70/71 Fuel Sending Unit - Impala Tech
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post #1 of 6 (permalink) Old 05-12-2019, 03:18 PM Thread Starter
 
 
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70/71 Fuel Sending Unit

Was researching a new fuel sending unit for my 70 and came across something that sparked my interest.

Specifically the Spectra 105A (70) vs 106A (71).

I am going to do a Holley Sniper EFI kit with a return line. All the oem units like the 105A don't have the return line provision. Would have to take to a fabricator to make it work. But when I looked at the 106A for the 71, I noticed that it does the tthe return line provision.

Would these be interchangeable?

I know the tubes on the top bend slightly on the 105A and the 106A is straight.

I'm thinking that I would be able to use the 106A and possibly just have to shorten the tubes on the top.

1970 Impala Custom coupe
400ci SBC
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post #2 of 6 (permalink) Old 05-12-2019, 03:49 PM
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Only cars with return line that I know of where the 396 with Rochester QuadraJet carb (325 horse variant). Not present with either the 350 horse 4160 series Holley or the 375 horse 4150 series Holley carbs. In 1971 it would be a 402 engine.

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post #3 of 6 (permalink) Old 05-12-2019, 04:23 PM Thread Starter
 
 
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Even Spectra's website lists these.

For 70 with the 400ci, it lists the 105A. For the 71 with 400ci, it lists the 106A.


https://ecat.spectrapremium.com/products/FG105A

https://ecat.spectrapremium.com/products/FG106A


Either way, Would I be able to use the 106A? Possibly shorten the inlet and outlet tubes.

Or just easier to get the 105A and have them fab up the return inlet?

They do look slightly different but not sure how much the tank changed from 70 to 71.


Or is there another fuel sending unit that would drop in no problem with the return inlet?

1970 Impala Custom coupe
400ci SBC
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post #4 of 6 (permalink) Old 05-12-2019, 05:09 PM
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1965-'70 was one body style; 1971-'76 was another. Many changes in car body size and styling. 1971-'76 was the largest and heaviest that the B-body ever achieved. In 1977 the B-body shrank in weight and size down to A-body dimensions (1968-'74 size Chevelle body) to increase CAFE numbers (mileage).

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post #5 of 6 (permalink) Old 05-12-2019, 06:29 PM
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You might want to double check that the "return line" looking thing on that sender isn't actually a vent or a tube for a vent fitting. Having a return line dump fuel that close to the pick - up seems suspect to me, which is why I say this. It will aerate the fuel being sent and will cause stall /hesitation.

Installing a proper return line in your tank isn't a big deal either. The holley EFI master kit comes with everything you need. You just want to make sure to get any and all metal shavings that result from drilling the hole. 9/16" hole, debur, get the shavings out, install the fittings, done.

1968 Impala SS
496 Stroker
T56 Conversion
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post #6 of 6 (permalink) Old 05-13-2019, 08:36 AM Thread Starter
 
 
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Quote:
Originally Posted by 68WASAGOODYEAR View Post
You might want to double check that the "return line" looking thing on that sender isn't actually a vent or a tube for a vent fitting. Having a return line dump fuel that close to the pick - up seems suspect to me, which is why I say this. It will aerate the fuel being sent and will cause stall /hesitation.

Installing a proper return line in your tank isn't a big deal either. The holley EFI master kit comes with everything you need. You just want to make sure to get any and all metal shavings that result from drilling the hole. 9/16" hole, debur, get the shavings out, install the fittings, done.


I thought the same thing and that is what lead me to their website. They label it as an inlet so I can only imagine it is a return.

I bought the master kit but have yet to open it and go through it. But if it has all that, I will jsut stick with the 105A.

Really wish Holley made the in tank oem sending unit like they have on some of the other cars.

1970 Impala Custom coupe
400ci SBC
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