Tuning Questions and Answers

The car didn't want to start right off when I went to take it for a second test run. It starts right up cold, but warm it was a little more reluctant. And it idles way too fast (otherwise it dies). Tuning, I guess?

Most likely. Try turning the volume screw out just a fraction (richens the idle mixture). Might make it idle a tad fast and need a little adjustment, but might help with the stutters. Hopefully the fast idle will just be a little adjustment.

I just put the finishing touches on my 1600cc dual port with a new Bosch 009 distributor. The carburetor is 34 pict 3. I've plugged the vacuum hose that used to be for the vacuum advance. The dwell is set at 50 degrees and the valves are adjusted. What I need to know is:

1. What should the timing be? What are the variables to consider when determining where to time it?
2. Is the static timing method appropriate considering the distributor is centrifugal and not vacuum advance, or would I be better to strobe it?

The Beetle engine needs around 28-32 degrees maximum advance. The actual amount depends on your engine setup, and maybe a bit on the quality of fuel you have. 009s vary a bit in the total advance they provide, so:

1. Strobe time it for maximum advance - try 30 degrees first.
2. Check the static timing--should come in at around 5-7 BTDC. The exact amount doesn't matter, so long as the max advance is OK.
3. Run the vehicle, and try some high speed and lower speed high acceleration runs. If it runs fine, you've got it right. If it pings a bit, or has a flat spot on acceleration, try backing off the max advance to say 28 degrees, and try again.

The 009 does often cause acceleration flat spots, and these can usually be overcome by ensuring the accelerator pump is adjusted for it's maximum stroke, and you might need a richer main jet in the carby.

This last point is particularly relevant if you live in an area which has a lot of MTBE or similar additives in the fuel (California, etc.). These additives cause carburetted engines to run a little lean, and VW engines prefer to run a touch rich.

Are you using the 009 distributor? If so, this does sometimes cause an acceleration flat spot, as it does not have the vacuum advance adjustment of the original distributor.

Make sure that the original vacuum points on the carby are properly plugged (from your description they probably are - but check anyway.

When you say "tune-up parameters are right on the money" -- the 009 requires different static timing to the vacuum dizzys. You should have about 5-7 BTDC static timing, for about 30 max advance at high revs (about 3000 or so).

One good trick I use is (once you've sorted out the leads) to wrap each lead at each end with some thin copper or other wire, plug lead 1 gets wrapped one turn, plug lead 2 gets wrapped two turns etc. and then twist the ends to gently grip the plug lead (that's why I use copper it twists easily). Do it at each end of each plug lead. Then you don't have to 'follow' leads to work out which lead is going to each plug, and if you pull off all plug leads when you change plugs you don't end up trying to put No4 lead on to No3 plug etc.

I would start by setting your timing to about 5 degrees BTDC static. Then I would strobe it up the RPMs until the distributor stopped advancing. You should get a total advance of about 26 or more. Subtract the 5 you added statically and you now know for sure what your 009 is doing. Depending on where the 009 was manufactured it may have a different amount of advance. Mine advances to 21 degrees. The amount of total advance varies for each individual engine and what you intend to do with it. More advance makes more heat. I use about 28 degrees of total advance on my ride, which means I set my advance statically at 7 btdc. I tend to want to check my distributor occasionally with a strobe to make sure that nothing has gone wrong. I have heard that they have nylon tabs that can break off and send the advance into the engine killing zone when they wear out (after several hundred thousand miles of course).

Looks like I'll be installing a new distributor soon. I suppose the timing and all will be different with a vacuum advance distributor--I'll have to ask my good friend down in Australia some questions when I get around to making the switch.

Easy - if you are using a single vacuum distributor - static timing is 7.5BTDC.

If you are using the double vacuum distributor, 5ATDC (that AFTER), set with a timing light and the engine idling. You can't set this distributor engine-off, as you need the idle (front) vacuum line working to pull the distributor plate back to the idle setting.

Thanks for your timing advice. Something I've never gotten straight in my head is the requirement to plug the vacuum line(s) during timing. I take it from your instructions that one of the two (if you're using the double vacuum distributor) must remain attached. Is the other one plugged? And if so, which way (i.e., is the distributor port plugged or the carburetor port plugged?) It seems to me that the 34 PICT/3 carby was designed for use with a double vacuum distributor, since it has two vacuum ports (I'm still baffled by the port down on the intake manifold).

Yes that port on the manifold has me foxed too. But anyway, as I understand it, with the double vacuum carby hooked up, you have both vacuums still on and set the idle at 5 ATDC with a timing light and the engine running. With the single vacuum distributor (or with the double vacuum which has the idle retard circuit permanently disabled/plugged), you set the timing with the engine off static to 7.5BTDC. I suppose you COULD plug the retard line and set the double vacuum distributor to about 7.5BTDC (static) then reconnect the retard vacuum line, but that's not how I've seen it written. Does Muir or something else talk about temporarily disconnecting a vacuum line just for the timing?

I'm confused. The specs say that the timing for the double advance distributor should be set at 5 degrees ATDC at idle (850 900rpm) with both vacuum hoses attached. Our engine absolutely refuses to run at this setting and demands 7.5 degrees BTDC, which is 12.5 degrees advanced beyond the specification. I don't understand.

What I'm saying is that you are dealing now with both vacuum and centrifugal effects on the distributor. At 1200rpm the idle circuit of the carby would be shutting down and the low speed ciruit starting to operate, so the IDLE vacuum (the retard vacuum line) is probably inoperative at 1200rpm, and setting the 5ADTC would not be possible, as this retard vacuum circuit is designed to work with the throttle shut -- idling at 900rpm.

And at 1200rpm, the centrifugal advance would be just starting to work, so you can't set it with the engine running at 1200 for 7.5 either it probably needs to be higher than that. You could try either...

1. Setting is at 7.5BTDC with the engine off (when both retard vacuum and centrifugal advance are inoperative). It's not supposed to be set this way, but you could then check the max advance, and if it is around 28 30, it HAS to be somewhere near right for the idle.
2. Setting the high revs at 28 30, and hoping that the idle will come in about right. Until you get the car to idle at about 900 (and neither of us is sure how to accomplish THAT yet), you are going to find it difficult to set the timing the 'normal' way for that distibutor/carby set up.

I can tell you this: it doesn't come anywhere near the 30 degree mark on the pulley when I rev it up I would say on the order of 25 26BTDC. But if I advance it such that it approaches 30 degrees BTDC at 3000 rpm that's going to advance the timing at idle even more. I'm missing something here!

As I said above, you're 'missing' the fact that the centrifugal advance is starting to advance the timing at 1200rpm, so the 'idle' timing at 1200rpm SHOULD be higher than 7.5 . Hope that makes sense. The 009 is set STATIC, and you're now setting the vacuum distributor DYNAMIC, with two variables vacuum and centrifugal advance.

I guess I'm going to need some tutoring here, too. How can you tell that the retard circuit is not functioning properly?

You probably won't be able to test this until you are able to get the idle at about 900rpm. Then with the timing light connected you should see it jump from 5ATDC to 7 8BTDC as you crack the trottle open and the retard vacuum line 'disengages'.

Do I use a timing light and set total advance at about 20 degrees at 2500 rpm?

20 total advance is WAAYYY to little. It's VERY important to set the 009 to between 28 and 32 degrees at 3000rpm, and let the idle fall where is may.

Reasons are:

1. 009s vary in how much total advance they make - you're would appear to be 12 degrees (20-8) which is less than most. Since they do vary, and max advance is more important than idle advance, set the engine at 3000rpm. (Once you've done that, you can measure the idle (static) advance and use THAT setting for THAT 009. This would normally be from about 5BTDC to about 10BTDC with most 009s, but not with yours! - it's likely to be about 16 degrees at idle given the figures you've quoted. The reason we use 3000rpm is that the 009s provide max advance from about 2500-2600rpm, and you want to makes sure it's all there before setting it.
2. The reason for 28-32 max advance... The vacuum distributors all provide up to about 40 degrees total advance, for example cruising at medium speed with part throttle. This is great for fuel economy. But these distributors will reduce the amount of advance if you floor the throttle to accelerate from that cruising speed, until the rpm increases to "match" the new throttle position (it's actually increased airflow v amount of advance, but you get the idea). The change in vacuum when you floor it takes the advance back to roughly 30 degrees. This ability of the vacuum distributors (which also provides a shot of advance off idle to help the engine spin up) is called load sensing.
3. The 009 can't load sense - it only rpm senses, and because it's a "one size fits all" distributor, it has to be set for "worst case" which means wide open throttle at lowish/medium rpm, and THAT's 28-32 degrees.

Any more than that and the engine will detonate (ping) when you floor the throttle.

Any less than that and it's under advanced at higher rpm and will run hot, and you don't want THAT on your high capacity engine.

Use as much of the 28-32 as the engine can take without detonating (this gets is a fraction closer to the 40 degrees the vacuum units make and so improves mileage a fraction). If you can't stop it detonating at 28 degrees, then you need a higher octane fuel or (last resort) lower the compression ratio of the engine a little.

My timing is set to 5 degrees advance my points and valves are correct. Also I have a 009 distributor in case that matters.

Yes - the 009 matters big time - you HAVE to set this using a timing light at 28-32 degrees at 3000rpm. They vary a lot (cheap build) and the max advance is more important than the idle advance, so you set the max advance and let the idle fall where it may. You can then measure the idle advance and use THAT setting for THAT 009, and it would be anywhere from about 5 to 10BTDC, but I have seen them up to 16BTDC to get the correct max advance - so you can see how important that is. The other thing is that you need to set the carby to run a little rich when using the 009, so checking what the main jet size is, is important.

Since they vary a lot in the amount of total advance they make (they are built rather cheaply), they MUST be set at 3000+rpm using a timing light. Maximum advance is much more important than idle advance, and for the aircooled VW engine and 009 distributor, the maximum advance MUST be between 28 and 32 degrees.

The 009 is usually set at 3000+ rpm because they produce their maximum advance at 26-2700 rpm, and using 3000rpm ensures that it's all in.

Once the maximum advance has been set, you can then measure the STATIC (engine off) timing timing and use THAT setting for THAT distributor in future. The static timing using this method is commonly between about 5 and 10BTDC but I have seen reports of up to 16BTDC, since these distributors DO vary in the total advance they can make.

So 7.5BTDC MIGHT be right for some 009s, but it sounds like it's incorrect for YOUR 009, since you say the max advance is then 26 degrees. That would indicate to me that YOUR distributor (if it's a 009) should be set at around 10-12BTDC at idle so the max advance is in the 28-32 degree range.

7.5BTDC is correct for most single vacuum distributors on aircooled VW engines (some variation depending on the model year and the country - emissions considerations and such).

If the 009 is set with more than 32 degree max advance, the engine is over-advanced in certain throttle/rpm conditions, and this can cause the engine to ping/detonate.

If it's set with less than 28 degrees, it will be under-advanced at high rpm and cause overheating (possible cause of the damaged head?) Overheating certainly puts an extra load on the head and it's components, especially the already very hot exhaust valves.

The vacuum distributors used on aircooled VW engines can provide up to about 40 degrees of total advance under the right conditions - for example part throttle cruising (this is good for fuel economy), but the "load sensing" ability of the vacuum canister reduces this amount to around 30 degrees or so when required (for example, flooring the throttle at medium speeds, until the increasing engine rpm then feeds the advance back in as the rpm catches up with the "new" throttle position). It's actually an airflow-through-the-carburettor thing, rather than actual rpm, but you get the idea. The 009 can't do this load sensing, so must be limited to "worst case" of a little either side of 28-32 degrees.

For doing static timing, you say to use a 12 volt bulb, but if car has a 6 volt system, should you use a 6 volt bulb?

Yes - a 6v bulb would be better, but a 12v one will work too - you only need something to show when the points are open/closed, so a dim light will do that as well as a bright light can.

It doesn't really matter what wattage bulb you use either, but preferably not a headlight bulb, as this would be trying to pull more amps through the points than they were designed for (so any small wattage bulb is better).

Can you tell me the procedure for adjusting the idle and timing on a '60 36hp motor?

These came with either a 28PCI or 28PICT carburettor (probably 28PCI, since the 28PICT first came with the 40hp 1200).

The later 30 series carbs, and the modern replacement H30/31 should also work on this engine - with suitable jetting. The last of the 30s - the 30PICT/3, plus the H30/31 have two adjusting screws, so the setting process is the "two adjusting screw" procedure on our Web site.

To my knowledge, timing is 10BTDC (if you have a vacuum distributor), set static (or at idle with the vacuum line removed and plugged on the carby - open on the distributor).

For a 009 distributor, you set the max advance at 28-32 degrees at 3000+ rpm, and let the idle fall where it may (usually somewhere between about 5 and 10BTDC).

Idle rpm should be about 800-900rpm. You use the throttle arm screw on the rear (rear is rear of car) to set this (28 and early 30 series carbs - you DON'T use this screw on the 30PICT/3 or H30/31 for idle speed adjustment - that's what the second (larger) screw in the left side of these carbs is for).

For setting the carby (28s and early 30s), you can use the "one adjusting screw" procedure on our Web site.

I've read a couple other places that the timing should be set at 7.5 BTDC. Are you sure about 10 BTDC?

10BTDC is used on the 1200cc engines which have lower compression (6:1 and 6.6:1). Low compression needs more advance than higher compression (relates to the larger proportional head volume on low compression engines, and the amount of residual burnt gases being mixed with the fresh stuff which lowers flame speed).

The 1300/1500/1600s engine all had compression of 7:1 or higher, and 7.5BTDC is normal for these.

When I bought the car it ran half decent -- it had a little miss but decent. So I started messing with the timing and its been down hill since. Everything is set to spec and now it won’t even start. The distributor shaft seems sloppy to me at the bottom -- I can grab the end and wiggle it considerably. I don’t know if that is normal.

It's possible that the distributor a problem, but it shouldn't prevent the car from running. So long as the points are opening there will be a spark, and so the worst a worn distributor causes is a little "hunting" in the timing, which isn't super critical in getting the engine running decently (although it obviously needs replacing eventually if that's part of the problem).

Sometimes I think there is not enough spark. Could you tell me how to check the coil?

Pull the centre wire out of the distributor cap and connect it to a spare spark plug which has been gapped the same as the others. Put the side of the plug on the engine case, and get someone to crank the engine (with the key in the ignition). Hold the plug with thick leather gloves or insulated pliers -- you don't want a shock. You should get a nice stream of blue sparks (do this test in the shade or at dusk when you can see the sparks better). A yellowish colour means the spark is not so good. You get all four sparks that way, so more to see, and with the plug you have the right gap so it's like it would be inside the engine (near enough).

Coils rarely go bad (I still have the 33 year old one working in my 1970 bug). A bad condenser is more likely (and cheaper to replace too!)

I just don’t know what order to start checking all of these things out.

In the order above, then for the tuneup, follow the order in our Tune-Up Article (starting with a cold engine, ending with a warm one).

I am running a ‘64 with a 1500cc engine rebuilt by me. It doesn’t get very good mileage -- maybe 20 mpg. I have 3 notches in the crankshaft pulley. I am running 30 PICT carburetor and an 009 distributor; everything is switched to 12 volt. The car runs great as long as I am into the pedal, but when I back off to cruise at 45-55 mph the car seems to bog down -- sputter and lose power. It’s the same in 3rd gear but at different speeds. I have tried adjusting carburetor, the points and the valves.

Is this problem common to the 009 distributor, or should I be looking somewhere else?

The timing and mixture seem to be the most obvious places to look.

The 009 distributor MUST be timed between 28 and 32 degrees at 3000+ rpm. Use as much of the 28-32 as you can without the engine starting to ping/detonate. If it still pings at 28 degrees, us a higher octane fuel -- NEVER use less than 28 degrees or the engine becomes under-advanced at higher rpm and will run hotter than it needs to. Using as much of the 28-32 as you can helps reduce any 009 flat spots a little.

Just for info, the vacuum distributors run up to a max of about 40-42 degrees under the right conditions (part throttle cruising for example). This is good for economy, but they can reduce this advance back to around 30 degrees when you floor the throttle (to stop the engine detonating/pinging) and only allow the extra advance back in gradually as the rpm rises to the "new" throttle position; this is called load (throttle) sensing. The 009 can't do this, it only rpm-senses, so has to be held back to the "worst case" 28-32 degrees. That means a lot of the time it's actually under advanced to some extent, so you use as much of the 28-32 as it can stand, to reduce that under-advance.

If you don't have a degree pulley -- 28 degrees is 43.5mm to the right of TDC, around the rim, and 32 degrees is 49.5mm to the right of TDC.

Earlier you said the engine was (or was going to be) 1641cc. This is a little on the larger side for the 30 PICT carburetors -- it will work OK but tends to make the smallish carburetor run lean at higher rpm, and the carburetor will just start to run out of breath at higher rpm, so the top speed may not improve much -- if at all. Low and mid-range acceleration would improve of course.

You could try these jets for an "in the ball park" set-up -- 55 idle (it probably has that already - the cut-off solenoid screws into this jet in the right side), a 127.5 main jet and a 115 or 120 air correction jet. You MIGHT need to use a 130 main jet (try the 127.5 first).

These changes will richen up the mixture from about 1500rpm upwards, and should reduce/eliminate the flat spot.

Your mention of a flat spot and the sluggish performance plus the engine/carburetor you have makes me think it's almost certainly running a little lean. The 009 distributor NEEDS a richer running carby than the vacuum distributors need, and the larger capacity 1641cc tends to make the carby run a little lean at higher speeds, so it's a double whammy.

You might like to think about getting an SVDA (single vacuum-double advance) distributor - John at Aircooled.Net will build one to suit the carby (vacuum signal) you are using. The SVDA is like a high quality 009 (32 degrees) with added vacuum advance (8-10 degrees). VW used them as standard from ‘74 onwards (and from ‘71 onwards in countries which didn't use the double vacuum distributor from 71-73).

You should also make sure that the tiny transfer ports in the side of the throat (close to the opening throttle plate) are not blocked. The idle jet provides fuel through these ports up to about 2500rpm -- slowly handing over to the main jet between about 1500 and 2500rpm, so any partial blockage there will affect the low/mid range performance. Never use wire to clear those ports - the best method of cleaning is an overnight soak in carb cleaner and then compressed air or WD40 with the little straw to blast any gunk out of the passages.

You mentioned building a 1776. Do you intend using single-port heads or dual-port heads? The single-port heads and smaller carbs these use (the 30 series or the Brosol H30/31 replacement) will work with 1776 but will be seriously restricted at higher rpm. So low-mid range torque would be good but your top speed may actually be lower, since the smaller carbs will definitely run out of breath sooner. The minimum size carburetor for a 1776 would be the 34PICT/3.