Backfire through Carb!!!!

[Anonymous]

I have been working on this project now for a long time....

My timing is correct and my ballencer hasn't shifted.

I just adjusted the valve rockers to the specs online.

I starts and idles great, but once I accelerate, it seems to backfire through the carb and sputters till i release and go back to idle.

I have a 264 Clifford Cam and am thinking that I should get a adjustable Timing Chain sprockets.

Should I?? or what else could be the problem??

Thanks Again,

 

[WhitePony]

When you installed the cam did you degree the cam? I had a local shop do the rebuild on my shortblock using my cam, dual roller timing set, and ARP fasteners. They did a great job on the shortblock, but they installed the cam straight up. When I degreed the cam I found that it was in at like 10* retarded. Thank goodness for the multiple keyways on the timing set, because I was able to dial it in to 2* advance like the came manufacturer recommended.

What kind of distributer do you have? Your advance may not be working properly.

 

[MustangSix]

Could be something else. check for:

Vacuum leaks;
Incorrect firing order;
Moisture inside distributor cap;
Bad ignition wires;
bad gasoline;
Bad PCV valve

I doubt the cam timing is causing this.

 

[Stubby]

Also points and condensor if you still have them. More than likely something firing at the wrong time or valve not sealing for whatever reason.

 

[Anonymous]

how would I degree my cam... I just installed it the old fashioned way alligning the two dots on the OEM sprockets.

Should I buy a multiple keyway cam gear set??

 

[Anonymous]

I have a petronix Digital Distro retrofit kit that was working great prior to this rebuild.

My valves should be closing correctly... I adjusted them recently with the instructions listed here.

I have checked for all other leaks, none yet.

 

[MustangSix]

Loosen the valves a bit. You may have them too tight. At sppeds above idle could be pumping up just enought to hold a valve off the seat enough to cause a backfire. It's a long shot, but give it a try.