Re-plumbing fuel lines for Webers

[wkrtsm]

The leak in gas line post before reminded me that I needed to re-plumb the fuel lines to the Weber 40 IDF carbs.

The current plumbing involves a single line going out of the fuel pump and in front-center of the fan shroud, then up to the top of the fan shroud where the tee is, and then the two lines for each carb branch down the top of the fan shroud into the back sides of the webers.

My current thinking is to run a single line from the the fuel pump directly into the left carb for cylinders 3&4, then by use of another input fitting, run a line out the back of the left carb to the right carb on cylinders 1&2 along the back of the fan shroud -- using rubber-protected hose clamps that screw into sheet metal.

Is there a reason why the tee splits directly at the top center of the fan shroud and then routes to each carb with equal length lines? In other words, does the fuel flow have to be symmetric such that the tee is exactly between both carbs?

Also, should fuel lines be positioned away from the engine casing to minimize heat?

[wkrtsm]

Below is an image of the current plumbing, which tends to look ugly.

I think it would be better to hide the lines behind the fan shroud.

[BoxsterGT]

Porsche used this for the Fuel Lines on the early 4 cyl models.....



Why not duplicate this for your Webers? If you can find a used one I will be happy to Re-Hose the Flex center and provide you with E-85 Rated Fuel Hose if needed.

For your Oil Lines, I cannot say. That's a complicated system.

Len.Cummings at verizon.net

[wkrtsm]

I decided to use 3/8" aluminum line (and 5/16" Gates Barricade hose) coming out of the pump, and feeding around back into both Webers. (Porsche OEM for fuel lines has always been 8mm lines and 7mm hose, meaning to go one size greater for the line so it fits more snug at hose connections).

Here's the line coming out from the pump, and going between the fan shroud and the Weber 40 IDF for cylinders 3 & 4:



Around back, I attached the aluminum line to the sheet metal with two rubber-insulated sheet metal tube tie-down clamps:

[Slanski62]

May I ask why an auxiliary oil cooler is necessary? I do like your setup and I’m going to do something like it when I put my 914 based motor in my 912. How much temperature drop do you get with that cooler? How much extra oil do you use? Thanks!

Steve in N.C.

[wkrtsm]

The external oil cooler is not auxiliary -- it's primary. I installed an oil cooler by-pass plate (from 356 Enterprises) where the original tower cooler sat underneath the fan shroud about 17 years ago, since the large rubber seals on the original towers tend to leak. Since then, oil cooler leaks have never been an issue.

As far as temp drop, the surface area of the external cooler is probably 2-3 times greater than the OEM tower, so the discrete (yes/no) answer would be that it's cooler. Also, with the tower removed, more cooling air hits cylinders 3&4, so this is another advantage of not having the OEM tower inside the fan shroud.

Extra oil used is about a quart.

If you look at the pics in another post from about a month ago, you can see the by-pass plate bolted onto the case. There was no oil around this plate when I had the engine out now (17 years later).

Congratulations on making the decision to convert to an external cooler. I also just noticed that the Mocal oil cooler I have, the oil thermostat (180F), and the oil filter housing are still available from British American Transfer in Florida.

The installation and fabrication instructions I developed for mounting the external oil cooler can been seen from the 2002 restoration pages here

[Slanski62]

Thanks for posting this wkrtsm. Very helpful and interesting. I'll check out BAT.

Steve