I’m swapping my ‘72 over to fuel injection and working my way through the associated challenges. I ordered an entirely new fuel tank from Holley with an integrated fuel pump and a new sender unit. I thought I’d share my progress for the next guy.

 

After removing the original tank, I touched up the paint on the rear section of the frame.

 

Next on my list is the vent line. I’ve spent a lot of time thinking about this one. It needs to be as high as possible, but you can’t get much higher than the fuel tank in the back of a C3 convertible. I was also looking to utilize an existing hole or bolt instead of adding another hole to the fiberglass. I found a viable hole, just below the rear deck.

 

Next challenge was to find a way to mount my vent cap to that hole…

 

It was snowing outside, so I was happy to waste WAY too much time making a bracket to mount the vent cap. Starting with a piece of scrap steel, I drilled a couple holes, milled it to the desired width, and bent it to 90° on the hydraulic press. After that, a little black paint and it was ready for installation.

 

I decided that a pop rivet and some epoxy would probably do the job of securing the bracket, but the fiberglass is very thin, so I wanted to put a washer on the backside of the rivet. This turned out to be trickier than anticipated due to fat fingers and tight clearances, so I came up with a way to extend my reach with a paper clip and some super glue.

 

With a dollop of adhesive on the back of the bracket, I pushed the rivet through the hole and then fished around with my improvised washer carrier until I could slide it over the blind end of the rivet. From there, the rivet gun worked fine and the paperclip actually broke free just as the rivet popped. This allowed me to sandwich the fiberglass between two metal surfaces for a secure fit.

 

With a little Loctite Blue on the threads, I was able to mount the vent cap just about as high as possible, forward of the tank, and almost perfectly level. That seems to be important as there’s an integrated tip-over valve in the aluminum vent body. I’m hoping this will do the trick.

 

Good job so far! Do you think using a vented gas cap would do the trick if no there was no gas smell as a result?

 

I wondered about that myself after spending way too much time trying to find a suitable location for the vent and thinking a cap might be an easy solution. However, none of the vented gas cap threads that I could find seemed authoritative. Some said that the cap wouldn’t flow enough air for the fuel injection system and some suggested that I’d smell gas all the time. I can’t say, for sure, what the correct answer is, so I’ll share my approach, but I won’t say it’s the best or most correct approach. I probably won’t even be able to tell anyone how good or bad it worked for another 6 months. 🤔

 

Here's what I did for my vent- put it in the antenna hole- it's a stainless steel piece used on boats.
Mounted a roll over valve on the tank for the vent at the highest point.

Then used a carbon filter on the vent line - no smell at all- several years later-

 

OK, I'll share my EFI tank vent, again.
vented gas cap. For about 5 years now. Absolutely no issues whatsoever. Tiny, and I mean tiny, attached 1 car garage that also is the laundry for the household. If there were fuel smells I am certain the Female Hitler in my house would have let me know by now!
No vent, no charcoal canister. Just a vented gas cap and done.

 

Same here. Back when I had a carb the gas smell was a problem. Attached garage and fumes would seep into the house. When I swapped to EFI 20 years ago I also swapped to a vented gas cap and I've never had even a hint of gas smell in the garage.

 

I have a friend who switched an 82 over to carb as the crossfire EFI was just to problematic.
Attached garage. He never stops complaining about the fuel smells.
Seems the Carburetor it's self is a much bigger issue than a vented gas cap.

 

Hi Richard. I did read about your approach and it does look very clean. It certainly gets the vent as high as it can physically go in one of these cars. I was headed down that road, but then I didn’t want to give up my radio antenna for the sake of nostalgia. You just don’t see them on many cars anymore and I still enjoy listening to the crackly local radio station playing reruns of Casey Kasey’s Top 40 from the 70s. 🤣

 

Thank you-

Really nice work you have done!

Casey Kasey? I remember skipping out of church a few minutes early and getting in the family car to listen to him!
There is always a cassette tape!!!

 

Did you mean Kemal Amin "Casey" Kasem?

Also a little known fact is:
JT

 

For my EFI system I simply used the original factory fuel tank as it was in good shape both inside and out. Then when I ordered the EFI system I also bought the Holley OEM Style In-tank fuel pump module and pressure regulator which were so simple to install. I removed the old parts and installed the new parts in way less than an hour. They even give you a piece of Holley's wonder product Hydra-Mat which helps draw in gasoline from extremes.

I drained the fuel tank out by siphoning out the fuel. Then I pulled the plug out of the bottom of the tank and installed the new in-tank fuel pump and regulator and replaced the plug. Then the wiring took a few minutes and I had 58 psi at the throttle body like it was supposed to. I had budgeted $2500 and ended up only spending less than $1700 for everything including the entire fuel system.

The salesman at EFISYSTEMPRO.com and they were trying to find ways for me to get the most without buying things I didn't or wouldn't "need". I was prepared to buy an EFI fuel tank but after seeing and using the OEM Module I am very glad I kept that money in my pocket. The sales people were actually trying to help me get what I needed, versus what they would like to sell you. The guys at EfiSytemPro also give you 24 months of Post Sale Support to ensure that you are happy with your running system. They also keep the parts in stock and have awesome service for anything Holley provided that you bought it from them. With these guys you don't have to call Holley's tech support because they employ a Holley Tier 3 Expert on their staff and he is incredibly useful and knowledgeable in anything EFI.

EFISYSTEMPRO is the one stop shop for quality Holley EFI systems and I strongly recommend them to any Corvette owner.

 

Any issues when taking corners when the fuel level is low? I originally used the stock tank but had fuel starvation in turns when the tank was below 1/4 full. This was back before hydramat was available so I spent the $$$ on a new tank. Very happy with it, all stainless steel with internal baffles and pump. But yeah, not cheap.

 

You’re certainly not the first person to report success with the vented cap. I wonder why the aftermarket companies don’t simply offer that as the baseline solution. Vented caps are readily available and it’s certainly a simpler installation. 🤔