Alright, about time I made one of these for my truck, here it's mostly for me to keep track of what I've done and been doing to it.

 

So today I drove my truck about 8 miles, ran good but it sounded like it's getting a bit too much gas, sounds like it labors and struggles when you get on it at about 1/4 throttle. After that it pulls very hard and sounds pretty normal. My Edelbrock 1406 has stock jets, stock metering rods with 3" blue step up springs. I have my accelerator pump on the largest shot (that helped greatly with the stumble), base timing is at 12* BTDC. Last time I got a vacuum reading it was with everything stock on the carb at 800 RPM warm idle was 17" of vacuum.

 

I'll sub to it even if i have a Bronco. Mine also kind of labors i guess but it's more like at 1/8th throttle. Barely pressing it and there is a lot of missing and shaking but after i push a bit more it runs fine.

 

Haha thanks, mine used to do that when the vacuum advance canister was screwed all the way in. I had to screw it out a lot to get that to stop.

 

Mine might be because i still haven't timed it since i swapped the vacuum to where it should be. And the idle screw could probably use work.

 

If you can stick a 3/32 (I think) allen key in to your vacuum advance can you turn it? mine is adjustable.

 

I read about that. I haven't looked at it but i will eventually.

 

I'm subscribing.

 

Yep, I'm subscribed. I also read what was said on WHYDTYTT. A vacuum reading of 17" at 800 RPM, which is a fast idle, isn't very high. I say that because a stock engine in good condition should be around 20 or so. Even my 351M with an RV cam is showing 18-19" at 600 RPM, and would be higher at 800 R's.

So, is your engine stock? Have you used the vacuum gauge to adjust the idle mix?

 

Where do you guys have the timing set? I have found when I change everything around and go out on my own as far as engine tune, it seems to run better if I disconnect the vacuum advance, and turn the distributor so the initial timing is somewhere above 10 degrees, usually around 14 or so BTDC. It drives good and has good throttle response like that, and then later on you can mess with the vacuum advance unit. The factory puts a lot of vacuum advance in the dist from the factory, but you need to turn this way down if you advance the initial timing. I seem to remember my stock vacuum advance adding up to 20 degrees timing. I drilled a hole and put different sized pins int he vacuum arm to get it down to a more reasonable 10 or so.

For a long time I just ran without the vacuum advance. With the initial timing so high, it didn't have as much noticeable affect on the mileage without it.

 

I'm running 16 degrees of initial advance, and haven't changed the mechanical nor vacuum. And, in probably 2000 miles of driving it that way it hasn't pinged or knocked once. Further, it hasn't kicked back against the starter, although at one point a bad battery cable made it seem like it was.

 

That's a lot of advance. I usually find when cruising with it like that, it will start miss-firing and jerk a little bit. Are you sure the vacuum advance is working?

 

Yes, it is working well. I can see the change on timing when I hook it up to manifold vacuum, although I run it on ported. I don't have any jerking once the engine is warm. But it is temperamental when cold, although I think that is due to the lean jetting.

Having said that, I do hear a slight part-throttle burble at cruise when running the stock jetting, but I was attributing to richness. And, the AFR meter shows it to be rich - about 13 - 14:1.

 

Crane Cams 99607-1 adjustable advance kit is available again.
This fits all DSII distributors.

Springs, adjustable advance can and complete instructions for ~$40

 

I'm running their adjustable vacuum advance, but haven't played with it.

Well, we've done a good job of hijacking Matthew's new thread. I hope he will tell us about his engine. That low vacuum at high idle worries me. I'm wondering about burned valves.