TheSamba.com :: View topic - Stupid question about ignintion and idle adjustment

Tue Jun 03, 2025 4:51 am

Hi! Before you can adjust the carb you must set the right ignition timing. The timing should be set to 5tdc at 800 rpm with a strobe light. How could i adjust the timing without adjusting the carb first to idle at 800?

1600 ad engine

Tue Jun 03, 2025 5:20 am

First static time- adjust the points at the correct TDC point.
Adjust the carb to get it to run good at the proper idle.
Adjust timing with light to get the best timing WHEN AT OPERATING TEMP.
Adjust carbs at idles AT OPERATING TEMP.

Tue Jun 03, 2025 5:27 am

sctbrd wrote: First static time- adjust the points at the correct TDC point.
Adjust the carb to get it to run good at the proper idle.
Adjust timing with light to get the best timing WHEN AT OPERATING TEMP.
Adjust carbs at idles AT OPERATING TEMP.

THANK YOU

Tue Jun 03, 2025 5:30 am

And if you are using points replacement module like Pertronix Dale M uses this technique.

“ Actually you can use static timing (test) light with electronic modules .. Connect one side of test light to #1 terminal of coil... Connect other side of test light to ground ...Put crank pulley at 7.5° BTDC and turn key on, and rotate dist till test lamp lights..... JUST LIKE POINTS..... This will get you "start up" every time you set new engine...

In essence it is what you are doing with your STROBE method....

Been doing it that way for years...... BUT usually set engine at 28-30° BTDC at 3000 RPM for final tune....

Dale
_____________”

Tue Jun 03, 2025 6:49 am

^ that works 50% of the time.

The other 50% of the time, the test light is already lit when you turn the key on 8)

On the plus side, that’s true for points as well.
Robbie

Tue Jun 03, 2025 8:44 am

why can't you lower your RPM at idle?

Tue Jun 03, 2025 1:11 pm

SGKent wrote: why can't you lower your RPM at idle?

Because i've read that you set the timing before you touch the carb, but i guess i can just cheat a little and lowering the idle first!

Tue Jun 03, 2025 2:20 pm

each bus model was built with specific equipment, and specific tuning needs specified. Some are hoses on, some are hoses off, some are BTDC, some are ATDC, some are 800 RPM, some are 900 RPM. This all assumes that all parts of the equipment is mounted, connected and functional.

Most Bosch distributors have weights inside that change the timing once the RPM gets to around 1000 RPM. So, if someone has their idle set at 1100 RPM, setting their timing will not be accurate. Hence the RPM should be where VW specifies, and the timing set hoses on or hoses off per the specs.

Many here set it an alternative way. They disconnect all the vacuum hoses at the distributor, rev the engine with a tachometer attached and bring the engine up to around 3500 - 4000 RPM, which is where the timing stops advancing. Then they set it to about 30 degrees BTDC, lock it down, let the RPM fall and hook the hoses back up. The timing will be about correct, maybe a couple degrees off but the engine will run cooler. If you have a vacuum advance, you should make sure that it will hold a vacuum.

Tue Jun 03, 2025 7:56 pm

This is one of the reason to set your timing at 28-32° before TDC @3800 rpms, with the hoses removed from the vacuum can and plugged. In general this way of timing your engine will still give you the correct time under high load high rpm conditions even if the vacuum canister is bad, or the distributor and/or carb are a bunch of mismatched worn parts. If you set your timing at 5° ATDC at idle both the distributor and the carb must function to factory spec, which is very likely no longer happening.

Tue Jun 03, 2025 11:07 pm

This table in the manual does not seem to cover my engine. Mine is a 73 1600AD so i have no idea of how to set the timing

Wed Jun 04, 2025 1:17 am

Post pictures of your distributor, pulley, and a close up of the notches on your pulley. Engine code doesn’t matter unless it’s fresh off the assembly line in Germany.

Robbie

Wed Jun 04, 2025 1:31 am

airschooled wrote: Post pictures of your distributor, pulley, and a close up of the notches on your pulley. Engine code doesn’t matter unless it’s fresh off the assembly line in Germany.

Robbie

Do you know how to read these timing marks?

Wed Jun 04, 2025 2:33 am

halmis wrote:

Do you know how to read these timing marks?

You are going to need to determine TDC by using a wooden pencil or dowel rod into the #1 or #3 cylinder. Alternatively you could just find another pulley.

Wed Jun 04, 2025 2:44 am

You are going to need to determine TDC by using a wooden pencil or dowel rod into the #1 or #3 cylinder. Alternatively you could just find another pulley.[/quote]

ok, so you dont think anyone here has ever seen these marks before?

Wed Jun 04, 2025 3:13 am

It’s *likely* (but not 100%) that those are the marks for 7.5 and 10 degrees btdc. You can use either one to static time and get the engine started.

With a TDC tool, you can mark exact TDC and use a strobe light with advance to find maximum advance timing. Or you could buy a degree pulley for a little more money. The CB aluminum pulleys are very well balanced and perfectly round, unlike most original steel pulleys that are warped from Neanderthals trying to remove them with screwdrivers.

Robbie

Wed Jun 04, 2025 3:51 am

halmis wrote: You are going to need to determine TDC by using a wooden pencil or dowel rod into the #1 or #3 cylinder. Alternatively you could just find another pulley.

ok, so you dont think anyone here has ever seen these marks before?[/quote]

Along your pics, for me it´s 99,99 percent sure, you have a 1600 ccm engine.
There is a tag on top of original engine number, so its most probably a aftermarket overhauled engine.
The distributer 211 905 205 S (with single vacuum dose) is correct for your engine.
It was used between Aug 71 and July 73 for *AD* engines. Ignition static and when idling at 850 +- 50 rpm, vacuum hose disconnected and plugged at carb at 7,5° BTDC.
The dizzy should make 22° to 25° of advance, so reach a max advance of 29,5° to 32,5° at around 3000 rpm (vacuum hose disconnected)
Pulley: here it´s not clearly visable if it´s correct. Assuming the left mark is 7,5° BTDC and the right one 10° BTDC.
To make this sure, find TDC and check, if that´s really true.
(for models 1971 there were pulleys with only one mark at 5° ATDC) (if this would be a such one and the right mark was added later on, the marks could be 5° ATDC and 2,5° ATDC or so)

Wed Jun 04, 2025 4:28 am

wagen19 wrote: halmis wrote: You are going to need to determine TDC by using a wooden pencil or dowel rod into the #1 or #3 cylinder. Alternatively you could just find another pulley.

ok, so you dont think anyone here has ever seen these marks before?

Along your pics, for me it´s 99,99 percent sure, you have a 1600 ccm engine.
There is a tag on top of original engine number, so its most probably a aftermarket overhauled engine.
The distributer 211 905 205 S (with single vacuum dose) is correct for your engine.
It was used between Aug 71 and July 73 for *AD* engines. Ignition static and when idling at 850 +- 50 rpm, vacuum hose disconnected and plugged at carb at 7,5° BTDC.
The dizzy should make 22° to 25° of advance, so reach a max advance of 29,5° to 32,5° at around 3000 rpm (vacuum hose disconnected)
Pulley: here it´s not clearly visable if it´s correct. Assuming the left mark is 7,5° BTDC and the right one 10° BTDC.
To make this sure, find TDC and check, if that´s really true.
(for models 1971 there were pulleys with only one mark at 5° ATDC) (if this would be a such one and the right mark was added later on, the marks could be 5° ATDC and 2,5° ATDC or so)[/quote]

Ok thanks. Whats a ccm engine?

Wed Jun 04, 2025 5:32 am

Ok thanks. Whats a ccm engine?[/quote]

ccm means cubic centimeters or 1,6 litres, nothing special.

Thu Jun 05, 2025 4:45 am

Why is there a different engine number on the block? Is the number at the pump restamped? Why?

I dont understand these numbers, can someone please explain?

Thu Jun 05, 2025 11:03 am

halmis wrote: Why is there a different engine number on the block? Is the number at the pump restamped? Why?

I dont understand these numbers, can someone please explain?

The numbers that are cast in are part numbers, while the stamped in number may be factory or something stamped in over the years. Typically they may tell you something about a previous rebuild by may not tell whether that is what you still have. As a general rule don't order internal engine parts until you have the engine torn down so you know what is actually in there.