Super M camshaft into M block

[MT Matt]

Any problems with this?  Same cams?  I have a 1940 M in the shop for what I’m assuming is a failed keyway because the timing mark is off about a 1/4 turn when at TDC.  I was pulling a big hill and it started to spit and sputter, then died.  Found the timing mark to be way off after that.  

I have a parts SM motor to rob from. I have a M&W live pump to add to the M so I want to change the distributor gear to the Super M gear. Since the front cover will be off to investigate, might as well get this done. 

[560Dennis]

Interesting post , tell us what you find out . 
 

[rustred]

3 hours ago, MT Matt said:

Any problems with this?  Same cams?  I have a 1940 M in the shop for what I’m assuming is a failed keyway because the timing mark is off about a 1/4 turn when at TDC.  I was pulling a big hill and it started to spit and sputter, then died.  Found the timing mark to be way off after that.  

I have a parts SM motor to rob from. I have a M&W live pump to add to the M so I want to change the distributor gear to the Super M gear. Since the front cover will be off to investigate, might as well get this done. 

i dont see how the timing mark can be 1/4 turn out when the stroke is at top dead centre. there is no vibration dampener on the front pulley to slip . how are you checking for the piston at tdc ?  get the timing marks lined up at tdc on compression then check to see if the rotor is pointing to #1 cylinder . if its out of whack then you have a cam timing problem , such as a sheared key or more.

[chadd]

I put a 450 cam into my 1951 M block.  There were no issues with this.  The lengths and cam journal diameters are all the same.  The lift and duration are different.  I didn't do it for the performance increase; I did it because I added a live hydraulic pump and the 450 cam when used in combination with a thicker webbed 450 cam (6760DB) gear with a tighter fit, and the reverse hand threads makes the setup much more reliable.

I agree with rustred.  Not sure how the timing mark could be way off, unless you mean you were checking distributor timing with a timing light or looking at distributor rotor position relative to the cap and had to cheat the crank position by 1/4 turn.  Depending on how many times someone was in there and what parts were put in the motor, the distributor advance kit may have been changed, but that should just be an additional mark (or two) on the crank pulley to check timing against.

[MT Matt]

2 hours ago, rustred said:

i dont see how the timing mark can be 1/4 turn out when the stroke is at top dead centre. there is no vibration dampener on the front pulley to slip . how are you checking for the piston at tdc ?  get the timing marks lined up at tdc on compression then check to see if the rotor is pointing to #1 cylinder . if its out of whack then you have a cam timing problem , such as a sheared key or more.

Probably didn’t describe it properly. I’m assuming I have a keyway sheared like I said.  The timing of the magneto isn’t jiving with the pointer/mark on the crank pulley. I wasn’t asking about how to time it. Just can the camshafts be swapped?  I already know I need to pull the front cover off to find out why  the timing is off. 

[rustred]

43 minutes ago, MT Matt said:

Probably didn’t describe it properly. I’m assuming I have a keyway sheared like I said.  The timing of the magneto isn’t jiving with the pointer/mark on the crank pulley. I wasn’t asking about how to time it. Just can the camshafts be swapped?  I already know I need to pull the front cover off to find out why  the timing is off. 

if your asking if the super gear and cam will work replacing  the 1940 cam,... yes.  i gave that procedure so u can actually see where the rotor is pointing once the marks are lined up.  why pull a front cover without knowing for sure.

[farmalldr]

Couldn't the timing issue be within the magneto?  Just asking.

[rustred]

4 minutes ago, farmalldr said:

Couldn't the timing issue be within the magneto?  Just asking.

it could, he said it was running and stopped. i would be checking the mag first also.  he did not say how far the rotor is off either. number one cylinder wire sits at around the 2  oclock   position on cap , factory position.

[MT Matt]

The magneto is fine, pulled it off and put it on another tractor.  I’ve done the trouble shooting to determine that it needs to be opened up. I didn’t describe all of the trouble shooting because I wasn’t asking about that.  Just giving a little context. I also need to open it up to change the gear for the live pump.

Since I have the cam from the Super M, I’ll be able to swap them out if needed and not wait for other parts to show up. That’s the information I was looking for. Looks like I can do that. Thank you. 👍🏻

[DWV]

Original SM and SMTA were same as M. But after IH started putting left hand thread camshafts in C-281 engines with revised valve timing they became the replacement part for M through 450. C-264 in 400 tractors and part of the C-281 engines used the same spec but with right hand threads for cam gear retaining. One IH bulletin suggested installing the Later cams at rebuild for a extra 1 to 1.5 HP.

[MT Matt]

2 minutes ago, DWV said:

Original SM and SMTA were same as M. But after IH started putting left hand thread camshafts in C-281 engines with revised valve timing they became the replacement part for M through 450. C-264 in 400 tractors and part of the C-281 engines used the same spec but with right hand threads for cam gear retaining. One IH bulletin suggested installing the Later cams at rebuild for an extra 1 to 1.5 HP.

Thank you, that’s what I was looking for!