Z-11 and Mystery Motor Camshafts

[Blk61409]

I’ve been thinking about sharing this info and figured now is a good time.

I put the original EONIC electric pencil scribed camshaft out of Dick Harrell’s Z-11 engine beside an “0” MM camshaft that came out of Smokey’s shop and was in my engine.

Anyway, what’s shocking is just how different the cam lobe positioning, and width is! The Z-11 has the wider lobes.

The Z-11 cam is on the left, ignore the first cam lobe, it was damaged and is rounded considerably.

I knew how different the lifter hole positioning in the MM was just by looking at it, but this side by side is incredible!

 

[Blk61409]

Cam marked 3837736 is the Z-11 cam.

 

[Phil Reed]

Where did you get that Z-11 cam Pat???

 

[Blk61409]

Oh, that old thing.

Someone north of here was using it to pry wheels off of axles on a junky 62 Corvette

Ok, full disclosure, Phil was kind enough to give it to me.

Thank you Phil.
Its actually the only real 1 of 50 Z-11 camshafts that came in the original engines I have ever seen.

Chevrolet contracted with EONIC Machine shop to grind this cam. There were only 50 made and installed in the Z-11 engines.

I got it the first time out of Dick Harrell’s engine about 50 years ago or so.

 

[Phil Reed]

Oh......I didn't know that!!!!!!!

 

[409envy]

I’m glad this thread was started because I have been looking for “exact” cam specifics for an actual Z11 cam. The cams reproduced today that call themselves Z11 cams aren’t actually the same specifications.

From some period literature I’ve read the original cam was .565/565 lift and 325 degrees of advertised duration. Can anyone provide me with the duration at .050” lift, the lobe seperation angle and the intake centerline?

also looking for the numbers for intake opening and closing events and exhaust opening and closing events ie, before & after top dead center/ before & after bottom dead center

 

[Phalen409]

I’m glad this thread was started because I have been looking for “exact” cam specifics for an actual Z11 cam. The cams reproduced today that call themselves Z11 cams aren’t actually the same specifications.

From some period literature I’ve read the original cam was .565/565 lift and 325 degrees of advertised duration. Can anyone provide me with the duration at .050” lift, the lobe seperation angle and the intake centerline?

also looking for the numbers for intake opening and closing events and exhaust opening and closing events ie, before & after top dead center/ before & after bottom dead center

WHAT??.......way above my pay grade!!

 

[Blk61409]

I’m glad this thread was started because I have been looking for “exact” cam specifics for an actual Z11 cam. The cams reproduced today that call themselves Z11 cams aren’t actually the same specifications.

From some period literature I’ve read the original cam was .565/565 lift and 325 degrees of advertised duration. Can anyone provide me with the duration at .050” lift, the lobe seperation angle and the intake centerline?

also looking for the numbers for intake opening and closing events and exhaust opening and closing events ie, before & after top dead center/ before & after bottom dead center

I will get my yard stick and check it out.

I will take the original cam to an engine builder friend of mine and get all the actual specifications.
More later

 

[63impalass409]

Here is the cam I have in 2 of my 409's one is running and sounds awesome other still in progress. I got it from show cars and told them I wanted a Z11 equivalent

 

[Blk61409]

I have a Comp Z-11 cam in the Colbert car. This will be a good exercise to see if what everyone is selling/using is really the same.
EONIC Cam Co made cams for lots of Mfgrs.
They made the cams for the Ford 427 SOHC

 

[409envy]

Hold the press... I just checked Rustys book and found it in the AMA specifications. I’m not sure when each event happens in the four stroke cycle but I’m sure a cam expert would know. Pretty standard for 8 cylinder four stroke engines I would imagine.

this was a BIG cam with a lot of overlap and duration. I think this was typical for the time period given the constraints of cylinder head and combustion chamber technology.

Timing:

Intake-
Opens @ 50* 46’ 40”
Closes @ 94* 46’ 40”
Duration advertised 325* 33’ 20”

exhaust-
Opens @ 97* 46’ 40”
Closes @ 47* 46’ 20”
Duration advertised 325* 33’ 20”

valve overlap 98* 33’ 20”

lift at zero lash (theoretical)
Intake: .5566”
Exhaust: .5566”

 

[Blk61409]

Great catch! AMA data is what Chevy submitted to them. I think I will check it anyway. I’ve always heard the cam in the engines were different than the over the counter ones. A good way to check

 

[1964SuperStocker]

Hold the press... I just checked Rustys book and found it in the AMA specifications. I’m not sure when each event happens in the four stroke cycle but I’m sure a cam expert would know. Pretty standard for 8 cylinder four stroke engines I would imagine.

this was a BIG cam with a lot of overlap and duration. I think this was typical for the time period given the constraints of cylinder head and combustion chamber technology.

Timing:

Intake-
Opens @ 50* 46’ 40”
Closes @ 94* 46’ 40”
Duration advertised 325* 33’ 20”

exhaust-
Opens @ 97* 46’ 40”
Closes @ 47* 46’ 20”
Duration advertised 325* 33’ 20”

valve overlap 98* 33’ 20”

lift at zero lash (theoretical)
Intake: .5566”
Exhaust: .5566”

Pretty wicked but I guess I don't know how that would compare to a modern race cam.

 

[Don Jacks]

Put one on a degree wheel and check the .050 numbers.These old cams had a long clearance ramps that ate a lot of that large adv.duration and overlap just going by the numbers.For your power numbers,these old tech.numbers are useless for any kind of comparison,it'd going to be the numbers at ..050 that are the most telling.

 

[Phil Reed]

Pat....when you take the cam in to be checked.....are you gonna take your own yard stick so it could be verified also??????
Asking for a friend!!!!

 

[Blk61409]

I got this!!

Nothin’s going to get by me

 

[Tooth]

Nice Pat! Now if I only had one of those 62 Corvette pry your wheel off bars I’d be set too

 

[Blk61409]

Perfect for Precision!!

 

[Tooth]

Phil, since I’m not on your Christmas list anymore can you put me on the list for one of those Corvette wheel prying bars too!
Just like the one you gave Pat? I have the measuring tool, perfect for precision Pat says!Even the correct year...

 

[Phil Reed]

You realize that was once in a life time deal, don't you John!!!!!!!
Pat and I both knew the dealer who sold it to me. He told me he wanted a lot of money for it. When he told me....I couldn't write the check fast enough!!! Think I sent it Next Day Air!!!!!
That's all I'm sayin'!!!!!!!!