Michail

Hello

I had problems with the fuel pipe to my Rochester Quadrajet.

It's embarassing, but I gripped the steel pipe and turned the nut and the next time I looked I had twisted the pipe like a roll of tape several turns around itself.

I'll see if I can put up a picture of it later so you can laugh at me.

Anyway , I replaced the ruined piece with a rubber hose (fuel approved) secured with hose clamps in both ends.

Now to the problem: that flared connector that is screwed to the filter house nut thing is leaking. I think I have abused it once too many.

I don't mean the usual Q-Jet problem with wrecked threads between the filter house and its nut, I mean the flared pipe nut thing connecting to the filter house nut thing.

I figured that this is probably not the last time I will be dorking around with the carburetor, so I went and bought a nice quick-connect thing with built in check-valve - hose fitting on the valve side since I have a rubber hose there anyway - and a 1/4" NPT male fitting on the stem end, falsely assuming that the filter house nut thing had a female 1/4" NPT thread. Instead, I just now learned that it has an inverted SAE 45° flare connector.

http://www.jgbhose.com/base_pages/co...#invertedflare

Now to my question: Can I get a 3/8" NPT-threaded stem and put it on the filter house nut? Using a pair of calipers it seems as if it might be ballpark right diameter, and the thread pitch is 18 threads per inch, as is the NPT.

Maybe perchance this already is a 3/8" NPT thread, only with added cone on the bottom to facilitate flaring? Suppose I shove a drill down there to remove the cone, do you think I could squash an NPT stem in it?

I would appreciate it if someone more experienced would give me some advice here.

This is a later-than-1976 Quadrajet, so it has the 1" male thread on the filter house nut thingy.

Michail

Might need to add:

The SAE 45° thread has an outer diameter of 5/8 = 0.625" (ø15.88 mm) while the 3/8" NPT has an outer diameter of 0.675" (ø17.15 mm), but it is also tapered 1:16 on the diameter so on ½" it should narrow to 0.6625" (ø16.23 mm) at the end.

Oh well, it seems I have answered my own question. The NPT won't fit, I will have to drill the hole to like 0.665" or 16.5 mm or such and rethread it. >_<

Well, thanks for reading anyway.

sofakingdom

iTrader: (1)

You don't need to be drilling ANYTHING. Don't even think about it.

SAE inverted flares are EXTREMELY common. You can buy all kinds of fittins for that. Even, a 3/8" hose barb. Just go to a "real" parts store, and look through their cabinet of brass fittings.

Rubber line is a bad idea. "Approved" or not.

You can buy a brand-new piece of steel brake line at the parts store, and make up a brand-new fuel line, if you have a tubing bender and a flaring tool.

Another possibility is to buy adapters for stainless braided AN hose & fittings.



Avoid the rubber hose. It is DEATH. Literally. Have you ever seen what happens to a car when it fails? ..... let's just say, the fire dept can't get there fast enough; and even if they could, there's nothing they can do to stop it.

Michail

You make a compelling case and my next purchase will be a steel braided hose and some adapter for the SAE connector.

Thanks!

Michail

Here's a picture of hamhanded expertise, by the way:



This is what happens if you put your left hand loosely over the bunch of pipes and hoses below and then twist away on the filter house nut, swearing and sweating.

Michail

Uhh, you don't perchance happen to know what type of connector the stock fuelpump has on an '86 IROC?

Some say flare, every replacement I see are NPT, pictures on the web don't help.

Apeiron

Inverted flare, maybe 1/2" or so.

sofakingdom

iTrader: (1)

It's 3/8" inverted flare. Same as the carb. Same piece of tubing, other end. Some fuel pumps (aftermarket "universal" ones especially) have NPT, and require an additional adapter. Stock and stock replacement pumps have the correct fitting.

Michail

Good, thank you!

I'll order the braided hose and required adapters right away.