Setting my timing

So I'm going to install a different ICM tonight and adjust my timing to see if this fixes my surging issue or at least makes it better. Adjusting the float helped a bit but the car is still funky between 2500-3000 RPM in 5th. It now happens on flat ground so I know the float isn't the issue.

My question is should I set my timing with the headlights on or off. The manual says to adjust my idle with the lights on so I'm assuming I should do the same for the timing. The car idles fine with the lights off but gets rough with the lights on. I'm using a Weber and have not swapped jets yet, trying to save that for last resort.

I would leave the lights off, but it probably doesn't matter.

The car drops by 50 RPM when the lights are on which is expected behavior according to the manual but then it gets a little shaky. I'm finally going to get the new ICM in this weekend and think I should check the timing and idle when I do.

So I put the new ICM in and set my timing and it feels better! The surging is almost gone uphill and happens in a much smaller RPM window than it did before. The problem is that the car runs better when I advance the timing to around 9 degrees (right after the 6deg mark disappears into the hole). I've read that the 32/26 likes advance but I'm not sure if it's OK to run the engine with the timing advanced. Any ideas? I've got the jet kit coming this week as well so I can swap those out and give it as shot.

If you're not getting any knock under load, I think the advanced timing should be just fine. That's really the only place where I think it could hurt your car. I think 5-6 degrees with the carb swap will not hurt anything.

Just a stupid question though, did you set the timing with the vacuum advance disconnected? Can't remember if you're supposed to do that or not according to the manual. Some debate about whether that should be done or not.

I set it then pinched off the line with pliers to make sure that it didn't move. After that I revved it up to make sure that it does move with RPM. I also set it with the lights on which makes a big difference. Some sites say set with no load, others say it doesn't matter, I think it does matter with this car since it now idles much smoother with the lights on. I've also been reading that there's usually a "sweet spot" on the timing and the manual settings are mainly for emissions, not running quality.

This other ICM I got is having major issues. Tach bounces and it doesn't want to idle after running it for a day. This time I kept my old one in the glove box and when I put it back in the car runs fine. I'm starting to think the ICM isn't an issue or RockAuto is sending out crappy units. Kinda sucks since this one was more expensive but I'll call them tomorrow and see if I can swap it.

It's also still doing the surging but it's not as bad. I'm kinda loosing my mind on this issue and if the bigger jets don't fix it I'm out of ideas. I guess it's take it to a shop at that point but I'm getting very frustrated with this problem.

And now it won't hold idle in this garbage 50 degree weather. I think it's time to sell this car.

Bah! Don't give up yet! You're so close to having it perfect. I know it's frustrating, believe me. These little bugs are THE hardest thing to work out. And there aren't a ton of people who work on them, like they do with old Chevys and such, so support is tough. It's a ton of, tweak, drive, tweak, drive, tweak drive. Since you don't have a dyno, it's really the only way to do it. But it runs and drives right? Just wait for that one day when everything settles in perfect. It'll totally be worth it.

Have you tried messing with the idle jets at all? Just go up a size and see what happens? Like you were saying, it could be a lean spot before you kick over to the main circuit. Idle jets run the carb all the way up to about 3000RPM. If you haven't messed with jets at all, I would say you need to. It kinds sounds like maybe just the primary idle jet, because then once you hit the gas a bit more, the secondary idle jet might be adding a little extra fuel to compensate and clear it up. Does that sound right?

The nice thing about messing with the idle jets is that you don't even have to take apart the carb. I talked to the guy who runs Carbs Unlimited and he says they come "jetted pretty close for most 4 cylinders." So I'm kind of doubtful at this point if even the ones that come in the kit are jetted properly.

Also, your distributor, is it connected to the vacuum port on the carb, or to the intake manifold? At this point, it sounds like you had better luck with the timing where it was, and with your old ICM, so maybe set it back up, and just mess with the carb and see if you can clear that up?

I have new wires, a new Super Stock coil and the jet kit coming by the weekend. I'm also going to check the ground for the ICM and see if I notice any bouncing voltage going on there. At this point I'm leaving the timing as is since the car does run and drive, it just gets sloppy between 2500-3000 then smooths back out above 3.

The vacuum is on the carb and the old ICM is back in and it's running like it did before the new ICM. If it's not pouring tonight I'm going to go adjust my timing and see if it makes any difference. I have a stretch of road that it does this on almost every time so that's my test track. The engine does get a lot smoother with the timing advanced which makes me think it's part of the problem.

Ya these last issues are the most frustrating. I've fixed the brake issues, flickering headlight issues and am now stuck on this surging problem. If I can get this resolved the car will be damn near perfect. I do like driving it, the car is fun and I like how small it.

One other thing that's annoying is that the choke doesn't pull down by itself as the car gets warmer. I don't know if it's supposed to or not but if I bump the gas before it's ready to drop it gets pissy. I wish it would drop by itself.

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Originally Posted by PDXAccord79

I also set it with the lights on which makes a big difference.

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50 RPM shouldn't make that big a difference. Are you sure there isn't something up with the distributor? Are the advance mechanisms working properly?

Advance works fine when I watch the mark with the light. The advance in timing is more noticeable with the lights on but the car will smooth out with them off as well. It's not like the car runs like crap with the lights on it just shakes a little bit. I'll try and take a video tonight. I was actually worried when I initially set up the car because it ran so smooth so advanced but ran rougher at stock settings. I set it stock because the manual wants that but I'm not sure the carb agrees. I am starting to think there may be a dizzy issue but I'm not going there until I have every other part of the chain verified. I hate going in that thing.

Hmm, have you tried using manifold vacuum instead of carb vacuum? I never noticed much difference going between them myself, but I think that stock it uses manifold vacuum... but I could be wrong.

I think what happens is you take the line off, set it to 0, then when you hook it up to manifold, it advances it to where it should be. Ugh, it's been so long, lots of confusing times. I'd check the manual and see where vacuum was hooked up originally to the distributor.

Mine doesn't have a vacuum on the manifold, that's an 80+ thing if I remember correctly.

Mine doesn't either, but I think it still draws vacuum from the carburetor base or something. The ported vacuum on the Weber is pretty much either full vaccum none if I recall correctly. And it goes full vacuum as soon as you barely even touch the throttle.

I had a similar problem when the magnet inside my distributor was broken, then the engine worked like crap. Can you try another distributor just to make sure is not a dizzy problem? You may even try a contacts (breaker) distributor.

I found how the vacuum works on a Jeep forum and there's 2 holes exposed by the primary butterfly that control the vacuum. The forum goes into detailed instructions on how to set it up so the vacuum at those 2 holes works properly at idle. I'll be trying that this weekend.

Also I'm really starting to think that this is a fuel mix issue. It ran like crap yesterday in really humid weather but tore it up this morning now that it's drying out. The jet kit comes today so we'll see how it goes.

Also I'm thinking of swapping out to a dizzy from an 80+ since it has an internal ICM. Anyone know if the internal one will fit? I won't be trying the points version since I really hate points.

And the latest! I've now swapped the 36 barrel up to a 145 jet, advanced the timing, reconfigured the choke and added the Super Stock coil and it's getting better. I'm going to try 145/145 for both barrels next and see if it clears the issue. It feels like I'm getting close!

Sweet dude! Sounds like you are on top of the tuning for sure! This is the fine tuning that makes everything work perfect. :)

It's getting there. I'm glad the jets are resulting in changes which is keeping me from getting frustrated. I've been jetting for 2 days now and can now feel the car change in little ways every time I swap out. The jets on this carb seem to want to go in pairs so I'm getting another 145 tomorrow morning. I figure I can use the air jets to fine tune at that point.

So 145/145 main jets have resolved almost all of the bucking when going uphill but it now feels like it's starting to lean out when it goes above 75. This is at about 3500 RPM when going slightly uphill and isn't as bad as the bucking before. It has more of a rough run feel to it that can be fixed by giving it more gas.

The vacuum at the throttle feels way better and my gas pedal now has some force behind it that it didn't before. Idle is also so much better but it still gets a miss every so often that can almost be cured via the idle screw. I'm thinking an idle jet increase will fix this.

So I don't know what size corrector I have in there now but I'm thinking I should try one size smaller corrector on the 36 barrel to make it richer on the high end? It didn't seem to like a 150 jet in the 36 but I'm tempted to try 150's in both now so I can make it leaner via the air correctors.

Any thoughts are appreciated since I only have other peoples notes and trial and error to go on.

So the way I understand the air corrector jets, is that they are more for fine tuning. So going up 3 air corrector jets leans it out *about* the same as going down one jet size. But I think it also affects emulsion too, which is what's critical for that crossover point between the idle jets and main jets which is around 3000-3500RPM typically. I may be off on this, but this is how I understand it. Which isn't all that well. :)

Well my idle screw is 2 1/2 out in order to keep it idling after starting hot so I'm fairly sure I need bigger idle jets. I was setting the screw at 1 3/4 turn out and that worked fine if I let the car go from cold to idle but if I shut it off then start it back up at 1 3/4 the tach would bounce all over the place while the car wanted to die. Turn it out to 2 1/2 and the car is fine. I can get it to do this almost every time so I'm fairly sure this is the issue with idle which was causing the new ICM to be strange.

This new bucking definitely feels like it's now happening once the car goes "balls out". I'm fairly sure the main jets need to be a little richer but not 150 richer so I'm going to swap the secondary jet to 150 and add 2 air corrector sizes to see what happens. Then keep bringing the air correctors down until it gets sloppy. After that I'll swap the 150 to the primary and start it all over again.

I also need to figure out how to get more pull on my gas pedal. The carb isn't opening up all the way which is preventing me from getting the most out of it when I put my foot down. At least it sounds mean being 3/4 of the way open. I really like the noise that comes off the Weber when it opens up and I'm seriously considering getting another exhaust pipe so I can put a sport muffler on the car.

I do have the choke solved and it now pulls down every time so at least I've got one issue 100% resolved.