how to set timing - mallory mechanical advance on '74 1.8 Options

[h16]

I need to set ignition timing on a '74 1.8 that has a mallory dual-points mech adv distributor. Model # of mallory distrib is 2354101, in case it matters to someone.

Anybody have tips on how to set timing on this setup, assuming the rest of the engine is basically stock?

Prior to any attempts to set timing, I plan to replace both sets of points, condenser, and adjust the dwell.

Thanks in advance for any help

[Dave_Darling]

Do you know the advance curve set up in the distributor? I think Raby used to say something about pink and gray springs, but I'm not hands-on familiar with what any of that really means.

A first approximation would be to hope that the curve is close, and set it for about 5 BTDC at idle. You could instead try for 30 degrees at 3500 RPM, and let the idle fall where it falls.

To do it right, you'll need a dyno. That will help you find the timing that the motor actually likes the best.

--DD

[rhodyguy]

'Old school' Mallory if it has points. The springs for newer ones with modules are gray/gray.

[Mark Henry]

Points are getting hard to find.

It should be a red top, so grey/grey springs work.
http://vwparts.aircooled.net/Mallory-GREY-...prings-pair.htm

You can turn it into a unilight.
http://vwparts.aircooled.net/Mallory-Unili...t-562-p/562.htm

You can change it into pertronix, part number ML-161 or ignitor II 9ML-161

You can also run it points only (no condenser) to trigger a MSD, this method the points won't have any high volts going through it and they should last almost forever.
You could also use the unilight/ignitor to trigger the MSD.

[h16]

Mark - very useful info, thanks a bunch.

I have the unilite conversion kit but have hesitated to install it because it's a one-way conversion that i don't want to mess up. I have had good luck with unilite earlier american cars of my youth.

The alternate source of points is really useful too.

For now I'm going to get my hands on a variable-advance timing gun, stick with dual points, and see what happens. I am aiming for ~30 BTDC @ 3,300 rpm.

[Mark Henry]

Mark - very useful info, thanks a bunch.

I have the unilite conversion kit but have hesitated to install it because it's a one-way conversion that i don't want to mess up. I have had good luck with unilite earlier american cars of my youth.

The alternate source of points is really useful too.

For now I'm going to get my hands on a variable-advance timing gun, stick with dual points, and see what happens. I am aiming for ~30 BTDC @ 3,300 rpm.

I don't like a variable advance timing gun for setting VW engines, if you use one make sure it's set at zero.
I'd aim for 28 BTDC, 30 degrees total advance would be the max.

[MarkV]

The range of advance is adjustable on that distributor with a key that was available from Mallory. I have one that I converted to a Pertronix II... I think I set the advance to a total of 16 degrees..... 12 degrees of initial advance plus 16 for a total of 28 degrees.

[h16]

I have located and ordered a set of keys, waiting for them to arrive.

Sorry for being slow here - I'm just thinking this through for the first time.

I will go with your recommendation of 28 degrees of total advance.

A couple of questions:

if I use the 16 degree key, then that will make my total advance be 16 degrees plus whatever advance I set at idle?

You said you use 12 degrees initial advance - does that mean that at idle you set timing for 12 degrees BTDC? If so, how do you know when it's 12 degrees without an advance timing light - do you have a timing mark for 12 degrees BTDC? Mine I *think* has marks at 0 TDC and 7 BTDC (stock timing marks for 1.8). For me to achieve 12 BTDC I would expect to use my 0 TDC timing mark and set 12 degrees of advance on my timing light - as I understand it.

Or perhaps I completely mis-understand.

Thanks again for the info and lesson.

[MarkV]

I have located and ordered a set of keys, waiting for them to arrive.

Sorry for being slow here - I'm just thinking this through for the first time.

I will go with your recommendation of 28 degrees of total advance.

A couple of questions:

if I use the 16 degree key, then that will make my total advance be 16 degrees plus whatever advance I set at idle?

You said you use 12 degrees initial advance - does that mean that at idle you set timing for 12 degrees BTDC? If so, how do you know when it's 12 degrees without an advance timing light - do you have a timing mark for 12 degrees BTDC? Mine I *think* has marks at 0 TDC and 7 BTDC (stock timing marks for 1.8). For me to achieve 12 BTDC I would expect to use my 0 TDC timing mark and set 12 degrees of advance on my timing light - as I understand it.

Or perhaps I completely mis-understand.

Thanks again for the info and lesson.

No, you understood. I have a timing light with a dial so I only use the TDC mark on the fan. I set the dial to 12 degrees and check at an idle or I set the dial to 28 degrees and rev the engine to 2500+ rpm and check it.

My distributor is an older (YL?) model with the black distributor cap and the key is a single key like in the drawing above. I think the newer units with a red cap uses a set of individual keys.

[Mark Henry]

A couple of questions:

if I use the 16 degree key, then that will make my total advance be 16 degrees plus whatever advance I set at idle?

Yes in this example 12 initial timing + 16 advance = 28 degrees total advance

My T4 engine is set at 8 degrees and is programed for 20 degrees advance, so 8 + 20 = 28 total advance.
Mine is a crankfire ignition, but I've also done this with a mallory using the 20 key.

To me 12 degrees initial advance is too much, I aim for 8 degrees and 900rpm idle. 10 is about the most I ever use.

[MarkV]

[/quote]
Yes in this example 12 initial timing + 16 advance = 28 degrees total advance

My T4 engine is set at 8 degrees and is programed for 20 degrees advance, so 8 + 20 = 28 total advance.
Mine is a crankfire ignition, but I've also done this with a mallory using the 20 key.

To me 12 degrees initial advance is too much, I aim for 8 degrees and 900rpm idle. 10 is about the most I ever use.
[/quote]

Interesting. Seems like when I tried setting the initial that low I had a problem with an off idle bog. That was using a Bosch 050 distributor. Don't know if I ever tried it with the Mallory. What is the issue with running too much initial advance?

[cgnj]

A couple of questions:

if I use the 16 degree key, then that will make my total advance be 16 degrees plus whatever advance I set at idle?

Yes in this example 12 initial timing + 16 advance = 28 degrees total advance

My T4 engine is set at 8 degrees and is programed for 20 degrees advance, so 8 + 20 = 28 total advance.
Mine is a crankfire ignition, but I've also done this with a Mallory using the 20 key.

To me 12 degrees initial advance is too much, I aim for 8 degrees and 900rpm idle. 10 is about the most I ever use.

I agree with Mark, because he is smarter than me, but also because I read the advance curve documentation that came with the Unilite.
Unilite grey/grey springs If you look @ this drawing you can see the slope of the curve is quite linear and comes on below 900 rm. Made sense to me to use less initial advance and key to 28 total.


.

[Mark Henry]

Interesting. Seems like when I tried setting the initial that low I had a problem with an off idle bog. That was using a Bosch 050 distributor. Don't know if I ever tried it with the Mallory. What is the issue with running too much initial advance?

Problem with answering this is I'd have to write a novel (IMG:style_emoticons/default/biggrin.gif)

I aim for 8 degrees. 900rpm and the carb idle screws out 1-1/2 turns. This with a warm engine, the linkage/throttle plate stop barely touching the stop screw and one linkage arm disconnected. Likely it will run a bit slow, so turning the linkage/throttle plate stop screw a 1/4 to 1/2 turn gets you to an acceptable idle.
This is the point that you sync your carbs and when you reattach the arm nothing should change. After this a quality linkage, opening at exactly the same rate, is what keeps it in sync.

Then comes jetting, but if your jetting changes you have to start again from step one.

As always when tuning a carbs this is assuming that you engine is in good mechanical condition. Beyond this point there's often an issue with the secondary jetting, dirt in jet/fuel, way too aggressive cam or another mechanical issue.
The idle screws out more than 2 turns and you are running lean at idle. Running more than say 1200 rpm at idle and you are off the idle circuit.

I'm no longer a fan of 009 and 050 dizzy's, they always seem to have or create a flat spot. I run a fairly aggressive WEB 163/86b cam (my favorite big T4 cam, 2270cc+) and have had no issues, other than a slightly lumpy, 900rpm idle using a mallory.

[Mark Henry]

For the OP who is using the L-jet (I assume) I'd set everything as if it was a stock dizzy. Gray/gray springs, set advance with 20 degree key, 800-900rpm idle, hitting the stock timing marks and use the TB screw to set idle.