Is this a fuel or timing issue

[Oliverguy-NE Ohio]

See attached video.

I'm talking about the banging. It's harder to hear in the video but it's a loud bang and it's backfiring through the air intake on the carb. The carburetor is pretty dialed and it was doing this for a while now. At first I thought it was fuel so I cleaned the carb really good but it didn't work. Is it still fuel? Or is it timing. The exhaust manifold is only a couple years old and there's no holes in it so I don't think it's that. Thanks

 

[CraigWis]

Take carburetor cleaner and spray along the Manifold to check for a Leak
If that is a plug in the Manifold Above the Carburetor. Take it out and Make up a Vaccum port that you can attach a Vaccum Gauge to
A Good Engine show show around 16-22 Lbs. at idle with very little movement. A sticking Valve or Engine Miss Fire will make the Vaccum jump by 2-3 Lbs at Idle
Did you do a Compression Test on the Engine?

 

[old]

See attached video.

I'm talking about the banging. It's harder to hear in the video but it's a loud bang and it's backfiring through the air intake on the carb. The carburetor is pretty dialed and it was doing this for a while now. At first I thought it was fuel so I cleaned the carb really good but it didn't work. Is it still fuel? Or is it timing. The exhaust manifold is only a couple years old and there's no holes in it so I don't think it's that. Thanks

A back fire can be caused by either running to lean or the timing being to advanced. If choking helps it is a carb problem if it doesn't timing

 

[Oliverguy-NE Ohio]

Take carburetor cleaner and spray along the Manifold to check for a Leak
If that is a plug in the Manifold Above the Carburetor. Take it out and Make up a Vaccum port that you can attach a Vaccum Gauge to
A Good Engine show show around 16-22 Lbs. at idle with very little movement. A sticking Valve or Engine Miss Fire will make the Vaccum jump by 2-3 Lbs at Idle
Did you do a Compression Test on the Engine?

No...was completely overhauled about 2.5 years ago... doesn't mean it isn't low on compression but it's unlikely imo.

 

[old]

No...was completely overhauled about 2.5 years ago... doesn't mean it isn't low on compression but it's unlikely imo.

Rebuilt 2.5 years ago may mean it needs the valve adjusted

 

[jhwis]

See attached video.

I'm talking about the banging. It's harder to hear in the video but it's a loud bang and it's backfiring through the air intake on the carb. The carburetor is pretty dialed and it was doing this for a while now. At first I thought it was fuel so I cleaned the carb really good but it didn't work. Is it still fuel? Or is it timing. The exhaust manifold is only a couple years old and there's no holes in it so I don't think it's that. Thanks

Broken pushrod perhaps? Had that happen on my rebuilt TO-20.

 

[caterpillar guy]

If it has gotten hot it could have a warped valve or burned valve. If out of adjustment could also be a burned valve if it has been held slightly open from need of adjustment.

 

[Oliverguy-NE Ohio]

If it has gotten hot it could have a warped valve or burned valve. If out of adjustment could also be a burned valve if it has been held slightly open from need of adjustment

Im gonna take the valve cover off and check and adjust valves. It it still does the banging then I will pull the head off and check for a burnt valve.

 

[MSD]

Probably lean if it is banging. Does it run warm?

 

[Oliverguy-NE Ohio]

Probably lean if it is banging. Does it run warm?

No I have never had the gauge over work zone