runs like crap

[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

[andrew]

Unfortunately, it's not the valves -- I adjusted the valves today and it's still exhibiting all of the bad symptoms. I'll do a compression check soon.

Next up is the fuel pump and lines, I suppose. It just seems like uneven fuel to me...

Any other thoughts?

[jonnyc]

OK, one thing before I did the valves was to seal every possible vacuum leak spot. I took both manifolds off and dismantled everything between the head and the brake booster, including my Rochester. Every joint got sealer, new gaskets (or both), new hoses & clamps. It didn't solve every problem, but it sure helped, and it eliminated vac leaks from the equation. That's what narrowed my issues down to the valves. Eliminate as many problem areas as you can.

[busboy]

Unfortunately, it's not the valves -- I adjusted the valves today and it's still exhibiting all of the bad symptoms. I'll do a compression check soon.

Next up is the fuel pump and lines, I suppose. It just seems like uneven fuel to me...

Any other thoughts?

Throw a fuel pump at it, if that's not it then you'll have a spare for trouble shooting next time. Make sure the lines are tight on the pump.

[Les Parker]

I would second the thought of a new fuel pump. Ethanol plays havoc with fuel pump diaphragms.

[bugeye88]

Speaking of fuel pumps, I've found an in-line low pressure electric fuel pump in-between the standard fuel pump and the Carb with an on-off switch inside the cab helps prime and fill the float bowels in the carb for easy starting and can serve as the pump if the diaphragm fails on the mechanical pump. Also use one of the many ethanol conditioning products out there to treat your gas and prevent ethanol damage to various parts of our Landy's. This goes for any older car as the rubber used on them does not hold up well to ethanol.
Motor On,
Bugeye88

[andrew]

I hate threads that I look up that have no closure, so here it is:

My next steps were to check the compression (great, by the way -- 170 plus or minus 5 across the board) and add a new fuel pump. I also blew out all the gas lines with compressed air while I was at it. No change really. Unrelatedly, I added a new water pump (had been developing a slow leak for some time), hoses, thermostat, belt, and heater control valve (broke upon removal of the hose).

None of this really helped or mattered very much. So, at this point I've replaced nearly everything that might have reasonably caused the problem. A lot of it I was going to replace anyway as maintenance (points, plugs, condenser, plug wires, water pump, belt; and valve adjust) so that was no big deal, but some was a shot at a fix that I apparently didn't need (fuel pump, etc.).

So...I said screw the specs I'm timing this thing by ear. Recall that I was at or around TDC (8:1 head)...I rotated until it sounded strong. Drove it for awhile. If it backfired I backed it off. If it was good I moved it more to see if it got worse or better. I always drove between adjustments until it was warm. After a bit of trial and error I settled in on a happy place. The truck sounds wonderful now and runs great again. I haven't pulled out the ignition light to see what the final number is but I'm guessing I'm at about 8-12 degrees BTDC, which seems way out of wack from where it's "supposed" to be. Oh well, screw it, it's quite happy.

I'll drive it, keep an eye on the temperature (see if it continues to run cool, so far so good) and the points (see if it burns through them), but I think it's resolved. It truly is running great (and so quiet with the new water pump and valve adjust!).

I guess the only question I have is whether it's possible that the crankshaft pulley was installed with the mark in the wrong place, or if it could have slipped/moved over time... I just can't imagine how else I could be running so well so far off the supposedly "correct" timing.

Happy driving.

[ArlowCT]

Sounds like you found your fix! I know every time I try using the timing light it never works and I always resort to my ear.

[stomper]

I am running at about 12 BTDC and that is where my engine is happiest. With ethanol in the fuel, you can't go by the book specs.

[Revtor]

On my the engine, the crank pulley has one tick mark and then the pointer has two points which basically get you around 0 degrees. So when you actually time it to run right, the markings really don't help because there are none out by where it's happy! (Unless I'm doin' it wrong) Time, check for detonation, tune, check, tune, check etc... you got it.


glad you figured it out..

~Steve

[stomper]

I have a few timing marks on my crank pulley, but like Steve, there are no marks out that far. That's why I said about" 12 degrees BTDC.