Runs great for 30 minutes then not so well

[Bill Blue]

My car's tanks build pressure. So does Van's. Mine also relieves excess pressure.
Bill

 

[hartmandm]

Mike, I'd say your cap is defective. Why have a spring loaded gasket seal if the vent hole is open all the time?
Bill

I assume the seal exists to keep water from entering the tank. Where the vent hole is placed, rain water / hose water would not enter through it.

Mike

 

[Thor 1211]

Being a 1960’s car with no emission standards, that the vent in the cap is just that, a vent. Neither holds vacuum or pressure. I would think the gasket was just to prevent fuel from sloshing out.

found at https://www.tanksinc.com/index.cfm/page/ptype=results/category_id=160/mode=cat/cat160.htm

Up through the 1960's, most vehicles used vented gas caps. This is simply a gas cap with a hole in it. Unfortunately, this hole would allow the fuel to splash out when accelerating or turning a corner.

All that makes sense to me and agrees with my experience. I can't figure out, nor have I had the experience with either a series 1 or a series V gas cap where there was pressure in the tank. I believe that the gas cap on my series 1 (now over 40 years ago) was vented because when some nitwit stole it I got a replacement at the auto parts store that wasn't vented. When I headed out onto the highway to go home, the car went about 10 miles then quit. I thought I had run out of gas. I kept a can of gas in the trunk and when I went to put it in I undid the cap and heard the distinct woosh of air going in. When I got home I punched a pin hole through the cap and never had another problem.

 

[Mike O'D]

Bill - I was thinking about a rad cap relieving positive pressure if it gets too high. I wasn't thinking about the modern cars that suck coolant back in when it cools.

 

[hartmandm]

I just did a simple test on a spare series 4 complete gas cap assembly I have. I used a syringe and a small rubber grommet with a hole in its center. The grommet was used to ensure an air tight seal between the syringe and the gas cap. Moving the syringe will attempt to pull or push air through the vent hole in the cap. The result was that air moved freely in both directions through the vent hole without resistance. As a control, I verified the syringe plus the grommet mated to a solid surface resulted in not being able to move the syringe in or out.

Mike

 

[Thor 1211]

I just did a simple test on a spare series 4 complete gas cap assembly I have. I used a syringe and a small rubber grommet with a hole in its center. The grommet was used to ensure an air tight seal between the syringe and the gas cap. Moving the syringe will attempt to pull or push air through the vent hole in the cap. The result was that air moved freely in both directions through the vent hole without resistance. As a control, I verified the syringe plus the grommet mated to a solid surface resulted in not being able to move the syringe in or out.no

Mike

View attachment 22888

Now, if we could only get you to do the same test with a series 1 cap . . . .

 

[Mike O'D]

Good job Mike! You can speculate all day about what is happening, but until you run the tests you will never know for sure. Science rules!

 

[Van Bagley]

The problem has been solved!
When I had my tach rebuilt I was told that with a Pertronix dizzy the tach would not read correctly. I then purchased a rebuilt standard dizzy from Advanced Distributors in MN. After trouble shooting everything mentioned in this thread and contacting Jeff Schlemmer at Advanced and following his advice with no avail I went back to the Pertronix. I have now put about 75 miles on it without any issues and the tach is not affected. I think it was a poorly rebuilt distributor that would work for a short period of time then fail.

 

[MikeH]

Just wondering. Did going back to the Pertronix dizzy also involve a coil change?

 

[husky drvr]

Mike,

I'll bet no coil change, but I think I'm safe to say the condenser was eliminated with the change. LOL

 

[RootesRacer]

IMO there is not much credence to the pertronix setup not working with your stock tach.
The pertronix coil is pretty mild and would behave much like the early internal ballast coil.

Unless the pertronix setup included their "second strike" controller, I see no reason it should not work
the current impulse circuit in the tach. Worst case, add or subract a turn in the current transformer (an external mod).

 

[Van Bagley]

Before switching to the Pertronics , I tried a new coil and condenser trying my best to make it work. I must have re-gaped and re checked everything a dozen times. I did an OHM test on everything, including the old coil and a new one, checked and re checked. I wasn't all that keen on using the Pertronics. I wanted the original style dizzy to work. Got into nasty discussion with Jeff and he told me never to contact him again...( I'm just a customer ). I'm thinking that maybe it's a possibility that something inside becomes out of round after a short time. I'm going to send it back to him, I don't want money back. It's not big deal, I just happy that it's been resolved.
I don't see any difference in tach reading with the Pertronics
Now to get the overdrive to work.