38Dgas fuel return
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38Dgas fuel return
Curious one. My car has fuel return piping from 38Dgas back to fuel tank but the return fitting on the carb has not been machined through and thus return is blanked off. Is this normal and do I have to drill out the return fitting to allow fuel to return to tank?
Many thanks for your help.
Many thanks for your help.
- peter freeman
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38Dgas fuel return
The Coupe's and 5's do not have a return line - I cannot think it is so important
38Dgas fuel return
Just seems strange to got to all the cost and effort of providing return fuel line to the tank and not using it.peter freeman wrote: ↑Sat Jun 29, 2019 11:39 amThe Coupe's and 5's do not have a return line - I cannot think it is so important
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38Dgas fuel return
Peter, the first half of your statement is correct, but the conclusion may be the wrong way round - perhaps it was important (especially in hot conditions) and that's why it was introduced in later (approximately Se6a-onwards) versions?peter freeman wrote: ↑Sat Jun 29, 2019 11:39 amThe Coupe's and 5's do not have a return line - I cannot think it is so important

As far as Chips' question is concerned, if your car has all the return pipework present and correct, but no fitting on the carb, then I'd guess it's quite likely that a PO has fitted an old carb (without the return) for some reason? Which model variant of carb is it (it should be stamped into the carb base)?
....Roger
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38Dgas fuel return
Many thanks. The code stamped on base is 020472.Roger Pennington wrote: ↑Sat Jun 29, 2019 12:04 pmPeter, the first half of your statement is correct, but the conclusion may be the wrong way round - perhaps it was important (especially in hot conditions) and that's why it was introduced in later (approximately Se6a-onwards) versions?peter freeman wrote: ↑Sat Jun 29, 2019 11:39 amThe Coupe's and 5's do not have a return line - I cannot think it is so important![]()
As far as Chips' question is concerned, if your car has all the return pipework present and correct, but no fitting on the carb, then I'd guess it's quite likely that a PO has fitted an old carb (without the return) for some reason? Which model variant of carb is it (it should be stamped into the carb base)?
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38Dgas fuel return
Yes, I saw from some of your previous posts that you had asked about Se6as
Fuel returns were introduced at *roughly* the point of the Se6/6a changeover.
There should be another number on the opposite side of the carb base (the autochoke side IIRC) - it should specify the carb type, eg 38DGAS 3C or whatever.

There should be another number on the opposite side of the carb base (the autochoke side IIRC) - it should specify the carb type, eg 38DGAS 3C or whatever.
....Roger
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38Dgas fuel return
Many thanks for your help. 38DGAS 3C and it has two fuel line fittings. One fuel in and one fuel return.Roger Pennington wrote: ↑Sat Jun 29, 2019 12:47 pmYes, I saw from some of your previous posts that you had asked about Se6asFuel returns were introduced at *roughly* the point of the Se6/6a changeover.
There should be another number on the opposite side of the carb base (the autochoke side IIRC) - it should specify the carb type, eg 38DGAS 3C or whatever.
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38Dgas fuel return
Are you sure it’s not drilled through? If it has a brass fitting it should be (although it’s a very small restrictor hole). If it’s not drilled, it should just be the alloy boss.
Jim King
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SECURE DRY STORAGE FOR YOUR SCIMITAR
Current: SE5 (8Ball), TI SS1 (snotty), 1600 SS1 (G97), 1600 SS1 (C686CCR), 2.5TD SE5a (diesel 5a), 6 x random other SS1s.
Previous: SE5, 3 x SE5a, 2 x SE6a, 3 x SE6b, GTC, 2.9i GTC, 3 x 1600 SS1, 1300 SS1, Mk1 Ti Sabre, Mk1.5 CVH Sabre
Chief mechanic for: 1400 K series SS1 (Megan3), 1400 CVH EFi SS1 (Grawpy), 1300 SS1 (Number One) & Sarah's coupe.
CURE THE FAULT - NOT THE SYMPTOMS
38Dgas fuel return
I have tried 1mm probe and the centre is closed. I was about to install an electric fuel pump and I was going to rely on the return pipe to cater for any over supply of fuel. What size of hole do you think I should machine? Many thanks, Keith
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38Dgas fuel return
It’s about 1mm IIRC - if you really feel the need for a return line, you can just T one in?
Jim King
SECURE DRY STORAGE FOR YOUR SCIMITAR
Current: SE5 (8Ball), TI SS1 (snotty), 1600 SS1 (G97), 1600 SS1 (C686CCR), 2.5TD SE5a (diesel 5a), 6 x random other SS1s.
Previous: SE5, 3 x SE5a, 2 x SE6a, 3 x SE6b, GTC, 2.9i GTC, 3 x 1600 SS1, 1300 SS1, Mk1 Ti Sabre, Mk1.5 CVH Sabre
Chief mechanic for: 1400 K series SS1 (Megan3), 1400 CVH EFi SS1 (Grawpy), 1300 SS1 (Number One) & Sarah's coupe.
CURE THE FAULT - NOT THE SYMPTOMS
SECURE DRY STORAGE FOR YOUR SCIMITAR
Current: SE5 (8Ball), TI SS1 (snotty), 1600 SS1 (G97), 1600 SS1 (C686CCR), 2.5TD SE5a (diesel 5a), 6 x random other SS1s.
Previous: SE5, 3 x SE5a, 2 x SE6a, 3 x SE6b, GTC, 2.9i GTC, 3 x 1600 SS1, 1300 SS1, Mk1 Ti Sabre, Mk1.5 CVH Sabre
Chief mechanic for: 1400 K series SS1 (Megan3), 1400 CVH EFi SS1 (Grawpy), 1300 SS1 (Number One) & Sarah's coupe.
CURE THE FAULT - NOT THE SYMPTOMS
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38Dgas fuel return
As Jim says, it's a very tiny hole (may even be smaller than 1mm) - it would be quite a lucky shot if you managed to get a pin thin enough, into the hole at the opposite end of the brass fitting. I presume it's designed that way to allow the delivery pressure to be maintained, while allowing excess to return to the tank. Here's an old picture from my archive of one that I removed, some years ago:
Re-reading your original post, it's not quite clear what your current status is - you've got the original return pipes present, and a DGAS 3c carb which has a return stub; has someone disconnected the one from the other in the past, and blocked them off, or were the pipes correctly connected, and you're just inferring that the return is blocked, because you can't poke something through it?
Re-reading your original post, it's not quite clear what your current status is - you've got the original return pipes present, and a DGAS 3c carb which has a return stub; has someone disconnected the one from the other in the past, and blocked them off, or were the pipes correctly connected, and you're just inferring that the return is blocked, because you can't poke something through it?
....Roger
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38Dgas fuel return
My original carb had a return where the carb I have now doesn't.
I'm not in the position to modify my current carb & as the return line is already fitted to the car may as well use it.
You can buy a t piece that has the return line restrictor already fitted.
That's what I am going to use on my car when I get around to sorting the fuel system out.
I'm not in the position to modify my current carb & as the return line is already fitted to the car may as well use it.
You can buy a t piece that has the return line restrictor already fitted.
That's what I am going to use on my car when I get around to sorting the fuel system out.
Paul
Previously owned:- 1969 se5 non o/d, 1972 se5a o/d
Currently owned:- 1976 se6 automatic
Previously owned:- 1969 se5 non o/d, 1972 se5a o/d
Currently owned:- 1976 se6 automatic
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38Dgas fuel return
Same engine and more or less same fuel tank as the earlier cars so I think the return line was fitted to stop the difficulty in starting when the early cars had been stood for a while and the petrol had drained back to the tank. Having a return line makes it easier to fill the carb.