Pre-heat hose on MFI - Inner and outer?

[Einspritzer]

I have a 1969 E with the MFI. I need to replace the air hose that runs from the MFI down trough the left engine pan, which connects to the exhaust (I believe).

the PET indicate I need an Inner ( 901.110.295.00) and Outer (PCG.110.296.00) hoses here.

Can anyone please tell me why there needs to be two hoses? Is it because the diameter at the MFI fitting is 28mm and the fitting at the engine pan is 35mm?

Would I just slide one hose into the other?

Thanks!

[RSTarga]

I don't ask why, it just takes both. The inner is sort of paper and the outer is black and shiny. Only the inner gets attached at the pump, (as far as I know). Wait for Ed to pitch in before confirming.

[72targa]

I don't ask why, it just takes both. The inner is sort of paper and the outer is black and shiny. Only the inner gets attached at the pump, (as far as I know). Wait for Ed to pitch in before confirming.

I’ve always assumed that the outer was for insulation. Same as found on my ‘72.

[Richy]

2 hoses , the outer hose is for insulation . Only the inner hose gets clamped to the MFI pump and engine tin , a detail that is often incorrect .

[edmayo]

All the above is absolutely correct!

[tom1394racing]

2 hoses , the outer hose is for insulation . Only the inner hose gets clamped to the MFI pump and engine tin , a detail that is often incorrect .

I learn something new every day here!

[gled49]

Wrong or not, I’ve found the inner paper/foil hose to be very fragile and tear easily, so I always clamp both hoses as the outer paper/plastic hose is more robust and holds up to remove and install year after year, like 20+ years.

[Chuck Miller]

Wrong or not, I’ve found the inner paper/foil hose to be very fragile and tear easily, so I always clamp both hoses as the outer paper/plastic hose is more robust and holds up to remove and install year after year, like 20+ years.

+ 1 Gordon

Also, my engine's smooth running is VERY dependent on those clamps being tight...
If they loosen, (because of me messing around... ) I know it as soon as I start it ....

[garycox]

Anyone have a source for the proper hoses? I have purchased a couple of "inner hose" from a couple of the usual vendors, both were too large diameter and did not fit the pump well.

[tom1394racing]

I think I have a spare. PM me with your email I’ll send you pictures and
more detail

Anyone have a source for the proper hoses? I have purchased a couple of "inner hose" from a couple of the usual vendors, both were too large diameter and did not fit the pump well.