AN-6 Fuel Line Plan for CIS to PMO Carb Conversion

[Gordo2]

Rough sketch - but you get the idea.

Stuff adds up...



Any thoughts or concerns?

Gordo

[m1franck]

At the point the hard lines exit the tunnel you may want '45 fittings to "kick" up the hose in order to clear other components that may be in the way. Also, heat wrap on the hose to keep the exhaust heat from baking your fuel lines.

[m1franck]

Also, where you connect to the carb fuel bars can be straight AN6 fittings. You don't need a 90' there.

[rsscotty]

There are good options to save some cash and considerable install and hose fab time.
The link below is for push lock hose ends..very good price on straight and 90 degree.
Use whatever brand suits your taste.

The hose and fittings are available in the Aeroquip brand...Goodridge...and I am sure many more. I prefer the black hose and fittings on a Porsche as they blend in well. This combo will save you dollars over the SS braided hose and fittings without any problems on a low pressure system like yours appears to be. I am sure that it would work equally as well at higher pressures for EFI, as we do it with no issues.

You can find heat proof sheathing like Mark has on his car through WireCare.com :: Your Cable Management SuperStore!
a great source for high quality products.

http://www.summitracing.com/parts/fst-30275-1/overview/

Hope this helps.

[Ayles]

Gordo, I am about done with this job. Same exact plan from the tunnel right down to the racor. I went with all aeroquip from racer parts wholesale. They had the best price I could find.

You have landed on figure a bit lower than mine. But not by much. I bought some An tools which help but don't totally eliminate the fittings from getting a little marred. Happy to help any way I can. I also think I have an extra m14 to AN adapter from bat if you are interested and I can find it.

Making up the lines isn't that fun and there is definitely a learning curve. Be prepared to swear a lot and mess up a couple hoses. Start by making up the short ones where a mistake doesn't cost you much hose.

[Pazuzu]

I don't think that you want the FS-1406 from Bat Inc, that is not the right adapter.
fuel rail metric to AN adaptor Pictures of it, meant for a 14x1.5 male STANDARD flare, we have a 14x1.5 male long bullet (inverted) flare coming from the tunnel.

Len claims he has an adapter that he builds now, might contact him.

I kept the steel (green) lines from the tunnel up to the engine bay area (no reason to rebuild good lines!), which have the correct female long/bullet connectors in each end. Then I took the factory rubber lines that connected to them (with the long/bullet MALE ends) and had a shop cut the fitting in half and weld a standard AN6 steel male fitting on, so I had 2 custom 14x1.5 bullet male to 6AN male fittings.

Then standard 6AN pushlock stuff throughout the engine bay.

More info here:
Fuel Line Help

[moneymanager]

I didn't add it up but it looks like it's costing you $100 or so to get from the pressure adjuster to the PMO's. A couple of feet of rubber hose and some clamps will do it for under $10. That's the way PMO does it when they sell you a kit and it works fine. This would also let you slip in a couple of $5 plastic fuel filters which might save you a carb rebuild once or twice a year and they'll be within inches of the PMO's, highly desirable in my experience. Your Racors are nice but pricey without much advantage and too far down the line for my taste.

[Gordo2]

Thanks, great tips guys.

Meanwhile Mike hit the nail on the head:

Originally Posted by Pazuzu

I don't think that you want the FS-1406 from Bat Inc, that is not the right adapter.

...I kept the steel (green) lines from the tunnel up to the engine bay area

I called Bat Inc today and was ready to order their adapter, but as we talked about it I came to the same realization Mike points out - it's not the correct adapter.

The fitting from the tunnel fuel line is a male 14mm x 1.5 fitting with a convex flare end (37° - I think...)

Like this:



Meanwhile, the BAT part # FS-1406 fitting is a female 14mm x 1.5 fitting with a convex flare end. Like this:



No workie - must have convex to concave

I need a 14mm x 1.5 female fitting with a concave flare like this:



I originally considered bringing my tunnel to engine compartment hard lines to a shop to have them add on AN-6 fittings as Mike suggests - looks like I'm back to that approach.

This is some painful stuff.

Thanks again,

Gordo

BTW, Bat was very helpful - above images provided from their website.

[Jonny042]

All the carb'd cars I ever had (and it's been a while) did not have a return-type regulator (if they had one at all).

In the interest of simplicity (and weight, and cost) could you not forego the return?

Nice sketch, by the way - nice to see someone can still draw, and print!!

[James Brown]

jonny on gordos car, he is going from cis high pressure pump to low pressure carbs so he needs the return line. Provided he kept the HP fuel pump

[Gordo2]

Originally Posted by James Brown

jonny on gordos car, he is going from cis high pressure pump to low pressure carbs so he needs the return line. Provided he kept the HP fuel pump

You got it - I have a CIS pump (actually the Walbro GCL604-1, a direct fit replacement with similar PSI and flow specs to the original Bosch) hence the need for the return.

I did find that some people run the original pumps with a regulator that doesn't include a return - but it's not recommended, and they often run into problems (unable to get consistent 3.5 PSI as recommended by PMO).

Meanwhile, I've read plenty of threads suggesting benefits of using a return line with carbs, even when using a low PSI pump:
- Cooler fuel (to help avoid vapor lock)
- Continuous fuel cycling through fuel pump increasing pump life (cooler).

In this case, it's not an absolute requirement, but still recommended by some.

Thanks again guys, and thanks for the sketch comment Johnny.

[frankc]

The timing of this thread is perfect - I'll be doing the same task in a few weeks with the same PMO AN pressure regulator & AN fuel rails.

I panicked a bit when I read that the BAT FS-1406 were the wrong fittings, because I already purchased them. But then looking at your diagram of the fuel line fitting, I realized the fitting on my lines exiting the tunnel are different with a concave flare (see photo). I think this is one of the differences between the fuel lines for mid-year vs. SC (mine is '77). Judging from the photo, the FS-1406 appear to the correct fitting - do you agree?

A couple of other questions:
1) Why the Racor filter instead of the OEM filter (which is what I planned to use)? I understand the filter used for the CIS cars performed very well.
2) As others had suggested, I planned to use a couple of in-line filters just before the carbs. Any reason you chose to leave these out?

[Ayles]

I have new tunnel lines from Len, not sure if they differ much from the stock lines. I am using this adapter and have extra one if you need it. It's M14 to AN-6.






Here's a screen grab of what I have into the fuel system so far.

[Ayles]

Originally Posted by frankc

The timing of this thread is perfect - I'll be doing the same task in a few weeks with the same PMO AN pressure regulator & AN fuel rails.

I panicked a bit when I read that the BAT FS-1406 were the wrong fittings, because I already purchased them. But then looking at your diagram of the fuel line fitting, I realized the fitting on my lines exiting the tunnel are different with a concave flare (see photo). I think this is one of the differences between the fuel lines for mid-year vs. SC (mine is '77). Judging from the photo, the FS-1406 appear to the correct fitting - do you agree?

A couple of other questions:
1) Why the Racor filter instead of the OEM filter (which is what I planned to use)? I understand the filter used for the CIS cars performed very well.
2) As others had suggested, I planned to use a couple of in-line filters just before the carbs. Any reason you chose to leave these out?

I have the same lines you do. The adapter I show should work.

Here is another view:

[Gordo2]

Originally Posted by frankc

the fitting on my lines exiting the tunnel are different with a concave flare. Judging from the photo, the FS-1406 appear to the correct fitting - do you agree?

A couple of other questions:
1) Why the Racor filter instead of the OEM filter (which is what I planned to use)? I understand the filter used for the CIS cars performed very well.

Frank - I believe the Bat FS-1406 is a direct bolt on to your existing tunnel line fittings.
As for the Racor - just went with what a lot of folks recommended here on the board.

Ayles - Appreciate the offer, but I think I'm going to have the hard lines from tunnel to engine bay modified with a 6-AN fitting. As such I shouldn't need the type of fitting you have.

Thanks,

Gordo

[Gordo2]

Anyone know what the thread size is on the PMO fuel rails?

Thanks

[Gordo2]

Too much work, too much head scratching at fuel system / plumbing options - too little wrench turning has been delaying my progress.

Not quite in accordance with my drawing, but close. I will provide an updated drawing with part #'s once I'm done.

I ended up sticking with the metal lines from the tunnel to the engine bay vice going to 6AN fuel line. The whole fitting fiasco nearly overwhelmed me.

I found the PMO fuel rail fitting size: 12 x 1.25mm. Ordered and installed a 6AN fitting from Summit: http://www.summitracing.com/parts/fra-491954-bl

A few shots of this evening's progress:


Fuel line routing from the original 8mm stainless steel hard-lines to Racor 110A filter and to / from the PMO regulator:



A close up of the fuel line plumbing to the Racor filter and the return fuel line



I made a bracket to raise/mount the PMO regulator higher to allow my fuel lines to clear the Clewitt Engineering / Electromotive coil pack platform:


Inching closer...

Gordo

[Ayles]

Nice!!! Looks super familiar

[VFR750]

I punted.

The CIS lines on the engine are flexible plastic/rubber hose crimped on to barbed fittings. The fitting screws into the metal lines from the chassis. I cut off the collar and removed the hose from the barbed fitting, installed rubber hose and a hose clamp. The rest of the system uses hose, barbed fittings, and clamps.

With the return loop, the fuel pressure is only 3-4 psi in the whole system. Barbed fittings and clamps work just fine.

It looks fine, but not as awesome as a full AN fittings with braided lines. Just a whole lot cheaper and easier to maintain.

[Gordo2]

Agree VFR - many less expensive, equally sufficient fuel plumbing options but...

The 6AN lines with some good fittings sure do look nice:



Gordo