timing

G

gayle marlowe

Member
38 sedan at high altitude. I want to advance the timing as others have suggested but don't know if I have to take the distributor off to do it or can I adjust the vacuum break to advance it? I have been recommended to advance it 3-4 degrees. How do you measure 3-4 degrees additional advance. Looked on VanPelt site but no instructions other than standard settings.
Thanks
 
On the side fo the distributor, near the top, on the driver's side, find a sliding plate with marks on it lining up with a mark on the distributor case. A small bolt with a screw slot holds it in place. Loosen the bolt. To advance the timing, tap the plate upwards by two marks; each division represents two degrees, so that would be 4 degrees. Tighten the bolt down.

Road test to see if you get any pinging on a hill, or accelerating briskly. If so, back off one division (two degrees).

The vacuum brake is only there to slow down the increase of spark advance during acceleration (low vacuum). It does not affect the spark advance once you are at a steady rpm. With the much better quality of today's fuels, that feature is generally not necessary. Some say you can back off the brake completely; others say keep a light pressure on the brake to stabilize the breaker plate. Probably best to not mess with that now.
 
You have the crab distributor I think you previously mentioned?

Pic for reference.

460511


How it was explained too me:
When you look at the sliding advance index on the side of the distributor, the center mark should be APPROXIMATELY top dead center ... but only a rough guide. This means you can advance and retard the spark. In an absolutely perfect world, it would end up 3 marks down from the top ... but, various things affect this adjustment such as your point gap.
 

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My timing started out quite retarded when my distributor returned from rebuild. I’m sure the rebuilder doesn’t have the bench timer. The engine simply had no get up and go. I gradually increased the advance one mark at a time until it ran like it used to. I tested for power by climbing a hill I used to tackle without downshifting until I could do it after the rebuild. I think the setting is now three marks below the middle, runs good and with no ping.
 
Thanks guys. Now I know which direction to move it. And because of the nicely done paint job on the engine, I could not see the little hash mark on the body of the distributor that Will D shows. I will scrap that area to find the hash mark and start my advance. Hopefully it unleashes Many extra horses!!!
 
You should be able to remove the bolt and plate with hash marks completely to clean it up, then reinstall. The internals will stay in place and shouldn't move as there is resistance on them. Then you don't mark up that beautiful engine:D
 
Well, I took the distributor off (with much effort as it is not easy to get to)
and checked the timing and the points. Found one set of points that needed touch up and the other set okay. Used Van Pelts method of timing the crab distributor with a little more advance, put it back in and would not start. Moved the timing marks back to the midpoint where the factory setting is and it starts but will not run except at high rpm. Moved it back again (retard?) and it still will not run at low rpm or idle. Will run at higher rpm.
So, am going to yank it out again and see what I did wrong. Was running okay, but wanted to take the advice of advancing for high altitude. Guess I should have left it alone!!!
Hopefully I will have better results this next time. If you all have suggestions, let me know.
 
Those are very strange symptoms. More like carburetion than timing. But first: Set the timing at full retard and see if it will idle. If not, then see if it will start and idle at full advance. If either of those extremes make a difference, the send the distributor to be set up by a pro. If neither helps much, reset the timing to one mark advance and look elsewhere. Like big vacuum leak, or carb idle circuit bad, or float sinking, etc.
 
Don't know what I did the first time?????
Took the distributor back out, went thru the Van Pelt timing method, put it back in, and VIOLA, it starts and runs fine. Now for a road test to see if I gained all those big horseponies I was hoping to get with all this effort!!!!!!
 
Bench setup for timing is a great starting point, but different engine, fuel and environment circumstances suggest fine tuning "by ear". That is, advance the spark adjustment a bit at a time until you get a ping on a hill or accelerating in second gear, then back off one mark.
 
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