fuel hose measurements

[vancelot69]

I searched the forum, and I found some information, but not this exact information that I'm looking for.

Can anyone verify or correct me if I'm wrong? I'm trying to replace all the rubber lines on my fuel system and a couple of the vacuum lines.

What I have measured using a caliper:

filler neck hose: 1-3/8" ID, about 12" long (with OE curved inlet neck).

big vent line that goes up by the filler neck: 1/2" ID, about 36" long.

all smaller vents (to include the two coming off each side of the tank, that go to the rear where three vent lines go up at the rear corner of the bed): 5/16" ID, 65" all told.

hose from sending unit to the metal line on the frame: 5/16" ID, about 12" to 13" long.

hose from the metal line to the fuel pump: I measured 3/8" ID, but it seems like it should also be 5/16", so maybe I didn't get my caliper straight, and 5.5" long.

vacuum hose from the intake to the brake booster: 3/8" ID, 18.25" long.

vacuum hose from the carb to the valve cover: 3/8" ID, 10.25" long.

vacuum hose from the carb to the distributor timing advance: 1/6" ID, 18" long.

Thanks in advance for any info!

[vancelot69]

Also, would you recommend getting the form fitted metal line from the fuel pump to the carburetor? If yes, where would you recommend putting a fuel filter? Before the fuel pump? If no, what would you recommend from the pump to the carb?

Thanks again!

[parb]

I got a fitted stainless steel fuel line from GMC Paul's.
I have a sock in the tank around a strainer in the fuel pickup (my new fuel pickup came that way). I have a paper filter in plastic (a cheap filter) after the fuel pump on the hose a few inches from the carb (maybe ten inches).

I'm going to replace the cheap fuel filter with a prettier filter, just haven't gotten to it. Mostly for looks, I expect it to perform about the same as the cheap plastic filter.

[vancelot69]

parb, would you happen to have any pics of how you did the stainless fuel line + a filter? The metal line from the fuel pump to the carb, at least the pic on the LMC site, looks like it's fitting to fitting with no room for an inline filter.

[hemi43]

Not sure what it's like in the US, but I had a hell of a time finding 1 3/8 FUEL hose up here. lot's of 1 1/4" and 1 1/2".
I ended up ordering one and it cost me over $100 for a 3 ft piece.

[kazoocruiser]

Originally Posted by vancelot69

Also, would you recommend getting the form fitted metal line from the fuel pump to the carburetor? If yes, where would you recommend putting a fuel filter? Before the fuel pump? If no, what would you recommend from the pump to the carb?

Thanks again!

If you are going to use a plastic (something you can see through) filter, it needs to be installed between the tank and the inlet side of the fuel pump. They aren't rated to carry pressure. Besides that, you want the filter on the inlet side of the pump to trap trash before it gets pulled into the pump.

[SeventyOne]

Originally Posted by hemi43

Not sure what it's like in the US, but I had a hell of a time finding 1 3/8 FUEL hose up here. lot's of 1 1/4" and 1 1/2".
I ended up ordering one and it cost me over $100 for a 3 ft piece.

Got mine on amazon for much cheaper:
https://www.amazon.com/Gates-24702-G.../dp/B002H5COTG

(shows a curved piece but it's straight)

[parb]

Originally Posted by vancelot69

parb, would you happen to have any pics of how you did the stainless fuel line + a filter? The metal line from the fuel pump to the carb, at least the pic on the LMC site, looks like it's fitting to fitting with no room for an inline filter.

I don't have a photo on me and my truck is away at the paint shop right now.
But its stainless line to the pump and a hard line up towards the engine where a flexible hose attaches to the line. The filter is attached to the flexible hose.

[kazoocruiser]

Originally Posted by vancelot69

parb, would you happen to have any pics of how you did the stainless fuel line + a filter? The metal line from the fuel pump to the carb, at least the pic on the LMC site, looks like it's fitting to fitting with no room for an inline filter.

There is a filter most likely in the carb already, so the metal line is designed to contain 3-8 psi from the pump. Plastic filters, or any filter for that matter, can break a seam and start pouring raw fuel under pressure all over a hot engine while you are oblivious to it while rolling down the highway. You ever see an early VW bug that caught fire with the engine in the back? That would happen because fuel from a worn-out carburetor shaft would leak down on top of the coil and/or distributor and lo and behold that would be the end of the Beetle.

I lot of people with these old vehicles run into problems with the inlet fitting on the carb, and end up ruining the line, so they cut it and patch in a piece of fuel line and a filter as a hill-billy shortcut to a proper repair. The next owner is oblivious to the lack of finesse of the previous wrench monkey. That kind of work would never be tolerated with regards to aircraft, where it is crucial to contain fluids. Unlike untrained car mechanics, aircraft mechanics don't shortcut, because they recognize risks that casual technicians are oblivious to.

The reason you don't see a place in the LMC metal line for a filter is because the line is designed to run as a continuous piece for safety reasons.

Not trying to be critical or anything, but if you take a brand new line and cut four inches out of it to put any filter in-line, I hope you invest in a really good fire-extinguisher, because your vehicle will burn completely before the fire department ever arrives. While the engine is running it will be pumping at least one pint every 15 seconds. From http://www.agcoauto.com/content/news/p2_articleid/360

[vancelot69]

Cool, thanks for the info. I always thought the see through filters were cool because I could see at a glance if fuel was being pumped, and having it before the pump I wouldn't be able to see it, but I've recently heard that to check for flow to disconnect the line from the carb and put it in a coke bottle or something to catch it, so that couple with your statement I feel the fitted line from the pump to the carb is definitely the way to go, and any quality filter, see through or not, before the pump like you suggested.

[parb]

Let me offer a counter point. The mechanical pumps of our era machines are designed to push not to pull. Thus a filter on the outlet side is preferred. From aeromotive https://www.powerperformancenews.com...lter-mistakes/

Of course a cheap filter that can't take the pressure should be avoided. And the replacement for should not be put on to of the headers. But I think it's worth considering a high quality filter after the pump.

[kazoocruiser]

Originally Posted by parb

Let me offer a counter point. The mechanical pumps of our era machines are designed to push not to pull. Thus a filter on the outlet side is preferred. From aeromotive https://www.powerperformancenews.com...lter-mistakes/

Of course a cheap filter that can't take the pressure should be avoided. And the replacement for should not be put on to of the headers. But I think it's worth considering a high quality filter after the pump.

parb . . .

I went back and read the article at the link. It doesn't support your assertion that "a filter on the outlet side is preferred", unless I missed that specifically from the article. As indicated within my previous post, there is most likely a filter on the outlet side of the pump anyway, inside of the carburetor, so it is overkill to install another one on the outlet side of the pump, which incidentally, will do nothing to prevent trash in the line from going through the pump, first, if that is the only filter "added". From the article you posted I found this:

The most critical location or position in any fuel delivery system is the INLET side of the pump. All pumps, including electric fuel pumps, will deliver maximum performance when the inlet to the pump is unrestricted. This is because pumps are designed to push fuel and are generally not efficient at pulling fuel into the inlet. This is why submerged, in-tank pumps are by far the most efficient. However, an INLET filter is still required because high pressure EFI pumps operate using very tight tolerances. If debris finds its way into the pump, the result is likely a quick failure.

Here is what is equivalent to what you might find inside the carb inlet.

https://express.google.com/u/0/produ...SABEgJjNPD_BwE

GM did not break the steel line to install a secondary filter, and as indicated within my previous post, it is likely that the vehicle you have has had the hill-billy hack done to it. Not that I want to insult hill-billies or anything, but Gomer Pyle's cousin Goober was the expert mechanic amongst a fantasy, non-existent community. Don't be that guy, or part of that crowd. Maybe what I have explained to the class here should indicate to you that you probably should go back and repair your hack-job plumbing instead of justifying it.

vancelot69 now has a correct understanding of proper fuel routing, so your "counterpoint" is counterproductive.

vancelot69, the only thing I would indicate to you is that I have a see-into plastic filter in line on the inlet side on my truck's mechanical fuel pump. I installed it when replacing my fuel pump as an upgrade from GM's budget limit stunt of using only a carb filter and in-tank sock. I can assure you, you can see plenty of fuel being pulled through it when the vehicle is running.

[parb]

Unfortunately i can't find articles that specifically talks about fuel filters and nothing but fuel filters except for industrial uses (cummins, detroit diesel, marine gas engine etc) where engine longevity is a serious concern. I won't quote those here as i think it invites a debate of applicability since they won't be directly comparable. Having said that, industrial users recommend course filters on the inlet side and fine filters on the pressure side to ensure engine longevity.

This recommendation comes from a magazine (superchevy). Its buried in the text so i pulled it out for all to read:
Choose & Position the Right Filters
Fuel filter type and placement are critical to achieving the proper fuel pressure and volume being delivered to the carburetor. A high-flow, fine-element fuel filter should be used between the fuel pump and carburetor on the pressure side, not between the tank and the pump on the suction side. Between the tank and the pump you'll want to run a coarse-filter screen no finer than 100-micron. This is because as a pump pushes, it also has to pull, and when a pump has to pull too hard to acquire fuel through a restrictive filter, a vacuum or low-pressure area develops at the inlet. To be sure of the specs for your fuel filter, always check with the fuel pump's manufacturer for a recommendation. A more restrictive filter on the suction side of the pump may fail to flow the full volume of the pump, which can result in cavitation at the pump inlet.
link http://www.superchevy.com/how-to/060...r-fuel-system/

The mesh filter in the carb (if you have it) is a 30-50 micron filter at best. It is also very small which means its lifespan before replacement is much shorter than a larger filter. Much of the aftermarket universal filters seem to be 30 micron filter. I would not put on one of those $30 pretty aluminum inline filters since they are not really offering any better protection 30 micron, and you already can get hat from the in-carb sintered filter. My point is that if you're not going for better filtration than 30 micron you may be better off just filtering in the carb.

In modern industrial use where longevity is important the standard is a 100 micron mesh on the fuel intake side at the transfer pump, and a 30 micron filter just before the pressure pump to the engine. A 10 micron mesh is typically placed on the pressure side right before the pressure regulator.

The design on my carb filter in my jimmy is such that it is held in place with springs that becomes compressed if the filter is clogged, allowing fuel to bypass the filter. I believe this was a the typical design feature of most carbs of that era. I really dislike that the filter gets bypassed if it clogs, and i won't even know about it unless i check the filter.

I have a 10-15 micron filter, on the pressure side of the pump. i don't advocate the use of rubber hoses due to the the flammability and suggest higher temperature braided hose for fuel or other more safe alternative. Almost all of the power shops carries suitable material that retains the safety characteristics found in the original design.

The person who owned the car before me put on a cheap plastic filter. i have since replaced that with something better.

On the point that if GM thought they needed it they would have placed it already. Let me suggest that basing an argument on the thesis that GM is infallible is flawed at its core and require no counter argument.

either way, I've provided my input. hopefully it was valuable to someone.

[hemi43]

Originally Posted by SeventyOne

Got mine on amazon for much cheaper:
https://www.amazon.com/Gates-24702-G.../dp/B002H5COTG

(shows a curved piece but it's straight)

By the time you add shipping to Canada, brokerage fees, duties and then 13% sales tax, that becomes over $100. You Guys don't know how good you have it.