Firing order issue. With new distributor

[03hdfatboy]

Question for you guys who’ve changed distributor. Bought a distributor for my early 64 bug with vac adv to make it accelerate smoother. Got ready to install it. With 1 cyl @ TDC button was at 4 o'clock on the orig. when I got ready to put new one in I had to turn it to 7 o’clock for some reason to line up with offset slot in the hole. Supposed to be the correct one. Anything I can do to correct it or am I SOL? Put old one back in so I could drive it for now.
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Early 1964 1835cc, single Dellorto 40 carb. Freeway flyer transaxle from Don's bus box. Replacing 4” narrowed Shockless front beam is my next project.

[03hdfatboy]

I done some reading and it says the one with vacuum, #1 will be 90* off compared to one w/o it, to put wires on cap to coincide with the new positions. I tried that but was already aggravated so maybe I screwed up the firing order. Will give it another shot tomorrow
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Early 1964 1835cc, single Dellorto 40 carb. Freeway flyer transaxle from Don's bus box. Replacing 4” narrowed Shockless front beam is my next project.

[Cusser]

Read text on this one:

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1970 VW (owned since 1972) and 1971 VW Convertible (owned since 1976), second owner of each. The '71 now has the 1835 engine, swapped from the '70. Second owner of each. 1988 Mazda B2200 truck, 1998 Frontier, 2014 Yukon, 2004 Frontier King Cab. All manual transmission except for the Yukon. http://www.thesamba.com/vw/forum/album_page.php?pic_id=335294 http://www.thesamba.com/vw/forum/album_page.php?pic_id=335297

[carcrazed]

For some reason, the repop distributors are not clocked the same half the time. I bought two of them and had to adjust my wires to match how much the clocking was off. Just make sure you have your engine at TDC, check where your rotor is, cap back on and adjust your wires accordingly.
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1965 Herbie Replica. 1776cc dual Kads.
1961 Beetle 33,000 Original Miles

"Just When you think you are getting ahead, you're always wrong."

[Glenn]

First off the location of the #1 mark on genuine Bosch distributors is different if it's a mechanical only or has vacuum advance. this is due to the vacuum canister not able to clear the fuel pump so they moved it. Generally the vacuum canister will be located facing the rear of the car.

A Bosch 034 SVDA on the left and a Bosch 009 on the right.

The driveshaft under the distributor has 11 teeth and can be installed in any of them. If not installed with the correct orientation, the location of the #1 mark will be different. Technically it doesn't matter as long as the distributor can be rotated for ignition timing and the vacuum canister or condenser is not hitting the fuel pump.

I'm a bit anal when it comes to details so I have re-indexed the driveshaft so the distributor is in the original factory orientation.

BTW.. that picture posted in a previous post is not true for a distributor with vacuum advance.
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Glenn
74 Beetle Specs | 74 Beetle Restoration | 2180cc Engine
"You may not get what you pay for, but you always pay for what you get"

Member #1009

#BlueSquare

[ashman40]

What is the model# on your new vacuum advance distributor and what model carb are you matching it with? Not all distributors will work with all carbs. Some combos don’t work well while others won’t work at all.

The function of the distributor is to deliver a spark to the correct cylinder when that cylinder is at the end of the compression stroke. Rather than looking at where the rotor is pointing and “hoping” that is the correct spot to place the #1 plug wire on the cap, realize this simple fact… when the #1 piston is at the end of the compression stroke… the distributor must be setup to deliver a spark to the #1 spark plug wire and therefore the #1 spark plug. Once you have confirmed which post on the cap is #1 the the remaining posts are wired in the CW order 1-4-3-2.

To know when the #1 cylinder is at the end of the compression stroke, remove the right side valve cover and watch the #1 intake valve as you manually rotate the crank pulley CW. After you see the #1 intake valve open (start of intake stroke) then close (start of compression stroke), continue to rotate the crank about 180deg more until the TDC or ignition timing marks line up with the case split (end of compression stroke). Remove the distributor cap and note where the rotor is pointing. This is where the #1 plug wire must be installed, for this distributor.
Without rotating the engine, remove the old distributor. Look down into the hole and check that the top of the distributor drive gear looks like this to confirm it is installed correctly.

Install your new distributor so the cog at the bottom of the distributor engages with the offset slot in the drive gear down in the case. It can only fit one way. With the new distributir fully seated, note where the rotor is pointing. It may not be the same as the old distributor. It doesn’t have to be as long as the #1 plug wire is again installed over the rotor tip when #1 cylinder is at the end of the compression stroke. The rest of the wires are installed in the CW firing order 1-4-3-2.
This method always works because it ensures the spark is being delivered to the cylinder that needs the spark at that moment in the rotation/stroke.
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AshMan40
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'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!}

[EVfun]

I just want to add a bit of advice for a new VW owner. Don't rotate the engine with the distributor removed. It is possible to damage the distributor drive gear on the crankshaft if you do.
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[Cusser]

I've assembled about a dozen VW engines and I've always had the distributor drive shaft oriented correctly.

A co-worker around 1979/1980 had his engine rebuilt by one of the largest VW parts/service shops in Phoenix, and they installed his distributor drive shaft off kilter. I rotated that into correct position for him, I had the tool.
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1970 VW (owned since 1972) and 1971 VW Convertible (owned since 1976), second owner of each. The '71 now has the 1835 engine, swapped from the '70. Second owner of each. 1988 Mazda B2200 truck, 1998 Frontier, 2014 Yukon, 2004 Frontier King Cab. All manual transmission except for the Yukon. http://www.thesamba.com/vw/forum/album_page.php?pic_id=335294 http://www.thesamba.com/vw/forum/album_page.php?pic_id=335297

[Zundfolge1432]

[03hdfatboy]

[03hdfatboy]

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I had to add a vac port. Was nervous about drilling into my carb.
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Early 1964 1835cc, single Dellorto 40 carb. Freeway flyer transaxle from Don's bus box. Replacing 4” narrowed Shockless front beam is my next project.

[ashman40]

[03hdfatboy]

I installed it this afternoon, got it running.
But I’ve read two different ways to set it up.
One says set it at 28-30* btdc @ 3krpm to get vac adv to work correctly. I set it at 25 @ 2k (didn’t want to bring it to 3k) and it was popping bad going down the road when accelerating.

Also found another one that says to set it at 10* btdc at idle

I have it at 10* btdc now but stumbles bad, was wondering should I turn down the accelerator pump adj. as I’ve read would have been adjusted up to help compensate for no vac adv.
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Early 1964 1835cc, single Dellorto 40 carb. Freeway flyer transaxle from Don's bus box. Replacing 4” narrowed Shockless front beam is my next project.

[ashman40]

You're running an aftermarket distributor. That basically means there is no single idle timing that will be perfect for every distributor. Even distributors from the same maker may need to be timed differently. This has to do with variables in tolerances that cause the same or similar models to have different timing curves. I would not trust the advice to time an aftermarket distributor at 10BTDC and all is good.

I installed an aftermarket SVDA distributor in my buddies Beetle. It was a clone of a 205/034 distributor and therefore should have been timed to 7.5BTDC at idle if the tolerances were the same as stock. Following the below steps, to avoid over advancing the timing at higher rpms we ended up with an idle timing to 2BTDC. Anything more than this and we would exceed a safe upper limit for mechanical advance.


When you are working with a non-OE distributor you need to confirm that it does not over advance at higher rpms. The point to keep in mind... mechanical advance timing advance responds only to rpm changes. It cannot tell of the engine is running @3500rpm with a heavy load, or @3500rpm with no load. To avoid pushing the engine into detonation you want to keep your total initial+mechanical ignition timing to 28-32BTDC. This is the max rpm-based timing for most stockish ACVW engines. Go above this and the engine could go into detonation at high rpms under a load.


To check this:

Disable any vacuum timing advance/retard so they do not skew the mechanical advance results. Disconnect and plug the distributor ends of the hoses.

If necessary, add pencil marks on the crank pulley for 28BTDC and 32BTDC. 30BTDC will be the middle of these two marks. At full mechanical advance the case split should fall somewhere between these two marks.

Warm up the engine to operating temp.

Rev the engine while looking at the timing marks under a strobe timing light. Increase rpms until the timing marks stops increasing. Your distributor has reached total advance. This could be as low as 2500rpm or as high as 3800rpms depending on the distributor. It doesn't matter what the rpms is as long as all the mechanical advance is "all in" and no longer increasing.
*You are trying to make sure the mechanical advance never takes you above the safe limit of 28-32BTDC.

While you hold the rpms above the point where timing is no longer increasing, adjust the timing to 28BTDC. Let the rpms drop back to idle and note the idle ignition timing. This is your idle reference point that equates to a total ignition timing of 28BTDC.
*You can increase the idle timing as much as 4deg so the max total mechanical ignition timing will be 32BTDC, but never go any more than this or risk detonation under load. There is nothing wrong with less ignition timing as long as you stay out of detonation under load.

Reconnect the vacuum hoses and take the car for a drive. Get it up to freeways speeds and accelerate listening for pinging/detonation.

A common mistake is thinking you should adjust your timing with the vacuum advance connected. This is rarely the case as vacuum controlled ignition advance varies due to multiple different conditions to include barometric pressure changes due to weather. Best to eliminate it as a variable.
For distributors with both mechanical advance and vacuum advance (eg. SVDA), these two systems work independently but complement each other. Mechanical advance varies based on engine rpms and increase as engine rpms increase. Above around 3500rpm additional mechanical advance is no longer needed even if the rpms increase. I've read that internal turbulence at these higher rpms result in the flame front inside the combustion chamber traveling faster. This has the same effect as increased ignition timing above 3500rpms. This is why distributors max out mechanical advance in this range.
Vacuum advance connected to ported or intake vacuum sources vary the ignition timing based on "engine load". Low load (high intake vacuum; cruising with the throttle mostly closed) results in increased timing advance. High load (low intake vacuum; accelerating to climb a hill or pass a car) results in decreased ignition timing. Except for specialized adjustable vacuum canisters, there is no real adjustment for vacuum advance in SVDA/DVDA distributors. They are an additional timing advance that kicks in when the load is low; providing more power and better fuel efficiency.
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AshMan40
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'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!}

[tasb]

If you are running an original carburetor on your 1964 engine you are not going to be happy with your new distributor. The vacuum signal from the carburetor is not the best match. It'll run thanks to the mechanical advance .
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Roads Scholar &
1957 Kombi low mileage 36 hp governor equipped M 178 Slow Drag Winner 2014, 2015, 2018

1965 hardtop Deluxe Microbus owned since 1990 M 620 factory 12 v 1500cc

1961 (October)Single Cab- Road Trip Workhorse