1970 Solex 30 Pict 3 issues/ one thing leads to another

[Tcash]

First set:
Valves
Dwell
Lube distributor

Setting Timing
T&S: RPM gauge, Timing light, #2 flat blade screwdriver, 10mm socket, 6" extension, Ratchet, Pencil.
1. Disconnect the vacuum hose from the distributor (dist.) and plug with the pencil.
2. Warm up engine. (86*-158*)
3. Adjust Idle to 800-900 rpm.
4. With the timing light reading off the #1 spark plug wire. Check that the timing mark is lined up with the crankcase parting line (centerline) as indicated below.

5. To adjust. Loosen the distributor clamp, 6mm hex nut with the 10mm socket just enough to be able to rotate the dist.
6. Rotate the dist. clockwise or counterclockwise to line up timing mark.
7. While holding distributor in the correct position tighten the 6mm hex nut with the 10mm socket.
8. Recheck timing. Adjust if necessary.
9. Reconnect vacuum hose to the distributor.

Checking Spark Advance Mechanism
This distributors means of Advancing (earlier) timing is the Vacuum Canister only. It has No mechanical Centrifugal advance mechanism.

T&S: Degree wheel, Vacuum gauge, "T" fitting, Vacuum hose.

1. Print, tape or past one of the degree wheels below onto your crankshaft pulley. Aligning "0" on the degree wheel with TDC (0) on your pulley.
Type I timing scale.

[wcfvw69]

[Tom Powell]

Thanks for all the replies to my posts.

The camper starts it's winter road trips at nearly sea level and crests Conway summit at 8,138 feet. A bit of advance would help at this altitude and a large sump oil cooler maintains near normal operating temperatures on the ascents.

I would assume that a vacuum can is designed so that it might be at rest with idle vacuum and not start advancing until a greater vacuum was created. I also assume that throttle position at rest, cruise, or under greater load controls the vacuum and that you can obtain maximum vacuum on the road or in the driveway. The vacuum is higher when there is less load on the engine.

IMO: Setting the timing at idle is only the first step in setting dwell and timing.

I am also of the the opinion that timing that is too retarded can cause overheating and timing too advanced causes detonation and damage.

In the interests of "science", the next time I'm on the mainland and headed on a road trip, I'll set my idle timing at 0*TDC and check the results and post my opinions back to this thread. In the meantime the camper is in storage and no harm is being done with an incorrect or unsuitable timing procedure.

I'm here to learn and a little knowledge can be a dangerous thing.

Aloha
tp

[airschooled]

Tom, you have years of experience under your tires, so I'm never going to say you're doing something wrong, but if engine longevity is something you strive for, you might be well-suited to try a 0* timing setting at sea level. ANY feeling of loss of power due to overheating can mean permanent damage to the engine. With my air-fuel O2 meter, I see my engine produces the richest mixture under full throttle, telling me the carb and distributor are working together to produce good power and keep the engine from overheating. When I let off just a tiny bit, the mixture leans, partially due to jetting but also due to the timing increase as shown in the images below. With a stock 0* setup, I could not get my engine to overheat this summer, flooring it up every hill I could find in Southern California. You lost an engine on the Sherwin Grade years ago, did you not? Do you recall how that was timed with what setup?

(In case you're not sold on it yet, understand that with more retarded timing comes greater cabin heat from the exchangers. This is because the combustion reaction continues later in the cycles, so the exhaust flow carries the final instants of combustion out the manifolds. MANY people think that overly-retardd timing can overheat an engine; I do not find this to be true. In fact, retarding the timing, even beyond allowable limits has shown me time and time again that cylinder head temperatures will cool off. Doing this, however, royally increases exhaust system temperatures, because the combustion is still happening in the heat exchangers. This in turn heats up the apron and much of the surrounding metal in the engine compartment. Mere mortal humans touch the apron, say "Ouch!" and assume the engine is overheating, while the cylinder heads are practically taking a nap. Because of this, if my timing drifts to 3-4*atdc in the cold winter, I say "thanks!" and enjoy the extra cabin heat. This comes in handy on ski trips.)


Also in the name of science, here's a quick rundown on the vacuum-only advance system, with images courtesy of Juanito84.


The SVA or SVSA distributor vacuum port is a link between two vacuum drillings; one is in the venturi of the carb, and the other near the throttle plate. (This is opposed to an SVDA carb, which is just one drilling, and near the throttle plate.)

Here, at idle, the airflow speed through the venturi is low, and there is no air passing by the throttle plate, (because it's all going through the idle bypass circuit,) so there is no vacuum to pull the advance arm.

Next up, we have a partial throttle situation. This is most acceleration and steady-state driving scenarios. See how the air is moving at a lazy speed in the venturi but past the throttle plate at a high velocity, so the total advance is in the mid range?

Next up is where we're flooring it up a hill, because 47 net horsepower are nothing to fool around with. The vacuum signal almost "drops out" due to low air speed through the venturi as well as almost no vacuum pull past the throttle plate because the plate is wide open. This is a "safety" or "governor" that our engines are blessed with, which is why the 205 SVSA distributors are, in my opinion, the best for flogging an engine up any hill imaginable without gauges and worrying.

Now we've hit our target speed, and we'll keep the throttle down for science. The vacuum signal to the distributor increases, because airflow is speeding up through the venturi, but it is not at full advance because the throttle plate is too open to max out the vacuum signal.

Last up is a pictorial of when you're making good speed and you don't require much throttle to keep going. This is showing medium-fast cruising, downhill engine braking, or just needing minimal pedal to maintain speed. The advance is maximized because it is safe to do so at a high speed with little to no load. This is your "max advance," and it is safe to go beyond 28*-30* here, because the engine has no load.

So we want to make sure the total advance is not too high under load, but we don't really care how high it goes without a load. This is why it is fruitless to test for maximum advance with these distributors in the driveway; we have no way of simulating load, which will affect max advance when it matters.

Robbie
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[Tom Powell]

I'll succumb to the advice of my more knowledgeable and experienced superiors and try 0* when I'm next on the mainland.

In the 80's I did melt the engine on Sherwin grade in my newly purchased 69 camper. This was before I learned to correctly drive uphill in an ACVW and the need to downshift instead of mashing the accelerator. I had not yet done a tuneup so I don't know how the timing was set.

I will blame it on inexperience, lack of knowledge, and a nagging wife in the next seat. I was able to get the engine rebuilt in Bishop and got rid of the wife when I got back home. The engine is still in the camper.

After I got a Bentley, at the next tune up I set the timing as I read it in the book. If I recall correctly I experienced a slight loss of power and backfiring when decelerating. At times since then I've replaced the distributor and the carburetor and set maximum advance at 3000rpm in the driveway. I've been happy, but now question my procedures.

Before I bought the VW camper my timing experience was mostly with Datsun 510's of the early 70's. I timed the 510's by ear: Advance the timing until it pings when going uphill in the wrong gear and then retard a tad until the pinging stopped. When I joined TheSamba I got slammed by DBM for expressing those methods for tuning a VW. Since then I realize that an ACVW is deliberately detuned to maintain operating temperatures and prolong engine life.

Perhaps the addition of the deep sump has disguised the potential for overheating problems that the heads would experience and my perception of maintaining uphill power with a deep sump is due to advanced timing, not better cooling.

Aloha
tp

[busdaddy]

[Dana Champion]

This is awesome!..... almost feels like therepy.

Thanks for all the engaging responses, helpful tips and praise......

I'm still processing....


I'm getting itchy to drive this girl.

I took the two front wheels to get new valve stems today. It's not a good sign, when you move the stem and air leaks out.

I'd like to paint my wheels......later

My drivers side ball joints need help

[Amskeptic]

[wcfvw69]

http://www.thesamba.com/vw/forum/viewtopic.php?t=307450

Tom,

Since I think we've "sold" you on timing that "T" distributor to 0, you should go through this thread as well. You should double verify that you have the correct vacuum can on that distributor. I've seen other posts where people where timing there engines to the model of distributor, only to learn later that it didn't have the correct vacuum can on it.

In all likelihood, you have the correct vacuum can as these don't blow out too often. I just think it would be a good thing to double check that someone didn't put a different can on it.
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[Tom Powell]

Yes I have been sold on resetting my ignition timing to specs. My bad opinions have been beaten down and killed with facts and logical explanations. Thank you for that.

In the spirit of inquiry and gaining knowledge I have a question:

I know that the OG ACVW engine is detuned for several reasons, primarily longevity. But, if for some reason I wanted to get maximum performance from the OG engine without concern for its destruction, where would I set the timing? I assume it would be advanced to just short of causing detonation. Any opinions as to what BTDC that might be?

I did a short search in the performance section, but haven't found my answer yet. I did find some excellent information in this thread
http://www.thesamba.com/vw/forum/viewtopic.php?t=636890&highlight=timing
with contributions by Juanito 84

Aloha
tp

[airschooled]

[Dana Champion]

[Tcash]

[Dana Champion]

[Tcash]

I have a plugged port on the left side of the intake @ # 3&4 cylinder. Could I use this
Yes, you can. I wonder what that was for?

Tcash

[airschooled]

[Dana Champion]

[Dana Champion]

[Dana Champion]

Performed my first vacuum test. Any thoughts


Link

[Abscate]

No,sticking valves

Good valve springs

No vacuum leaks

Rings ok

Empty canister before next test.
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