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Holley EFI pump threads

3K views 31 replies 6 participants last post by  Charles Reeves 
#1 ·
I'm attaching a photo of the pump on a Holley EFI tank, showing how far I was able to screw in the 1/4" NPT fittings. I don't think I was able to screw them in more than 2-3 full turns. Would appreciate opinions, as this isn't as far as I've been able to screw these kind of fittings in the past.

I sent this question to Holley, but have not heard from them yet.
 

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#2 ·
I'm kind of suspicious about the type of connector you're using, as this is in conjunction with a high pressure pump, right? Most of the time you want to use compression fittings with fuel injection pumps instead of barbed press-on ones, due to the pressure involved. But if those are tapered seats and threads, a lot of times they do only go a couple turns. AN fittings screw all the way down and seal 'at the seat'. You don't use tape with those. The NPT ones are tapered, and DO require tape, as you've done, but they seal because of the taper, and don't go in as many turns.

Not being familiar with that particular pump, I'd check to see what their fittings are intended to work with, just to make sure you're all right You definitely don't want to be putting AN stuff into NPT, or vice versa.

I'm sad to say, I am intimately familiar with what happens when fuel system lines fail. It's a good thing to avoid when possible!
 
#3 ·
Thanks, as always, Grimbrand. All the Holley docs say is 1/4" NPT.

I ran a new 3/8" copper-nickel line for the pump output, with short lengths of rubber tubing at the ends, really heavy duty tubing intended for EFT. I'm using the old 5/16" line for the Return. Compression fittings on the ends of the hard lines.

But the barbed fittings also bother me a bit. They are for 3/8" tubing, but they slide into the EFT tubing much easier than I'm used to.
 
#4 ·
Thanks, as always, Grimbrand. All the Holley docs say is 1/4" NPT.

I ran a new 3/8" copper-nickel like for the pump output, with short lengths of rubber tubing at the ends, really heavy duty tubing intended for EFT. I'm using the old 5/16" line for the Return. Compression fittings on the ends of the hard lines.
Those brass fittings are not for EFI rated fuel line. Use NPT to AN adapters instead, then AN hose ends. https://www.summitracing.com/search...pe:hose-ends&SortBy=Default&SortOrder=Default

The way these work, slide a collar over the end of the hose, lubricate and insert the barbed end, then thread the collar back onto the fitting. Buy the hose to match the fittings.

AN stands for Army Navy and was developed by the military to be reliable and re-usable. I plumb my cars the same way- 3/8" steel fuel line with short hoses at the fittings. I typically use a 1/4 return. Use EFI rated hose and AN hose ends.

To convert to steel tube, use a AN to compression fitting adapter. Since a compression fitting isn't as reliable as AN fittings, locate that outside the passenger and trunk area and in an accessible location.
 
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#5 ·
Here's my connections at the top of the EFI pump frame.

The vent line is the lowest of the three using a barbed connection (like in your picture), and I put a hose clamp on it for extra measure.

I used Russel fittings and hose.
 

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#7 ·
That hose is not cheap, and it has to match the fittings.

EFI hose has a steel braid so you have to cut it with a hacksaw or similar. Build yourself a little jig out of scrap wood , like a 4" length of 2x4. Drill a hole the same size as the hose OD in the center, then cut the block exactly in half. The kerf that you remove from the wood will be enough to squeeze the hose into your new jig.

Use the jig to hold the hose in a vice. Then make a nice square cut, using the end of the jig as a guide. Use compressed air to clean out all the rubber crap that this generates. Don't be afraid to use water to clean, then follow up with compressed air.

Read the instructions with the hose ends or look online at the manufacturers web site. The Russel fittings have a collar that slides over the hose, you insert the barb, then screw on the collar into reverse hand threads.

Use WD40 to lube the cleaned hose ID. There's a video out there with some guy hammering a barb in with a wood block but mine went in using firm hand pressure.

It's a fun job doing this type of plumbing. Seriously- I can't wait to do my next EFI conversion.
 
#8 ·
Thanks again, Yadkin. The hose I have isn't steel braided, although is rated for EFI and also came from Summit. But I will use the braided hose just to be on the safe side. A neat trick with the cutting block.

Even at age 76 I still enjoy working with my hands (as much as the minor arthritis will allow), and learning how to do new things.
 
#13 ·
Yes it is for my one-owner 1966 289, a four barrel Holley Sniper, with a Holley fuel tank with built in pump. The fact that the pump and sender connections are on top of the tank; i.e., in the bottom of the trunk, was not an issue for me. I plan to build a cover over them. I just got the basic Sniper, not the one with all the accessories, since I didn't need the pump and some of the other stuff in that kit.

I also ordered the progressing throttle link mentioned in a thread on this forum or the VMF. The problem with the Holley design is that it opens both sets of throttle plates simultaneously, where most, if not all, 4-barrel carbs (including Holley's) only open the secondary plates after the primaries open a certain amount. The only reason I can see behind this is that the ported distributor vacuum port is on the secondary plates. But if so, why did they not put it on the primary side? This means that feature no longer works with the progressive link, but no big deal, since I hooked my distributor vacuum directly to engine vacuum.
 
#14 ·
Charles, when dealing with fuel injection, using a progressive linkage is counterproductive. With a carburetor, if you snap both blades open (like a double-pumper) you have too much air and not enough fuel. The squirters pour in gas to help compensate, until the airflow going by the boosters and venturii can compensate, and the air starts moving by fast enough to suck fuel into the stream. With vac secondaries, it uses the engine's vacuum to sense need for more air, and does the same thing.

But EFI actually doesn't require vacuum at all. It knows the RPM, knows exactly how much air is roaring through at any given time, and just adds fuel. It doesn't matter whether there is vacuum in the manifold at all to draw fuel out of the venturii. It doesn't even care whether the air going through the throttle body is going fast or slow.

A progressive linkage with EFI can potentially mean a lot more complicated math in how much gas you're supposed to be adding because the equation is not linear anymore, but more of a curve. That's why virtually no throttle bodies I know of do anything but open all four holes at once, and even with a dual-quad setup, a progressive linkage works worse with them instead of better.

And good on you for using manifold vacuum, since that's really what proper timing needs anyway. *high five*
 
#21 ·
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A progressive linkage with EFI can potentially mean a lot more complicated math in how much gas you're supposed to be adding because the equation is not linear anymore, but more of a curve. That's why virtually no throttle bodies I know of do anything but open all four holes at once, and even with a dual-quad setup, a progressive linkage works worse with them instead of better.
OK, I will hold off installing the link until I see how the car drives. If I have problems spinning tires on startup, like I've seen reported, I will install it.
 
#15 ·
The latest posts here have reminded me of an issue I had after I completed (or thought I completed) a F.A.S.T. EFI conversion on my big block 390. I went with a throttle body system because the manufacturer stated that I could use my existing manifold. This was of course a factor manifold, dual plane.

The throttle body injector setup was a direct bolt on from my Autolite 4100 regards to height and clearances. But the engine ran terrible and gas would burp back up into the air cleaner. Stink and fire hazard. I did more research and it turned out that I needed to swap out the dual plane for a single plane. After doing that the system works as intended.

I'm not happy with the fact that I was mislead. Small block owners may not realize this, but whatever a part for your engine costs, for the same thing on a big block it's basically double that. And your parts selection goes from a half-dozen or so down to two if you're lucky. I was even less fortunate and found out that currently there is only one company making intakes for my engine, Edelbrock, and it's a mid-rise and they state specifically that it will not fit under the hood of my car (Thunderbird).

I was stuck and ordered one anyway to see if I could make it fit. I had to grind the mounting surface on an angle, tossing another hundred bucks to a machine shop on a $500 manifold that I would not be able to return. Luckily it fit with my stock air cleaner, some minor mods on that, with about 1/4" to spare, verified by using balls of clay and carefully closing the hood to squash them.

Later on I swapped out the stock dizzy for an MSD which was taller and that required swapping my factory snorkel type air cleaner for a low rise 360 degree exposed element, and that improved performance of the EFI eve further. So they like an even distribution of air into them.

The other part of this story is that Edelbrock sells two versions of this Victor manifold for the big block Ford. both the same casting but one is machined for injectors at the port end of each runner. Had I known that I was going to end up with a Victor I would have spent another $300 or so and gone with a port injection system instead of a throttle body injector system. The non-injector throttle bodies for those are shorter, leaving less of a chance of hood clearance issues, and they burn fuel more efficiently.
 
#19 ·
In the direction of fuel flow:
1. New gas tank with EFI pump. Thanks are cheap, and an external pump is noisy, less safe.
2. NPT to AN adapter, AN hose end, short length of EFI hose, route through chassis with a grommet, AN hose end, AN to flare adapter.
3. 3/8" steel supply line, double flares both ends.
4. Flare to NPT adapter.
5. 10 micron high pressure fuel filter.
6. NPT to AN adapter, AN hose end, short length of EFI hose, AN hose end.
7. Choose either throttle body EFI or port injection. Single plane intake manifold.
8. AN hose end, short length of EFI hose, AN hose end, AN to NPT adapter.
9. Pressure regulator.
10. NPT to flare adapter.
11. 1/4" steel return line, double flares on both ends.
12. Flare to AN adapter, AN hose end, short length of EFI hose, route through chassis with a grommet, AN hose end, AN to NPT adapter.
13. See item 1.

Also need a bung welded onto the exhaust far enough from the headers or exhaust manifolds. This with carry the oxygen sensor that the EFI system needs.

Wiring for the EFI CPU. Usually this is powered directly from the battery. I like to mount these in the passenger compartment under the dash. Inputs from the throttle body, oxygen sensor, outputs to the injectors. There are about 30 or so wires in a computer-type connector that have to be routed correctly. Take your time, read the instructions and work through it.
 
#18 ·
Those Holley Hydramats are really something! i didn't even know those things were out there nowadays. Thanks Brian!!




J
 
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#20 ·
Or you could just get a Holley Sniper kit with all the fittings, etc. needed. Here's one kit:

https://www.summitracing.com/parts/sne-550-511k/overview/

It comes with a clamp on oxygen sensor, although you do still need to drill a 3/4" hole in an exhaust pipe. It also comes with a 3/8" rubber fuel supply hose. I chose to run a new 3/8" copper-nickel line; I'm using the old 5/16" steel fuel line as a return line.

As mentioned earlier in this thread, I did chose to go with a new Holley tank (#1 in Yadkin's list), so I just got the Sniper w/o the kit.

And has also been mentioned, all the AN fittings and hose really aren't required for the EFI systems most folks install, like the Sniper. I spent all afternoon yesterday making one AN hose, and am having second thoughts about going that route, even though I've probably invested upwards of $200 in hose and fittings.
 
#26 ·
And has also been mentioned, all the AN fittings and hose really aren't required for the EFI systems most folks install, like the Sniper. I spent all afternoon yesterday making one AN hose, and am having second thoughts about going that route, even though I've probably invested upwards of $200 in hose and fittings.
Each hose set-up I did took about 5 minutes per end using Russel steel core hose, braided nylon cover, and Russel fittings. Make sure you read the instructions correctly. The Russel sleeves go on the hose, then you lubricate the barb on the hose end and insert it. The sleeve then threads back onto the hose end, and has REVERSE threads. Yours might be different, so again, read the instructions. If there not clear, search Youtube for a video.
 
#22 ·
If you do have trouble with throttle control on launch, I suppose a progressive linkage would fix that! =)

Mass air systems would probably not care as much about the discrepancy between throttle position and airflow as a MAP system, but most throttle body EFI setups are MAP. Of course, they keep getting smarter though -so maybe it wouldn't be a big deal.
 
#23 ·
Thanks gang! I’m wondering what kit I should use? I see they have a two-barrel kit designed for a Holley 2300 application. Since I have the autolite 2100 I’m wondering if that kit would better suit me. I’ve submitted some questions on the summit website. I’ll repost the answers that I get. Feel free to offer your opinions. I’m excited to get away from the carb if it’s feasible.
 
#24 ·
Tlkmap, I would only consider using the old cast-iron 2V manifold on the most "geez I shouldn't really be doing this..." budget. It is heavy as sin, and has mediocre fuel/air distribution anyway. Definitely not a performance part. Get yourself on Facebook Marketplace and Craigslist, find yourself a nice Weiand Stealth or Edelbrock manifold (Performer 289 or RPM would be great) and improve your efficiency as well as ditching a good 20 lbs, up high in the engine where it can most negatively affect handling (and your back when you have to put it on or take it off).


Don't shoot yourself in the foot with a 2-barrel throttle body setup, even if you're only wanting to improve economy and driveability.
 
#27 ·
Whoops, yes, wasn't thinking clearly when I was giving manifold recommendations above. If you could find one, an original Torker 289 (not the Torker II) would work fantastic with EFI. Vic Jr, perhaps.

Dual-plane manifolds work best with carbs, because of how they pull fuel. It's vacuum-signal dependent. A throttle body doesn't care a whit about that, except to check manifold pressure. Most of them get a bit confused when strong pulses with two different values (from the two banks of the dual-plane) keep hitting the sensor, and that can screw up the readings.

A well-designed single-plane distributes the fuel and air more evenly, which is good, but just as important for a throttle body EFI unit, you get 'one reading' for manifold pressure because there's only one plenum.

You can sometimes make a dual-plane work better with EFI using an open spacer, but it's still not always ideal. For street use, dual plane is best for carbs, and for any use, single for EFI, if you have the choice.
 
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