Do i need the fuel vapor canister on my 305 tpi? if not i would like that extra room and to plug in some stuff at the trottle body where the 2 hoses are and if i do need it can i connect the 2 hoses that go into the trittle body into only one hose goin to the trottle body so i could possibly shoot fuel in the other for my nitrous?

 

Don't know the answer on your nitrous question, but the fuel canister I think is necessary. It provides a vent for the gas tank, and allows the fumes to be burned. Without it, you will get high pressures inside the tank and will have a gas smell in the garage ( and even while you drive).

 

ok thank you now just seeing if anyomne has the answer to can i just conbined the 2 vacuum lines

 

you can get rid of the canister if you use a vented cap... thats what i did...

 

Don't have two vac lines on pass side of TB

Two different ports on the TB
One has vac ( in ) and other has air supply (out ) to CCV system

 

There are 2 vac lines running from a plastic valve that runs to the canister. One goes to the TB, the other directly to intake vacuum under the plenum. There are 2 lines for a reason, other wise 2 lines wouldn't run side by side. Not sure what the reason is though.

 

Two different systems
The big line to TB vac port is tank vent line from canister.
The small line is a vac line that operates the vac valves on tank vent line.

OP is talking about the 2 ports on pass side of TB.
One goes to canister as above.
Other goes to rocker cover for CCV.

 

i have never heard of a vent where do you get them for how much? or did you build it?

 

So, WILL a vented cap make it possible to remove the fuel vapor canister from the system?

 

Wait-I just finished reading more of the threads on this same question, and do not want to open another can of worms! I am installing a TPI engine from a totalled '85 IROC in my '55 Chevy, and was just wondering if it would be possible to leave it off. Don't want fumes, don't want to insult Mother Nature if I don't have to, but also don't want to use this canister if I don't have to. Will keep researching, but if you can give me any guidance, it would be greatly appreciated.

 

The TPI system, with the return line to the tank, will cause considerable pressure inside the tank. You will need some way to vent that pressure. You may already have it if you are using the '55 tank. I seem to remember a vent line on the top of those tanks that came out to the filler inlet. Something like that is what you will want. Vented gas caps, at least on later cars, don't vent until you start to open them. Seems like a mis-named part, don' it. Caps made for your '55 might be vented to atmosphere- just don't know.

You can run it without any vent- I did for several months until I found my pinched line. Just be careful and don't fill it up- the pressure will later push gas back out the filler inlet. Also be aware that enough pressure can build up to split a gas tank seam.

 

I will be running a Spectrum tank designed for a fuel injected engine. I only see two lines coming out of tank-supply and return. Would a vented cap suffice, or should I run with canister?

 

If you are running TPI, then you need a sender with 3 lines- Supply, Return and Vent. I don't think a vented gas cap will work for you, as they don't vent until opened ( according to the Stant website). Even with 3 lines on the sender, the Stectra tanks have trouble venting when filling, so many add another vent line from the tank to the top of the filler neck for filling purposes.
Personally, I would not run without the canister. Otherwise, you will be dealing with gas fumes, which are not good in an enclosed garage. You may also split a seam in the tank if the pressure builds high enough.

 

you can drill a couple holes in your cap.... search its on here somewhere.... I have been running the modified cap on my TPI for a year with ZERO issues.... and this is in the southern heat...