Engine running! HG replaced. What do you think?

jwilliams81

jwilliams81

Senior Member
I have had my Town Sedan for a month or so. Quickly found water in the oil and proceeded to change the head gasket with the help and advice from this site. I just took a video of it. Let me know if this sounds about right.
I think I have it tuned well... but not sure if the idle is set to high.

Thanks.

https://goo.gl/photos/zQ9aLxsF71AzUHJZA
 
That is a blower motor. The previous owner had that welded on and the electric motor bolts on. Eventually I will try and see if it works, the wires have been cut so I will have to wire it up.

I have really been concentrating on getting the engine reliable.

What would cause a backfire if I give it a good couple gooses of the throttle? The GAV is basically closed.
 
jwilliams81 said:
Thanks Art! That is great to have something to compare it to. Is the car supposed to vibrate with the engine some at idle? Kind of like a motorcycle?
Click to expand...

Yea, mine vibrates a bit at idle, and even more here and there.:D

If the GAV is closed, the engine will starve for fuel when you crack the throttle open. Open it 1/8 to 1/4 turn, it shouldn't effect the idle much.
 
Art Newland said:
Yea, mine vibrates a bit at idle, and even more here and there.:D

If the GAV is closed, the engine will starve for fuel when you crack the throttle open. Open it 1/8 to 1/4 turn, it shouldn't effect the idle much.
Click to expand...

Ok, so opening the GAV a little will keep it from backfiring then?

It sounds like it is backfiring from the carburetor intake, not at the tail pipe.
Is that the GAV closed problem?
 
The GAV adjusts the fuel flow for everything except idle. I think 1/4 turn is pretty average, some need more, some less. You can play with it a bit while driving, too lean and it will backfire. When cold, I start the engine with 3/4 turn open, once it settles down a bit I (15 seconds or so) I close it to half, after driving a few minutes I close it to 1/4.
 
Obviously there are other things that can cause a backfire, but the GAV, if working propery needs to be open some for normal running.
 
My personal definition of backfire needs to be clarified. I call a backfire as just s you have said, back through the carb intake. This is caused by lean mixture. I call the bang through the exhaust as an afterfire. Caused by rich mixture. It is confusing to some to call the big bang a backfire as it occurs after contact with hot exhaust manifold or pipe. If I am wrong, I am teachable. Your situation appears to be too lean.
 
sphanna said:
My personal definition of backfire needs to be clarified. I call a backfire as just s you have said, back through the carb intake. This is caused by lean mixture. I call the bang through the exhaust as an afterfire. Caused by rich mixture. It is confusing to some to call the big bang a backfire as it occurs after contact with hot exhaust manifold or pipe. If I am wrong, I am teachable. Your situation appears to be too lean.
Click to expand...

Thanks for the clarification! I am new to this as well, so I wasn't sure if the "backfire" I was trying to explain was really called that. I was going to try and take a video demonstrating the condition I am trying to get advice on. But it does seem to be coming from the muffler/manifold clamp, carb intake area.

But it does sound like I might have it set to lean.
 
Play with the GAV setting. I did not believe how much it affected the running until I had my engine sorted out. Once everything else was correct, the GAV significantly affected running. I believe comments such as "run quarter open" etc. need to be tempered with the actualities of your particular engine, carb, etc.

A quarter open on mine results in backfiring on light throttle at speed, but one third open results in a nice smooth run.
 
I just found this post by Steve-S from a couple of years ago. This makes sense to me and I may have given some wrong information in my post 15 above. I just want to remain teachable and not lead anyone down the wrong path. Here is what he wrote about backfire :

"The paradox of backfiring is that accumulation/explosion of too-much unburned gas in the exhaust system is due to too-little gas getting into the combustion chamber. The air/fuel mixture is then too lean to ignite and gets swept on out in the exhaust, where it can accumulate and light-off every once in a while. Although the most obvious culprits would be too-low float or plugged carb jets, most of the time it's due to electrical problems, like closing-up points failing to provide enough spark."

"Steve"
 
If I turn the fuel /air mixture screw on the carb clockwise to close it, should the engine die or keep running?
When I seat that screw the engine still runs.
 
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