Marvel Carburetor unresponsive

G6 at Snook, TX

Well-known Member
I have a Marvel Carburetor that runs the motor well in that there are no pings or irregular misses. However, when you go to accelerate or decelerate it does not react initially and is sloppy when it finally revs the motor.

Some of you know these carbs real well, is there a dedicated chamber or passageway that assists in acceleration, but it doesn't have much to do with maintaining a stable rpm? I have cleaned it, but evidently I haven't gotten the bur or spec of dirt out.
 
Do some investigation on your governor and linkage. could be a carb problem but your gov and linkage needs to work right.
 
N series Ford tractor carburetors do not have accelerator pumps.

It is common for engines equipped with such carburetors to stumble upon acceleration, especially when not fully up to operating temperature or with lean mixture.

This is one of the advantages of the Holly carburetor used on Ford gasoline tractors post 64.

Dean
 
In the initial post I was typing quickly, but the fuller story is that the motor is running with a second, aftermarket, gold colored carburetor right now and it accelerates/decelerates smoothly. It has that irregular miss and pop in it that the real Marvel doesn't. In the scheme of things, I can live with the aftermarket miss and pop because at +- 1700 rpm it runs smooth, but down around 800-1000 not so much.

Simply, I would like to eat my cake and have it too. An original Marvel that does what it should.

For the chem dip, does the outdoor temperature matter? I have heard that it needs to be a warm day for the chem dip to actually do its job.
 
(quoted from post at 04:38:24 01/28/19) I have a Marvel Carburetor that runs the motor well in that there are no pings or irregular misses. However, when you go to accelerate or decelerate it does not react initially and is sloppy when it finally revs the motor.

Some of you know these carbs real well, is there a dedicated chamber or passageway that assists in acceleration, but it doesn't have much to do with maintaining a stable rpm? I have cleaned it, but evidently I haven't gotten the bur or spec of dirt out.

The MS carb uses an "Economizer System" to supply enrichment for good engine response upon throttle opening. The passages are in the upper part of the carb (the part that bolts to the manifold). It uses one jet - the economizer jet.

I currently have a import replacement carb on my 8N and it stumbles/stalls as the throttle is opened. The problem is worse with a cold engine and in cold weather operation. It tends to go away in hot weather with a hot engine.

When the weather warms up it will my science project to trouble shoot this system and determine the effect of jet size. For now I don't have any pointers as to what to look for.
 
Why on earth does it turn my photos upside down? Anyhow, here are the photos of the M/S.
mvphoto30635.jpg


mvphoto30636.jpg


mvphoto30637.jpg


mvphoto30638.jpg
 
(quoted from post at 19:40:58 01/28/19) Why on earth does it turn my photos upside down?

Because modern digital cameras embed an orientation tag in the data file which allows image software to correctly interpret the image pixel array. The camera always records the pixel data in the same order regardless of the camera orientation and the orientation tag is used by image processing software to reorder the pixels so the display matches the camera orientation. Many browsers ignore or do not understand how to correctly process the orientation tag. The result is pictures taken with the camera rotated out of traditional portrait orientation are displayed incorrectly.

TOH
 
G6, is that one of the carbs I rebuilt for you in 2015?
Kind of looks like my work. If so, it didn't stumble when it left here.
Where do you have the adjustments set at?
One common cause of that stumble on acceleration is a lean
main needle setting. Turn it out a quarter turn and try it again.
 

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