TO-20 Ferguson engine miss

[ttocs]

I recently replaced the carburetor on my TO-20 Ferguson and it ran so good. I then thought I would replace my manifold because it was cracked and loud. Now when I start it up it has a pop pop pop through the carburetor and as I increase the RPM's it gets louder and louder.
I also replaced spark plugs.
Any suggestions on what the problem may be?

 

[6 SLY PLACE]

I would check the firing order on the spark, plug wires

 

[Ericp351]

Bingo Above!!! Fire Order!!! Also, only if intermittent- wire routing.

 

[olddavid]

(quoted from post at 14:49:57 11/26/23) I recently replaced the carburetor on my TO-20 Ferguson and it ran so good. I then thought I would replace my manifold because it was cracked and loud. Now when I start it up it has a pop pop pop through the carburetor and as I increase the RPM's it gets louder and louder.
I also replaced spark plugs.
Any suggestions on what the problem may be?

Since the problem started when you replaced the manifold I would look there. I believe the exhaust manifold and intake manifold are cast as one piece, correct? Perhaps the intake portion of the new manifold isn't sealed. The gasket may have slipped or perhaps the surfaces (manifold and/or head) aren't flat enough to seal.

 

[Mad Farmer]

(quoted from post at 08:32:28 11/27/23)

(quoted from post at 14:49:57 11/26/23) I recently replaced the carburetor on my TO-20 Ferguson and it ran so good. I then thought I would replace my manifold because it was cracked and loud. Now when I start it up it has a pop pop pop through the carburetor and as I increase the RPM's it gets louder and louder.
I also replaced spark plugs.
Any suggestions on what the problem may be?

Since the problem started when you replaced the manifold I would look there. I believe the exhaust manifold and intake manifold are cast as one piece, correct? Perhaps the intake portion of the new manifold isn't sealed. The gasket may have slipped or perhaps the surfaces (manifold and/or head) aren't flat enough to seal.

There is also a threaded hole for a vacuum gauge. Pretty obvious but that needs a plug.

 

[Steve@Advance]

Check the firing order one more time just to be sure.

Check for vacuum leaks. The gasket may be out of place.

Popping back through the intake that gets worse under load is an indication of an exhaust valve not
opening.

It could be a flat cam, bent or dislocated pushrod, or adjuster screw backed off. A visual inspection of
the valve train in motion will tell the story. All valves should open the same amount . Check the
pushrods, look for broken springs, check the lash adjustment.

An occasional backfire when accelerating is a sign of too lean. Try backing out the main jet slightly
until it will take sudden throttle without hesitation.

Also check the points gap and the distributor shaft for side play. If it is worn the points will not stay
set.