Correct bottom design for original '66 40083 fuel pump

[Gary B.]

Based on looking thru the archives I can't determine which bottom design is correct for an original '66 40083 fuel pump. I've seen photos claiming to show original pumps, but one design has a single large dome with a gray finish and the AC emboss and the other design has two adjacent, smaller bumps with a gold-ish plating and no AC emboss. Which design is most likely not to get me a deduct for originality?

Thanks,

Gary

[Dan D.]

Re: Correct bottom design for original '66 40083 fuel pump

Gary, The one I pulled off my 63 engine (which I have owned since 1971) is the double bump. The goldish plating is most probably zinc dichromate. The replacement I bought this past summer (I believe cc but suppose to be correct) is the domed AC. So my guess is at some point they changed from the double bump to the domed. Don't know when. The double bump is formed steel, the domed is cast. The outlet fitting is in a slightly different position too. You would think the formed steel would be cheaper and would be the reason for change. If someone knows for sure I would appreciate it too. -Dan-

[Michael H.]

Re: Correct bottom design for original '66 40083 fuel pump

I've seen photos claiming to show original pumps, but one design has a single large dome with a gray finish and the AC emboss and the other design has two adjacent, smaller bumps with a gold-ish plating and no AC emboss. Thanks,
Gary

Gary,

Here's a section of a pic of a new 66 L79/350 HP engine about to be installed in the chassis at the St Louis assembly plant. Looks like it has the stamped steel bottom cover.

[Mike M.]

Re: Correct bottom design for original '66 40083 fuel pump

i've only seen the diecast cover in the 63-4 time frame. somewhere in late 64 /65 time frame,. the stamped steel gold cad cover showed up. hence , a 66 ouhgt to have the stamped steel critter.

[Peter J.]

Re: Correct bottom design for original '66 40083 fuel pump

Gary,
Like you I have a late 66 L-79 and it is a very original car. I did a lot of research on fuel pumps before sending mine off for a rebuild. My pump is like the first picture on the left with the cast base with "AC". I know what the JG says and if I were concerned about points I guess I would switch to a stamped steel bottom plate. But I know the fuel pump on this car was original as I have spoken to the original owner and have every receipt for work ever done (You have to love those accountants).

[Michael H.]

Re: Correct bottom design for original '66 40083 fuel pump

My pump is like the first picture on the left with the cast base with "AC".

I have to think it may be possible that both styles may have been used for 1966. We know for sure that the stamped cover was used but we don't know for sure that the cast cover wasn't.

[Peter J.]

Re: Correct bottom design for original '66 40083 fuel pump

Mike,
Ever since the captured belt on the L-79 question came up a few years a go as being wrong, I have been hesitant to change anything on my car that I thought was original.
My pump has the "AC" on the top as well as the bottom and has the part number embossed on the flange too. It will be interesting to see what else is out there.

[William C.]

Re: Correct bottom design for original '66 40083 fuel pump

I've seen the stamped and cast bottoms on originals with castings dated in most of the 65-66 models, I do know of one original owner car from 1964 that had the stamped bottom.

[William C.]

Re: Correct bottom design for original '66 40083 fuel pump

What some don't pay attention is that the top section is both a unique configuration and also made of magnesium, easy to spot an imposter without even getting under the car.

[Gary B.]

40083 fuel pump; Thanks all

Thanks all. I think I know what to look for now.

Gary

[Mike M.]

Re: Correct bottom design for original '66 40083 fuel pump

Gary,
[FONT='Arial','sans-serif']"The bottom section is stamped steel, cadmium dichromate and secured with four cadmium dichromate slotted pan-head screws with a tiny "S" headmark."[/FONT]
[FONT='Arial','sans-serif']HaND[/FONT]

[John D.]

Re: Correct bottom design for original '66 40083 fuel pump

What some don't pay attention is that the top section is both a unique configuration and also made of magnesium, easy to spot an imposter without even getting under the car.

Magnesium can be quite ugly to say the least. Very difficult to refinish. I have seen some 4657 pumps with the round magnesium bottom cover.
Not pretty at all.
Very dangerous refinishing magnesium if you don't know what you are doing. Been there. Improper chemicals to clean magnesium can be life threatening.
But the green smoke pouring up from the casting by submerging it to some unknown acid (I forget) is quite illuminating.

[Gary B.]

Pan-head screw with tiny S head mark

Anyone have a photo of such a screw? Or know of a source who sells used originals or repros?

Gary

[Alan D.]

Re: Pan-head screw with tiny S head mark

A little hard to see however these are the "S" screws used on bottom steel cover. Note the inside of the pump will have a date on it, mine was 64 so the steel cover was available in 64 and have one dated 67.

[Gary B.]

Re: Correct bottom design for original '66 40083 fuel pump

Alan,

Thanks for the photos. If a judge can detect incorrect screws with the pump on my car, more power to him or her.

Gary