46 Supersix idle RPM and timing

JMed

Hello everyone, I am looking for advice on setting the RPM idle speed and timing on a 46 super six.

Short version: Can I use a modern tachometer and timing light if the car runs on 6 volts? If not, what do I need? I have a modern timing light and it seems to work but the light is very dim which is probably because the car is running on 6 volts. I don't have tachometer and don't know if a new one from the auto parts store will work. Any advice?

Long version: The car is running a bit hot (about a little more than 1/2 way on the gauge and up to 3/4 on the gauge). It is also lacking power and having a hard time going uphill.

I set the idle mixture to optimum before checking for vacuum leaks, but the maximum vacuum was only 16 and I understand it needs to be around 20 or 21. I checked for vacuum leaks, including the wiper motor and I could not find any. So I tried to check the timing and my modern timing light is very dim, and I'm not sure how accurate it is on a 6 volt system. But I did advance the timing and the vacuum increased to about 19 very fast. After a test drive the car already feels better. A friend mentioned I can set the timing to maximum vacuum then go back a couple of degrees. That should be easy to do with what I have. But I also need to set the idle speed to 600 rpm. I don't have a tachometer and could buy one from the store, but will it even work?

Crazy idea: Optimum timing, idle mixture, and 600 rpm at idle are supposed to give 20 or 01 in. of vacuum. Then can I set the timing, idle mixture, and 20 or 21 in. of vacuum and expect to end up at 600 rpm? Seems like simple algebra.

Thank you in advance for any advice.

Jon B

Just a quick answer on the timing light: you could go to Ebay and see if there's a 6-12 adjustable timing light for sale. Otherwise, simply park your modern 12 volt car next to your Hudson and hook the power lead (from timing light) to the 12 volt battery. Then you'll have the 12 volts you need to run the light, but the timing light will still "read" the spark plug for the correct timing. Or hook a 12 volt battery to the light.

[Deleted User]

The previous poster is correct , very easy to fool the timing light with a 12 volt car.
And as far as your timing if it is off you could cause motor to run warm and lack power. You may also check your exhaust heat riser/damper to see if its stuck closed. That would give the same two symtoms,
Roger

[Deleted User]

Cant the timing lite be powered by a battery charger set to 12 volts? I think we did that once, but cant remember how it turned out. Thanks, Bob

Marconi

Battery chargers aren't filtered too well and have a lot of A.C. ripple in their output,it may work, but I'd say that the timing light would "flicker" in use and wouldn't give an accurate result. Better to pull your 12 volt car alongside and use the battery in it.

oldhudsons

as for idle speed, once you get the timing properly set up, I always found there will be a certain idle speed at which the trans. gears will mesh best when going from neutral into a gear and at which shifting between gears is smoothest; I'd try to find that "happy medium" rather than setting it at some predetermined RPM level.
Above esp. important when setting idle speed for pre-meshed trans. models that should be double-clutched when upshifting.

JMed

Thank you all the advice. Yes, the timing light works well with another 12v battery. On the downside, the car erroneously got a full tank of 91 octane gasoline. And come to think of it, that is probably not helping. I advanced the timing a little and it runs well. I suspect I will have to retard the timing once I go back to regular gas.

As for the temperature it is still running a little hot. Roger's post suggested I look at the heat control valve. The coil spring is disconnected and the shaft at the other end of the manifold has a spring holding it open (Opposite side from where the coil spring would normally hold the valve while cold). That should be ok right? I live in Southern California. But this brings me to another problem I am having. After I drive the car for a while it has a hard time starting. I was told it's just vapor lock. But one time I could actually smell the gas. Other times it just takes a while to get it going again.

ps - thanks for the advice. The car was last driven 4 years ago, and even then it had been parked many years before that. I have done a lot of work over the past two months and I'm actually very happy the car is now on the road.

[Deleted User]

The strong gas smell could be from the heat off of the exhaust manifold, it boils the gas in the lines and builds pressure that is pushing gas vapors thru the carb idle circuits.Does it take longer to start after you smell the odor?
Bob Hickson

JMed

Yes, it takes longer to start after I have driven for a while. Last weekend was the first time the actually went for a nice drive in many years. I drove about 100 miles. The first stop was about 25 miles into the trip where I met some of the club members. 30 minutes later we tried to keep going and the car didn't start. Took lots of cranking and starter fluid to get it going. Later in the day it did the same but with a strong smell of gas.

The car doesn't do that when I drive it in the streets, just when it has been driving at high rpm on the freeway.

JMed

Thank you all for the advice. Today I got my hands on a Heathkit Tuneup Meter and was able to read RPM and Dwell. Between that and the vacuum gauge I made lots of progress.

I can't teem to get the car below 700 rpm. I am not sure if the choke is stuck, but this was after the car had reached top temperature.

The dwell reads at 33. The mechanical procedure calls for a dwell of 35. How far off is that? Being new to working on this car I am not sure if I can adjust the dwell or if I need to gap the points until I get a dwell of 35.

Dwell and points have probably been discussed in this forum before but I can't seem to find it. I'm new here. If you know of a forum post, can you send me a link?

Thanks again to all, I really appreaciate your help. I love this car and I want to make sure I keep it in good running condition. Perhaps my 2 year old son will get to drive it some day, or so I hope.

Lee ODell

It was good to see your car cruising on the Apple Run.

The dwell is the number of degrees of breaker cam rotation from the time the points close until they open again. Closing the points gap will increase the dwell angle. Open points gap wider will decrease dwell angle. Close the points gap slightly and recheck the dwell again.

Perhaps the throttle return spring is not strong enough to close the throttle all the way. Try to manually close the throttle at the carburator. Check that the choke is open all the way.

It is interesting the 1942 to 1947 procedure manual says to adjust the throttle stop screws on all models so that the engine idles at a car speed of 6-1/2 to 8 miles per hour in high gear. This is equivalent of 600 to 650 RPMs per minute.

Spark plug gap should be .032

I'm glad the performance is increasing for you. You are on the right track.

Lee O'Dell

[Deleted User]

I was reading your reply about the gas smell and was thinking about gas boiling in the carb. Originaly Hudson had about 6 gakets and a metal heat shiel under the carb. Has someone maybe removed those and just put one gasket there?
You also need to keep the fuel line away from the exhaust pipe and manifold.
there was a simmilar setup on the fuel pump with a stack of gaskets to prevent vapor-lock there. That one is easy to diagnose ,if car wont start pour cool water on fuel pump and try again. if car starts you had a vapor lock in fuel pump,
Roger

lostmind

Your high Idle speed could be a result of a
vacuum leak.A light oil in a spray can with nozzle
should help find it.Idle speed will change if you find
a leak.Watch for exhaust manifold hazards.
Your float may need to be adjusted to compensate for
the gas your using.
I think somebody aready mentioned to check the heat riser
valvle.Very common on a car thats sat a long time.
Is it realy running hot ,or is the gauge showing higher than
normal.Best to check with another gage in radiator.
Most likely cause,if it runs hot at high speeds is
restricted radiator.
Hope some of this helps.
Roy

Jon B

Hard starting could be due to a number of causes.

First of all, do you have a fairly good battery with lots of Cold Cranking Amps, or is it an old "cheapie"? Are there two ground straps (one from the batt to the engine or the body, and the other between the engine / bellhousing / transmission and the body? Are all the electrical cable / ground strap connections "bright and tight"?

Secondly, are the cables of the correct diameter for 6 volts (like, maybe 3/4") or is it something that a previous owner copped from a 12-volt car?

Are the points gapped correctly and are they bright and shiny? Do you have a spare new condenser and have you tried substituting this, when the car is hot and won't start? (Might be worth letting your car run til it gets hot, in the driveway, then trying to re-start. If it won't start, try some of our suggestions. Much better encountering problems in your driveway than on the road.)

As to the remark about 6 gaskets under the carb, I have 8 of them! Four above the heat deflector plate and four beneath. The gas line (and even the exhaust pipe itself, where is passes near the carb) can be wrapped in modern heat-shielding insulation. In the old days we used asbestos.

The smell of gas may NOT mean that there's a fuel delivery problem, it may simply be the result of an ignition problem that doesn't start the car, thus resulting in a lot of unburned gasoline!

Anyway, those are a few additional ideas.

JMed

I have looked for leaks and I thim i'm good there. As for the heat riser, it has been disconnected. The car seems to start fine even on a cool morning - a benefit of southern california. The gauge goes up to 3/4 of the way. I may need to test it with a gauge that shows the actual temperature. Thanks!

JMed

Jon and Roger - I think you just found part of the problem! I don't know how I missed that but the fuel line from the pump to the carb passes very very close to the exhaust. Sure, the exhaust has some old insulation on it, probably asbestos, but I can barely put my index finger in between the fuel line and the exhaust insulation. There is no need for that as there is plenty of room in there to re-route the fuel line. I will install a new line away from the exhaust.

The battery and cables are all new. The cables are 1/0 gauge.

The points are not shiny at all. Do I need to replace them because of that? I have never replaced or gaped points and it makes me a bit nervous that I may break something in there. I will have to do some research on procedures if I need to do that. The dwell meter shows a dwell of 33, while the mechanical procedure calls for a dwell of 35. I am not sure if being off by 2 is a problem or not.

Thanks again!

Jon B

Don't be afraid of the points. Not nuclear science. You need to learn anyway and if you did break a set (which is totally unlikely) it would be for the good of your education.

I have actually installed brand new point with a dull glaze on the face, not realizing that these were either corroded (from age) or covered "at the factory" to keep them from corroding. Get some of that brown emery cloth, wrap it around a tongue depressor or whatever, and then get down there and slightly sand the face of both points so they are shiny. Get a set of thickness gauges and put them between the points to see if they're properly gapped. Actually it's easier to work with the distributor out of the car and in your hands. Get a knowledgeable friend over and ask him for a basic course in distributors (offer him lunch or dinner, it helps).

Buy one or two extra point sets and condensers and keep 'em handy on a trip. If the car suddenly starts to miss and gets worse, it's probably either the condenser or points. Either condition is quickly and cheaply fixed if you have spares!