Backfiring under decelleration

[Anonymous]

My 200 backfires under decelleration. Any time I take my foot out of it and coast, I get a series of small backfires. More of a *put* than a *bang.* Is this the nature of the beast, or should I be concerned?

On a brighter note- I think she may be ready to actually start driving semi-regularly. Still rough on a whole lot of edges, but the clutch is going okay now, and the fuel-system treatment and fresh gas seem to have helped a lot of the other major issues.

--mikey

 

[Hot 6t Falcon]

The pup, pup, you hear is OK.

It is normal on carburetored engines. The carb is still delivering fuel as the engine is slowing down, so the raw gas is ignited in the exhaust manifold instead of in the cylinder as it would under acceleration or cruise.

It also means that on de-acceleration your engine is a little rich - but don't worry about it until you have the other kinks worked out.

Good Luck

 

[xctasy]

It's a normal sound with log head Falcons. Quite cool, I think. Any time you improve the exhast by reducing backpresure or by shoving tubing headers on it, they noise drops. When cross-flows came out down here, I remember they sounded rougher, but didn't mak the burble on over run.


(I used to get taken to kindergartern in a 67 Falcon Station wagon when I was 4. Dad used a 73 XB Falcon for work, same engine, same burble. Come the cross-flow, the burble was gone, but it never sounded as smooth as the older log heads.)

 

[Asa]

you might try replacing the PCV valve
mine was bad, and it would backfire real bad, basically it wasn't a valve, and it was just a tube running to the valve cover
i replaced it and most of it went away

 

[Anonymous]

Just to clear up some terms. I assume you are referring to a popping noise through the exhaust. That would be an after-fire where unburned fuel is ignited in the exhaust. Back-fires occur back through the carb. If you have carb back-fires, it is something to be concerned about. They are typically caused by improper ignition timing, bad valves or lean conditions.

 

[Anonymous]

Yes- it's a popping noise through the exhaust. Sounds like it'll be fine.

Stumbles a bit under acceleration, but that's okay. It's way better than it was, and it can manage legal highway speeds without miracles.

Hoping that finances perk soon, and I can get the Oz head on and buy some headers from AzCoupe. Then we'll be cooking with fuego.


--mikey