Backfiring out carb and wont run right
It might...
Do you have access to a known-good carb you could try for testing purposes?
Unfortunately no. I thought about that so we can eliminate something.
I am going to say timing. Backfiring on a fresh engine is usually timing. What type of rocker arms, adjustable or stock nonadjustable?
Stock non-adjustable.
Fuel pressure? pump shot? edelbrock carbs are finicky with fuel pressure.
Changed the fuel pump and the problem persists.
he does state "fresh rebuild" so I threw that out the window assuming they know what they are doing. but I could be wrong. I have the same exact carb that would backfire and spit when I would first fire the engine, it would also hiss and try to spit when I opened the secondaries. I put another smaller carb on without touching anything else, it never once backfired and ran tits. I jetted the 750 down, and it is running excellent, I still have not touched anything other than the carb.
without knowing where his timing is set , its all speculation
Ok time to come clean. I have a basic working knowledge of the mechanicals of a motor but this is by far the most I have done, meaning my first rebuild. My neighbor, who has a lot of experience, has helped me along the whole way. He has been an on and off mechanic as a job for 30+ years so I tend to trust where he has guided me.
We went out there this morning and talked about what it could be. I mentioned the timing chain being off by a tooth and he said know being he is the one who put it on. I mentioned the vacuum leak and he explained to me that we eliminated that by when he covered the carb with it running, it died down rather than rev up. I don't know if that is how it works because I am still learning. :sign3:
We have been constantly adjusting the timing because the car keeps changing the way it runs.
We did discover, if you slowly move the throttle, no fuel comes out for the first 1/8th of travel or so. If you move it quickly you get fuel. I am guessing that could be the float level or accel pump?
The plan: By next weekend, we are going to change the condenser and points to eliminate that. We are going to check the voltage at the coil to make sure it is getting what it needs. Attach a fuel pressure gauge to make sure we are getting the fuel we need. If that doesn't solve it, then I will contact national carbs and ask them if they want me to dive into the carb or if they will send a new one.
The video, I had a lot of trouble getting the motor to fire. I had to advance the timing a little to get it to start. Before this vid, on one start, I had a 3 foot flame shoot out the carb. Scary. I have to do what I did in this vid a few times until it warms up, then it will idle, once I out it into gear, and give some throttle, it dies down unless I give quick short bursts of throttle. Hopefully my explanations are clear and the video helps. Sorry for the lengthy post. :oops:
[ame="https://www.youtube.com/watch?v=Rrcd-MB0cd4"]360 run probs - YouTube[/ame]
