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Discussion in 'High Tech Retrofits' started by sbca96, Jun 21, 2010.
But I need the emissions tank, they only have the basic tank?
OK, working with RockAuto on this, I responded with the info that you listed
and got a different customer service rep. It is true that they only have the
non-EEC (evap) tank, but the Rep will be contacting Spectra to see what the
correct part number is, and also if they can get it. Sounds promising.
Looking good so far, they are going to be adding the EVAP tank to their
catalog and fixing the year listings. I also asked them to check with Spectra
and see when the 75-81 tank will be available. I figure that a LARGE online
distributor like RockAuto would have considerable pull to light a fire under the
Spectra management to make the later tanks happen. Worth a shot. Doubt
it will fit MY schedule, but might help others.
Cant wait to see the build happen. I am going to go similar route with my 81Z. Original motor long gone so might as well upgrade to something newer. I would think that there would be enough demand for the later tanks that the Spectra folks would be able to make that happen. We will see, good to see someone engage them to get the ball rolling hopefully.
If you look at the thirdgen F-body EVAP system, they don't have EVAP lines on the tank itself. It's part of the sending unit. There are four lines coming off the thirdgen sender- 1 supply, 1 return, and two EVAP lines. One of the EVAP lines runs to the EVAP cannister in the front of the car. The other line runs a short distance to a one-way valve that only lets air into the tank, but not out of the tank. The vacuum applied to the cannister line pulls fuel vapors out and fresh air into the tank through the line with the one-way valve.
I recently switched over from the from my factory 2nd gen EVAP system to fully mimicking the 3rd gen setup, complete with electronically controlled cannister. I plugged up the 2nd gen tank vent lines and am using the EVAP lines on my thirdgen sender. Surprisingly it actually made a dramatic difference in the way the car runs- smoother idle (I even picked up an inch Hg of vacuum) and much crisper throttle. There was also a slight tendency to want to stall when I would shift from park to drive and I could never get rid of it with tuning. Changing to the correct EVAP system solved that problem immediately.
I think the key is is maintaining the proper vapor pressure in the tank. Since I'm using an in-tank pump, my suspicion is the vapor pressure can affect the pump pressure and therefore the engine performance. I'm still unclear about why the 2nd gen EVAP setup didn't work well with my EFI setup. But what triggered me to make the switch was that one day I decided clean the EVAP line to the tank from the front of the car. I sprayed some carb cleaner and then blew compressed air through the line. To my surprise, the car ran remarkably better for a few miles, then regressed back. I repeated the process and got the same result. It got me to investigating the EVAP system and I ended up making the change over.
Anyway, moral of the story is make sure the EVAP system you use mirrors the vehicle the system came out of.
I'm not sure why Spectra lists this as only for a 1970. In the Classic Industries catalog, the 1970 tank also fits 71-73 as well.
RockAuto was listing only the 70 non-Evap tank, and not the 71-73 Evap one. I
am installing a '94 LT1, how does the EVAP compare to the 2nd Gen? I need for
it to pass smog when done, thats why I was trying to get the EVAP tank, but if
I can use the base tank, and some later EVAP?? I just dont know. Thoughts?
I'm not sure about a 4th gen. What I'd do ideally is find a friend with a 4th gen and copy his EVAP system exactly. I have a friend with a factory 91 Z28, so I used his Camaro as a model for my setup. If this isn't feasible, get a 4th gen Camaro shop manual and use that as a guide. All I'm trying to say is try to get the setup as close as possible to how GM did it. The engine will run the best when it has no clue that it's not in a 4th gen. It should see all the same inputs and outputs (electrical and mechanical).
4th gen uses all connections through the sending unit, nothing on the tank body. 4 hookups, supply to engine, return from engine, vent line, and line to the evap canister which is mounted behind a panel in the drivers side rear wheel house..so the tank itself should not need any special evap items to work if you copy the factory 4th gen system.
Interesting, but the Spectra tank wont have those provisions in the pump for
me to use. So I guess I would have to use the 2nd gen style? This is SUCH
a pain, trying to do this smog legal as I watch others throw together a tank to
get their car on the road in what seems like weeks. Grrrrr.
I have a complete 1994 Firebird in the backyard that I can steal anything I need
off of, I just havent dug into the EVAP since the stupid tank is above the rear
axle and not easy to remove. I do have a shop manual. I found this online :