kanvasman

Starting to gather up things for the TPI swap into my '78 S/A. Any thoughts on using the original 78 charcoal cannister or do I need to switch to a c-4 cannister with the elec purge valve? No emission checks here in SC and Engine will be all stock. Thanks.

lonebull

I run a early 90's Camaro TPI in a '29 Desoto & never even considered a canister. I haven't had any problems. Are you concerned about fumes? I have the original canister in my '78 so I know they serve a useful purpose- just thought I'd share my experience. Ain't openin' no can of worms either- just sharing. Maybe someone could tell us the difference in an older can & one from a early 90's Vette? I do know you need to service the can if its to do its job- fresh charcoal I believe. lonebull

lonebull

On second view I see the difference is the electric purge. Do you know how it is wired into the TPI harness? Are you using an original harness or an aftermarket harness?

kanvasman

I am going to get an aftermarket harness, no point in using wires from20 years ago. And that is why I am asking the question now. Most of these aftermarket guys will build whatever you want, so I need to figure out what I need. I guess the elec valve is the only difference between the years. I just don't want the garage smelling of gas but my experience is that most of that smell comes from a leaky carburetor which won't be an issue. I have a new filter in the old can from the '78 so maybe that's where I am headed. Thanks for sharing your experiences. The vacuum hook ups appear to be almost the same.

David Mc

What computer are you going to use for your TPI swap? You should be able to run it either way.

lonebull

I can confirm that there is NO smell of gas in my garage without using the canister & I am running a TPI. The canister is just another item that might develop a vacuum leak down the road so I didn't use it. Do you have the reprogrammed chip for your computer already? I found a good source in AZ if I can find the contact info. Cost was less than $100! Let me know if you need one & I'll do some looking. Lonebull

kanvasman

Lonebull, no I do not have a chip for the computer yet. Have started looking around and I am leaning to a one stop shop for the computer, chip & wiring, that way if somethign doesn't work, I know who to call! But any additional info would be great. Thanks.

Priya

You can run your TPI computer without the carbon canister and there's a good reason to do so. One of the things that commonly fries a tpi computer is the carbon canister purge valve failing and this causes the computer to burn out as well. I'm going with TPI myself and while I like to keep all the emissions equipment there even though I don't have to have it I won't be having a carbon canister.

kanvasman

Thanks for the input. I hadn't heard about the bad purge valve thing and I will look into it some more. But what did you do with the vent line coming off the gas tank. There have to be fumes coming out of it. thanks.

Priya

Well, like you I am still collecting pieces to put TPI on my 79 so I haven't gotten that far in the planning as to what to do with the vent line coming off the gas tank. My husband is the mechanic and the one who told me about the purge valve going bad and taking the computer with it, so he'll be telling me what to do with that vent line as well - body work is my specialty, not mechanical.

lionelhutz

You could probably get a canister purge solenoid from another application and use that with the 78 canister. I think the LT1 engines had the purge valve on the engine. Any small solenoid where you apply 12V and it opens would work.

kanvasman

I am going to look into just using the original can. There's no elec to it, just vacuum.

KENS80V

The original charcoal canister is overdue to be replaced so I'd suggest upgrading to make your install easier. The original canister is more complicated (there is also fuel bowl venting included). Install the newer C4 style canister and purge valve and call it a day. Here are a couple of pictures of how I first upgraded. I later change to a LS engine control system and swapped to a LS3 style of canister and mounted it back by the fuel tank (third picture).

lionelhutz

That's not a great plan since you'll introduce a vacuum leak the EFI isn't expecting when the canister is purging.

If the valve failing is a big concern for you then drive a Bosch style relay with the ECM and use the relay to drive the valve.