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Sun May 18, 2025 12:55 pm

I can’t believe I am seeing one of the distributor cap spring clips NOT indexed into the cap. It actually looks like the retaining clip is inside the distributor cap. Please tell me I am wrong.

Sun May 18, 2025 12:59 pm

Wasted youth wrote: I can’t believe I am seeing one of the distributor cap spring clips NOT indexed into the cap. It actually looks like the retaining clip is inside the distributor cap. Please tell me I am wrong. we are going to give you a nickname of "old eagle eyes." Yes that is what is in the picture. I hope it was not run that way.

Sun May 18, 2025 1:21 pm

Wasted youth wrote: I can’t believe I am seeing one of the distributor cap spring clips NOT indexed into the cap. It actually looks like the retaining clip is inside the distributor cap. Please tell me I am wrong.

lol, I just had the cap off to take the other photo. I just set it in place for the pic so it wasn't hanging in the way

Sun May 18, 2025 1:26 pm

SGKent wrote: there is a lot of debris at the base of the distributor. I am puzzled by why that would be on a fresh install.

When you set it to say 30 degrees BTDC at 3400+ RPM, that is with the hoses off.

We didn't replace the distributor, just the points and condenser. Does it the distributor need to be removed to replace those?

With the hoses off? It is a centrifugal advance distributor, so no vac hoses, if I am understanding your question right.

Sun May 18, 2025 1:32 pm

SGKent wrote:
You can turn the rotor to see if the distributor is fully seated. If not it will spin if you pull up just a little on it. Do not turn too hard of the nub in the bottom that locks in in place will break off. You can also look at the bottom of the rotor to be sure that has not happened already.

Gave that a try. It doesn't "spin", but it does have maybe 3-5 deg of movement or slop when I apply gentle pressure to the rotor.

Sun May 18, 2025 1:44 pm

Greg Schoolbus wrote: SGKent wrote: there is a lot of debris at the base of the distributor. I am puzzled by why that would be on a fresh install.

When you set it to say 30 degrees BTDC at 3400+ RPM, that is with the hoses off.

We didn't replace the distributor, just the points and condenser. Does it the distributor need to be removed to replace those?

With the hoses off? It is a centrifugal advance distributor, so no vac hoses, if I am understanding your question right.

If it was not loosened then it would be engaged the same as it was. However the clamp has to be loosened to change the timing so it can raise up then. Use a paint brush of something to brush away the debris at the base and take another photo. I would replace the condense with the one I suggested. That said, Wasted Youth is someone you should try to work with as a Mentor. He has a lot of experience with these bays as he has used one to get to and fro with his work. He is a great person to learn from. I am in the Sacramento area but we never get down that way. These buses pretty much require that the owner end up learning how to work on their own tuning and problems.

You should have two tools for sure - an inductive timing light, and a dwell tach.

Sun May 18, 2025 2:08 pm

SGKent wrote:

If it was not loosened then it would be engaged the same as it was. However the clamp has to be loosened to change the timing so it can raise up then. Use a paint brush of something to brush away the debris at the base and take another photo. I would replace the condense with the one I suggested.

You should have two tools for sure - an inductive timing light, and a dwell tach.

I have played with the timing quite a bit in the past two weeks by loosening and tightening the clamp at the base of the distributor. I have a borrowed inductive timing light, and am putting it on the list to purchase. I do have a dwell tach meter.

I have the condenser ordered. :thumbsup:

Here's a photo of the spot a little more cleaned up.

Sun May 18, 2025 2:17 pm

One other thing I am thinking about is the leak at the intake manifold. Would this gasket be an acceptable choice? Thanks (hope it's not taboo to introduce another question to the conversation. i am wondering if this may be contributing to the problem)

https://www.jbugs.com/product/022129707F.html

Sun May 18, 2025 2:48 pm

when you loosen the clamp on the distributor, push down on the distributor to keep it seated as you tighten the clamp again.

You can take a propane torch, not lit of course, and run it around the manifold area. If the idle speed changes, it is because it is pulling in propane around a leak. Or you can get a smoke generator and check for leaks that way. A spray can of Berryman's B12 can also be used to spray just a little around the base of the carb, runners etc., to check for leaks also.

Another test you can do is with the engine running at idle, and your shirt sleeves and hair, chains etc out of the way so the belt does not grab them and hurt you, use a dry rag to carefully pull one plugs wire at a time. See if the engine speed drops rather evenly and that all cylinders are firing equally.

Sun May 18, 2025 3:00 pm

SGKent wrote: A spray can of Berryman's B12 can also be used to spray just a little around the base of the carb, runners etc., to check for leaks also.

A test someone online recommended was spraying brake cleaner near the manifold, and that did affect the idle.

Sun May 18, 2025 3:14 pm

just about any flammable liquid spray would serve,

Sun May 18, 2025 3:17 pm

SG Kent makes me out to be way more than I actually am. But it’s a nice compliment.

Yes, that is the correct intake manifold gasket. Some people might refer to it as a phenolic block. Sometimes those blocks are sold without the gasket material.

Definitely change those out. Your picture of the crumbling phenolic block is a red flag in my book. Those are way past their lifespan.

My first experience with those on the 73 bus was a surprise and an interesting learning experience. I had a very shrill whistle coming from the engine and it freaked me out. It was a perfectly tuned vacuum leak from one of those blocks!

You can also check for vacuum leaks with a squirt bottle with just plain water. It’s not as effective as flammable gases, but if the engine sound changes when you start spraying the water on it, it’s because the vacuum leak was temporarily filled with water.

Keep in mind that if you have a “leaking“ secondary ignition system, and you’re using propane torches or acetylene gas, you can have an interesting experience with fire.

My favorite tool for finding vacuum leaks is an oxy/ ace gas outfit, with the acetylene turned off, the small gas welding tip applied and using just oxygen. The welding tip is very nice, because you can really pinpoint where the leak is, the oxygen is not flammable, it’s cheaper than starting fluid or brake cleaner or any other stuff. It’s dry so it doesn’t leave a residue, and introducing raw oxygen into the airstream definitely will change the engine RPM quickly.

Sun May 18, 2025 3:17 pm

Greg Schoolbus wrote: SGKent wrote: A spray can of Berryman's B12 can also be used to spray just a little around the base of the carb, runners etc., to check for leaks also.

A test someone online recommended was spraying brake cleaner near the manifold, and that did affect the idle.
some brake fluid is flammable, some is not. That is why I did not suggest it. If you spray too much the fumes will carry up to the carb. If you spray just a tiny bit with the wand and just a little in certain spots changes the idle, then you have a leak in those spots. It may or may not cause the backfiring, but it does need to be dealt with.

Sun May 18, 2025 3:30 pm

I have never been able to make those phenolic blocks work on the Prog manifolds, or the paper or aluminum gaskets for that matter, the flanges are so weak and warpy the only thing that stays sealed is 3/16" cork that you cut yourself from gasket sheet.

Sun May 18, 2025 3:30 pm

And after you get ready to replace those phenolic block gasket things, also renew the lock washers under those 13 mm nuts. Those nuts do loosen up over time and cause more vacuum leaks even when you think there shouldn’t be one there cause, by golly I just replaced those damn things six months ago.

You said you did those initial tasks I suggested, so at this point, your engine should be mechanically timed at its base timing arrangement. Your next timing will be fine-tuned with the timing light.

If your engine still runs like shit, and you have replaced the primary and secondary ignition system components with good quality components, (that are actually functioning as designed, and not just dog shit wrapped in pretty paper), you may have fallen into some rabbit hole, which is gonna suck but will be a good learning experience.

The Weber progressive carburetor can actually be made to run correctly, but it first needs to be jetted correctly. You’ll just jerk yourself off until your ball sac is empty trying to make your engine run if that Weber is not jetted properly.

Or, you can screw around with so many different combinations of troubleshooting so much, that your brain goes numb and you start doing things that make no sense and actually risk causing more damage.

If the Weber is actually jetted properly, you have the correct volume and pressure of fuel delivery to the carb, and the accelerator pump is working and it’s not fouled with varnished gasoline and there’s not pieces of an earwig hiding in one of the jets or some other bullshit, you may have mechanical defects in your engine.

This is where I would reach for the leak down tester, which can probably be found at Harbor Freight. It doesn’t have to be some super dammed expensive thing with half degree increments and alcohol filled gauges like some people claim.

I got mine off eBay for $28, and it was a set from that was FAA approved, but was rather rudimentary… and all you’re doing is looking at percentages anyways. If you can read a gauge and make notes that’s all you need to do.

The reason you’re gonna do a leak down test is because you may have mechanical defects that are causing an imbalance in your air fuel mixture.

You may have worn valve guides so bad that compressed and/ or vacuum are going to places where they shouldn’t be going at the worst possible moment, you may have burned exhaust valves, you may have cracks in a cylinder, or a piston head that is starting to erode through with burn.

A compression test doesn’t check all of that.

Read up on how leak down tests are done.

Sun May 18, 2025 3:59 pm

I don’t know if this is what you need exactly, but this is what I was talking about when I said properly jetted from Parts from Redline

https://www.amazon.com/Weber-Carburetor-Pack-DGAV-701-DGV4/dp/B08643SYCP

Sun May 18, 2025 5:20 pm

You want heat to get into the manifold from the heads and the thick phenol gaskets like you are already running will greatly lessen the heat. There are two holed gaskets (use two per side, so four total) that were sold for use with the stock dual carbs. A liquid gasket maker that can handle gasoline would be good here as it will let more heat through than any gasket will.

This isn't hard to do, and I wouldn't recommend it to a novice unless he was sure he needed to rejet his carb, but if you disable the power valve in the carb, tuning these carbs becomes much much easier as the power valve is just not needed or even wanted in the Type 4 application. If you do decide to rejet your carb get back to me and I will try to walk you through it. I have been running without a power functional power valve for 20ish years at this point and see no reason to go back to using it. Many aftermarket carbs for VW aircooled applications come without power valves and some aftermarket carbs for VW's actually use reverse power valves which do exactly the opposite of what the standard power valve does, so I am certainly not the first to see a problem with running power valves on these engine.

Sun May 18, 2025 6:37 pm

Wasted youth wrote: And after you get ready to replace those phenolic block gasket things, also renew the lock washers under those 13 mm nuts.
will do.

Wasted youth wrote:
Your next timing will be fine-tuned with the timing light.
Ok, we have done this. I'm quite certain. 7+ deg at idle, 28 deg at approx 3400 RPM. Is that what you're saying?

Wasted youth wrote:
If your engine still runs like shit, and you have replaced the primary and secondary ignition system components with good quality components
I'm assuming here you mean the coil, points, condenser?

Wasted youth wrote:
If the Weber is actually jetted properly
This is something a bus owner should be able to do on their own?

Wasted youth wrote:
Read up on how leak down tests are done.
Oh man. I'll read up. It does sound intimidating.

Sun May 18, 2025 6:39 pm

busdaddy wrote: I have never been able to make those phenolic blocks work on the Prog manifolds, or the paper or aluminum gaskets for that matter, the flanges are so weak and warpy the only thing that stays sealed is 3/16" cork that you cut yourself from gasket sheet.

ok, sounds like experience and wisdom. I'll try the set I ordered from Jbugs, and go the 3/16 cork route if that seems unworkable. I appreciate the heads up.

Man, this forum is pretty amazing. [-o<

Sun May 18, 2025 6:43 pm

Gauge comparison with leakdown tester.

You’re simply comparing percentages. You’re not assessing compression.

Speaking of heat… Wildthings is absolutely correct. The fuel air mixture from the Weber is colder than it should be for these engines, and worse by the time it gets into the cylinder after traveling those running tubes. One method I have applied, which was super easy and cost next to nothing was this:

I used some aluminum roofing flashing, and made a strip to circumnavigate the outside of the intake screen, and made the width of the aluminum strip so it is held captive by the bottom and top sections of the air filter.

Then I made a hole with lame aluminum tabs to affix a heat rising duct from the original dual carb heat rising chimney. Now most of the intake air for the carburetor is drawn in from the heated chimney pipe, and there is a nickel sized hole I added to the other side thinking maybe I shouldn’t have all the air coming from the chimney, but that’s sort of a goofy thought. That nickel size hole is probably unnecessary.

I can run the bus up and down the San Joaquin Valley on the shittiest of August afternoons and pull off the highway, grab the running tubes and the base of the carburetor all still feel very cold to the touch.

It is my belief that the cold temperatures caused by the Venturi effect (?) ruin the mist of the atomized fuel and help condense it to spattering drops of fuel, but it’s not like the 1700 cc engine is critically affected by that. It’s just not ideal.