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| Running a fuel return line on a '71 https://slantsix.org/forum/viewtopic.php?t=45983 |
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| Author: | the_shadow [ Tue Aug 16, 2011 6:03 pm ] |
| Post subject: | Running a fuel return line on a '71 |
I've done some searching/reading on here and understand the fuel tank venting system for my '71 Dart. That being said, I am getting ready to install the 3-fitting fuel filter for vapor return and I have a question. I was looking around under my car today trying to decide where/how to install a seperate 1/4" vapor return line all the way back to the tank, and just T into one the four vent lines coming off the side of the tank. After looking at it for a while, i've come to the realization that it would be a major pain. I would have to do a significant amount of hard line bending, fitting, tweaking, splicing, etc...I really want to avoid doing this! I don't often try to find the easy way out on projects, but this one I really want to find another way. I was looking at the fuel tank vent line that runs into the engine bay on the passenger side wheel well and connects to the valve cover breather. Down along the frame rail (lowest point in that line) there is a short piece of rubber fuel line splicing 2 of the hard lines together. It seems I could easily T into. Would this be a good or a bad idea? How much fuel is pumped out of that .060" hole for the vapor return? Is it a constant stream while the car is running? Would that cause problems when the tank is venting having liquid fuel in that line? If I could T into that line along the frame rail (lowest point) it would make this task soooo much easier. Just wondering if this is a good idea or not. Also on that subject, is that vent line 3/8 or 5/16? I couldn't tell by looking at it. It looks slightly larger than the 5/16 fuel line that runs next to it but I wasn't sure. |
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| Author: | SlantSixDan [ Tue Aug 16, 2011 7:40 pm ] |
| Post subject: | |
Because you are working on a '71, you needn't go through the hassle and (manageable) danger of attaching a new tube to the fuel tank itself. You can add the vapour line fitting to the top of the vapour separator in the trunk of the car; see here for detail on how the '71 (+'70 California) evaporative emission control system works. While you are reading up on it, take note that it is aggravating the problem you're experiencing, because fuel vapours accumulate in the crankcase after engine shutdown and flow freely into the intake tract (making the mixture too rich) as soon as you sit down and start cranking. You can eliminate this part of the problem by moving vapour storage from the crankcase to a '72+ type charcoal canister with a purge valve as described here. No changes would be needed at the back of the car to add the canister, just plumb it in as described and install an easily available '72-up crankcase breather (without the extra hose fittings). |
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| Author: | the_shadow [ Tue Aug 16, 2011 8:20 pm ] |
| Post subject: | |
Dan, thanks for your response. I've actually already read both links you posted (the first one you posted you said the same thing on this site, too). Adding a charcoal canister is definitely a good idea and I will be doing that, however, my hot start problems happen even if the vent line is left disconnected from the breather --- venting directly to the atmosphere. It seems that the main source of my problem is lack of external carb vent. Originally I had a Holley 350 (7448) on my car, I referenced it before in this thread with hot start issues as it had no external vent: http://www.slantsix.org/forum/viewtopic ... +tank+vent I currently have a Holley 2280 (new original, you posted a link to them a while back) however it also has no external vent. Installing the 3-fitting fuel filter will (hopefully) fix the problem by alievating excess fuel pressure after shutoff. This same symptom happened with both of my carbs --- even after replacing new needle/seat. So my question really resides in an 'easy way' to run a vapor return line. I know I can run a line all the way back to the tank and T into one of the 4 lines coming out of the side up into the vapor canister, but running an additional line would be a huge pain. An easier way seems I could just T at the lower most point along the frame rail of the fuel vent line (that runs from the vapor canister up into the engine bay passenger side, and connects to the valve cover breather). I was wondering if this was a good idea or not. If a lot of liquid gasoline comes out of that .060 3rd fitting on the fuel filter, maybe not...but if it's just a small amount or a vapor after shutoff it should be fine. Thoughts? thanks. |
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| Author: | the_shadow [ Fri Aug 19, 2011 2:20 pm ] |
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Bump. Dan could you explain how I can just connect it to the top of the vent canister? Like I said I read your post before. Do you mean to T into one of the 4 vent lines coming out of the tank, before they go up inside the canister? Also like I said in my previous post, would it be OK to just T into the tank vent line at the lowest point (down on the frame rail) to save the hassle of running an additional line all the way back to the tank/canister and connecting it? Or is this ill-advisable? |
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| Author: | SlantSixDan [ Fri Aug 19, 2011 3:35 pm ] |
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Quote: Bump.
Drill, tap, install threaded hose nipple (with epoxy).Dan could you explain how I can just connect it to the top of the vent canister? Quote: T into one of the 4 vent lines coming out of the tank, before they go up inside the canister?
I wouldn't.Quote: would it be OK to just T into the tank vent line
I wouldn't.
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| Author: | the_shadow [ Fri Aug 19, 2011 3:40 pm ] |
| Post subject: | |
Quote: Drill, tap, install threaded hose nipple (with epoxy).
Wow, I certainly didn't think of going directly to the metal canister itself. Thank you!
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