C85 Conversion Complete!

[PA1195]

Thanks Scott for absolute facts and challenging a 45 year personal and extended to others experience with the above theory. Without sarcasm intended respectfully I can now inform that Marvel carbs are not better in cold temps or otherwise. In Alaska Strombergs are replaced when able and where -25C is still warm. But seriously if you like them run them but I assume you're well insured. Few still do in colder climates and that includes millions of road vehicle owners without patience when needing response. This is one reason why Taylorcrafts as equipped are selling for less than value compared with others.

Come on up someday and we'll go ski flying in the cold. I'm open to actual new experience.

Gary

[Scott]

I understand the assumption that the absence of an accelerator pump equals no enrichment as the throttle is advanced, but this is an assumption not a fact.

Fuel injection systems have no throttle pumps but the mixture is enriched when you advance the throttle. This is achieved by sensing air pressure/mass at different points in the induction system.

Believe it or not the Stromberg does the same thing. It uses ventury pressure verses ambient pressure to increase/decrease fuel from the main jet. At the point of throttle advancement the mixture is richer and as ventury pressure changes mixture gets leaner. Ventury pressure is also used to reduce the head pressure in the float chamber which causes a leaner mixture. The mixture control varies the amount of ventury pressure applied to the float chamber.

All this to say that if the stromberg is the correct part number for the application, and it is properly set up and maintained, there are no issues.

I flew my aircraft on skis at temps down to -25C (with a metal prop) and never had a dull moment! At that time the mixture control was wired full rich. Since I rebuilt it I use the mixture control just about every flight and other than the fact that a little extra patience is needed, it works just like any other mixture control (except no idle cut off).

As I've learned more about the Stromberg, I've become more impressed with it's uncomplicated yet sophisticated design. Somebody did their homework 75 years ago!

Stromberg.jpg

[PA1195]

At this stage of the discussion cold weather ops typically gets injected...it's a yes, but what about in this situation argument. Under certain regimes transition from low to higher power is aided by an accelerator pump device in the carb. A few million road and other vehicles that require something beyond what a stationary power plant or farm implement needs for example. I also suspect a heavy prop - metal vs the traditional wood - adds resistance to and can slow engine spin-up.

No doubt Strombergs work but there are some local old timers I've talked with that flew them pre and post WWII that developed survival techniques prior to the Marvel's pump. I don't recall any that missed the Stromberg if the situation called for a quick power recovery. I know two that were left with damaged planes that refused to fly in the cold when needed. Warm ops...well not so risky I was told.

I had a Stromberg on both my Taylorcraft 85's. Truly both were the Prince of Cold Weather Silence until I installed a Marvel, but that may have been just my lack of technique.

Gary

[N96337]

Amen, Scott! I'm not saying the Marvel wouldn't be great!! I'm just saying that my money would be much better spent on gas in my opinion, and use what is working fine and has for many years!
John

[Scott]

I don't know... it's only worked for 73 years.... I think I'll take my chances. Last time I went through it, I put in a new needle and seat.... wasn't very expensive.
John

exactly, the Stromberg is a simple reliable carb, and because of that I think they end up in service without much attention for a long time. Eventually the throttle shaft wears to the point where odd things start to happen that get blamed on the absence of a throttle pump or the "innovative" mixture control (plus perhaps a little fear of the unknown).

I salvaged mine by machining .005" off the throttle shaft and machining undersized bushings to suit. It already had the steel float valve so all I had to buy was a gasket kit and new screws. (I can't imagine paying, or charging, $900 for this work)

Works fine, including the mixture control.

[3Dreaming]

Are you ready for toe brakes yet?

Why? I have over 7500 hours flying time, and around 1300 in airplanes with heel brakes. Personally I see no reason to switch, they work just fine.

[astjp2]

For what it's worth, core value for the Stromberg is about $300 when exchanging for a marvel. I was lucky to have a buddy with a marvel core laying around.

Are you ready for toe brakes yet?

[N96337]

I don't know... it's only worked for 73 years.... I think I'll take my chances. Last time I went through it, I put in a new needle and seat.... wasn't very expensive.
John

[Kerbs]

For what it's worth, core value for the Stromberg is about $300 when exchanging for a marvel. I was lucky to have a buddy with a marvel core laying around.

[Kerbs]

That is the same model I installed. I was unable to reuse the stomberg as it was the B model only certified for the A65. Regardless, I was due for an overhaul and it made sense to go with the Marvel. Having the accelerator pump and throttle response is awesome.

[astjp2]

Holy buckets, for that money my Stromberg works just fine!!!
John

You say that up until your engine conks out on short final when you push the throttle in trying to do a go around and all of a sudden you are committed no matter what you want to do...and a Stromberg will cost you about 950 to overhaul your carb from a certified shop.

[N96337]

Holy buckets, for that money my Stromberg works just fine!!!
John

[Jim Herpst]

Thank you

[astjp2]

https://msacarbs.com/product/ma-3spa-carburetor-10-4240-1/

[Jim Herpst]

What is the number of the Marvel/Tempest carb approved for the 85?