Carburettor - Stromberg NA-S3A1 and NA-S3B for a Cont. A-80

[IanLaw]

I have a Continental A-80 that came with an obsolete "High" fuel injection system that can't be overhauled.

From what I've found on the web, the correct Stromberg for the A-80 with a gravity feed is the NA-S3A1. I think the "Parts List" number is A-18033B. As far as I can tell from that list, the sizes for the components and various jets are the same as for the A-65, right through to the A-80. Fuel pressure on that list is shown as 1/2 lb, which would tie in with the gravity feed in my W11 Boredom Fighter project.

I have an NA-S3B carburettor, dismantled and awaiting rebuilding. It seems identical to the NA-S3A1 except for:

Main air bleed arm assy.
Throttle shaft assy.
Throttle lever.
Throttle valve and one or two other small parts.

I'm waiting for the arrival of another NA-S3B I've bought for some parts. The rest will come from A/Spruce or maybe Fresno, I guess - if they have them. Unable to find any manuals on the web relating to the -S3B and would be interested to know exactly why and how the -S3A1 and the -S3B differ. I understand the -S3B was used with the A-65 and with larger venturis and different jets, with the C-75/85/90. I have downloaded various items from the web, dealing mostly with the -S3A1.

My particular NA-S3B came with a mixture control and I know that is another difference (No mixture control on the -S3B normally), but I have seen that this was available as an option on my carb and I think it is original. It will stay wire locked in "Rich"; I'm not likely to fly high enough to need it.

Can anyone confirm my findings and advise me why I should not be able to use my NA-S3B, after overhaul, replacement of the fuel float seat and needle valve set, along with ensuring all the jets etc. meet the requirements in the Parts List ( if I can find them)?

Thanks!

Ian

[champ driver]

Try contacting Robert Kachergius at Uni-Tech, he rebuilds these carbs and should be an expert.

http://thestrombergspecialist.com/index.php/86-news

[IanLaw]

Thanks Champ Driver and I'll try that.

Ian