runs like crap

[artpeck]

One other thought. No idea what your fuel lines are but recently I had to replace a section on a piece of equipment where the line had delaminated and internally ballooned. Took me a long time and process of elimination to find the blockage. I would make sure your lines from tank to pump and pump to carb are free. And have you checked the sediment bowl and filter on the pump?

[andrew]

I don't see any vacuum system leaks.

It is difficult to start but idles ok, better when warm. It's under acceleration that things really start to be a problem.

The ignition wires are in the right places (from memory: 1, 3, 4, 2 going counterclockwise from #1, which is at about 2 o'clock if I stand on the passenger side of the car, looking toward the distributor).

Carb gaskets appear ok, certainly not leaking air or fuel as far as I can tell.

When I checked to see if it was pumping fuel, I disconnected at the carb and cranked -- it got gas, not gushing, but a flow...don't know what's normal, though. Sediment bowl appears clear, did not yet check the pump on the filter (though replaced the inline filter near the carb). I have not disconnected and checked all of the fuel lines so the possibility of a blockage (esp. internally) is there.

Thanks for all the feedback, everyone, keep it coming, please...

[busboy]

My initial thought is its not getting enough gas, is your inline fuel filter before the sediment bowl? Pumps always push way better than pull so perhaps that's a problem. Is your gas fresh gas, for many years I would leave mine sit then it would run rough (old gas) so now I only party fill so there is always room to top up with fresh if it starts running poor. Gas today is not what it used to be and for small engines I only use premium gas. Do you have an oil bath air cleaner if so 5W30? or is the paper element clean? You seem to have covered a lot of stuff already.

[andrew]

Inline filter is just before the carb, after the fuel pump. Gas is fresh and since I drive it so much--with such poor gas mileage--it never gets old. I have an oil bath air cleaner, which is freshly cleaned.

[CKubinec]

It is interesting. I have run across simular problems and often it comes down to a vacuum leak. It may not be obvious. Spraying the manifold and carburator gaskets with carb cleaner usually shows something. If it has power brakes pinch off the vacuum hose to see if things change. If you have a PCV valve use your finger to block it's opening briefly to see if it makes a big difference. A small change at the PCV valve is OK. I have had brand new PCV valves be bad. Good luck!!

[SafeAirOne]

I would say that the variable ignition timing at idle will be a prime concern. If you aren't able to nail down the timing using a few conventional methods, something's wrong.

I'd check the security/gap of the points, the integrity of the centrifugal advance springs and weights, the function and integrity of the vacuum advance system and mechanism AND, since almost ALL of the brand new capacitors are crap, I'd also replace the capacitor just because. Probably try to source a GOOD capacitor from from Advanced Distributors. Though I have no distributor on my engine, I've heard nothing but good things about them, their distributor rebuilds and their capacitors.

Might also check for excessive play in the distributor and shaft.

Compression check is also in order, though I don't think It'll reveal a cause for your problem, personally. Maybe throw a vacuum gauge on there as well. Check for vacuum leaks while you're at it. Check for malfunctioning choke too.

Anyhow...that's the tack I'd take initially. It just boils down to the old fire triangle; fuel, oxygen and an ignition source.

[EDIT:] Wow--missed a whole other page of replies. Apologies for the duplicate recommendations en masse. I think the Advanced Distributors recommendation is original though...

[jonnyc]

I had similar problems, not exact - but close, and got many of the suggestions below. After fixing most of the relevant items, problems persisted. One guy suggested that I should check/adjust my valves. Well, one rocker was apparently out just enough to cause me all sorts of grief. If you haven't adjusted your valves in 15,000 miles, it might be worth a shot.
My SerIII is currently running like a champ.

[Billy5]

Funny, I have the same timing pointer and its been driving me nuts too. I am relatively new, but I could not but wonder about your timing. If i am not mistaken, which I very well could be, when you throttle up the timing mark on the pulley will move away from the pointer, to the left as you say. This is advancement, I do believe. Now did you throttle up, then set timing according to the advanced location on the pulley? If so, then your timing is off I would think. What I did was set my light to 0. Then rotated dizzy until pulley mark lined up with the first pointer which is zero. Then I adjusted. I found 12 degrees BTDC is good. I cant help with the carb as I got a Weber 32/36.

[andrew]

Adjusting the valves seems a good idea -- I'll do that and see (and report) if it helps. As for the timing, I set it at idle (about 775 RPM) at TDC (and other settings I tried, as mentioned). After setting the timing in this manner, I throttle up and the mark will move off to the left (facing the engine from the front of the truck). I believe that it's supposed to stay relatively constant throughout acceleration, though, which I believe is the job of the centrifugal advance springs and weights in the distributor, but that's really beyond my knowledge -- can someone clarify if that's the case for me? And, how do I check if the springs/weights are working properly? And what to do if they are not?

[SafeAirOne]

I don't believe that the purpose of the centrifugal weights and return springs is to keep the timing constant through acceleration...the purpose of the centrifugal advance is to advance the timing as the rotational speed of the distributor shaft increases (as engine RPM increases, in other words).

The faster the distributor shaft rotates, the more the hinged weights want to spread apart and away from center. The weights are mechanically connected to the 'floating' distributor plate (that the points are attached to) so that as the weights spread apart, the relationship between the cam follower on the points and the cam on the spinning distributor shaft change, altering the moment when the points open and therefore the ignition timing.

You should see a rising advance angle as RPM increases within the mechanical limits of the centrifugal system. The vacuum advance does essentially the same except based on amount of vacuum and generally kicks in after the mechanical limits of the centrifugal system, AFAIK.


See: http://en.wikipedia.org/wiki/Ignitio...timing_advance