I was definitely above 700 rpm. I have one of those timing light that has an inbuilt tach on it. I don't know if you guys came across one of those or not.
I will try re-timing with 600 rpm and than see if centrifugal mech. adv any of it.

Subford, where can I get hold of a Ford manual? The chilton is very vague.

 

http://cgi.ebay.com/ebaymotors/1979-Ford-Pickup-Truck-Van-Bronco-Shop-Manual-Set-79_W0QQcmdZViewItemQQcategoryZ34221QQitemZ79989485 02QQrdZ1

He's a little high but if you keep checking ebay you can find a set for a little less.
It looks like he has the only set up to buy today.

 

This is weird - the last time I tried to set timing, I found that my throttle linkage is sticking. Meaning, once I let go of the accelerator pedal, there is resistance to push it back to rev the engine. I am pretty sure it has to do with the carb. Found some gas dripping out of the accelerator pump. Also wierd is that I cannot bring the idle speed down to bellow 650 with the idle speed screw !! So, was not able to set the timing at 600. Anway, set my base timing at 650 rpm. Took the truck for test drive. I found that on the way to my destination, there is no spark knock. On the way back, there is distinct spark knock !! Does this means that either my carb is little too lean and engine running hot?! What are your thoughts guys? This is driving me nuts by now. I hate that knock and I want to get rid of it the right way, if there is one.

 

One more question I had. Can I install MSD ignition with the current distributor I have? If not, what all are involved in that? Is it any better than the duraspark ignition system?

 

Try retarding your timing one degree and see what it does. Its not going to hurt it. The mechanical advance doesent affect the timing that much.

If you notice the spark knock is a little less, retard it a little more. Some of our trucks have to be timed by ear. Mine is one. My gas mileage has improved drastically after the dist. replacement. Its the best money I've spent on my truck.

I wouldnt replace it with MSD. You already HAVE a fine high-voltage electronic ignition system Let me know. I want you to get it running right.

Try spraying carb cleaner on your linkage. Should help to free it up.

 

Ok. Checked to see what was making my linkage stick and this is what I found:

I was trying to reduce my idle speed to 600 rpm. Well, I backed off the idle speed screw all the way out. I mean the linkage is not resting on it anymore ! But speed will NOT decrease beyond 650 !! I would expect the truck to die in such a case. Anyway, when it is not resting against the idle speed screw, it sticks. I back the screw in enough so that it rests against the screw. Now, it is not sticking anymore. I do not know what to make of all this. Anyway, got a vaccum gauge to see what kind of vaccum I have during idle. Will post back with the findings.

 

"Found some gas dripping out of the accelerator pump."

Replace the accelerator pump diaphragm, it has a tear in it. They are cheap and only four screws to change.

If the engine is hot it will have a spark knock under load.

There is no adjustment on your carburetor for rich or lean other than changing the main jets.

There is a two screw idle adjustment but that is only in the circuit at idle and out of the system when you put your foot on the gas.

Of course the choke setting would affect rich or lean, but that would mean it was too rich and it would be all the way open by that time anyway.

The last adjustable carburetor I know of was in about 1948 and I think it was on a farm tractor.

 

Now I am getting all kinds of messed up. I am posting this in the carburation and fuel injection forum as well, but wanted to post here too:

1) After the sticking problem is resolved (as I mentioned in my earlier post), I now notice that when I first start my truck, it does not start idling where it should be. It starts idling at around 500 - 600 and gradually climbs up. Takes about couple minutes. So, if I put it on gear, it tries to die on me. Also, since I have to back the idle screw in so that the linkage rests on it, once it climbs up, the idle is around 900 - 950 rpm.
2) When I press the gas pedal, the truck does not want to go for a few seconds and then only it revs up and moves. There is a kind of delayed response in acceleration.

I want to know what you guys think of this.

 

Replace the accelerator pump diaphragm, it has a tear in it. They are cheap and only four screws to change.

The cold idle speed is set on passenger side of the carburetor. The screw rides on a step cam. The screw on the drivers left is used only when the engine is warm and the choke is wide open. At the same settings an engine will run at a lower rpm when cold. The two screws on the front of the carburetor are for idle mixture only and have no effect on the running of the engine when it is off the idle stops.

 

The sticking problem is gone. I checked the diaphragm, it seems to be in pretty good shape - did not see any tears or anything like that. I do not see any screw on the passenger side of the carb. You are talking about Edelbrock's. Right?

I did try to set the idle mixture screws using a vacuum gauage. The vacuum turns out to be max. at about 1 1/2 turn for each screw. Just for checking I put them at 2 1/2 turns - I can see fumes coming out of the tail pipe.

Of course, I did readjust the link to the plunger (accelerator pump). There are three holes that the link can be connected to. As per manual, if the link is connected to the hole closest to the carb body, the stroke of the plunger will be more and there by more transient fuel. I did that and it did help a little, but still not something I can go YEAAAAHHH !! Anyway, I will take out to highway and punch the gas pedal to see what she does.

 

No, I was talking about a FORD carburetor.Sorry

 

Well, still got the highway pings. BTW, it was not 1 1/2 turns - it is about 2 turns. Still got a little stumble at take off. Wonder if my fuel pressure is too low - I have a pressure regulator. I guess I will take the regulator off and try again.

Also, I can smell gas from around the fuel pump area.