setting timing

garycroix · Post by **garycroix** » Sat Dec 13, 2008 11:04 am

I've set timing plenty of times, but it's been a long time since I've done it. 1969 F100, 360. Do I set the timing with the hose to the vacuum advance hooked up, or off? Also, if I set the timing with the hose off, should I plug the hose while I am adjusting the timing? The hose for the vacuum advance is above the throttle butterfly, if that matters.

Thanks.

fordman · Post by **fordman** » Sat Dec 13, 2008 11:44 am

the hose should be off and plugged. the postion of that hose isnt right. it should be on the bottom of the autolite carb. unless its some different kind of carb that has the connection on top for some reason.

garycroix · Post by **garycroix** » Sat Dec 13, 2008 11:54 am

It is an Autolite carb as far as I can tell. The port that I have going to the dist is right next to the throttle plate, maybe is is coming from under the butterfly, I don't know.
I set the timing with the vacuum hose connected. Starts great. When I increase the rpms ( no tach attached), by the time the throttle is about 1/2 way open, the engine is running crappy. If I pull off the hose at this point, the engine runs great. I drove it like this, but can only go to about 50 mph. I know I shouldn't do that, but it is my only car right now.
I'll try setting the timing to 10 degrees and plug the hose and see what happens. I'm beginning to think my dist is screwed up.

70shortwide · Post by **70shortwide** » Sat Dec 13, 2008 12:11 pm

youll need to pull the hose and plug it, then time it, then replace the hose. i wont run right with the hose disconnected. im sure you knew that, just figured id throw it out there

garycroix · Post by **garycroix** » Sat Dec 13, 2008 12:27 pm

It shouldn't run right with hose disconnected, but it sure seems to. I went out, plugged hose, set timing @10. Connected hose, started right up. Increased rpms to about 1/2 way throttle. Engine running crappy, engine shaking. Pulled hose, engine smoothed out.
I don't know what to think.
I just went out again. Watched timing mark as I increased rpms. With no hose, it advanced to about 18 BTDC and stopped, no matter the RPM. With hose, it did advance, but it eventually got above 20 BTDC and the igniton stopped (no light from timing light), immediately let off throttle and light came back...appears like it keeps advancing till the engine runs lousy..then will die.
Is it possble that I need to move the wires on the distributor over one hole? I don't want to think that, but I don't understand the cutting out/lousy running. Is it also possible that I need new springs on my vacuum advance? The distributor is original. I put a new diapragm on it, could it be overpowering any springs?

Thanks

garycroix · Post by **garycroix** » Sat Dec 13, 2008 1:12 pm

From the first reply, I understood that the vacuum for the advance should come from the intake side of the manifold. I decided to use the port for the transmission. Starte the engine, timed to 10 BTDC. As soon as I connected the vacuum, the timing was advanced off the charts and the engine died.

Now what?

garycroix · Post by **garycroix** » Sat Dec 13, 2008 2:29 pm

Here's what boggles my mind. Went out, set timing with no hose attached.
Went on a drive, drove truck pretty hard, laid rubber around a corner, no hesitation. Going 55, mashed gas, up to 80, no problem. Still no vacuum advance connected. Odd.

Using the vacuum port for the transmission was a disaster. Makes sense, because the vacuum pulls on the distributor plate to move points to advance timing. So if you set timing, put on vacuum from intake on distributor, that advances timing so much it dies. I was not able to get the engine to start with the vacuum from the intake attached. Blows my mind. No vacuum advance, truck runs fine, no hesitation ever, up to 80 mph no problem. Attach vacuum advance, runs like crap.

Post by **DuckRyder** » Sat Dec 13, 2008 3:49 pm

Is it running points?

Does the distributor have vacuum retard as well (does it have a hose to each side of the diaphragm)?

Is it possible that the wire to the points is grounding on the housing or losing continuity when the advance plate is moving?

Does the port that you have the vacuum advance hooked up to have vacuum only when the engine is raised above idle?

Are any temperature-vacuum switches left in the advance circuit?

fordman · Post by **fordman** » Sat Dec 13, 2008 3:52 pm

the hose hooks straight to the front hole on the bottom of the carb. dont hook it to the intake. and i dont have a pic either i thought i did. but i must have deleted it. what year is the carb?

Dragon · Post by **Dragon** » Sat Dec 13, 2008 5:52 pm

garycroix wrote:Attach vacuum advance, runs like crap.

Are you on the right vacuum port. If the initial is 12 and the dizzy gives you 20 and the vacuum advance gives you 20 you would have 52 and that only works on blown engines. Vacuum Advance drops off with throttle opening like wide open no advance. If you are on the wrong vacuum port the advance will be on all the time.

Any engine will run right with the vacuum advance disconnected. Just not timed right for cruising.

On a 2100 2V Autolite the Vacuum advance comes from under the Choke Front Edge passenger side.

You can tell an Autolite because they have a clock face on the driver's side of the float bowl. A stock 360 should say 1.21 in the center. That makes it a 350 cfm carb.

garycroix · Post by **garycroix** » Sat Dec 13, 2008 8:19 pm

Dragon, that's where my vacuum advance hose comes from...under the choke, front edge passenger side. I plugged this hose and set the timing, 10 degrees BTDC. Leave hose off the diaphragm. Truck starts great. Very Very slight hesitation just off idle, but other than that, it runs great. Going 55, stab the gas, you're going 80 with no problems. Cruising around? Fine. Turn it off and no dieseling, which tells me the timing is right. But if I hook up the vacuum from the carb, it will run like absolute crap if you increase the rpm. It acts like it gets too much advance when it is hooked up like that, and I don't know how that can be. I want to think that the plug wires are off one hole on the dist cap, but I'm setting the timing with my light attached to #1 plug wire and it runs fine.
Is is possible the port is slightly plugged perhaps? I have no vacuum from the port at idle, which makes me think the port is above the butterfly. Off idle, I have some vacuum and the engine runs like I said above if I hook up that line.
The clock face is on the front of the bowl, I'm sure that 1.21 is there but I didn't look for/see that.

I'm happy with the way the truck runs, I just don't understand why it is running, with no vacuum advance and all. Could the dist be screwed up?

Dragon · Post by **Dragon** » Sat Dec 13, 2008 9:15 pm

You have it off and plugged it is alright. How about if the hose is on and plugged. But here comes the kicker get a new vacuum advance unit the diaphragm is torn. Rare but it happens. That is why they are available to this day.

http://www.partsamerica.com/productdeta ... 09&PTSet=A

You don't have vacuum advance at an idle. It comes in once the throttle plate reaches about 10% and goes away when engine vacuum drops below 8 inches of Mercury.

garycroix · Post by **garycroix** » Sat Dec 13, 2008 9:56 pm

Nope, not torn diapragm. I took off dist cap and sucked on the hose and watched the timing plate moving back and forth. Even took off the diaphragm to look at it. It is only about three months old. I agree with thinking that the diaphragm was the culprit; it would explain the lousy operation at increased rpm. 'Hose off and plugged,' what do you mean? Hose off of dist and plug the vacuum port coming from the carb? I can try that. But as is, I am driving the truck with the carb vacuum port open to atmosphere, no connection to the dist, and she starts and drives great. I just don't understand it.

garycroix · Post by **garycroix** » Sun Dec 14, 2008 12:25 am

Only one diaphragm on dizzy, only one vacuum connection on the diaphragm. I can't post pictures currently, but I would if I could.

When I'm going about 80 I can hear a little bit of backfiring/hesitation, but that must be in the high RPM range where the mechanical advance isn't enough.
I haven't capped off the port on the carb, it must be sucking air all the time, but I can tell no difference in operation, though you would think I would.

I read on this site's tech data to use 10 degrees BTDC, and that's what I've used, yes I have a timing light. I've held the light while sucking on the hose..it does advance, but I haven't measured how much it moves.

Dragon, read this article I found on Ford distributors/mechanical advance/timing and let me know what you think:
http://www.bob2000.com/dist.htm

fordman · Post by **fordman** » Sun Dec 14, 2008 12:32 am

im going to take a guess and say that the reason you can just leave the vacuum open. is that the fuel mixture is too rich. and isnt or wasnt getign enough air through the carb. and the loose or open vacuum gave it what it needed. the advance not working i dont know. that sounds strange. maybe if you get the carb straightened out if it impropperly adjusted then the hose hook up might be needed. and then start workign maybe.

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