BUILD THREAD “The Juggernaut”
- Thread starter Rktpwrd
- Start date
Recently bought several aftermarket locking gas caps from rock auto. They claimed to be vented but it is not vented either way. Cold it pulls a nice vacuum, hot has a lot of pressure when you remove the cap.
Without buying all of them and giving a test there is no way to know what is or isn't vented.
Without buying all of them and giving a test there is no way to know what is or isn't vented.
After reading all the posts and replies, and in conjunction with the research I’ve done, I’ve come to the same conclusion. So much so that I bought that exact same Holley vent off Amazon last night. Should be here Friday along with my Summit order, looks like I’ll be redoing the tank vent.
I’ll mount it on the front of the trunk kickup, up high and with a couple of loops in the hose to prevent fuel loss. That way it’s done properly, and it’ll never be an issue. I seem to have misplaced the original tank filler cap for reuse with the new Spectra tank, so I am still going to need one.
It just doesn’t have to be a constant venting style anymore.
I just checked the rollover valve by putting suction (mouth) while holding it upside down. I was just curious. Works perfectly.
Please show where you mount it specifically if you can. Thanks
Edit... I think it's supposed to be as high up as possible which isn't the easiest thing.
Please show where you mount it specifically if you can. Thanks
Edit... I think it's supposed to be as high up as possible which isn't the easiest thing.
No problem Tony, I plan on reworking it this weekend. I’ll do another update to document the changes and where I mount the vent. I’ve got an idea in mind, it should work pretty well I think. It’ll definitely be above the top of the tank, and that’s all that really matters.
The bottom of the 22525300 (GT172) factory cap found on many 78-up B, D, C, Y, and G-body gas cars looks like this belly up. I think early versions had a handle, but I could be wrong. Seems like I recall that vaguely for some reason. Anyway, it appears there is some sort of valve assembly inside the cap. So there's at least one valve involved. It appears there's some sort of spring-like apparatus inside, leading me to believe the way it's setup is to vent into the tank to prevent vacuum. Of course, I could be wrong. I've never taken one apart or cut into it to determine what's going on in there. It's one of those things I never thought about because I've always run the charcoal canister. So I knew it was always vented, regardless.
The way it's made with the vent holes and everything make me lean to some sort of vent path, but then again, it depends on internal construction. They may just use the same mold for the insides and simply plug the guts. Who knows?
Not sure if I have an old, dead cap laying around somewhere or not, or I'd cut into that bad boy and see what was up. Maybe use a hole saw on the top cap cover and peek inside.
The way it's made with the vent holes and everything make me lean to some sort of vent path, but then again, it depends on internal construction. They may just use the same mold for the insides and simply plug the guts. Who knows?
Not sure if I have an old, dead cap laying around somewhere or not, or I'd cut into that bad boy and see what was up. Maybe use a hole saw on the top cap cover and peek inside.
Looks like I'm adding "tank vent" to the old to do list (will be a super easy kill I think). I believe I have a rollover vent on hand from another project that never came to fruition. I never even thought about filling the tank being a concern.
It definitely shouldn’t be underestimated. Many performance and drivability issues can result from improper venting for sure, to say nothing of the well known gas pump handle kickback problems with aftermarket tanks.
The addition of this rollover vent should all but eliminate both issues.
I think if you use a GM cap, plus that vent/rollover valve, I think you'll be golden.
Your car ORIGINALLY came with a 560524 cap. It was metal topped with a slight bump handle and the part number stamped on the edge of it. Problem is, you can find them new, but zowie! Close to 100 bucks USD a pop on ebay.
The latest supersession number for your car is GT195, GM p/n 22591476. Found them for like 14 bucks or so. Although there is another source that says the 22525300 without the handle will also fit. These cap numbers will get your head spinning.
Your car ORIGINALLY came with a 560524 cap. It was metal topped with a slight bump handle and the part number stamped on the edge of it. Problem is, you can find them new, but zowie! Close to 100 bucks USD a pop on ebay.
The latest supersession number for your car is GT195, GM p/n 22591476. Found them for like 14 bucks or so. Although there is another source that says the 22525300 without the handle will also fit. These cap numbers will get your head spinning.
