Valve Index Timing - Possible Culprit?

[My-hobbies]

Ohhh.... BTW.. let me try the value lash setting the way you suggest and let me get back to you !

One problem I am now facing that that I have exhausted my rather large supply of totally unused plugs. I have a spark plug bead blaster, but nothing beats a totally new plug (learned that from dirt bikes). Some when clean work fine, some when I clean them run as if the plug is still not cleaned (If I put in another cleaned plug, engine rungs great for 10 min again), so I think I may be past the point of cleaning any of the fouled ones (do not want to introduce new issues).

The next plugs I want to try (hotter with full 3/4 " reach) it seems I will have to order (see my previous update) from Amazon or NAPA or somewhere else (delays). Unless someone has a good plug to suggest that the local parts store or NAPA, CarQuest, etc may have in stock (that I can ask them to check inventory). Otherwise I am maybe dead in the water until a spl order of new plugs can be got.

Thanks !

Jim

[ashman40]

I have a few suggestions you may want to try...

Have you tried swapping the #1/#3 plug wires with the #2/#4 plug wires?

Run the engine at night w/o lights and look for sparks jumping which would indicate a "leak" in the spark plug wire insulation.

I noticed you have a yellow (Accel?) ignition coil. What is the primary resistance through the small + and - terminals? The stock points needed 3 to 4ohms of resistance in the primary winding. Some aftermarket electronic points also needed the same while other models could handled as little as 1ohm of resistance. Confirm what you are using for points (mechanical or electronic) and what is the primary winding resistance needed.

Not mentioned anywhere above is that #1 and #3 cylinders SHARE the same two cam lobes. Yes, the ACVW cam only has four lobes shared by four cylinders. That's two lobes each shared by the opposing cylinders. So a damaged/flattened cam lobe for #1 cylinder also affects #3. This is the one area where #1 and #3 share a common component.
I was going to put this forward as a possible cause, but you confirmed that all cylinders are reading the SAME lift at the valve (relative to intake or exhaust), so this is probably not the case.

You should still try to map the opening and closing of the valves to their rotational position. They could give you an idea if your cam is indexed incorrectly, though I would think even if it were off by one tooth you would have a very badly running engine.

There is an EXTRA spark plug wire in your videos. It looks like a second coil to distributor HT wire. Why is that there?

Have you tried hotter spark plugs? You mentioned trying different heat ranges but also said you could only get your hands on a set of "6s". Hotter plugs will resist fouling better.

Are you replacing these plugs as they foul or are you attempting to clean them? The only good way to clean plugs is with a media blaster and non-conductive glass beads. Using a wire brush can create conductive paths of carbon between the electrode and the grounded casing that shorts out the spark and it doesn't ignite fully/at all. Unless you have the proper cleaning tool you should just replace plugs that have fouled.

If you are just letting the engine IDLE for 20min you are asking for the plugs to foul. To properly READ the spark plugs you want to run the engine at speed. Much of the deposits can be burnt off by an engine running at constant rpm (like 2500rpm+).
If there is a noticeable temp difference between the front (#1 & #3) exhaust pipes and the rear (#2 & #4) exhaust pipes this is a BIG clue that the cylinders are NOT firing at idle.
With new (hotter) spark plugs, start the engine and take her for a drive on the freeway. Maintain a constant speed for 10min and them pull over quickly shutdown where you can work on the engine. Pull the plugs (may need to let the engine cool) and see if there is a difference in the spark plugs when all four are running HOT / under load. Check the temps of the exhaust pipes and see if there is still a front/rear difference?
It is not uncommon to see #1 & #3 not firing consistently at idle.

Have you looked closely at the ignition system? Check that the resistance through the plug wires is nearly the same? Are you running resistor/supression wires or solid core? Solid core will have metal conductors that pass the maximum current. Suppression wires are not typically needed in a Dune buggy as radio noise quality may not be a big concern. Also, your plugs are also resistor and if you are running a stock Bosch distributor rotor it has a built in resistor. The stock Bosch plug wires were non-resistor solid core. I cannot tell what type your nice "yellow" wires are, but most aftermarket wires are suppression core which are not needed in Beetles. Typically you only want ONE resistor in the ignition circuit and and it can be any one of the following:
- HT resistor wire between coil and distributor cap
- Resistor in the rotor
- Suppression (resistor) plug wires
- Resistor spark plugs

Your #1 spark plug wire is at the 7-o'clock position. This tells me your distributor drive gear is installed incorrectly. Nothing wrong with this as long as you are aware of this. Depending on the distributor model the #1 spark plug wire should be at the 1-o'clock or 4-o'clock position.
If you are running an electronic point module this might explain the shift too.

Check the temp of your riser pipe after you have driven it hard. The heat riser pipe is meant to have exhaust gases flow in one side and out the other. One side should be connected to the exhaust manifold near the head port, the riser tube carries the heat to the intake where it prevents condensation and icing by heating the intake manifold. This is a BIG problem with the center mounted dual barrel carbs.
The return pipe should connect to the exhaust manifold at a point of low pressure which will draw the exhaust gasses through the heat riser. Most cheap after market headers will just add flanges to the exhaust manifolds and expect the heat to magically move in the correct direction. This typically causes exhaust gasses to ping pong back and forth within the heat riser and never get to the proper temp. Here is a pic of what a proper header + heat riser setup should look like with the exit pipe running to the merged section of the header where the flow can draw gases through the heat riser pipe:



This is what the stock exhaust looks like:



Fuel condensating in the intake could flow into just a pair of cylinders (like #1 and #3) depending on the rake of the car and the intake manifold. The temp of the heat riser tubes plays a BIG part in preventing liquid fuel from collecting in the intake. If you see condensation forming on the outside of the intake, then the inside is colder than the outside and can cause the fuel to pool.

The last item is my best guess at your problem.
_________________
AshMan40
---------------------------
'67 Beetle #1 {project car that never made it to the road }
'75 Beetle 1200LS (RHD Japan model) {junked due to frame rot}
'67 Beetle #2 {2019 project car - Wish me luck!}

[My-hobbies]

Hi ashman40.

Thank you very much for the detailed response and the effort (typing) and thought you have given this. In 40+ years of the old car hobby, this VW issue ranks right up there with the top ‘aggravation… have wasted so much time…. frustration…. What the heck can the issue be….’ of all my life in this hobby. And that spans at least 10 car restoration projects done hands on by me. This VW buggy, is turning into something like a bad old flame (gal) that in the end was not worth the effort….. putting lots of lovin’ in but aint’ getting any back

Let ne hit your points, point by point to stay organized…

I have a few suggestions you may want to try...

Have you tried swapping the #1/#3 plug wires with the #2/#4 plug wires?
JD; Yes.. brand new ignition wires, but as I am trying anything at this point, have also swapped around wires between the diff cyl to see if it is a wire.

Run the engine at night w/o lights and look for sparks jumping which would indicate a "leak" in the spark plug wire insulation.
JD; Yes.. did that about 3 nights ago. I saw some arcing between the (-) on the coil and the coil tower when the plugs were fouled. I attributed this to that the ignition charge was having no place to go when the plug was fouled and was looking for the path of least resistance.. arched across the coil tower to the coil (-) terminal. That was on an Accel coil in there (came with the buggy). I had the same coil in my GTO, so as a test, pulled the one from the GTO and put it in the buggy 2 nights ago. No chg. But on closer inspection of the old buggy coil, I did see a crack on the old coil between the (-) and the tower. All the fouled plugs could have done it, forcing the current to go someplace and eventually cracked the coil between the tower and the (-) terminal. Nonetheless, the coil I know works from the GTO is still having plugs foul.
JD; I think I will test the ohms on the new ignition wires that are installed and report back on that. They were installed when I was first trying to diagnose this issue.. so they are now not technically ‘brand new’, but an thinking that all this running with fouled plugs could have raised the resistance (burnt) a little the core of these new wires as well.

I noticed you have a yellow (Accel?) ignition coil. What is the primary resistance through the small + and - terminals? The stock points needed 3 to 4ohms of resistance in the primary winding. Some aftermarket electronic points also needed the same while other models could handled as little as 1ohm of resistance. Confirm what you are using for points (mechanical or electronic) and what is the primary winding resistance needed.
JD; As part of diagnosis (really as part of frustration) after changing the stock points and condenser twice with no fix, I installed a Pertronix (spelling) electronic module in the dist. That did seem to prolong a bit the time it took to foul the 1 + 3 plugs. I have not checked the resistance on the Accell coil, but as you suggest, I will. I will check the primary and secondary resistance and report back.

Not mentioned anywhere above is that #1 and #3 cylinders SHARE the same two cam lobes. Yes, the ACVW cam only has four lobes shared by four cylinders. That's two lobes each shared by the opposing cylinders. So a damaged/flattened cam lobe for #1 cylinder also affects #3. This is the one area where #1 and #3 share a common component.
I was going to put this forward as a possible cause, but you confirmed that all cylinders are reading the SAME lift at the valve (relative to intake or exhaust), so this is probably not the case.
JD; Yes… The deltas in the valve min and max height points (from my ref measure points on the valve spring caps) were identical across all cyl, intake to intake, exhaust to exhaust.

You should still try to map the opening and closing of the valves to their rotational position. They could give you an idea if your cam is indexed incorrectly, though I would think even if it were off by one tooth you would have a very badly running engine.
JD; Did it, and it is consistent across all cyl. (and that would make sense.. if one cyl was late or early in the valve timing they all should be). See my most recent post where I wrote some findings on the Intake staying open until about 80 degrees into the compression stroke, and the exhaust starting to open about 110 degrees into the power stroke.

There is an EXTRA spark plug wire in your videos. It looks like a second coil to distributor HT wire. Why is that there?
JD; Yeah… good eye. That is an extra coil wire hanging there as I was swapping ignition wires between my GTO and the VW to see if any diff would be made (even though the VW wires are relatively brand new.. see prior note on wire theory and ohm test)

Have you tried hotter spark plugs? You mentioned trying different heat ranges but also said you could only get your hands on a set of "6s". Hotter plugs will resist fouling better.
JD; Yup.. see prior post on the plugs that I have used. All have been NGK plugs for what it is worth.
JD; That prior post wrote that I did not have long reach plugs in the 5 and 4 heat range. Today I located and picked up some BPR5ES and 4 ES plugs. Going to try them soon as I am done writing this.

Are you replacing these plugs as they foul or are you attempting to clean them? The only good way to clean plugs is with a media blaster and non-conductive glass beads. Using a wire brush can create conductive paths of carbon between the electrode and the grounded casing that shorts out the spark and it doesn't ignite fully/at all. Unless you have the proper cleaning tool you should just replace plugs that have fouled.
JD: I have a plug media blaster device that I clean the plugs with. But even then, I do not fully trust any ‘cleaned’ plug (learned that from dirt bikes). But also I have been going through so many plugs within 10 minutes that I cannot just keep throwing them all out. So I have been balancing between totally new when I have a ‘new theory’ and cleaned ones when I do thing like reset the valve lash for the 14th time.
JD; As noted.. I now have some long reach ‘hot’ and ‘hotter’ plugs to try that I picked up this morning. So this nest test with the ‘hot’ long reach will be brand new plugs.

If you are just letting the engine IDLE for 20min you are asking for the plugs to foul. To properly READ the spark plugs you want to run the engine at speed. Much of the deposits can be burnt off by an engine running at constant rpm (like 2500rpm+).
If there is a noticeable temp difference between the front (#1 & #3) exhaust pipes and the rear (#2 & #4) exhaust pipes this is a BIG clue that the cylinders are NOT firing at idle.
With new (hotter) spark plugs, start the engine and take her for a drive on the freeway. Maintain a constant speed for 10min and them pull over quickly shutdown where you can work on the engine. Pull the plugs (may need to let the engine cool) and see if there is a difference in the spark plugs when all four are running HOT / under load. Check the temps of the exhaust pipes and see if there is still a front/rear difference?
It is not uncommon to see #1 & #3 not firing consistently at idle.
JD; After I complete the top end a week or so ago, new plugs, I drove and thought ‘yeah… !!!! it is working… solved this issue’. Then about 5 miles later plugs started fouling again and had to limp home on 2 cyl (not far as I stayed on a test run loop within ½ mile of home).
JD; On the current fouling, I do not drive it as I know I will not get far. So I simulate a drive my reving the engine up and down, and in about 5 min (8 max) the plugs on 1 and 3 are fouled.

Have you looked closely at the ignition system? Check that the resistance through the plug wires is nearly the same? Are you running resistor/supression wires or solid core? Solid core will have metal conductors that pass the maximum current. Suppression wires are not typically needed in a Dune buggy as radio noise quality may not be a big concern. Also, your plugs are also resistor and if you are running a stock Bosch distributor rotor it has a built in resistor. The stock Bosch plug wires were non-resistor solid core. I cannot tell what type your nice "yellow" wires are, but most aftermarket wires are suppression core which are not needed in Beetles. Typically you only want ONE resistor in the ignition circuit and and it can be any one of the following:
- HT resistor wire between coil and distributor cap
- Resistor in the rotor
- Suppression (resistor) plug wires
- Resistor spark plugs

JD; Very good theory !!!!! Something new to test. Let me look. The new wires I purchased I do not recall if they are resistor or not. I also do not see any marks I recall on them. The rotor (also new) I think is a Bosch. But I do not know for sure now… havce tried so many things at this point do not remember all the details. Plugs… as the plugs are BPR(number)ES (eg; BPR5ES) the ‘R’ as I recall would mean resistance. So we may be picking up resistance in 3 places; Rotor, Wires, and Plugs.
JD; Let me photograph and post what I have.. perhaps some people can weigh in as to what the wires and rotor are.

Your #1 spark plug wire is at the 7-o'clock position. This tells me your distributor drive gear is installed incorrectly. Nothing wrong with this as long as you are aware of this. Depending on the distributor model the #1 spark plug wire should be at the 1-o'clock or 4-o'clock position.
If you are running an electronic point module this might explain the shift too.
JD; Position of rotor when cyl #1 is at compression stroke TDC is how I got the buggy. If it is in the wrong position, the dist could have been put in off a gear tooth or 2. I will take a photo of the dist w/o the cap on to show the rotor. But as you suggest, as long as the dist can be rotated to compensate, even if out a tooth, should not cause a problem.

Check the temp of your riser pipe after you have driven it hard. The heat riser pipe is meant to have exhaust gases flow in one side and out the other. One side should be connected to the exhaust manifold near the head port, the riser tube carries the heat to the intake where it prevents condensation and icing by heating the intake manifold. This is a BIG problem with the center mounted dual barrel carbs.
The return pipe should connect to the exhaust manifold at a point of low pressure which will draw the exhaust gasses through the heat riser. Most cheap after market headers will just add flanges to the exhaust manifolds and expect the heat to magically move in the correct direction. This typically causes exhaust gasses to ping pong back and forth within the heat riser and never get to the proper temp. Here is a pic of what a proper header + heat riser setup should look like with the exit pipe running to the merged section of the header where the flow can draw gases through the heat riser pipe:
JD; Will give a detailed pic of the aftermarket headers that came on the buggy. They are of the type that you write. Just a flange on cyl 4 and 2, each flange connected to a riser that runs to the bottom of the carb manifold (manifold under the carb). I wrote yesterday that the risers are hot to the touch, but only about ½ way up them. Then they are only ‘warm’ as the surrounding engine area. This would suggest that they are either clogged, or the gases pinging as you suggest.
JD; Is this really a ‘huge’ deal and a very strong candidate as a likely cause ? I frame this in the context of level of effort…. that having pulled that intake manifold off and on 3 times now as part of troubleshooting theory, it is a lot of work (it does not come off w/o removing all the dog house tin, to make room to lift the alternator perch, to make room to remove the intake manifolds, to finally get the carb base manifold off (which has the heat risers press fit into). Lots of work that I hate doing each time and each time I say ‘this better be the last time’  I mean.. will it run, but perhaps stumble with bad heat risers, or can it be so bad that plugs are fouling so soon ? A lot of work if it is a dead end. BTW.... Last week was humid up here in the Northeast US, and when running, I would see condensation on the manifold below the carb.

Man.. I am really not feeling the lovin’ back from this dune buggy !!!! Ha ha !!!!

Thank you so much for the effort !!!!

Jim – West of Boston area.