have!!!!!!!!!!!!!!!!!!
I was gonna suggest we meet in Oklahoma City for dinner...................but..........if I'm travelling that far..........I'd just come on down to see the additions to your collections!!!!!!!!!!!!
