I successfully set timing (I think)!

[benji808]

Timing has been a mystery to me for some time - didn't understand it, and didn't know how to measure or adjust it. Decided to try and learn - got a light off of amazon, watched some youtube videos, and read through my shop manual. It ended up being pretty simple! Hardest part was actually getting to the distributor bolt, but eventually I settled on a swivel/hinge socket attachment that worked nicely.

I let the engine warm up, plugged the vacuum advance, and set her right at 6 above TDC per the shop manual (she appeared to be almost right at TDC...I think the previous person who set it may have done it without unhooking the vacuum advance). Seems to be running better now, so that is exciting!

Wanted to share. Open to any thoughts or critique you folks may have.

Thanks!

[TJ Hopland]

Did you try revving it to see if the mechanical advance is working? 

Now that you have the timing light you need a hand vacuum pump to test the vacuum advance.  If you get one like this you can do all sorts of other automotive projects too.



https://www.harborfreight.com/brake-bleeder-and-vacuum-pump-kit-63391.html

[The Tassie Devil(le)]

Congratulations Ben,

Isn't it great when stuff turns out to be simpler than first thought?

If the Vacuum was attached to the Advance Diaphragm, then you would have been reading an advance of in the vicinity of 24 Degrees.

Bruce.

[benji808]

Actually got the air pump a few weeks ago and have learned a lot poking it around places. Great tip!

[Big Fins]

Set the base timing to 8-10^o BTDC and you get even more pep and smoothness out of it. After reconnecting the vacuum advance, you should reset the idle mixture screws and base idle on the carb. 

Using a RPM meter to set you mixture screws is the best way, unless you have a really good ear for tones. The flexible screwdriver fitted with a 1/4" older Craftsman socket works best. There are also n assortment of distributor wrenches for various engines in 1/2" and 9/16' sizes.

If you need pix, let me know.

[TJ Hopland]

More base could hurt if the vacuum advance has been replaced with one that has way too much range in it which is pretty common.  That could be a reason it was set to zero, it was pinging and someone kept backing it up till it quit. I see that a lot and it really kills the performance. That is why I was suggesting the vacuum pump.  Shop manual will have all the advance specs at various vacuum settings and rpms so you can make sure things are in the proper range.

If your timing light isn't the 'dial back' type you will have to make some temporary marks on the pulley to see the higher timing numbers.  To figure out the scale required measure the existing gauge.  IF say 0-10 is 3/4" of an inch you then make your first new mark 3/4" from the original one and another 3/4" from that.  You then read it the same but add 10 for each new mark so if the first new mark is at 5 on the scale you are at 15 if it was the 2nd you would be at 25.  I'm making up that 3/4" and 10, you have to go by what ever your existing gauge measures. 

[35-709]

Excellent point about the replacement vacuum advances.  Put an adjustable one on my '71 472 and could not get rid of the ping no matter where I adjusted it, and of course the vacuum advance timing was way over what it should have been.  In frustration, I backed out the little adjusting screw in the vacuum port all the way until I felt it disengage.  THEN I put my timing light on it and the vacuum advance worked almost perfectly to the 472 specs.

[benji808]

Yeah... she seems to be "over running" a bit and I'm getting some pinging, so I guess I will back it back down. Any recommendations on how to do it scientifically, or just experiment?

[The Tassie Devil(le)]

The "over-running" is what is called Dieseling, so the Idling needs to be dropped down a bit, and make sure that the Anti-dieseling solenoid is correctly adjusted.

The pinging is just because of the poorer octane rated fuels available now, and this can be corrected by decreasing the Advance till it is no longer there.

Once the timing is correct, check the actual timing with the timing light, and note what the reading is for future reference.

Bruce.