Just got done rebuilding a 351c for friend in his 73 mustang. He tried to take it out on the road and give it some gas then the thing backfires. He comes to a stop and it starts to die. What is wrong here? My thought was the timing naturally, but im not sure if there could be anything else wrong with it. As far as I know the motor is a stock rebuild.

 

What's the timing at? What carb? Was the carb rebuilt?

 

check timing, make sure its about 14adv, check your plugs to make sure they are the correct size (size does matter). check the valves to make sure they are all tight and make sure your compression is OK. then come back and let us know. make sure carb is tuned properly ok. once you do all these, then you can start to eliminate things...

 

Mine did this just about a week ago. I had retarded the timing too much and it was backfiring through the carb. When I advanced the timing to 10* the problem went away. It's now at 8* and still pinging but it doesn't backfire anymore. Also mine would hesitate just before it backfired, don't know if yours is doing that.

 

Ya have to agree with timing.....however i just grabbed my book and looked up timing for 351 (isnt it sad i have a mustang book next to me at all times?). it says 16B. might wanna try both. probably depends on the setup

 

Cool thanks. My friend said that the timing was around 12 or so to start with, but I haven't heard back from him yet on how well its running now. I asked about the carb and he said that its a brand new 650 thunder series and that every part on that engine is new. So IMO it would have to be the timing.