Rough idle + pinging

[thesameguy]

Hi guys -

Sorry for the length of this, just wanna get everything out in the open. I am committed to enjoying this car this spring!

About a year ago I picked up a '62 Falcon with a 170 and have been slowly chipping away at various 50 year old car issues. It's going pretty well, but I've hit a roadblock. It starts up readily (almost *too* eagerly!), but seems to have a very rough idle. I say "seems" because placing my hand on the valve cover it doesn't actually feel too awful, but inside the car you can hear and feel the entire body shudder with each revolution. Under even slight power, it smooths out almost immediately.

Unfortunately, there is what I'd describe as pinging under all throttle conditions - light, heavy, doesn't matter. Pulling away from a stop it's pinging. Cruising down the road, it's pinging. Honestly, it could be a lot of things as I've never heard knock this bad, but that's what it sounds like. Perhaps I'll try and make a recording of it? In any case, it *does* seem to have good power, and does go down the road nicely except for the noise o' death.

I have had the carb (a factory 1bbl Holley, not an Autolite) professionally rebuilt by The Carburetor Factory (very reputable) here in Sacramento. Plugs are brand new Motorcraft coppers gapped at .035". Plug wires are brand new Motorcraft. Cap & rotor are also brand new - I believe Standard Motor Products. I have installed a Pertronix ignition on a newly rebuilt distributor. The carb spacer plate was removed, cleaned, reinstalled with a new gasket along with the rebuilt carb, also with a new gasket. It seems to draw good vacuum - the advance on the distributor works great. Timing is set at 10 degrees, vacuum advance line removed & plugged at the time.

Here are some things I know:

1. I have never manually adjusted valves before in my life. But, I bought a good stepped feeler gauge and I'm pretty sure they are all adjusted to spec. In adjusting them, I noticed several of the adjusting nuts were extremely tight, some extremely loose. I'm not sure if that's symptomatic of something.
2. I have heard that these old harmonic balancers are prone to slipping, and that timing marks on them may not mean anything. How can I set the timing for sure, reliably, in such a situation? I have some doubts about mine - but have zero issue replacing it if there's a good source for new/rebuilt ones! Maybe I just have a timing issue?
3. It appears the mixture screw doesn't affect the engine running in any useful way. I'm not a pro at carbs, but it doesn't get much simpler than this. The factory manual says to lean it out til it stumbles, then back it out til it rolls, then turn it in to suit. Well, I can bottom out the screw (gently ) and the car doesn't run appreciably worse. I can back it out til it smells like gas at the tailpipe and it doesn't run appreciably worse. Regardless of the mixture, I *still* get pinging!
4. The previous owner replaced the fuel hose from the pump (still mechanical) to the carb with a big pretty stainless braided hose when he replaced the fuel pump with a rebuilt. He never ran the car (sold it non-running, with the spark plug wires in the wrong order!) so I don't actually know if the fuel pump is any good. In any case, is it possible that the bigger hose is somehow lowering fuel pressure at the carb, and either resulting in bad atomization or just an overall lean condition? I have actually never thought to check fuel pressure until this very minute. I will do that - however I am thinking about installing a Carter (P4070?) if I can figure out what to do about the vacuum-powered wipers... I've been thinking about using a vacuum pump from an Audi (they have vacuum locks) to handle the wipers. I think that would work.

I think that's all. Any thoughts/advice are greatly appreciated! I've tried just about everything I know and it honestly doesn't run much better now than it did six months ago!

 

[CobraSix]

1) The shudder you feel is likely worn motor and/or transmission mounts.

2) From everything you've described, my first bet is your timing is not set right. It can be less about balancer slipping and more about the dizzy not being set properly. I made a post on my procedure for determining TDC. I'll try to dig it up. I'm about to put in another dizzy so I'll be sure to document and make a write up this time.

If you timing is extremely advanced, it can actually be causing your engine to run fast (did you check RPMs?). Once you get over a certain RPM, the idle screw does nothing since you are on the cruise circuit of the carb. Also sounds like you are running extremely rich, but may be a function of poor timing and not running on the idle circuit as a result.

HEre is a copy of my procedure:

The way I determine TDC is simplistic, but works. Get a yard stick and a telescoping magnetic pick up wand. Pull #1 plug. You do need to determine the compression stroke. Two ways. #1 is to pull the VC off and watch the valve When both valves are closed on the upstroke, that's your compression stroke. The other way, is to put your thumb over the spark plug hole while you rotate the engine (by hand). When you feel pressure pushing your thumb, that's compression stroke.

Once you've determined that, get the piston within sight of the plug hole. Put the magnetic wand into the cylinder to rest on the piston. Extend the other side of the wand out. Place the yardstick perpendicular to the block towards the end of the wand. The further out you can put it, the more accurate the results of the process will be. When I do this, I use a 2x4 across the top of the engine to inside of the fender lip. Using a wax pen, I mark the spot the 2x4 is on the fender. I clamp the yard stick to the 2x4. This allows me to do this solo and with consistent results.

Now slowly rotate the crank in the normal rotation direction until the wand appears to change direction. Don't worry about getting it dead on the direction change, just when it appears to change direction. Now, keep rotating the engine until the wand is about 1" (or pick a value, doesn't really matter) below the spot you saw the direction change on the yard stick. Mark this spot and do NOT move the yardstick or wand. Now, rotate in the opposite direction (counting the number of rotations) until the wand is on the same marked spot on the yardstick. When I do the rotation, I try to do it in 45* increments as best I can. Say it took 4 45* rotations (just pulling it out of thin air) Now, go back the normal rotation 4 rotations and you should be back at the same mark. If so, now go backwards half the rotations (so 2 for this example) and you will be at TDC. Check your timing mark. If it's not at 0* on the indicator, then use a paint pen to mark the balance where the indicator's 0* mark is located.

One of these days (likely when I put my new dizzy back in) I'll take some pictures of this process and post them.

 

[JackFish]

Just so you can verify that it is in fact pinging, while at idle you can loosen off the dizzy and advance it until it does ping.
Then you will know for sure if that is the sound you're hearing.

 

[MPGmustang]

I agree with the timing, it's possible to have it off just enough. please tell me you did hook the vacuum back up for driving. without vacuum it's possible to ping. timing I had was roughly 8* max 9* and 10* was a guarentee ping.
I would play with the initial Idle screw, not the idle AF, usually it's a screw somewhere on your gas pedal linkage, turn this one to make it run slow/higher while fiddling with the AF, you'll know you're close when the AF affects it. IIRC the AF usually doesn't affect properly untill the RPM is less than 1000rpm
the rough rattle could be many things, I once had one for 4 months before I figured out my starter was loose. check everything that attatches to the engine/tranny, tighten all. and check the rubber on the mounts. then see if the exhaust pipes are rattling against anything. (I have a sensor on my AC hose that rattles against the shock tower every once in a while)

Keep it up and GL
Richard

 

[thesameguy]

Thanks guys!

I found a Dorman harmonic balancer on Amazon.com for $100, so I ordered that to install this weekend. That should address any issues with timing marks. That could definitely have affected my distributor installation! I will see about motor mounts too - they look just like simple pieces of rubber - hard to believe they can go bad.

My timing light also shows RPM, and I have it set to about 675rpm. That gives a ~640rpm idle when the car is in Drive - it's still the original Ford-o-matic. On the Holley, the choke cam acts on the idle screw directly on the carb. I can readily control idle, 675 seems to be a good setting. I have not seen any evidence of the mixture screw affecting anything at any time.

I forgot to mention, but I just replaced the exhaust system this past weekend. The old, original pipes (!) were rusty to the point of being brittle and the muffler was crumbling. I was hoping it was just blocked up and a new system would sort everything out, but no dice, it runs about the same albeit much quieter and with a nicer note. I did have the guys weld in an O2 sensor bung so I can check basic A:F - I will wire that up this weekend. In any case, the exhaust is nice and tight tip to tail.

Ridiculously advanced timing would explain it's eagerness to start and pinging. I'm glad nothing about this scenario makes anyone think "horrible mechanical issues," as my only theories at this point are really messed up timing or a mechanical engine problems... low compression in a cylinder, etc. If this engine is shot, I'll have wasted a fair amount in parts and probably just put a Zetec in it.

Happy to hear any other thoughts - I'll see what the new crank pulley tells me on Friday.

 

[CobraSix]

The other issue is you may have a worn out timing chain. They stretch over time. My advice is while you have the balancer pulled, to go ahead and replace the timing chain. The combination of the two should solidify the timing.

 

[thesameguy]

I should have the balancer on Friday - I'll compare it against the one that comes off and see if there is any indicating the pulley has slipped. A timing chain is probably more than I am ever going to invest in this engine - I'm serious about putting a Zetec in. Although, all the other parts I've invested in the six, maybe it's here to stay. I'll check the manual tonight and see what's involved in doing the chain.

 

[thesameguy]

I replaced the pulley today - I am glad I did as the rubber on the old one was destroyed, however it does not appear the pulley ever shifted on the hub. With the new one on, timing was still exactly where I left it - 10 degrees, vacuum advance disconnected and plugged.

Engine speed fluctuates a few RPM at idle here and there, ignition seems very strong/regular. Interestingly, today it idled better than it ever has in the past, so I am wondering if perhaps running for "some time" with a bad float (reason I had the carb rebuilt) just carboned up the combustion chambers, and now it's cleaning itself up. That would be nice.

Anyone have any experience with the various "engine cleaner" type chemicals on these motors? I'm talking about Seafoam and the like. I've had extremely positive results with "GM Top Engine Cleaner" on turbo Saabs - they lack EGR and can be emissions headaches for NOx. I don't think that stuff is legal for sale in California anymore, but perhaps something similar?

Tomorrow I'm going to install an O2 sensor in the exhaust and see if that gives any insight. Maybe also see if I can find a reputable shop in the area that still remembers how to manually adjust valves, just to give my work a second, professional look.

 

[thesameguy]

Couple other things:

In playing with the mixture screw, leaning it out will positively increase engine RPM and going the other way will decrease it. That seems to be the only function of the screw, for whatever that is worth.

Also, I took this video with my digital camera - you can'r really see the vibration of the engine, and the sound is pretty awful. I tried to show what the engine running "feels like" in the cabin, but it's just noise. I also tried to capture a particular squeaky-ish sound at the tailpipe, but it's just noise, too. Still, you can see a pretty solid idle speed (it drops slightly as the car warms up) and the big fuel line I was mentioning earlier. I doubt this is useful, but maybe someone will spot something I've missed.

http://www.sacsaabs.org/sacsaabs.org/misc/MAH01078.MP4

That's a 720p MPEG4 - I think Windows Media Player will happily play it, but not sure about players & operating systems. It's huge being 720p, about 70mb. Be patient if it loads slowly.

 

[thesameguy]

I finished my work for this weekend - installed a DPDT relay to power the Pertronix ignition, an O2 sensor heater, and a narrowband A:F. I pulled the Pertronix into the equation just to eliminate the possibility that getting power through the old ignition switch was somehow involved with my issue. It's now getting full battery voltage. I poured a pint of Seafoam into the gas tank and let the car idle for about twenty minutes, shut it down for a couple hours, ran it another twenty minutes, let it cool again, then set out for a test drive.

On the way out - a ten mile drive on city streets with plenty of stops and speeds from 25-50mph - it was doing AWESOME. Good power, no bad noises, and the A:F gauge showing:

70% - WOT
80% - Cruising, or light-medium throttle (fairly rich, but still within the realm of reason)
90% - idle

I stopped for two hours, had dinner, and hopped back in to head home. A:F was totally different, immediately:

50% - WOT (quite lean)
60% - Cruising
70% - idle

Pinging like crazy under any throttle, more of it with more throttle.

This is totally par for the course, exactly what the car has been doing since I started working on it - it's fine one drive, messed up the next - but NEVER changes its behavior while it's running, only when stopped. Now at least I have the gauge to confirm what my ears are telling me - something about the mixture is changing at random. I will check ignition timing tomorrow to ensure it hasn't changed, but I imagine I am going to see the same numbers. What else could *possibly* cause such a dramatic shift between two drives? Any ideas - this is *maddening*.

Edit: On the way back tonight, I pulled over and adjusted the mixture screw. I turned it out several rotations, and that made zero impact on what the A:F gauge was reading. That possibly lends some support to the fact there is a delivery problem - it adjusting the mixture doesn't in fact adjust the mixture. As a point of reference, does anybody else have this carb? Where is your mixture screw? I realize this isn't 1:1 science, I'm just looking for a comparison - mine on the way out tonight was about 1.5 turns out; on the way back I moved it to 2.5 turns out (with no change in indicated A:F)

 

[CobraSix]

Is it always driving good the first time? And then poorly after you've stopped?

Wondering if you are just having a severe boil off problem. Do you have another carb lying around?

 

[thesameguy]

In general, no, it doesn't matter whether the engine has been sitting for minutes, hours, or days for this problem to reoccur. A specific example from a while ago - car sat in the parking lot at work for nine hours, drove it to the dry cleaners two miles away pinging, stopped the car for five minutes to drop some clothes off, got back in and had a great drive home. More recently, after installing the rebuilt carb and changing the plugs I started it up, let it warm for about 5 minutes, then drove it back and forth up my driveway (it's several hundred feet long) with it pinging.

I don't have a spare carb, but this one was literally just rebuilt. It *seems* like if the problem was the carb the behavior would at least change somewhat before and after, but it seems exactly the same.

What are the chances it's something in the fuel pump? I ask because the previous owner installed a new (rebuilt?) one prior to my ownership so I don't know if it was done right or not. I feel like a mechanical pump should either work or not work, and not work intermittently, but?

Last night I did some shopping for an electric fuel pressure gauge so I can watch that while driving, and while taking some measurements I noticed a small white "something" floating in the fuel filter. It's always been spotless in there, so whatever that debris is it appeared in the next day or two, and probably on last night's drive. It looks like a small piece of white plastic. I'll get a picture of it this evening, but any idea where something like that might have some from? Maybe it's a piece of some obstruction in the fuel system?

Thanks for sticking with me - this is the second worst automotive puzzle I've ever had... the first being a permanent alternator whine on a 1988 Saab 900. Argh.

Side note: Do you know what the proper fuel line hose size is? I'm guessing 5/16ths? The 3/8th hose that's on there is seems larger than the rest.

 

[JackFish]

Please check, and back off your timing. This is what is giving you the pinging, and is dangerous to the engine. It's either the distributor being advance too much mechanically, or it's getting too much vacuum. One thing you can do is disconnect and plug the vacuum to the dizzy. Go for a drive. Does it still ping?

Another thing that can cause pinging is an engine with carboned-up pistons. The top gets a layer of hard crud that can get thick enough to increase the compression ratio. You can try a hi-octane gas and see if that helps.

Another thought I had was that of the choke. Perhaps if it's not set correctly it can cause the conditions you describe?

 

[thesameguy]

Please check, and back off your timing. This is what is giving you the pinging, and is dangerous to the engine. It's either the distributor being advance too much mechanically, or it's getting too much vacuum. One thing you can do is disconnect and plug the vacuum to the dizzy. Go for a drive. Does it still ping?

I am currently running 10 degrees. I have run everything from 8 degrees to 14 degrees. It does not change the behavior - even at 8 degrees it will still randomly ping. I have taken numerous successful drives at 14 without issue. I think too-aggressive timing should net reliable pinging - but I can drive for a half hour with no pinging, then not make it 10' before it sets in again. I think it's highly unlikely this is an actual timing issue, but I will try disconnecting the vacuum line and seeing what happens. It *seems* like if it was getting too much vacuum it would get that all of the time, not just sometimes.

Another thing that can cause pinging is an engine with carboned-up pistons. The top gets a layer of hard crud that can get thick enough to increase the compression ratio. You can try a hi-octane gas and see if that helps.[

I only run high-octane in this car. I can't get behind running cheap gas in an old engine designed for leaded fuel. But, again, I think if the combustion chambers were carboned up I'd see reliable pinging - not great running on one drive followed by bad running on the next. In any case, I am hoping a few tankfuls of Seafoam will clean that up... unfortunately, it takes a LONG time to go through a tank of gas since I can't reliably drive it.

Another thought I had was that of the choke. Perhaps if it's not set correctly it can cause the conditions you describe?

I feel like I am having the opposite effect of a choke - a choke should increased fuel and/or restrict airflow. That would result in rich running. I am getting the opposite, too much air and not enough fuel. The choke on the 1909 is pretty simple - a cable that acts on a cam which closes a butterfly and increases the base idle speed. At "open" the choke butterfly is totally open, and at "closed" the butterfly very closed. It does not appear to move at all during driving - I had thought that maybe it was shifting around, but that doesn't appear to be the case. The carb was just rebuilt, so I can only hope that any issues with the internal workings of the thing were addressed; when I picked it up they said the only actual problem was the float being damaged.

What are the chances I have a vacuum leak, and the engine is drawing air in from some place other than through the carb? That would lean it out, yeah? I notice plugs at the ends of the manifold... are they replaceable, are they prone to leaking? Maybe heat-cycling the engine causes something to shift, resulting in an unpredictable leak?

 

[thesameguy]

Is there any negative side effect of capping off the vacuum port to the fuel pump/windshield wipers and leaving the fuel/vacuum pump exposed to air?

 

[bubba22349]

The carb was just rebuilt, so I can only hope that any issues with the internal workings of the thing were addressed; when I picked it up they said the only actual problem was the float being damaged.

Was this repaired or replaced? The one area of these carbs that most people don't check is the throttle shaft play this can cause what you are experiencing.

Is there any negative side effect of capping off the vacuum port to the fuel pump/windshield wipers and leaving the fuel/vacuum pump exposed to air?

only dirt just cap them off

 

[CZLN6]

Howdy All:

I've been puzzling along with you on this perplexing problem. It is clear that something is being switched on and off to cause the Dr. Jeckel and Mr. Hyde transformation. Carbon build up is either there or not there. Initial advance is either too much or not. So those are two things that can be ruled out.

Thesameguy- you mentioned that this is a rebuilt Holley carb. Is it the service replacement #1940? I don't recall. How did the engine run with the original Holley #1908 carb? I'm guessing that the distributor is the original Load-O-Matic (LoM)? Does it still have a metal vacuum line from the carb to the distributor. Is the Spark Control Valve (SCV) there and functioning reliably? Some kind of malfunction between the SCV, the vacuum canister, and the LoM advance/retard mechanism is likely the cause for the on/off symptom of too much advance- assuming what you are hearing is pre-ignition pinging.

What do your spark plugs look like? Is there any sign of peppering? Is this a manual or auto trans combo? Have you removed the vacuum line from the carb to the distributor and blown air through it to make sure it is clear? If the SCV/LoM vacuum advance is working properly you should be able to watch it move from under the hood, by manually reving the engine. That's not to say it can't get stuck in the maximum advance position.

Keep it coming and hang in there.

Adios, David

 

[thesameguy]

Was this repaired or replaced? The one area of these carbs that most people don't check is the throttle shaft play this can cause what you are experiencing.

It was rebuilt by a local shop. I trust their work, but you're right, it could be an issue like that. Is there a way to check without disassembling?

 

[thesameguy]

I've been puzzling along with you on this perplexing problem. It is clear that something is being switched on and off to cause the Dr. Jeckel and Mr. Hyde transformation. Carbon build up is either there or not there. Initial advance is either too much or not. So those are two things that can be ruled out.

Yeah, that's kind of my thought.

Thesameguy- you mentioned that this is a rebuilt Holley carb. Is it the service replacement #1940? I don't recall. How did the engine run with the original Holley #1908 carb? I'm guessing that the distributor is the original Load-O-Matic (LoM)? Does it still have a metal vacuum line from the carb to the distributor. Is the Spark Control Valve (SCV) there and functioning reliably? Some kind of malfunction between the SCV, the vacuum canister, and the LoM advance/retard mechanism is likely the cause for the on/off symptom of too much advance- assuming what you are hearing is pre-ignition pinging.

It's the carb that came on the car (when I bought it, anyway ) - I believe it's a Holley 1909:

http://www.carburetorfactory.com/expvw12.html

(and, these are the guys that rebuilt it )

I don't believe it's the LoM - I think it's a straight old-school distributor. There is no spark control valve. I *think* both of these were introduced in the later '60s, and something tells me we didn't ever get the LoM in California. I was told by someone more knowledgeable than myself that the 1909 was substituted in California when stock ran low on Autolites... no idea if that's true or not.

What do your spark plugs look like? Is there any sign of peppering?

I haven't pulled the Motorcraft ones yet as they've done exactly 20 miles on them, but I will yank them this evening and check them out.

Is this a manual or auto trans combo?

Ford-o-matic!

Have you removed the vacuum line from the carb to the distributor and blown air through it to make sure it is clear?

It's brand new, purchased late last year from Falcon Parts in North Highlands. It was one of my first thoughts, as the one on the car had a messed up flare on the distributor side. I replaced it when I replaced the distributor and installed the Petronix. None of that made any difference.

Keep it coming and hang in there.

Falcons are simple, they told me! Anyone can make them run, they told me! Horse puckey! I have a 300hp 25 year old turbocharged Saab in the driveway and can't make the Falcon run. It's reasons like that why I drink!

At lunch I did this:

1. Pulled the PCV/crankcase breather hose off the carb. The PCV valve is shot. I will replace that, though I don't think it could lead to these symptoms.
2. Checked vacuum to the shift modulator on the transmission - it holds the kind of vacuum my mouth can generate. I'll check it with a Mityvac later... what type of vacuum will these motors pull under normal conditions?
3. Pulled the windshield wiper vacuum hose off the carb. It does not hold vacuum - I can hear the diaphragm in the fuel pump vibrating. I pulled the hose off that runs to the wiper servo to cap it, and the entire metal fitting came out in my hand. Probably not a good sign. Normally, should the vacuum pump hold vacuum itself, or just pass it through? This may be a dumb question, but where does the vacuum pump pump vacuum to? If the answer is "into the motor" then I may have found my answer - the vacuum pump could be sucking air from the broken fitting and pumping it into the motor - my own little supercharger! Sound plausible?

Related to this, if I replace the fuel pump with an electric, how do I power the wipers? Is there convention here?

Thanks guys.

 

[thesameguy]

Here's what I did:

1. Flared some 5/16" pipe and installed it in the carb's fuel inlet
2. Bought some 5/16" fuel hose and connected the pump to the fuel inlet
3. Flared some 5/16" pipe and installed it in the vacuum port for the vacuum pump, then capped it
4. Replaced the metal PCV pipe & worn out rubber couplers with rubber hose

http://www.sacsaabs.org/sacsaabs.org/mi ... ngine1.jpg

I realize there is no filter in the fuel hose - the filter on the car had 3/8" fittings (zero idea how the previous owner worked that out) and didn't fit. I'll pick up an inline filter tomorrow.

Here is the vacuum/fuel pump - notice the fitting is totally gone.

http://www.sacsaabs.org/sacsaabs.org/mi ... ngine3.jpg

That's because it's on the ground...

http://www.sacsaabs.org/sacsaabs.org/mi ... ngine4.jpg

I'm not sure if this can just be epoxied back in or what. Or maybe I don't care at all right now, since the chance of rain, or me driving in it is slim to none.

Lacking a fuel filter, and with it getting dark, and me uncertain about the whole deal I didn't drive it. I'll get a filter and do that tomorrow. High hopes...