Potential Vapor Lock?

[woodie49]

Woody, Are you sure you are at ATDC and not at BTDC? At modern fuel your car will probably run best about 4 deg earlier than on old fuel from 1950 as it burns more slowly. Greg G has written a few posts in this issue. When I did my timing I came to the same conclusion reading the vacuum meter.

Dutch,

Well, this is the kind of thing that really makes me feel stupid to have to admit. I am not sure. I get confused on the direction of the distributor and where the timing mark is. I was convinced I was BTDC a little while ago and then thought about the direction I was moving the distributor to move the mark and figured I was ATDC. I rotate my distributor clockwise to move the timing mark away from the pointer. So, I am moving away from the rotor, which would give me a later spark, which would mean I am retarding the timing. By retarding the timing, the timing mark is moving progressively away from the pointer. I started at zero and I am now six degrees away from the pointer. So, I assume ATDC. Am I thinking about this backwards?

Although the car is running good, I think this weekend I will pull the distributor and re-check the points. The only non-machanical thing I can think of that might alter the timing so much is the dwell. I did replace the points as part of my recent project. Maybe I totally messed this up. A dwell meter would be nice.

I am going to try to find the posts you mention. The timing looks great according to my vaccum meter.

[woodie49]

I hooked this up again last night. I am running currently at 6 degrees BEFORE TDC. When I accelerate my mark moves further from the pointer. As pointed out, that is pretty conclusive. Maybe the reason for the advanced timing is modern gas and point gap off a bit. I still want to look at the point gap this weekend. Thanks for the input to date.

[mikehalek]

Please save yourself a potential disaster. Move your gas filter from above your manifolds. Metal filters are better than plastic ones but one drop of gas on a hot manifold and your nice engine is toast. Mike

[DutchEdwin]

I hooked this up again last night. I am running currently at 6 degrees BEFORE TDC. When I accelerate my mark moves further from the pointer. As pointed out, that is pretty conclusive. Maybe the reason for the advanced timing is modern gas and point gap off a bit. I still want to look at the point gap this weekend. Thanks for the input to date.

Woody, glad that's sorted out. Be aware, when you move the timing too much deg BTDC you can get an engine knock, that can destroy your engine. Although I've heard Greg mentioning 6 deg as a good result before.

I'm still working on a method to detect engine knock. But I'll guess that's the winter job research.

[DutchEdwin]

Recently, I installed an electric fuel pump on my 52 car to aid in starting. I only use it prior to start to fill the carb with gas. Starting is easy now plus there is help if a vapor lock happens. The original pump is still in the system and everything works great.

Hi Suntennis, can you tell what type of pump you used for the electric? and is it protected for too high pressure with a shut off?

[suntennis]

The NAPA fuel pump I believe is just a universal one they have at a cost around $70.00. It may be made by Federal Mogal. The pressure as I recall is 4PSI to 5 1/2 or 6PSI. I tried it and found that the carb could handle the pressure. To be on the safe side, one could place a filter before the pump and maybe a pressure regulator after the pump. On my install, only the pump is added to the system.

Edited August 26, 2010 by suntennis

[desoto1939]

I have put on the new 6v Airtex pump I think it is model ew001. I you do some searching on ebay you will see them listed for around 48 dollars.

They produce around 3-5 lbs and will not hurt or our cars or trucks. I have one on my 39 Desoto. There are two wires. If you are running 6v positive ground then the positive wire onthe pump is he one that you hook to the fram because of the polarity of your car. The other wire then should hook up to a toggle switch then run the wire from the switch to the iginition switch.

This will prevent the pump from running allthe time and run can turn it off an on when needsed. Most of use are using the pump as a back up and also toprime the carb after the car has sat for a while. The electric wil pump trough the mechanical pump if when it goes bad so this is why the the electic is a good item to have onthe car.

I run my pump about 10 seconds max to get the gas upto the carb and then the car fires right over without grinding the engine and wearing down he battery.

Do a search on www.airtex.com and then on electric pumps and you will get the model number and all of the data.

rich Hartung

desoto1939@aol.com

[TodFitch]

I have put on the new 6v Airtex pump I think it is model ew001. I you do some searching on ebay you will see them listed for around 48 dollars.

They produce around 3-5 lbs and will not hurt or our cars or trucks. I have one on my 39 Desoto. There are two wires. If you are running 6v positive ground then the positive wire onthe pump is he one that you hook to the fram because of the polarity of your car. The other wire then should hook up to a toggle switch then run the wire from the switch to the iginition switch.

This will prevent the pump from running allthe time and run can turn it off an on when needsed. Most of use are using the pump as a back up and also toprime the carb after the car has sat for a while. The electric wil pump trough the mechanical pump if when it goes bad so this is why the the electic is a good item to have onthe car.

I run my pump about 10 seconds max to get the gas upto the carb and then the car fires right over without grinding the engine and wearing down he battery.

Do a search on www.airtex.com and then on electric pumps and you will get the model number and all of the data.

rich Hartung

desoto1939@aol.com

Looks like www.airtex.com is a company that makes pillow stuffings...

Probably want http://www.airtexproducts.com/ and on that site it looks like the 6v pump for carburetor applications is E8011

[DutchEdwin]

Hi Woody, I did make my heat insulator for the fuel pump.

Made it from 4mm thick PA (nylon). I checked that the arm still touches the cam, with 1/4 inch to spare. Also the bolts still have enough length.

I also installed a new pump.

Took the car for a drive to heat up the engine. Stopped and started after two minutes. No problem, started up right away, Also after 5 and 10 minutes. I hope I have solved the hard starting problem this way. Also the pump was only a bit warm at the arm where it is bolted to the engine.

I'm going on an oldtimer trip tomorrow in Germany. My first long trip, about 150 km. Hope all things go well.

[P-12 Tommy]

Dutch, Good luck on your run tomorrow.

Tom

[woodie49]

Hi Woody, I did make my heat insulator for the fuel pump.

Made it from 4mm thick PA (nylon). I checked that the arm still touches the cam, with 1/4 inch to spare. Also the bolts still have enough length.

I also installed a new pump.

Took the car for a drive to heat up the engine. Stopped and started after two minutes. No problem, started up right away, Also after 5 and 10 minutes. I hope I have solved the hard starting problem this way. Also the pump was only a bit warm at the arm where it is bolted to the engine.

I'm going on an oldtimer trip tomorrow in Germany. My first long trip, about 150 km. Hope all things go well.

Nice work. Hope that fixes the problem. I put a couple freeway/street hours on the Woody this weekend with no starting issues and it is runing pretty strong. It seems to me to run a bit to the hot side, but I think that is due to the timing. I ordered a dwell meter to continue investigating my issue.

How did the weekend run go?

[woodie49]

To further follow up on this, I bought a dwell meter. It is for meant for 12V Neg ground, but the label seems to say it will work on all motors using points.

It has a 6 cylander scale. I needed to hook it up backwards to read properly because of our positive ground.

Initially, I got a 46 degree dwell. I regapped several times to .050, but still get about 46 - 48 degress. I adjusted slowly to get to about 36 degrees, which is where I am now, but I am defineately over ,050. Does anyone have an idea whether the 6 vs. 12 volts should affect the dwell meter?

I cranked the timing back to TDC (10 dgress off dwell should be 5 degrees off timing, so this made sense). Adjusted the idle using the vacuum guage (which shows the timing to be good). I am idling at about 600 RPM. I get a small stumble when I gun it under no stress. When driving, bottom end and mid-range is good, but it definately falls apart at the top of the power curve, especially in 2nd gear. I get a slight sputtering noise from the exhaust upon releasing the gas.

By contrast, it was really running well at about 6 degress BTDC and apparently 46 degrees of dwell. But, it was running hotter than I am used to, so I thought that might be timing. It does seem to run a bit cooler now, but not nearly as well.

Earlier, I did raise the float from its former position (where it had been for the past couple years and running well). It is starting and idling well.

[TodFitch]

... Initially, I got a 46 degree dwell. I re-gapped several times to .050, but still get about 46 - 48 degrees. I adjusted slowly to get to about 36 degrees, which is where I am now, but I am definitely over ,050. Does anyone have an idea whether the 6 vs. 12 volts should affect the dwell meter?....

A dwell meter should work for the 6v system as all points type cars are 6v at the points (a 12v car uses either an external ballast resister to drop the voltage or has an equivalent resistor built into the coil).

Did the gap/dwell settings change that much from the 1930s? My 1930s manuals show 0.020 gap giving 36 degrees dwell for 1933 or 38 degrees dwell for 1937. A gap of 0.050 sounds really big to me.

If you can't get the correct dwell with the correct gap is means that the lobes on your distributor cam are worn.... And if they are worn then the points may not be opening far enough or quickly enough to give you a good spark at higher RPMs.

[woodie49]

A dwell meter should work for the 6v system as all points type cars are 6v at the points (a 12v car uses either an external ballast resister to drop the voltage or has an equivalent resistor built into the coil).

Did the gap/dwell settings change that much from the 1930s? My 1930s manuals show 0.020 gap giving 36 degrees dwell for 1933 or 38 degrees dwell for 1937. A gap of 0.050 sounds really big to me.

If you can't get the correct dwell with the correct gap is means that the lobes on your distributor cam are worn.... And if they are worn then the points may not be opening far enough or quickly enough to give you a good spark at higher RPMs.

Sorry -

020 is right. I am a crummy typist and apparently a worse 10-key operator, hitting the 5 instead of the 2.

Dwell should be between (from memory) 34.5 and 38.

Maybe my next step should be to replace the points with the ones I pulled out. The arm to the contacts did look slightly different. If I still have the issue I think I do have a spare Dist to try.

[woodie49]

My 12v dwell meter was useless for my 6v system. Gave a high dwell reading. I bought a vintage Sears model 2185 which operates on 6v and was able to check it with that.

EDIT: thread with my dwell meter readings:

http://www430.pair.com/p15d24/mopar_forum/showthread.php?t=16624

Shel,

Thanks for the input, I was wondering if that might be the case. I ran out this AM before work and checked the dwell on my '41 Packard (also a 6 v. +ground, but 8 cylinder). It was right at 30 degrees, so I think this meter works on 6 V. I would have checked it a week ago, but it was at my friendly packard shop. Might have been better if it was way off.