Timing

[Willie dog]

Next dumb question.  How do you check ignition timing on a 401? 

I noticed there is an opening in the bellhousing above the starter that looks suspiciously like a place to check? How about the specs for the timing?

As the dog said when the train ran over it's tail, "won't be long now". 

[h67st]

I have no idea how to check the timing on a Mack engine, but I was talking to an older mechanic in Oklahoma one time and he said to watch the fan blades spinning as you turn the distributor. If they appear to spin smoothly your timing is real close, but if they look erratic then it's off. I've never tried this so he may have been full of it.

[Freightrain]

Sounds fishy to me.  I understand the principle of seeing the blades flash and if they are steady it is running smooth(steady rpm).   But what does that really have to do with timing?  An engine will run smooth if the timing is retarded or advance, to a point.  But it gives no actual true reading of what the timing is.

In the racing world, I've heard many a story of tuning a car by "sound".  Ya, okay.  Again, to a point, but it can still be really far off the number you really want and never know it.  Lots of bad things happen with too much timing.

[eddeere]

Do not know anything about this engine but look for marks on the harmonic balancer . Some older tractor engines had a window on the bell housing with marks on the flywheel . Hook up a timing light and see what shows up .

[HarryS]

Absent a shop manual I would manually turn the flywheel and watch the hole to see if timing marks show up. If and when then you can mark them so you can see them with the timing light. Having said all of that check first as Ed mentioned for a timing pointer and marks at the harmonic balancer.

[41chevy]

If that is the timing mark on the bell housing, be sure to set the point dwell first. Point settings effect timing. Also with todays crap gas you may end up getting the timing close with a light and fine tune it by road timing it to eliminate ping.   Paul

[Willie dog]

7 hours ago, HarryS said:

Absent a shop manual I would manually turn the flywheel and watch the hole to see if timing marks show up. If and when then you can mark them so you can see them with the timing light. Having said all of that check first as Ed mentioned for a timing pointer and marks at the harmonic balancer.

No marks on the balancer. That's what threw me off.  For the time being,  I have the distributor in between way retarded and way advanced to where it "sounds about right".

[j hancock]

I should be able to get the timing degree info for the gasser from a friend when he gets back from vacation. 

[mowerman]

i have a 1983 motor manuel....if jim doesnt come thru....im sure it covers it.....bob

[B-42]

Willie dog,

Don't know much about these things but check the shop manual I sent you...section 101-3 and section 302-2.  Hope this helps.

[Willie dog]

1 hour ago, B-42 said:

Willie dog,

Don't know much about these things but check the shop manual I sent you...section 101-3 and section 302-2.  Hope this helps.

Oh yeah.  When all else fails, check the manual. 😁

[609albert]

Quote

put in a electronic to replace the points etc. and it takes care of that

 

[j hancock]

On 8/3/2018 at 6:05 PM, Willie dog said:

Oh yeah.  When all else fails, check the manual. 😁

Friend's manual says 3 degrees BTC at the flywheel.