[654door]

I'm getting some backfiring out my tailpipes when I let off the gas. I have a 65 with a 194, 3spd manual and split manifold. It started doing this shortly after I replaced the carb(1bbl Rochester). I've also got a surging problem at cruise(about35-40 mph), Is this because of the carb? It is a rebuilt unit from Kanter in NJ. The choke on my other one quit working, so I changed it out. Any help is appreciated.

 

[danthegeek]

I would check the timing first to verify that isnt the problem. It usually is, but if it checks out ok, it could be the carb. The surge when cruising sounds like it may be running lean at a cruise. The backfiring out of the exhaust sounds like it is rich under load, then burning off the excess fuel in the exhaust as you decelerate. I would also pull a few plugs and take a good look at them. They can tell you a lot more then i can.

-Dan

 

[Foxbat33]

Backfiring from the exhaust could be caused by several things most likely spark or timing. Start with the simple stuff. Make sure uor distributor is in good working order, ie. points, no loose screws, wires in good shape,advance working, etc. Double check your timing is set correctly. Then check to make sure your getting spark from each plug - might just be a bad connection or wire.
For the hesitation, check out

http://www.thecarbureatorshop.com Do a search for "bog" or "surging". Everything you want to know about carbs. Plus, do a search here at Steve's and you'll be surprised at all of the info you can get!

 

[654door]

Thanks everyone for your replies. I forgot to mention that I have an Ignitor kit in my distributor, as I got rid of the points etc. I will check the plugs etc first though, as I like to do things the easy way first.

 

[JRouche]

The backfiring out of the exhaust sounds like it is rich under load, then burning off the excess fuel in the exhaust as you decelerate. I would also pull a few plugs and take a good look at them. They can tell you a lot more then i can.

-Dan

And thats what I thought. My EFI engine was backfiring on throttle lift. I was too lean. It was leaning out on throttle lift verified by the computer. I had it leaned out cause it was just nasty with a rich smell and black deposits on my driveway during idle. Once I dialed in more fuel it completely stopped the backfiring. And to be honest, I have yet to really drive it, just tooling around the neighborhood at this point. So the rings havent set and theres no miles on the engine. The rich condition at idle will prolly get better once she is driven and I get some real heat in the chambers to burn off any carbon I have built up babying it in the neighborhood. Still trying to dial in this EFI. Cant really do it till I get her road worthy though. JR

 

[JRouche]

Thanks everyone for your replies. I forgot to mention that I have an Ignitor kit in my distributor, as I got rid of the points etc. I will check the plugs etc first though, as I like to do things the easy way first.

Yeah, read the plugs. Let us know how they look. JR