Vented or Not Vented Gas Cap
 

I just bought one of those after market gas caps with the V8 logo on eBay. Came none vented, do I need to drill a hole it it? Hate that idea, its so purty.

Re: Vented or Not Vented Gas Cap
 

The tank has to be vented, if there is not a vent anywhere else for the tank, then the cap has to be vented.

Re: Vented or Not Vented Gas Cap
 

Check the tank neck for the vent.

Re: Vented or Not Vented Gas Cap
 

What year car are you working on?

Charlie Stephens

Re: Vented or Not Vented Gas Cap
 

I have a 1936 model 68 what is this little pipe inside the fill, could it be a vent?

Re: Vented or Not Vented Gas Cap
 

Appears to be a vent. Is it kinked? Did your other gas cap have a vent hole in it?

Re: Vented or Not Vented Gas Cap
 

Yes, looks like someone drilled a hole in the old gas cap but I can't stick a wire threw it. I guess I could just drive it and see what happens, if the motor dies and I unscrew the cap and hear it suck air I will know I have to drill a hole in it.

Re: Vented or Not Vented Gas Cap
 

If you look at the outside of the neck just below the ring where the cap seats, you should see the end of the little tube. That is the vent, and if it isn't stopped up the cap does not need to be vented. I have one on my 33 pickup and works fine with an un-vented cap.

Re: Vented or Not Vented Gas Cap
 

Yes, that is a vent.

Re: Vented or Not Vented Gas Cap
 

Run a piece of wire into that small tube to make sure it is not plugged up

Re: Vented or Not Vented Gas Cap
 

Where might I see the other end or an opening? I took a quick look at the fill pipe and did not see anything on the outside.

Re: Vented or Not Vented Gas Cap
 

Good idea, I will try that tomorrow, thanks.

Re: Vented or Not Vented Gas Cap
 

Believe its in the tank.

Re: Vented or Not Vented Gas Cap
 

Not sure that would work how would it be a vent everything would still be self-contained. I would think a vent would be looking for outside air.

Re: Vented or Not Vented Gas Cap
 

I found an interesting post here on the barn on this exact discussion back in 2010, not sure how to share it but its says that little pipe inside the filler is a vent to the outside on 1936 cars. I will do the wire test tomorrow.

Re: Vented or Not Vented Gas Cap
 

Thats exactly why you need a vented gas cap.

Re: Vented or Not Vented Gas Cap
 

Put the cap on as is and drive it. If after awhile the engine looses power or stutters as if running out of gas, that will be a sign. Even if it runs fine when you park it slowly open the gas cap. If you hear a hissing sound that's a clue that it needs to be vented.
This was common with Model A's. They need a vented cap and some of the new ones didn't come with a vent hole.
I was almost stranded once in my "A" and remembered to open the cap...hiss! Drove home with the cap just loosly on... Chap

Re: Vented or Not Vented Gas Cap
 

Well I could not get a wire through the vent pipe but I could blow air through it. Took about a 20 mile ride with cap tight, no issues and when I got home released the cap and no gush for air sound. Looks like no need to drill a hole in the nice V8 cap for me. :)

Re: Vented or Not Vented Gas Cap
 

I had one of those caps . I don't believe it was vented , but my tank is on my '37 , so all was fine . - F F