Mechanical Fuel Pump For Nailheads - P/N Please

[XframeFX]

My replacement Fuel Pump was changed prior to my acquisition in 1980. So, want to change. However, all the replacements appear to have a fixed 5/16 inlet when I require a 3/8" inlet.

Any knowledge on who manufactures a fuel pump for our engines with 1/8"-27 NPT ports on the inlet and outlet?

Edited March 11, 2022 by XframeFX
. (see edit history)

[Turbinator]

Error

 

 

Edited October 17, 2021 by Turbinator
Error (see edit history)

[telriv]

John,

 

    Just buy the aproprent fitting.

 

Tom T.

 

 

[XframeFX]

I'm looking for a pump with 1/8"-27 NPT ports for both, the inlet and outlet.

Anyone know of a brand and P/N?

Looked at a Spectra Premium at the counter and left it there. It had a fixed 5/16" barb (Left).

 

Internet images show the same for a Delphi (middle) and Carter (right) with specs indicating 5/16" inlet

[XframeFX]

I'm back on this again, chasing a suitable Fuel Pump. Today, I again walked away from the Parts Counter after inspecting yet another Fuel Pump with a 5/16" inlet (X's above). Seems they don't manufacture one with a 3/8" Inlet.

 

Jobber parts searches refer to only 1 type, the one they are willing to support. I'm sure if I'd have done this 40 years back, they'd ask if the application was 2 or 4 barrel carburetion and with or without AC.

 

A member offered an original core to rebuild with a pre-ethanol kit. not going there. Just want to install a new unit and move on.

 

I prefer to purchase locally so I can open the box on the parts counter for inspection. I just need a part number. Anyone?

[telriv]

Have you tried NAPA???

 

Tom T.

[XframeFX]

NAPA Unit B0151P is like the others with only one 1/8"-27 FNPT on the outlet and a fixed 5/16" nipple for an inlet. Must be for a 2BBL application.

I've looked at Units from Carter, Spectra Premium and Delphi, still no 3/8" nipple or dual 1/8"-27 FNPT ports.

The non original unit on my nailhead now has dual 1/8"-27 FNPT ports (top image).

 

Changing the fuel pump will be for several reasons. 1) Maybe the outlet pressure of the current unit is too high and the reason for my rough idle. 2) Want to inspect the Nylon timing gear while I still have access to a borescope. 3) I'd like to think a recent pump will be compatible to ethanol blended fuels and not have a diaphragm that swells and, 4) Piece-of-mind I have a fresh pump when far from home on a trip.

 

[telriv]

John,

 

The NAPA number used to be M4553. This was the correct pump that had a separate Brass fitting for the inlet which was 1/8th. NPT. Have the store do a search. Some other store in the country may have an older one in stock or MAYBE at a warehouse somewhere in the U.S.   The Carter number is also the same at M4553.

I just measured the one I have & in fact the inlet is .325" & is shaped as the ones you pictured & AGAIN measures as 3/8ths. 

I am really not looking to sell as I may need it one day for myself or a customers car.

 

IF it's any constellation to you I still DO HAVE the original fuel pump on my '64 I've owned since new & I KNOW it has not been replaced.  I bought a rebuild kit for the original rebuildable pump many years ago in case it was needed. My original pump started to leak oil from the weep holes so I decided it was time for a rebuild.  Upon taking it apart the bellows that encased the arm was broken. Upon further dis-assembly I didn't like the construction of the replacement diaphragm & left the original diaphragm in it just using the bellows to stop the oil leak. 

This was around 2000 at the drag strip in Ohio. 

 

The only thing I can tell you is to find an original rebuildable pump & send it out to get rebuilt.

 

Tom T.

Edited March 12, 2022 by telriv (see edit history)

[RivNut]

What is the size of the hard line on the opposite end of the hose from the pump?  One of the old original pumps that I have has 5/16” inlet on it.  These are not screwed in but permanent. Perhaps somewhere in past history, someone installed a 3/8” fitting on your pump.  You can easily clamp a 3/8” hose down to fit a 5/16” pipe.  Maybe you’re looking at someone else’s screw up and treating it as OE.  Just a WAG on my end here.

[XframeFX]

If I had someone kind enough to ship an original OEM core to Canada for me, I don't believe I will be able to find a fuel pump rebuild kit for it. Nothing found online.

 

What's needed is a pump with dual 1/8"-NPT ports. This arrangement is readily available for SBC applications. Maybe buy one and change the arms - LOL

 

Thought I did good scooping-up a water pump locally (AC only 5-vane) but it is the Fuel Pump that's become un-obtainum. 2BBL application only I believe.
 

So, if I had and X-Block engine with 2X4 carburation, 5/16" to the pump inlet is adequate? The Shop Manual does not indicate size, but my hose and tubing are 3/8" from the P/U to the pump.

 

I am putting this on the back burner again and do nothing for now. "If it ain't broke - don't fix it".

 

Thanks All.

[Jolly_John]

I offered an original 1963 RIVIERA AC pump to XframeFX in a PM earlier today. It is the OE style with the screws for easy disassembly and reassembly. Was working when i replaced it years ago as part of my preventative maintenance before a 2,000 mile tour. I suggested he could rebuild this AC pump with a modern kit, as a number of you have also mentioned. I thought Terrill Machine offers the new kits. Looks like it's a mute point I guess, since he's now putting this "on the back burner".  John

Edited March 13, 2022 by Jolly_John (see edit history)

[XframeFX]

I PM'd John on this with thanks on his offer to help.

 

Still on this and a word on anyone wanting to replace in the future. Aftermarket replacement Fuel Pumps seem to have done away with dual 1/8"-27 NPT ports using 1 style-fits-all Unitac caps. They chose 5/16" as the fitting for most applications. I believe SBC replacements could still be had as OE pumps given their popularity (Ecklers).

 

So now, If one were to rebuild an original AC/Delco Pump. I did find some kits. No mention of ethanol compatibility but all kinds and some from farm suppliers

 

Also, there's this Hemmings post on rebuilding a fuel pump:

https://www.hemmings.com/stories/article/fuel-pump-restoration

 

Kits for Chevs: https://www.paragoncorvette.com/

 

From the UK for Landrover: https://www.bearmach.com/product/fuel-pumps-enfefefp/fuel-pump-repair-kit-br-3217/BR%203217

[Jolly_John]

Very helpful, John B.. Thanks for taking the time to share this info. John

[XframeFX]

Still on this, becoming a challenge!

 

Something about Fuel Pumps for 1966 full size Buicks and Skylarks with the "400 engine", the last year for the Nailhead. No mechanical Fuel Pumps available. Why is that? Images of when they were available whether OE or replacement clearly show different port sizes. I know, can't trust online images but they all show the same. Also, 2 applications for 1966, with or without AC.

 

Again, not available for 1966 but replacements available for 1965 and older Nailheads even the 2X4, all having an incorrect inlet port size at that.

 

1966 Buick Fuel Pump AC # 40250 / GM 6416167 shown <OBSOLETE>:

[1965rivgs]

10 hours ago, XframeFX said:

Still on this, becoming a challenge!

 

Something about Fuel Pumps for 1966 full size Buicks and Skylarks with the "400 engine", the last year for the Nailhead. No mechanical Fuel Pumps available. Why is that? Images of when they were available whether OE or replacement clearly show different port sizes. I know, can't trust online images but they all show the same. Also, 2 applications for 1966, with or without AC.

 

Again, not available for 1966 but replacements available for 1965 and older Nailheads even the 2X4, all having an incorrect inlet port size at that.

 

1966 Buick Fuel Pump AC # 40250 / GM 6416167 shown <OBSOLETE>:

John,

  That is the correct `66 AC fuel pump...according to something I read somewhere (?) the chamber on the pump is to prevent hydraulic hammering in the fuel line. I`ve suggested this pump many times for folks complaining about the "Riviera Rattle" but no one has ever provided any feedback. I guess its a moot point now that the `66 pumps are increasingly harder to find.

Tom Mooney

Tom

[XframeFX]

13 hours ago, 1965rivgs said:

now that the `66 pumps are increasingly harder to find.

I wouldn't want a new one that has sat in a sleepy warehouse and then expose that 40 year old diaphragm to todays ethanol blended fuels.

Also, non vented fuel caps started in 1966. Vented caps prior to that even though our Rivs have that hose over the filler necks.

[XframeFX]

Last weekend my fuel pump failed or, the checkvalve inside is toast. It is a cheap crimped canister replacement that was on my nail when I acquired my Riv in 1980.

I wanted to pro-actively replace it but couldn't find any with dual 1/8" NPT ports or 3/8" inlet.

NAPA M4553 is no longer on the books.

 

It is clear to me I have to go with an original "rebuildable" fuel pump. Which leads to a question:

What is the correct AC fuel pump? P/N" 4706 or 4399?

 

Of course, any leads on locating any pump with a 3/8" inlet would be appreciated. TX!

[avgwarhawk]

Try rock auto 

[arnulfo de l.a.]

43 minutes ago, XframeFX said:

Last weekend my fuel pump failed or, the checkvalve inside is toast. It is a cheap crimped canister replacement that was on my nail when I acquired my Riv in 1980.

I wanted to pro-actively replace it but couldn't find any with dual 1/8" NPT ports or 3/8" inlet.

NAPA M4553 is no longer on the books.

 

It is clear to me I have to go with an original "rebuildable" fuel pump. Which leads to a question:

What is the correct AC fuel pump? P/N" 4706 or 4399?

 

Of course, any leads on locating any pump with a 3/8" inlet would be appreciated. TX!

I bought two off ebay and the # 4706. 1965 rivi gs

[arnulfo de l.a.]

Forot to add i have ac

[XframeFX]

4 hours ago, arnulfo de l.a. said:

I bought two off ebay and the # 4706.

4706 it is, Thank-you.

Crazy having to buy a core and then having to rebuild it. Just want a ready to install unit, even those offshore crimped pumps will do. But all those pumps are incorrect for our nailheads, rockauto as well.

 

I have AC as well. Can't understand fuel delivery with the 1/4" return line. So, staying with Like-for-Like replacement and the reason I didn't opt for an electric pump at the rear.

[EmTee]

8 hours ago, XframeFX said:

Can't understand fuel delivery with the 1/4" return line.

The return line just routes excess fuel back to the tank, rather than having it linger in the metal fuel line in the engine compartment picking up heat.  The return line keeps the fuel cooler and helps avoid vapor lock.  Since the underhood temps on A/C-equipped cars tend to be higher, the return line used to be included as part of the factory A/C installation.

[XframeFX]

3 hours ago, EmTee said:

The return line just routes excess fuel back to the tank, rather than having it linger in the metal fuel line in the engine compartment picking up heat.

Yes, thanks, makes sense. Just wondering about pressure from the split (fuel filter) to the float bowl. Not a big difference in size from the 1/4" return and the 5/16" delivery lines.

If an electric fuel pump conversion were to happen, shut-out the return line?

Until I locate and original 4706 rebuilt or core fuel pump, an electric fuel pump conversion is still up for consideration. I have a dual pole oil pressure switch in-place which would work with an electric fuel pump.

[EmTee]

7 hours ago, XframeFX said:

If an electric fuel pump conversion were to happen, shut-out the return line?

I don't think having the return line would be of any consequence with an electric pump.  Most new fuel injected cars use a return line after the pressure regulator.  When the needle valve is closed and the carburetor isn't taking any fuel, gas will be returned to the tank.  That would happen with the mechanical and/or electric pump.  Depending upon the electric pump you choose, it would probably be a good idea to add a pressure regulator to make sure that the fuel pressure doesn't overwhelm the needle valve in the float bowl and flood the engine.

[telriv]

That small return line has a very small orifice inside to re-direct fuel back to the tank otherwise little to no fuel will reach the carb.  It's to vent vapors to PREVENT vapor lock.

Liquid is like air, it will take the easiest route.

 

Tom T.

[johnrex]

Here is a photo of the inside of the dual port filter

[XframeFX]

4 hours ago, telriv said:

That small return line has a very small orifice inside to re-direct fuel back to the tank

Which begs the question: "Where's the orifice?"

Next post, its in the filter! A Filter for AC cars.

Thanks John, Tom and Tim!

 

[XframeFX]

I received a so-called NOS AC Delco 4706 Pump from flea-bay Friday. My expectations were low. At least I'd have a core to rebuild if it were sketchy. Kits were available from Paragon Corvette.

Well the pump I received is clean but old. Appears to be rebuilt long ago with hammer marks around the pin with washer underneath. I wouldn't trust this pump for cross-country travel.

Now, it appears Paragon just discontinued the rebuilt kit. They were my lone source.

Help needed in sourcing a rebuild kit for AC Delco 4706 - anyone? 

 

BOP Parts offers the Kit below. Expensive and it is not complete. The diaphragm is not an assembly with the saucer and rod, just a diaphragm that I could cut on my own.

 

Addressing the Fuel Pump for the Nailhead here in 2022 is ridiculous, unobtainum!

 

https://www.bopparts.com/shop-parts/fuel-exhaust/fuel-pump-related-items/1964-1965-buick-riviera-with-401-v8-and-425-v8-engine-ac-type-4706-fuel-pump-rebuild-kit.html

[Bloo]

If the diaphragm is removable from the metal parts, what is the problem? If it is not, then I guess that kit won't work.

 

You might check with Then n Now for a kit.

 

https://www.then-now-auto.com/

 

[SwedeDownUnderR63]

1 hour ago, XframeFX said:

I received a so-called NOS AC Delco 4706 Pump from flea-bay Friday. My expectations were low. At least I'd have a core to rebuild if it were sketchy. Kits were available from Paragon Corvette.

Well the pump I received is clean but old. Appears to be rebuilt long ago with hammer marks around the pin with washer underneath. I wouldn't trust this pump for cross-country travel.

Now, it appears Paragon just discontinued the rebuilt kit. They were my lone source.

Help needed in sourcing a rebuild kit for AC Delco 4706 - anyone? 

 

BOP Parts offers the Kit below. Expensive and it is not complete. The diaphragm is not an assembly with the saucer and rod, just a diaphragm that I could cut on my own.

 

Addressing the Fuel Pump for the Nailhead here in 2022 is ridiculous, unobtainum!

 

https://www.bopparts.com/shop-parts/fuel-exhaust/fuel-pump-related-items/1964-1965-buick-riviera-with-401-v8-and-425-v8-engine-ac-type-4706-fuel-pump-rebuild-kit.html

Why not use a new one until you can source a kit:

https://www.nailheadbuick.com/product-page/57-to-66-new-fuel-pump

[Chasander]

Old Buick parts.com list a rebuild kit. 

[XframeFX]

2 hours ago, Chasander said:

Old Buick parts.com list a rebuild kit.

Bingo! That's it! Thank-You. Haven't checked Old Buick Parts in a while. They've changed their website and catalogues are in PDF form now, more parts too.

 

FYI: All NEW Pumps have an incorrect "fixed inlet". Gaskets appear to be Chev versions as well.

My theme is to maintain or improve original functionality. A "Downgrade" from 3/8" to 5/16", not part of my plan.😠

 

 

 

 

 

 

Edited September 20, 2022 by XframeFX (see edit history)

[XframeFX]

Update - CARS has the Fuel Pump Repair Kit in-stock and now have one on order (NOS Fuel Pump failed bench test).

[XframeFX]

Update, Again - Just received a "Fuel Pump Repair Kit". It is for the NORS 4706 AC Fuel Pump I purchased on EBay that was rebuilt in the 70s. Not trusting that pump, had planned to replace all soft parts with fresher items from that kit, rebuild the rebuild.

The rebuild kit came with all items except diaphragm spring. Included were 2 versions of pivot pins, neither original.

 

To my dismay, the kit has a plain flat diaphragm. The diaphragm on the rebuilt pump (Made in USA) is molded around the saucer cup like a plunger and is thicker.

The 2nd observation were the check valves. They were machined from aluminum stock, nice. But the passages appears smaller.

 

I appreciate the effort sourcing and fabrication that went into this kit. But, I think I'll run the EBay pump as-is and keep the kit as an emergency spare. In fact, throw it into the box of my Chinese water pump, also an emergency spare. So, an FYI what to expect from the Kit.

 

Would be nice to forego all this and just go out and buy a pump locally. I don't care if its a crimped "Unitac" pump. Just don't want a Chevy pump with a Buick arm and no ability for a 3/8" fitting, incorrect!

 

 

 

 

 

Edited October 18, 2022 by XframeFX (see edit history)

[gungeey]

It's not molded it's just taken on that shape from the decades. Make sure it quacks like a duck before you install it 

[EmTee]

I'd probably stick the original diaphragm in some E10 and let it soak awhile before putting it back together.  That way, if is starts swelling or otherwise decomposing, you can replace it with the one from the kit.

[gungeey]

2 hours ago, EmTee said:

I'd probably stick the original diaphragm in some E10 and let it soak awhile before putting it back together.  That way, if is starts swelling or otherwise decomposing, you can replace it with the one from the kit.

By the way, just for sh!ts I did just that.. about 6 years ago and that car gets driven a lot.   No problem. The original material was about 3/32nds. The new ethanol proof stuff was thin as an inner tube. 

[XframeFX]

HELP, It appears obsolete P/N #4706 is incorrect!

Checking on this Forum and my parts exchange, says AC #4706 is correct. I assembled it retaining correct Suction and Discharge locations. All good there.

 

I have interference with a diagonal bracket from the engine mount to the alternator. The pump will not flange up to the Timing Chain Cover.

I could remove that bracket and gouge a notch into it but why? It boils down to installing a correct fuel pump for a 1963 Buick Riviera.

Even if the pump cleared the bracket, it is almost up against the block.

 

1) Anyone encounter the same fit problem?

2) Any recommendations?

3) Still require a correct P/N but at this point considering a blanking plate and do yet more research for a suitable electric fuel pump.

 

 

 

 

 

 

 

 

 

 

Edited November 19, 2022 by XframeFX (see edit history)

[1965rivgs]

  I always remove the bracket and then reinstall after the pump is installed. About half the Nails I've worked on are missing the bracket anyway.

  Not sure if the pump arm/eccentric is preventing you from seating the pump but if it is rotate the engine to get off the high point of the eccentric.

  I know the 4706 number is correct for the '65, among other replacement numbers, but I'm not sure about the '63...I would think it is.

Tom Mooney

[gungeey]

Like Tom said. Take out the bracket. I leave it out. 

I just want to say the aftermarket pump plenty of fuel regardless of 5/16 or 3/8. They'll fill up a coffee can in 10 seconds. More gas than we could ever burn in that time. (I think it takes me about a whole minute 😆) They also are chinese junk with plastic and thin metal parts that are unreliable.  I use the originals because they're tanks. They also create more mess as you can see. Fair warning ⚠️ 

 

You have to find the spot that allows the shaft to enter ... yeah baby... on the eccentric Start at TDC. 

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