Stromberg...Marvel Schebler...A-65/75/80? FACTS Please!

[Tcart95268]

I am hoping that out there another tcrafter may be willing to direct me where look to find the the list of correct sizes of venturi, main and bleed jets (and anything else required for a Stromberg carb) to upgrade an A&C-65 to an A-75? I'm guessing I will need to get a Continental service manual/overhaul manual. I've also heard I can make an A-80 out of my A-65. Is this true?

How about the Marvel Schebler carburetor.
Where do I find what carb, model#, venturi, and jet sizes are approved to make an A-65 an A-75, or 80 with this carb? Or are they the same as a Stromberg? Are the parts interchangeable? I understand that there is a myriad of approved parts in some cases and not in others? Where do I get the list of approved parts/part#'s.

I thought an MA3 #4113 was ok, but heard another fella mention a different model, I believe. Whats the difference between MA# A, P, PA, & SPA?

Id really like to know where I can back this up in writing for my IA's approval; I'd like to not have to hire him to go on a paperwork goosechase...and he is happy when I do the legwork. He is particular about having the proper, APPROVED, part numbers and such on certified airplanes.

I'd appreciate an education in this particular area from someone who is familiar.

[Garry Crookham]

Re: Stromberg...Marvel Schebler...A-65/75/80? FACTS Please!

I’ll answer some of your questions, but my advice, after reading your post is to pay your IA to do the research since you seem to be unfamiliar with the basics.

Obtain a copy of the following manuals: Maintenance and overhaul manual for A-65 A-75, Stromberg Carb Manual, Marvel Carb Manual. All of these manuals frequently appear on Ebay.

Per Continental Service Bulletin M47-16: Model conversions which are not approved:
(c) Conversion of model A65, or A75 to model A80.
If you are considering installing an A-80 in a Taylorcraft, you better make sure an approval can be obtained. I am not aware of an STC to install an A-80 in a Taylorcraft. Someone might have obtained a field approval in the past to do so, but field approvals are not easy to accomplish today.

The A-65 and A-75 use the same Stromberg carb. Stromberg float carburetor specification sheet A-18033B-4 gives all the data for venturi sizes, jets, etc.

Stromberg and Marvel parts are not interchangeable.

Be happy your IA is “particular.”


Garry Crookham
N5112M
Tulsa, Ok
CFI A&P/IA

[Tcart95268]

Re: Stromberg...Marvel Schebler...A-65/75/80? FACTS Please!

Im assuming the Maintenance manual for an A-65 A-75 would tell whether or not the Marvel is also approved for the A-65 A-75...or exacly which Marvel models are approved, if any?
Another wild guess, the A-65 A-75 overhaul manual will specify whats necessary to convert my 65 to a 75?

See...I'm learning already!

Thanks for the reply!

[Mark Julicher]

Re: Stromberg...Marvel Schebler...A-65/75/80? FACTS Please!

The overhaul manual will indeed show you the differences in the engines. Get a manual from Fresno Airparts (page 3 of any Trade-a-Plane).

The upgrade to 75hp is fairly simple; however, you will need to spend $$ to get a new propeller which allows the engine to spin faster = more HP.

Getting the installation approved and legal is problematic because the A-75 isn't in the TCDS and 337s are much more difficult these days.

[Garry Crookham]

Re: Stromberg...Marvel Schebler...A-65/75/80? FACTS Please!

As Mark stated, going to an A-75 is a simple upgrade: pistons, exhaust valves, drilled rod caps (most A-65's have been drilled). Depending on what p/n piston your A-65 has installed, the connecting rods might need to be rebushed to use the piston pin needed for the A-75 piston. The A-65 and A-75 use the same Stromberg carb (actually the A-50 through the A-80 all use the same Stromberg carb) and the same Marvel carb. I believe there are two Marvel MA3PA carbs approved, the 10-2948 and 10-4233, but this is from memory since my books are at the airport.

You can look at the type certificate data sheets for the engine and the airframe at www.FAA.gov. This will give you a lot of the legal and approved info you will need, such as what engines are approved for a Taylorcraft.

Get everything pre-approved before doing any work, I can't stress that enough.

Garry Crookham
N5112M
Tulsa

[tim]

Re: Stromberg...Marvel Schebler...A-65/75/80? FACTS Please!

just wondering why not just use a c-85-8??

[taylorcraftbc65]

Re: Stromberg...Marvel Schebler...A-65/75/80? FACTS Please!

Right on, Gary, I have an A-65 taken to an A-75 in Manu Sina, it's in the logbook, and at NO annual have I EVER had a problem with the paperwork.
Brie

As Mark stated, going to an A-75 is a simple upgrade: pistons, exhaust valves, drilled rod caps (most A-65's have been drilled). Depending on what p/n piston your A-65 has installed, the connecting rods might need to be rebushed to use the piston pin needed for the A-75 piston. The A-65 and A-75 use the same Stromberg carb (actually the A-50 through the A-80 all use the same Stromberg carb) and the same Marvel carb. I believe there are two Marvel MA3PA carbs approved, the 10-2948 and 10-4233, but this is from memory since my books are at the airport.

You can look at the type certificate data sheets for the engine and the airframe at www.FAA.gov. This will give you a lot of the legal and approved info you will need, such as what engines are approved for a Taylorcraft.

Get everything pre-approved before doing any work, I can't stress that enough.

Garry Crookham
N5112M
Tulsa

[Larry Lyons]

Re: Stromberg...Marvel Schebler...A-65/75/80? FACTS Please!

Just to float this here, but one of the tribe has a C-65-8 for sale. If interested ask here if he does not respond shortly I will for him. Larry

[Tcart95268]

Re: Stromberg...Marvel Schebler...A-65/75/80? FACTS Please!

Thanks for all the replies, you guys are all kinds of help. Just what I needed!

I would love to get an 85 and then the STC for 100HP upgrade, but our 65 is the original engine. My grandpa bought this airplane in alliance in '47, so this particular 65 has some sentimental value I suppose one could say.

Thanks again for a little direction!