SD220 Timing Help Needed

I've been running my newly rebuilt SD220 around with timing based on ear. I know this isn't the way to do it but I've really been struggling getting what should be a good reading.

What is the initial timing these engines generally like?

Whether the end of the vacuum line at carb is connected or pulled off and plugged it always reads the same. Seems like there may be an issue here?

It wants to run best at a reading of 24 advance. This obviously seems way too high. If I back it down to 18ish, it wants to backfire A LOT when I drive it down the road. 18-20 it backfires rarely. Over that and it doesn't backfire at all.

Possibly there's something wrong with the distributor vacuum and initial timing is actually lower than 24?

When I rev it timing does go up.

Guidance please.

http://www.binderplanet.com/forums/inde ... 20.132821/
I hope this helps.
There is a difference between the manifold vacuum and the carburetor venturi vacuum. I do not remember which is called for, in your application. I have had Diesel engines in my Binders for many years, so I have forgotten. CB89 remembers everything.

Somethings not rite, I assume your distributor is installed with the vacuum advance working. With the engine off, can you turn the distributor by hand some. Does the vacuum advance move when spinning the engine. Do you have a timing light? Can you see the timing marks on the bell housing at top dead center. Disconnect the vacuum line, when timing. Initial timing at 400 rpms, if you can idle it that low and set at 4 or 6 degree BTDC should work fine if every thing else is set rite. Hope this helps.
See what's up let me know,
EDIT Where is your vacuum line coming from. Any pics would help.

Who put the distributer in, you or the machine shop. Is it possible it was installed one tooth off? Same goes for the timing gears. I've seen either one off by a tooth and the motor still runs but the timing is way off the mark to compensate for it. I've also seen this in V8's with badly stretched timing chains.

Since I brought this truck home, I haven't touched the pointer. It is still stuck in place with gunk and is set a few degrees retarded. I should free this up.

Embarrassingly I think this is also an issue. I had snapped the original distributor bolt with the spring. I obviously didn't understand how all that worked and didn't have a replacement so I threw in a normal bolt I had laying around. Now I'm realizing the bolt was probably supposed to be left loose with the spring applying a little pressure but this allowed the distributor to move slightly by hand or when it does/doesn't need vacuum. Is that correct? At this point the original screw/spring have been disposed of so I will need to find a spring suitable for this. Possibly this is why my timing doesn't change at all whether vacuum is hooked up or plugged. I have it locked in place?

Yes I have a timing light and can see the timing marks on the bell housing and flywheel.

Vacuum line goes from distributor to base of carburetor.

Machine shop put the distributor in and I believe from I remember he said it did not have teeth, it had a "keyway". Pretty sure I didn't dream that up.

The distributor won't be a tooth off. It's either right or 180 degrees off. You would know if that was the case. If you have the distributor locked down, the vacuum advance won't work, and that sounds like a good part of your problem. You need parts 10 - 13.

If your timing is actually advanced up in the 20's that may be contributing to the hard starting problem you have been having. I had that with a hard starting tractor one time. Just a thought
Dennis

The distributor won't be a tooth off. It's either right or 180 degrees off. You would know if that was the case. If you have the distributor locked down, the vacuum advance won't work, and that sounds like a good part of your problem. You need parts 10 - 13.

Vacuum Advance.jpg

I disagree, I have purposely set them one tooth off on a V8 to compensate for a stretched timing chain in a Jeep I had until I could replace the timing set. Yes you can get them 180' out of phase and have them look right but as you said this results in an engine that won't run.

The difference between a V8 and the six is that the V8 has the gear on the distributor shaft. The 6 doesn't. It's driven by a tang on the oil pump. So it's either right, or 180 off.
I suppose the cam could be installed one tooth off from the crank, but that would also throw valve timing off.

Actually you can stab the dist in anywhere, and as long as you put the wires in the right order, and set it to fire #1 When #1 is on Compression, it will work. It doesn't need to be stabbed an any particular place, esp where the vacuum advance move the whole dist and will not get fouled on the block if you have to turn it.
The spaces on the cap, and breaker point cam are evenly spaced.