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Discussion Starter #1 (Edited)
How's my timing/vacuum numbers? - Update: appears to be distributor failing

Recently put an edelbrock carb (#1406, 600cfm, electric choke) on my '71 351c 2v. I either didn't notice it, or only recently it's been running VERY VERY rich across the rpms. At idle its bad enough to make my eyes start burning really bad. The other night I was stuck in heavy stop and go traffic and it stalled out and could not be restarted, not by a long shot. I initially thought I lost all spark, but it appeared that it flooded out, after getting it towed back to my shop that night, it started and ran perfectly fine the next morning.

I have been having issues with hesitation/misfiring at low rpm + throttle application (heavy load). Tonight I retuned the idle mixture screws to the lean side (was riched out before) of the band, set the accelerator pump to the leaner setting, and adjusted timing to what appeared to run the best. It's still running very rich and at times dumping enough to start running rough and backfiring out the exhaust.

I need to know I've got my timing looking good before I start digging into the carb tuning. I'm not sure how much base timing I need, from what I read it appears 12-16 is appropriate for non-stock ignition.

I have an undercap hei conversion from points, accel super stock coil, plug gaps are at .035, I would like to regap to .045 after reading that it's appropriate for the non-stock coil.

First check of timing (that its been set at for 5+ years with no problem) showed 11-13 deg at idle, up to about 26 at full advance. A function check of the vac advance shows it adding about 12deg when connected.

The manifold vacuum appears very poor as far as I know. Fiddled with the timing, stepped up to around 16 deg at idle, saw 13-14in Hg, ramping up to 42 deg at full advance, with 18-20in Hg vacuum. There's a possibility that I had the vac advance reconnected during this test, as 42 sounds high in retrospect.

I suspect my issue is with a stuck float level in the carb. The carb has been on for several weeks and is only now giving me an issue to this extreme.

I'm extremely novice at carb tuning, I'm going to study the included manual and snag a 1487 tuning kit. I just want to be 100% sure my ignition is dialed in before messing with fuel.

Previous post/issues are here

Thanks again, signed the guy with the burning eyes.
 

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if your car was running fine before you put the new carb in then your problem shouldnt have anything to do with anything but the new carburetor. Take a shot at tuning the carburetor yourself, just dont get frustrated it may take a couple of times


also, is your choke operating properly? If the choke isnt opening up soon enough you will have an overly rich mixture





i found this on google :)

How to Fine-Tune Edelbrock Carburetors | eHow.com
 

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Discussion Starter #3 (Edited)
also, is your choke operating properly? If the choke isnt opening up soon enough you will have an overly rich mixture
Choke appears to be operating properly, I haven't adjusted the high-idle from its out of box setting, though I have had it set 2 steps leaned.

What's weird is after I got done tuning it, I went to leave work after it was fully warmed up and it was falling on it's face, missing, backfiring and dying again. Just as a shot in the dark I disconnected the power to the choke and that BS hasnt returned all night. Of course it's still running just as rich in this condition, just not wanting to have the excessive rough running issues.

This is pretty confusing as if the choke isn't working, in theoretical application its producing an even richer mixture. And the choke flap doesnt start to open manually until nearly full throttle. This makes no sense, that an even richer application is making an already super rich engine run better? :shrug:

EDIT: I was wrong, I have had the choke 2 steps rich, not lean.

One of the first things I checked was #5 plug condition, (didn't have time to pull all the plugs) and it was apparently normal, very clean and no fouling or any soot.

I know that a misfiring engine will have just as much, if not more unburned fuel coming out the pipes. But it's running pretty smooth, definitely not constant missing, just rich enough to leave your eyes stinging for hours.
 

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Pull some more plugs and try to determine if you are in fact rich. Lean can cause eye burn too.
 

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Discussion Starter #5 (Edited)
Update, pulled all the plugs and verified a definite lean condition. Was messing with my timing some more and noticed many things very odd. First off, I saw my best vacuum around 16-18deg base timing, and I had been running it at 16 all weekend with pretty good power and very good cold startup. I hooked up our 5gas analyzer and got my idle mixture screws tuned in perfect. Car was idling well for 20-30 min and th burning eyes sensation was eliminated.

Gave it some cruising rpms to check what the numbers changed to on the analyzer, after a few seconds it backfires and dies. Can't get it restarted, then whoof - fuel fire in the carburetor. Never had this happen to me so it was going for nearly 30 seconds before we were able to smother it.

Agreed 16deg was too much, turned it down to 12 but it was nearly impossible to tune with this timing. It would die out before we could get the CO and HC down to proper levels. I settled with a slightly rich mix and said it was good enough. Again, idled for a long time before I went to test drive it. Before pulling it out I gave it some revs, it clearly was missing alot of power just revving in neutral, started backfiring, and hasn't been able to get running again.

My two best guesses are distributor failing, advancing or retarding on its own, or timing chain has skipper. Distributor would be my best guess, I DID get it to fire back up at the end of the night by getting lucky with distributor placement, but I picked up my timing light and it was idling with 30+ degree of advance, tried to turn it back down and it died before it could get below 20. Even when it had around 16 initial, it was only ramping up to around 28 at 2500rpm, with vac adv disconnected. And I only saw a 12deg increase under cruising rpm with the advance versus what o read should be 20.

Distributor would also agree with theories of previous running issues, such as slow return to idle, intermittent lack of power in different rpm ranges.

What's daunting about my dizzy is its from a 460 application, has magnetic pickup conversion, and the advance springs aren't even visible under the cap. Not to mention I've never replaced one and don't k ow the potential pitfalls of dist removal and install. Gave up tonight, left the car at the shop and took the bus. Have no idea what to try tomorrow besides bitching up and getting a real daily driver.
 

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Don't give up now you're making some progress. It took me about a week of constant daily trying before I got my car to even stay on and then it would miss and run rough...this was all as I was learning about carburetors and tunning them. Trust me I blamed everything I could as i was trying to figure out my issue. In the end I got it figured out and all that truble was worth it:)

One thing I noticed you said was that your choke would be closed when the car was warmed up. That causes a rich conditon he only time your choke needs to be closed is during cold start. I don't think you have a distributor problem focus on your tuning for now. If you're too lean you could be detonating causing missfires, too rich and you'll foul the plugs. Is your car auto? Are you doing your tuning with the car in gear? If not you should be. If its manual no need to worry about it being in gear. The car dying and not turning back on could be an issue with heat soak or your carb/fuel filter clogging up. Do you have good fuel pressure? There are many little things that cause these cars to act funny but just keep at it you'll get it soon.


Edit: a lean condition will make your car run like crap so if it runs better with the choke closed when the car warms up then you do have a lean condition. So when you tune make sure your car is fully warmed up and its in gear(auto). When you're done check all your readings with the car in gear(auto) warmed up and with the choke completely open. That should take care of all your issues
 

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Discussion Starter #7 (Edited)
I'm sure the problem is not the carburetor at this point. I understand it was tuned improperly before, leaned out making the plugs white and producing the NOx giving the burning eyes sensation. That's been fixed, the carb is only a few weeks old, never been disassembled, only messed with the accelerator pump, idle mixture screws and choke setting. And the choke is working properly.

I did replace my pan gasket tonight and the little bit of the timing chain I could see/feel from the bottom appeared to be normal. Also, these issues are sporadic and intermittent, but most common when the engine is fully warmed up. My knowledge is leading me to guess the issues resides in the distributor advance weights/springs sticking. It's an educated *guess* I know, but nothing else fits the combined symptoms.

To the other questions: it's a manual, the fuel filter is as new as the carb, clear-view and not clogged. I had the air fuel ratio tuned nearly perfect using a 5 gas analyzer. It was only when giving it rpm that the problems arose/re-arose.
 

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^^ I see, that makes sense well hopefuly it is just the distributor and not a jumped tooth on that timing chain
 

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Discussion Starter #9 (Edited)
I'm racking my brain trying to figure out what replacement distributor application is necessary for my motor. It currently has a duraspark distributor from what I can tell. Sadly this is my daily driver and I'm trying to bypass any inconvenience and just get something to plug and play.

I wouldn't mind throwing a stock repro points distributor at it, but I would assume the resistor wire was removed during the P.O.'s install.

EDIT: Who knows at this point what's in the car, again another example of not knowing what the P.O. did. I'm contemplating a straight duraspark dizzy replacement - http://www.performancedistributors.com/fordduraspark.htm
 

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you're probably correct about that wire being removed, it doesn't hurt to check though. Have you pulled the cap and rotor off n taken a look at it? what about checking for any busted springs inside the distributor?
 

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Discussion Starter #11 (Edited)
Cap and rotor have come off, but I have never tried removing the top plate that houses the pickup. I just found this tonight and will try to open it up and inspect first thing in the morning.

Found this, maybe it can save my life/sanity.
 

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Discussion Starter #13 (Edited)
Didn't have any time this morning for testing. Attempted to take a look under the breaker plate in the distributor but pulling off that reluctor wheel was sketchy and I didn't want to risk it. I don't have any rotational play in the distributor housing, and the shaft seemed to rotate without binding on the advance screws, and return to base without sticking.

However, it did start up immediately and drive (only drove it very short distance to park it) just fine. Which has seemed to be the common issue, heat. The problem has happened only, or most commonly when the engine was fully warmed up (not overheating, just fully warm). And at bone cold, no issues.

I was reluctant to replace the entire distributor, it seemed like a foolish way to throw parts at a problem. After discussion I'm thinking the most likely cause is the magnetic pickup is overheating. Hopefully that by itself is replaceable in the duraspark setup.
 

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Discussion Starter #14
I have a backup coil which I will try tomorrow. But the one thats on in a brand new Accel Super Stock so I doubt it's overheating. I did change my coil mounting location semi-recently when I removed my power steering pump bracket (since the pump has been long gone), the coil bracket was mounted to that. I wouldnt think enough heat is coming off the water pump.These issues didn't start when I moved the coil mounting, but only in the last couple weeks. But I guess residual/transferred heat from a source of nearly 200deg F could be overheating the coil. If the coil is overheating being mounted to the water pump, where else can I move it to? Currently the previous owner's wiring gives it little to no negotiation for mounting, so I'd have to do some wiring mods to move it.

I will also try taking a heat gun to the pickup to try to make it fail on a cold engine. Man this magnetic pickup replacement part is hard to track down if it's the culprit.
 

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Discussion Starter #15
Ok it ended up being the magnetic pickup. I was able to cross-reference a Motorcraft part number to a part that Napa carries. Got that installed and it fixed the problem. It was failing completely. First of all, I had reset base timing a few days ago to 13d btdc, after replacing the pickup and restarting, I was reading over 50deg initial timing! The pickup was so delayed that it was lagging behind by almost 40 degrees. When the engine was fully warmed up, the pickup was fluctuating even more wildly, causing the inability to start and backfires out the exhaust/intake.

After replacing it I got the car back on the 5-gas analyzer and reset the carb mixture screws. Even though the exhaust has an H-pipe I could see a clear difference in the numbers. Drivers side CO and HC were adjustable to pretty much perfect, but the passenger side bank was showing signs of missing, no matter where CO was set, HC was 2-3x the target levels. Vacuum improved after replacing the pickup, but its still fluttering by 1-2 PSI, fluttering at 14-16in HG at idle. I suspected a burnt valve, and it wouldn't be a wild assumption given the recent plethora of backfiring.

On top of that I have a rough running condition at low RPM load again, pretty pronounced. It's also not running as strong as I'd expect in the higher RPMs, on first test drive it was backfiring out the exhaust in the upper RPMs. I set the accelerator pump to the lean setting and the backfires ceased, but it still doesnt feel strong when getting on it.

I recently the spark plugs set at .045 gap, suspecting the flame is blowing out I'm going to set them back at .035 when I perform another compression test.
 

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thats great well i'm glad you got it sorted out. Now pull out the plugs on that bank and figure out which cyl is missing
 
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