timing cause pinging or other reason

[Bob]

Rather than continue using an older message thread about venting the engine I thought I should begin a new one here.

My test drive today didn’t go well at all, even though the pinging might have been less with timing at 28 degrees. Didn’t seem to have the same power anymore and had run-on when shut off, worse than when timing was at 32 degrees. I just about had the run-on trouble gone at 30*.

Sorry I left that detail about the run-on or dieseling out of the equation.

 

So now if 29 degrees (talk about fine tuning!) isn’t getting me anywhere I suppose I will give higher octane a try like Royal was suggesting.

BTW I’m using 100% gasoline right now, not the 10% ethanol around here so the ethanol blend would be another thing to try for better or worse.

Got to get a look inside the cylinders anyway in an attempt to confirm carbon deposits aren’t a problem.

[Royal]

Bob, the worst part of your troubles is the time of the year that they are occurring. This is get out and drive it time.

I assume that this problem is rather new and you did not have it until recently? ??

Switching to ethanol fuel should make the problem worse since E10 more readily vaporizes.

I can’t think of a timing reason that would justify worse pinging at 28 than at 32.  Going from 32 to 28 would lead to a decrease in power in a good healthy engine, as you know.  Were ambient conditions the same for earlier run @32 and later @28 when pinging was worse?   Engine fully warm on both test runs?   

Can we assume that there are no vacuum leaks?  Do these Webers have a vacuum port?  (I can’t remember.)

I would first change back to standard plugs.   While you have the plugs out, run a compression check.  (just because it’s easy….. I wouldn’t expect this to reveal the cause of dieseling or pinging) 

Change to the highest octane fuel they sell.  (although this shouldn’t be necessary)

Are you sure that the guts of your carb are clean and you are not running severely lean? 

I just hate pulling an engine in May. 

But if you gotta, then you gotta.  And if you do gotta, pulling a VW engine is almost fun (comparatively).  

How ’bout some help from somebody else.  Kent?  Ed? 

[edward ericson]

Cam and higher compression, are my guesses. This is an engine owned by a person who knows how to set static timing, right? So if it’s right for a stock engine–and 28 btdc at 3000 is right–then the timing ain’t the issue. We don’t know how stock it is though. A short duration, high lift cam (or ratio rockers) could raise the comp ratio into the danger zone, theoretically.

More likely it’s carbon on the tops of the pistons from running only in parades and cruise-ins and never on highways or autoX tracks. I’d mix some h2o and alcohol in a pint container with a small vacuum hose going into it, connect the hose to the carb’s vac port and run the engine about 2-3k rpm to suck it into the cylinders. Five or ten minutes of that should clean out any carbon deposits.

If she still pings then, new, right plugs, then check the rockers, then resign to running hi-test.

[KentT]

Run-on or dieseling is normally reduced when timing advance is slightly reduced, so it’s hard to picture why 28 degrees total advance would be worse than 30. It’s also typically a factor of lean mixtures, as described. The stock 34 PICT Solex for dual port engines had an anti-dieseling solenoid that completely shut off fuel flow when the ignition switch was turned of to prevent the engine from sucking in additional fuel as it spun down, preventing/reducing potential run-on. The stock distributor also had vacuum retard at lower RPMs in addition to vacuum advance at higher RPMs.

Which specific Weber carb are you running? It likely does not have such a solenoid. My guess is simply a too-lean mixture on the primary circuit for the RPM range that you are typically operating. This is a common symptom of the 32-36 Weber-type progressive carb mated to an 009 distributor. The combination of the faster advance of the 009 and the lean mixture of the primary circuit at the 3000-3500 RPM (or so), before e secondary circuit kicks in, leads to higher head temps (not necessarily oil temps), and causes the run-on.

This is typically resolved by either rejetting the carb to give a richer mixture on the primary circuit (and likely a slightly leaner mixture on the secondary circuit to balance that), swapping to a different distributor, or carb, or both. That’s why progressives on VW engines have often gotten a bad reputation with their out-of-the-box jetting. Once correctly jetted, they’re fine, but…

30 degrees total advance should not be a real issue, IMO. I’d recommend trying to find a local air-cooled mechanic who can help with these jetting/timing issues… If the carb has a vacuum port, swapping to a different distributor such as stock or a Pertronix may resolve the issue, as would a carb with an anti-diesel solenoid, but swapping/experimenting can get expensive. That’s why I’d recommend a professional – they may even have spare or other used carbs/distributors that they could experiment with…

And yes, general engine cooling is a factor in run-on, since hot engines are more prone to do so, though your oil temps sound fine, assuming your gauge is accurately reading and reporting that…KentT2015-05-06 08:34:07

Early FF TDr on 69 VW pan
Slowly coming back from the ashes...

[edward ericson]

Kent is smarter than me.

[john barry]

[KentT]

edsnova wrote:

Kent is smarter than me.

Nope! Maybe just more “hard knocks” with VWs that I’ve paid for on VWs over the years… 😉

Early FF TDr on 69 VW pan
Slowly coming back from the ashes...

[Bob]

In this case everyone here is probably smarter than me since I just started learning about VW’s a couple months ago.

That fuel shut-off solenoid is what I was trying to remember, had read about it somewhere. Fairly sure I don’t have it. This Weber does have plugged off vacuum port(s). I think it says DFAV on it, not easy to read the “F”, could be an E.

A little background about the car… PO was builder but had it finished by pro builder company, and I don’t believe he did anything to the mechanical stuff himself. So the unknown factor is what the “replacement” engine really is (blank serial # area below alternator pedestal base). I know it is said to be a 1600 and that makes me think it’s simply a straight from the factory stock setup.

Although I found the basic non-vacuum 009 distributor was installed 90* CCW from what it should have been (according to various sources), seems to me that might only be a quirk of the builder and not indicate custom parts were used. All really guesses, of course. I have all, or almost all, paperwork but nothing I’ve seen shows engine parts.

I will go about testing compression and checking on things best I can. What you tell me about timing alone not being the real reason for this particular problem is what I needed to hear, so a tremendous thanks for that!

Will check back again sometime.

LRH2015-05-06 18:20:58

[KentT]

I’d check for vacuum leaks everywhere – manifold end castings where they bolt onto the head. The rubber/neoprene connectors where the manifold center section connects to those end castings on each side. The gasket where the carb bolts to the manifold. And where those vacuum lines are plugged. A vacuum leak will cause the pining/rattling you describe…

If that doesn’t work, I’d consider replacing the 009 with a Pertronix SVDA with electronic ignition…

Typical complaints with the Weber DFAV 32/36 are either bogging when the secondary kicks in, or backfiring when you let off on the accelerator – neither of which you’ve mentioned.

KentT2015-05-06 22:28:11

Early FF TDr on 69 VW pan
Slowly coming back from the ashes...

[Bob]

KentT wrote:

Typical complaints with the Weber DFAV 32/36 are either bogging when the secondary kicks in, or backfiring when you let off on the accelerator – neither of which you’ve mentioned.

It did backfire upon releasing accelerator when it had 32* advance, which is why I thought I should try 30*. And the run-on was really bad before I did. 30* was best, other than noticing the pinging when accelerating hard, as in putting the pedal to the floor.

Definitely has the bogging at first quick push of the accelerator, have since learned to give it a little time and take off smoothly. I don’t really notice bogging at speed, RPM up around 2500 or more, and flooring it. Only the slight feel of going to the secondary. Note here that I’m comparing the change a hard acceleration causes from other cars. I just know the carb is doing something of a boost in a weaker way than I’m accustomed to.

All the pinging comes when I do that, floor the pedal or give it more gas on a hill. If it does it other times I can’t be absolutely sure but I’ve imagined hearing a similar sound of singular pings once in a while going downhill or cruising at higher speeds.

I will definitely search for air leaks per your advice. That was a prevalent problem from my air-cooled motorcycle too (even though it never had an obvious ping sound it has had a curious growl noise before I fixed leaks).

Going to try the idea of funneling something into the vacuum port, too, I have a can of Seafoam that should suffice for that.

[Derek]

I’ve got a Weber progressive on my 1600DP and I’m not getting any pinging. I got mine from ACN (Aircooled.net) and had them jet it for me based on my altitude. My main circuit is leaner than the secondary. The reason for this is smooth cruising on the idle circuit but more power on the secondary. ACN has some good tech articles if you want to check them out. http://www.aircooled.net/vw-technical-articles/

You might also shoot John over there an email as he has dealt with a fair amount of these carbs and he was very helpful when I had questions.

[edward ericson]

Hey would having the disty out 90 degrees mess with that slightly retarded #3 timing the VW people engineered in? Or does the 009 lack that feature?

And BTW, wasn’t the 009 made for dual carb setups where a good vacuum was not convenient to get? Seems like a good SVDA disty hooked to the 32/36 vacuum port would be the way to get the timing advance right. 

I concur on the vacuum leak check though. Definitely should be an early check.

[greg press]

When I was 20 years old I had a 1965 Ford Falcon with a 289 in it . It did a lot of pinging . I was told it was cheap gas . I assumed it was.

[Bob]

edsnova wrote:

Hey would having the disty out 90 degrees mess with that slightly retarded #3 timing the VW people engineered in? Or does the 009 lack that feature?

And BTW, wasn’t the 009 made for dual carb setups where a good vacuum was not convenient to get? Seems like a good SVDA disty hooked to the 32/36 vacuum port would be the way to get the timing advance right.

Thought I could put up with the hesitation of the centrifugal advance. Not really costly to make the switch to vacuum so I think I probably will.

You know what, I realized just now that I had read about the DFAV being a water controlled choke. Can’t imagine that’s the actual type then, but I remembered looking for a DEAV and didn’t find anything, so I’m confused about what the model type actually is. The choke mechanism looks purely mechanical to me, however I have yet to get a very good look at it behind there.

That thing about the #3 cylinder with a possible difference is another thing I read about before and wondered how the heck it gets implemented. I was thinking it couldn’t be the distributor itself, only a single lobe to actuate the contact points. Unless there’s something additional in there. I figured it was internal to the engine, a valve cam lobe or some such. Or some way the worm gears mesh from engine to distributor, although less likely right?

I’ll look at SVDA distributors while I learn more about all this and decide later what to do.

Oh BTW, got pictures or my #2 spark plug and piston top, and a small area of the piston edge and cylinder wall. Not the best photo, being a camera picturing a LCD display, but maybe it’ll show what I’ve found there. By comparison to my motorcycle this VW is very clean, just looks like a minor amount of carbon wetted by fuel, whereas my motorcycle pistons show obvious rough edges on the piston top indicating much more carbon buildup.

[KentT]

The retarding of the timing on the #3 cylinder on the 009 is done my slightly offsetting the location of the sparkplug wire on the distributor cap.

The 009 was originally designed for stationary engines used to power air compressors, generators and such, unless I’m mistaken. The 010 was designed for use in the much heavier VW busses, and is considered a much better performance distributor. But, they’re no longer available new and good used/rebuild able ones are hard to find. A Brazilian company, Brosol, I think, used to sell a clone. I have one lying around somewhere. 010s use 2-piece points that are a PITA to set and adjust and are VERY hard to find.

Back on topic – that piston looks fine to me, and it looks like the mixture may be just a tad rich overall based on the sparkplug. (Note this is overall and not indicative of either the primary or secondardary jetting.) Excessive pinging aka predetonation will sometimes show on a plug as brown, but I don’t see that on yours…

My advice is unchanged…KentT2015-05-08 18:25:14

Early FF TDr on 69 VW pan
Slowly coming back from the ashes...

[Bob]

Okay, that’s interesting. I changed the distributor cap to a clear red one so I’m going to go back to the other and see if I can notice a #3 offset while I’m at it.

😮

Also going to see about turning the fuel mixture screw in a little, and try different gas too. The 100% stuff isn’t cheap, of course, but it isn’t a major brand either.

Thanks again Kent!

[Bob]

Interesting twist to all this, literally. I might have been using the new digital timing light wrong. It’s a Actron with the advance adjustment buttons and is shown on the display.

I was setting it to the degrees advance and then revving the engine, twisting on the distributor to get the pulley timing mark lined up with the crankcase split when the RPM reads over 3000.

If you’re not familiar with this timing light the advance setting and RPM is shown using a single button, pressing it repeatedly to display either one.

I was trying another timing adjustment before going for gas today and noticed the timing mark was in the right place, or very close to it, without revving the engine. That was with the light dialed in for 30 degrees advance.

The curious thing about this was how I had been turning the distributor before checking with the strobe light, finding where the engine seemed to run best.

I can only guess I misused the timing light. Trying to understand this now. And talk about misusing it… I had been powering it directly from the alternator and the display went out and I noticed a little smoke from the timing light before disconnecting it.

I’m totally unfamiliar with these digital gadgets, so I not only might have timed the engine wrong before but wasted $80 and a very useful device!

😕

I will leave you, reading here, to say what you will. 

Oh yeah, almost forgot to tell that I filled the tank with almost 7 gallons of 89 octane 10% ethanol from Chevron and no pinging! Not yet noticed anyway, and I tried hard accelerations and high gear uphill. Plenty of power, like it hasn’t had before, not that it’s considerably different though just better.

LRH2015-05-10 19:45:01

[Bob]

Update: I can be so stupid sometimes and this one is a perfect example. I was using the wrong timing mark on the pulley! The little v notch for 5 degrees ATDC instead of the small dent or dimple on the right of it. These are the only two markings my pulley has.

Somehow I got it in my mind the dimple was to be ignored in favor of the 5 degree mark for a starting/ending point with this 009 centrifugal distributor.

I was like, why oh why couldn’t I have made sure again before attempting to use a timing light not once but over and over again!

Not only that, I still hadn’t checked for true TDC until today. After I physically found TDC for #1 using a straw in the spark plug hole, moving the pulley clockwise and CCW repeatedly, and seeing the distributor rotor point to #1 spark plug wire I did another timing strobe (with new light) on the dimple while revving the engine above 3000 to about 3500 RPM, and was sure I had full advance. Had timing light dialed in for 30 and then 32 degrees where it seemed to want to be.

Idle speed adjusted downward, because of an increase, about 860 to 900. Going to recheck tomorrow since I didn’t get to do a test drive today with other important things to do. Really wanted to find out if this will solve the pinging, but was nice to shut down the engine and not have it doing the run-on I was experiencing almost every time since I got the car. Can’t count on that meaning something yet; the run-on was never a certainty at every shut off, just happened a whole lot before. Can’t wait to find out for sure.

Now I’m wondering why spark plugs have a lean fuel mix look (fairly white insulators) on only #1 and #4 but plenty of color on #2 and #3. Those will have to be rechecked after I get a test drive done.

Just glad to get past the dumb mistake with the timing marks for now! Really appreciate the helpful advice given me before anyhow. Many thanks.

BTW, sorry for not answering all the questions put forth way back there, asked by Royal (aw heck, how many chances do I get to edit!!? ha ha!) . Thought I had said at least something about it being warm weather, temps in the 70’s and 80’s. Drives were 15 to 45 miles or thereabouts so oil temp varied from 170 to less than 220. But now, of course, this is practically meaningless with me timing the engine 5 degrees off until now. I guess that made it 23 to 27 degrees advanced instead of what I thought was 28 to 32. Weird, right? Pinging from being under-advanced! Not that I really know anything yet but that would seem to be what it was.

LRH2015-05-15 01:09:44

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