Cam degreeing problems

[Beck]

I have a cam that's way off from where I want it installed. I'm using an OEM cam in a "back up" motor. In my "primary" motor I had a cam reground. I provided a "cam doctor" sheet from the OEM cam to the regrind company and ask where I should dial that one in at. Either they aren't the brightest or Mercruiser really missed the mark in the cam or timing set. The factory cam with factory timing set has the #1 intake centerline at 116 deg. I want to put it in at 108 to 109 degrees.  That means I need to move it 7 to 8 deg. An offset key will give me 2 deg. A new timing set with the 3 crank keys will give me 2 deg more. That still lets me 3 to 4 deg off.

The only way I can see to get this dialed in is to broach a new keyway in my original crank sprocket. If I move it about a half a tooth I should get 8 deg. There are 22 teeth in my crank sprocket, so one tooth is about 16 deg.

Anyone have a better idea?

[enjenjo]

I think broaching a new key way is your only sensible choice. You should be able to have it done fairly cheaply, that is a common key size.

[wayne petty]

what would happen if you installed the offset keyway in the cam end..  that would double the offset of the offset keyway on your cam timing.

i forgot if you have the 2.5 or 3.0 MM motors.

[chimp koose]

I had a farmer once tell me he was going to put longer push rods in his big block to get more lift . Maybe I could get him to come over and take a link out of your timing chain .  

[chimp koose]

Seriously though , is this a sprocket that could be mounted on backwards ? It is likely not broached exactly on the center of one tooth so mounting it backwards if possible may help or make the situation worse . You wont know until you try . I had a machinist racer friend who was into Karting big time with spec. Honda engines . I asked him once how you would cheat these motors . He shows me a long bar with 3 cam sprockets welded on it to grip the one on the cam by meshing teeth . With a degree wheel mounted to the bar you could advance or retard the pressed on cam gear an exact amount of degrees and look bone stock . In your case broaching a new key is probably the best answer .

[Beck]

Sorry for the delay in response. I didn't see a notification that anyone had replied.

Wayne, The cam end has a key but also has a 3 bolt mounting system. Moving the bolt holes would be tough.

chimp koose, The crank sprocket cannot be mounted backwards on this one. It uses a BBF sprocket.

I have decided to have another keyway broached. Unfortunately when I retired those tools became unavailable to me. I will need to hire it done. The crank is 1 3/8" The key is 3/16". The broach sets are set up to cut a 1/4" key for that size shaft. I will need to make an insert to accept the 3/16" cutter.