All Small Six POLL: Blown up or exhaust leak

[marquis83]

Well the car started making a new noise while driving home last night.

It felt sluggish accelerating. Not sure what happened yet.

 

[DON]

A piece of tubing in your ear and move the other end around header junctions and you will hear it with out a doubt

 

[Frank]

Yeah. Does it have air injection into the exhaust ports? Check that tubing. Loose sparkplug. manifold to head gasket.

 

[marquis83]

Air is puffing out near the front spark plug.

 

[marquis83]

Uh oh...

 

[marquis83]

Ok I put a spare plug in the car and it seems fine now.

I guess that thing on the old plug was an anti fouler that was stuck in the head.

 

[Frank]

Verify all plugs are tight. glad this solved it!!

 

[DON]

Nice when it is something simple

 

[DannyG]

The last time I saw one of those anti fouler adapters was when I was driving a '72 Vega. Boy could that car burn oil...

 

[rocklord]

Ok I put a spare plug in the car and it seems fine now.

I guess that thing on the old plug was an anti fouler that was stuck in the head.

Keep an eye on that cylinder, it may be burning oil. May need new valve seals.

 

[marquis83]

Seems like the random backfires have gotten louder with the latest updates to the car.

 

[DON]

Well, at least you won’t fall asleep at the wheel
Backfiring is sometimes a lean situation ( on deceleration) or maybe a spark jumping to another post in the distributor cap or maybe along a plug wire. Might be tune up time

 

[marquis83]

It happens if i'm driving and I abruptly let off the gas. The car also only has 1ft of exhaust

 

[DON]

oh!!! You want it to sound like that.

 

[marquis83]

Well, life happens. I didn't think the current engine would last this long with the beatings I've been giving it

 

[Frank]

It happens if i'm driving and I abruptly let off the gas. The car also only has 1ft of exhaust

OK! this is 100% the cause of backfiring. It is completely normal and every carbureted engine ever made will do that with a 1' exhaust pipe. Here's the deal: when the throttle is closed quickly from a load the engine goes way rich for 1-2 seconds. Too rich for much of it to burn in the cylinder. With a short open exhaust, when the very hot rich gases hit the open atmosphere, they ignite. The flame travels rapidly back up the exhaust pipe and manifold, making an explosion of pressure shoot out the pipe. No tune up or anything else will eliminate the deceleration exhaust backfire -except a longer pipe. Ever watch NASCAR? If so, you've seen this often. The throttle is snapped shut entering the corner, and half second later a blast of fire shoots out of the short, hot exhaust. That's the over-rich mixture reigniting when it hits open air.