Rubber fuel hoses in engine bay question, All the same size? How many meters? Options

[DC_neun_vierzehn]

'73 2.0 w/ original FI

Since I sprung a fuel leak in the engine bay, I've decided to replace all 4 injectors and replace ALL the rubber fuel hoses in the engine bay. I have no idea how old these items are and I'd rather have peace of mind with new hoses and injectors (vs. trying to skimp and deal with an engine fire).

I order the replacement injectors (Standard Motor Products FJ67) that come with the rubber elbows. Now I need to order the rubber hose. Are ALL the rubber fuel hose lines in the engine bay the same size (7mm)?

I don't see a precut kit on any of the usual 914 suppliers. I'm guessing I need to buy several meters of it and cut it myself. If so, how much do I need to order?

I'm looking at this option, but I'm open to recommendations : )

https://www.autoatlanta.com/Porsche-7-Mm-Fu...N-RN202811.html

[914werke]

So this seems to be a good segue to advise of a item 914werke offers. (IMG:style_emoticons/default/rolleyes.gif)
I try not to overtly market in others threads but in this case it made sense (to me)

So based on the descriptions provide by OP they are working on a D-Jet equipped (2.0L) motor.
Wisely they have recognized that it is prudent to replace old fuel lines with new (ASTM D4806) lines that are resistant to Ethanol blends found in so may locations now.

One design flaw I recognized with D-Jet equipped motors was the routing of a rubber line over the top of the motor from rail to rail.
OG, that line was clad in a plastic sheath presumably to protect it. Nowadays you'd be hard pressed to find a car with that sheath still in place & if you did IT NEEDS its line replaced!
Then reason this "design" is problematic is the top of the motor case is a very hot spot on the engine.
With the OE routing you ARE inadvertently heating the fuel being fed to the injectors.

914werke offers a simple kit that solves this issue that reroutes that fuel line using a pre-bent, & flared SS line in front of the impeller housing.
This location has the secondary benefits of being located in the stream of air being sucked into the Impeller, cooling the contained fuel rather
than heating it & limiting the amount of perishable rubber in the engine bay!

[wonkipop]

So this seems to be a good segue to advise of a item 914werke offers. (IMG:style_emoticons/default/rolleyes.gif)
I try not to overtly market in others threads but in this case it made sense (to me)

So based on the descriptions provide by OP they are working on a D-Jet equipped (2.0L) motor.
Wisely they have recognized that it is prudent to replace old fuel lines with new (ASTM D4806) lines that are resistant to Ethanol blends found in so may locations now.

One design flaw I recognized with D-Jet equipped motors was the routing of a rubber line over the top of the motor from rail to rail.
OG, that line was clad in a plastic sheath presumably to protect it. Nowadays you'd be hard pressed to find a car with that sheath still in place & if you did IT NEEDS its line replaced!
Then reason this "design" is problematic is the top of the motor case is a very hot spot on the engine.
With the OE routing you ARE inadvertently heating the fuel being fed to the injectors.

914werke offers a simple kit that solves this issue that reroutes that fuel line using a pre-bent, & flared SS line in front of the impeller housing.
This location has the secondary benefits of being located in the stream of air being sucked into the Impeller, cooling the contained fuel rather
than heating it & limiting the amount of perishable rubber in the engine bay!

nice theory but i myself would not think thats so good in practice.
routing fuel line around fan casting.

why.
1. when the engine is running the magnesium fan casting itself does stay cool due to the flow of cooling air. agree with that. simple test. put your hand on it while the engine is running. even after a good long hot run. it will be cool immediatey after hot shut down.
2. similarly the engine tin on top of the engine is relatively cool while the engine is running. you can also touch that. try it as an empirical test.

its after shutdown that the fun begins.
that fan casting gets very hot.
why. thermal conductivity. the heat flows from the cast iron cylnders and alum engine block into the magnesium casting. thats the direction of flow and conductivity.
so hanging a fuel line off it is bound to get the fuel very hot. the very same symptoms are in my view the reason for the fuel vaporization problem that plagued the cars up until 1974. radiant heat from the fan casting after hot shutdown directed at the fuel pump and the fuel lines along the firewall in front of the engine.

basically that magnesium fan casting becomes a heat sink for the engine.
as does the gearbox to some extent too.

the fuel line in original form is relatively suspended above the engine tin/block using the vac hoses etc.
id be cautious saying its a fault or design flaw.

a test anyone can do is touch your engine about 5-10 minutes after a good run. the fan shroud casting just gets hotter and hotter for a good half hour. you won't be able to touch it its that hot. but you can touch all the other components on top of the engine including most of the tin. they cool down quicker. thats what happens after shutdown as a consequence of the volumes of cooling air no longer moving through the engine.

the old vapor lock problems always occurred during that time period.

i live in a hot warm country too, so its not cold air temps in frigid conditions that i make these observations from.

id be cautious about reengineering the fuel line layouts.

but each to his own. and its just an opinion on my part. (IMG:style_emoticons/default/beerchug.gif)