I searched, but I can't find any threads about adding larger fuel lines to the fuel tank sending unit. I know it's gotta be here somewhere. How would you do it - braze, JB Weld, silver solder? And what would you use for running new fuel line from the tank to the engine compartment? I'm thinking the newer plastic line might work well. Thanks.

 

I haven't looked at a thirdgen sending unit up close in a few weeks, but I'd venture an educated guess that the stock tubes are just soldered in. I would remove the existing tube, then use an alignment tool (smoothly tapered punch) to carefully expand the existing hole to the size needed. That should leave a flared flange around the hole that will help support the tube and give a bit more surface area and support, then just solder the new tube to the sending unit with a good solder. Rosin core 60/40 electrical solder would probably work just fine. Most hardware store grade "silver solder" products aren't much stronger, and the acid flux will just make a corroded mess. A real silver solder like Safe-t-Silv is overkill. JBWeld has about as much place on a car as wire nuts. I also despise the nylon fuel lines. FWIW.

 

Why? The stock line will support 600 hp.

 

Years ago I tested my fuel delivery system for flow restrictions. When doing 1/4 mile runs on the highway, the carb was running out of fuel at the top of 2nd gear (700R4). I was also using the stock, block mounted mechanical FP. I made my own tester like you use for NOS, where you screw a Holley jet in the end and then see how much time it takes to pump 1 gallon. I don't have my numbers in front of me, but if I remember correctly, the stock metal line from the tank to the engine compartment was a 17 gal/hr restriction. I searched every inch of that line for kinks - none were found. I band-aided the problem by installing a small electric FP at the tank to give the fuel a push up the block-mounted mechanical. It worked, but shortly after the engine ate the camshaft and the car has been parked since. This time around I will be using the Carter M6626 and Edelbrock 1904 QJet instead of the E4ME CCC carb.

 

Nice ideas. Thank you.

 

It's sort of well known that the Qjet runs out of juice once you go north of 400whp due to the flow restriction, it can't keep the bowls full but that's a carb issue not an upstream fuel delivery issue.

That said, my Qjet, retro-fitted 255lph in-tank pump (in 84 originally mechanical pump), never ran out of fuel on my 320hp 355 even when running at the strip.

 

Yes, the quadrajet has very small fuel bowl(s), certainly waaaay smaller than any Holley.

I had this problem with my 334 SBC, emissions legal, fully loaded 84 TransAm. I tried larger block mounted mechanical fuel pumps. No difference. That is when I tested for restrictions. I just looked for my old notes - no luck. But I did find some old notes from running the quarter on the highway with a G-Tech. The car would not spin the wheels and had a hard time getting off the line. When it finally decided to get going, at about 3500 rpm, it would take off like a rocket. So the ETs sucked, but I did manage a 108 MPH top speed.
As I tuned it more, the more power I made, and that's when the running out of fuel at the top of 2nd gear (700R4) problem surfaced.

So what kind of HP does a 108 mph calculate to?
And I got this out of a 334 with problems......

 

Is that with an .049" needle/seat?

 

Yep. Tried them all - .125, .135 and .149.
CCC carb was rebuilt and calibrated by the Carb Shop in Ontario, CA.
I had to modify it even more.
A small electric Purolator fuel pump at the tank worked as a band-aid to push the fuel up to the block mounted mechanical.
This time around I will be using an Edelbrock 1904 QJet recalibrated using a recipe from Cliff's HP QJets.

 

Sorry, brain fart. .149" (been awhile).

 

I knew what you meant.

It is definitely a WTF feeling when you're going WOT down the highway at 100 mph and just shift into Drive, and then............. nothing. It's like someone turned the ignition key off. Pedal still to the metal. Then the engine sputters, stumbles, and catches back up.

 

Since you mention block mounted FPs, have you thought about dropping in a low pressure TBI in-tank pump and sender? It is a whole lot more efficient to push a liquid (in-tank) than try to pull it (block mount). You would also need an AFPR and return line... which you should have had with the helper pump you tried before.

 

have you thought about dropping in a low pressure TBI in-tank pump and sender?

If the Purolator electric at the tank with the Carter M6626 on the block does not cut it, then the TBI in-tank pump will be the next step.

But I personally would rather have my fuel pumps mounted outside of the fuel tank, because if/when it craps out, repair/replacement is MUCH easier.

 

So what kind of HP does a 108 mph calculate to?

Wallace calculator: Your HP computed from your vehicle MPH is 363.17 rear wheel HP and 403.52 flywheel HP.
I used 4000# for weight (fully loaded 84 TA, fuel, me, extras) and 108 mph.
It is also what Desktop Dyno comes up with.

And I got this out of a 334 with problems......

99% emissions legal, too.
I'll take it. It will be even better next time with all the bugs worked out, lighter, 3400 stall.....

 

In-tank pumps are a pain. External of tank pumps have their issues. But if that's what you prefer, why not just go for the external electric pump and reg.?

Mech pumps are less common, and I doubt you're going to have excellent quality out of them in today's market.