Technical Strangest backfire issue

If you're running a mechanical fuel pump, remember that if the pump diaphragm fails and leaks it will pump some amount of fuel into the crankcase. Are you seeing an excessive amount of oil when you drain the pan? (Maybe draining 6 quarts when you only put 5 quarts in for your last oil change?) You might pull the fuel pump and tip it to see if you have any fuel coming out around the pump mounting flange area. A failing pump can also make a clicking or tapping sound similar to a noisy lifter.

I don't think I've seen it mentioned whether you have an intake or an exhaust backfire. If your carb has a choke are you sure it's staying wide open once the engine warms up a bit? The Air-Gap intake isn't doing much at idle and low RPMs to help keep the air/fuel mixture atomized since it has no exhaust crossover ports to heat the floor of the manifold.

 

I was wondering if aluminum heads were being used, never used it on iron heads.

 

Electric fuel pump. Off-brand clone of the Holley blue pump. I have a pressure regulator with a gauge, and its reading a bit lower than I would like, at 5psi.

About the antiseize issue, I would like to say I was drunk, or someone else did it, but I didn't drink back then! It was all me! I have stock iron heads, I just like to put a bit of antiseize on parts that get hot that I know I'll be removing later. I never used that much on any other engine lol

I'll be taking a look at the carb tonight, it's a "new" carb for this engine. I'll be checking the curb idle screws first, then I'll check for a dry rotted booster, or maybe the main jets are running a number way above a reasonable size...

By the way, isn't there some kind of second break-in procedure after the initial break-in, where you are parked, and set the engine to 2k rpm+ for a few hours? I may have more issues to correct before I hit the road.

With my idiot mistakes, I need to get AAA lol.

By the way, thanks for all the replies everyone, glad to see the HAMB is still alive and didn't get absorbed into some Facebook group. I never gravitated into social media, and found Facebook to have a garbage level UI that drives me insane.

 

Well, I changed the oil, and I checked the carburetor, there were a few issues. Bear with me when I describe things, as I never get to talk to fellow car guys.

Anyways, I set the curb idle screws back to factory default: 1 & 1/2 turns both sides. It appears it was set to 1 & 3/4 turns.

The accelerator pump was adjusted too tight, and was partially compressed even when the throttle was completely closed.

She fired right up, and even idled perfect instantly. Went down my long and steep driveway to test the brakes and back up!

I have AAA now, will be doing an actual longer road test soon!

Thanks everyone, I think I mostly just needed a push and some advice to keep going at it.

 

Engine break-in, start the engine run at 1800 - 2000 rpm for 15 minutes, bump rpm up 500 rpm for 3-5 minutes. Slow it down and make adjustments not letting it idle more than needed to make adjustments. Don't run at idle for extended amount of time if restarted. Once in the car, it needs driven hard enough to load the rings. Run the rpm up in third or fourth gear to 3500 to 4000 rpm, let off and let the weight of the car slow the engine down to 2500 or so. Do this five or six times, then drive normal old man style for 10 or 15 miles. After that, go to town. Change oil after the ring break-in. Use the proper oil for the cam type installed, as to not turn this into an oil battle, you can google motor and read up on it. Oils changed formulas back in '07 and a couple times since, its not the same as it was.