Backfire through carb

[Purple Moo Cow]

Was trying to get my d24 to start, put some gas in the carb and cranked it over after a few seconds it backfired and got a big white blow of smoke out from the carburetor. If I continue to crank, it'll continue to turn over and then backfire every few seconds. I read that can signify a very lean mixture, not enough to properly ignite. 

 

Am I not getting enough fuel into the intake to start it? Or am I lacking sufficient spark? never seen a backfire through a carburetor before. 

Edited September 27, 2021 by Purple Moo Cow
Additional info added

[Sniper]

Might have a stuck valve

[kencombs]

9 minutes ago, Sniper said:

Might have a stuck valve

Or, timing issues.  A little more info would help.  Has the distributor been out?  Spark plug wires removed/installed.

[Purple Moo Cow]

2 hours ago, Sniper said:

Might have a stuck valve

...welllllll that'd suck. I assume I pull the valve cover to diagnose that? 

[keithb7]

Not necessarily. Quicker and easier in my opinion to performa a dry, then wet compression test.

[Purple Moo Cow]

2 hours ago, kencombs said:

Or, timing issues.  A little more info would help.  Has the distributor been out?  Spark plug wires removed/installed.

 

Distributor has been out. New plugs, wires, points, condensor, uh all new wires basically for the ignition circuit. New battery. Rebuilt starter and solenoid. New fuel pump (not necessarily working in engine...) rebuilt carb. Float level is correct, float works. No blockages in carb, New needles n such. 

 

I made sure to install the distributor as it was when it was pulled. But I guess it could very well be incorrectly timed previously. I guess I have to static time it? I know I have to get the front cylinder to the top but where do you then set the distributor to know it's firing at the one cylinder? 

[Purple Moo Cow]

1 minute ago, keithb7 said:

Not necessarily. Quicker and easier in my opinion to performa a dry, then wet compression test.

 

Never done that before, guess I'll need to buy more tools. 

[Ranger]

Yep! Sounds like timing. Distributor 180 off or plug wires mixed up. Easy enough to do even if you’re trying to keep everything in order.

[Purple Moo Cow]

Ya with more looking into the timing I think maybe the previous owner got it 180° out of wack or just threw off the timing significantly. Guess I'll find out next time I get to work on it 

[allbizz49]

Timing. As a rule of thumb, bacfires through the carb usually indicate timing. Through the pipes is usually carb issues.  Not always but most of the time. 

Edited September 28, 2021 by allbizz49

[47 dodge 1.5 ton]

For a motor that has sat over period of time, backfire can be any number of things. Bad fuel, vacuum leaks, carb plugged, ignition, timing, stuck valves, fouled plugs, would be the first to iron out. As said, I would pull plugs and get an idea of compression( don’t be disappointed if some are really light around 50psi or so) If good move forward with checking spark/timing while plugs are out. If both check good, move towards fuel & carb. If still good, start looking for vacuum leaks. If your car has a hand crank, take advantage of it, best tool IMO. You can feel a lot of what the engine is doing without force. You may need to get familiar with MM oil, Kroil, ATF or some special creative  blends. I would not advise ripping things apart until you know the issue.

Edited September 29, 2021 by 47 dodge 1.5 ton

[Purple Moo Cow]

So, did a 180 with the distributor n there's no more backfire through the carb but no starting either aha. Sprayed some starter fluid and it sputtered a bit, so I guess that's an improvement. I'll have to see about getting some gas into the carb bowl n see if anything will happen. 

[47 dodge 1.5 ton]

There is a plug in the head over #6 that you can use for timing. When I started, being cautious about wringing something off as my plug was very tight. I put my finger over #1 hole until a felt compression coming up, with the dist cap off, looked for a spark shortly after in the point and I observed where rotor was pointing, that established #1. That should get you close if dis had not been moved but will ensure you have fire @ #1. Again— I used a hand crank and had already checked compression readings with plugs out and then verified spark firing order to all six plugs.

Edited September 29, 2021 by 47 dodge 1.5 ton

[clarkede]

For what it's worth... I had the same problem backfiring just a couple months ago when getting my engine running after sitting for a long time (probably 5+ years).  To get it running again, I first installed a new fuel tank and lines, new brake lines and front disc brakes, and a new exhaust system. Then I had a new electronic ignition that I had always wanted to install in the distributor, which I did.  And finally it was time to get it started.  It would almost turn over and it would back fire.  I was able to get it running with starting fluid a few times, but it was really rough.  I thought that I had timing issues or possibly the carburetor that was causing it to backfire.  I then did a quick compression test and saw that cylinder 6 had no compression.  I pulled off the valve cover and took pictures with my phone of the valves.  Then I manually turned the engine over with the fan blade a little bit at a time, and I noticed one of the valves was left high-n-dry.  I managed to break it free with a screw driver and a hammer.  I figured I was going to have to pull the head or even worse take it to a machine shop anyway if I couldn't get it free. Pulling the valve cover and taking the pictures only took about 5 minutes to diagnose.  After getting the valve free and running it for a few minutes, it runs great now.  I am getting some smoke, so I'm wondering if the rings are a problem, but no backfire.  Hope this helps.

[Purple Moo Cow]

@clarkede do you need to replace the seal when you pull the cover? And this is probably a very dumb question but...you can't run the engine with the cover off right? You're saying you re-assembled it and then it started n ran?

[Young Ed]

You can run it without the side covers. That's how your supposed to adjust the valves- hot and while running

[Purple Moo Cow]

23 hours ago, Young Ed said:

You can run it without the side covers. That's how your supposed to adjust the valves- hot and while running

Appreciate it

[Los_Control]

On 9/27/2021 at 7:10 PM, Purple Moo Cow said:

I made sure to install the distributor as it was when it was pulled. But I guess it could very well be incorrectly timed previously. I guess I have to static time it? I know I have to get the front cylinder to the top but where do you then set the distributor to know it's firing at the one cylinder? 

That is kinda sorta the key. Easier to pull the pipe plug on #6 cyl, get it on top dead center with compression stroke, see rotor is pointed at #6 wire on distributor cap.

 

Really easy to read the manual on these engines then assume all before you did the same. Some like me do not read much ... oil pump installed wrong will cause this issue.

Get #6 or #1 on TDC, then install your wires to match.  See if it starts then.