I am reinstalling my cam in my 312 supercharged engine It is a Laneti cam. it has two key slots when I degree it one is at 92 the other is 112 nether seems right but it ran strong 13s. I called Laneti they found specks on this cam and they say it should be at 103 I did not build this engine I am just freshen it up. Anyone have any idea as to why it was 112?

How you are checking it will have a lot to do with the result.  If you are checking in the usual way, installed in a block, with the timing set and crank, then you have multiple components which have manufacturing tolerances.  Those tolerances can stack up, resulting in a centerline that appears to be off when it's not quite that simple.  The cam could have been manufactured perfectly and everything else is throwing it off.  You almost never have the cam end up where it should because of that.  That is why there are adjustable timing sets.  And there is always the possibility that something was plain and simply manufactured incorrectly.

It is interesting that the keyways are almost 10 degrees off of the specification  in each direction.  Maybe it was special ordered that way to be able to advance or retard the cam for some reason.


Lawrenceville, GA

If you can't seem to get an acceptible setting, you might want to contact Mummert Machine in Calif.. I believe they sell adjustable sets made in Australia. 


Paul

More information would be helpful here.  Are your numbers based on intake lobe centerlines?  I’m assuming the two key slots are in the crank gear?  Regardless of the gear being used for the additional slot, then I would expect two dots on that gear to accommodate using the correct dot in conjunction with the appropriate slot for the chain link count.  A picture of the gears would be helpful.
 
As an alternative, it may be possible to go with 11 or 13 links from dot to dot and see where the numbers fall in at.  You may need to do this with both slot positions to see which one is the best fit.  I have in the past simply broached a new slot in the cam or crank gear to get the camshaft to degree in where it needed to be.  Because you have an additional slot, this may be what has happened with your particular setup somewhere in the past.
 
As Paul mentions, Rollmaster makes a timing set for the Y that has nine slots in the crank gear.  While one of those slots is the zero postion, four are for varying degrees of advance while the other four are for varying degrees of retard.  Here’s a picture of the Rollmaster crank gear for the Y and what the various slot positions are in relation to advance and retard.

 

Lorena, Texas (South of Waco)

Thanks

Thanks Ted I have install now used an off set key. Much closer to Laneti specs.my concern is that it ran well at 102 can you think of any reason it was set there? thanks.
  

Knowing what the ‘as ground’ lobe centers are would give an idea of the actual amount of advance or retard for the numbers you have posted which I would assume to be intake lobe centerline values.  Also knowing the duration at both 0.020” and 0.050” along with the static compression ratio would be beneficial as that's a player in where you might want to install the camshaft.  Being as this is in a supercharged street engine, it’s typically normal to have a camshaft ground lobe centers as small as 110° to retain some kind of low end torque when not in ‘boost’ mode.  Because the compression ratio is typically lower in a supercharged engine, then a given amount of cam advance would be necessary to give a shot in the arm to the low end torque numbers.  In a racing environment, the camshaft would be ground with upwards of 114° lobe centers or more to minimize blow through of the boost out the exhaust during the overlap cycle.
 
I have by design installed camshafts with as much as eight degrees advance in those applications that would benefit from that.  It’s not unusual to have to move a camshaft as much as 4° one direction or the other to get a significant change in performance.  Just doing 2° sometimes doesn’t pick up much change.  I’ve found drag race engines that were responsive to retarding the camshaft to make more power.  As a general rule, if having to advance the camshaft a bunch to improve the performance, the camshaft is too big.  Likewise, if having to retard the camshaft to get a gain in performance, then the camshaft is too small.

Lorena, Texas (South of Waco)

Thanks Ted this is a full time race Engine the was built in the late 60s for a bracket car it sat from 78 I got it going ran it for six passes got it home and freshen it up so maybe the 113 was right I will be dynoing it next week so I will see if it like the factory spec. if not I will put it back. Thanks again.