460 needs help

[69CSF250]

I have a 460 that back fires through the carb if you punch the gas? I do not know much about this engine because I just got the truck however it runs good otherwise.
I was told that it has a holley 780 double pumper and a mild cam, it does loap a little. unfortunatly the PO couldnt give me any specs on the cam hope that does not cause issues.
i also need to know what the timing should be set to for this engine? as allways I apprisate the assistance...

[BobbyFord]

First of all check timing, 8-10* should be ok. What year 460 is it? What year are the heads? Double pumper is not good for a heavy vehicle. Check for lean condition (vac. leaks, etc.) How long ago was the cam put in? Cam going flat can cause backfiring under load. Check the basics first.

[69CSF250]

Thanks bobbyFord I will check for any vacume leaks and see what the timing is currently set too and make any sdjustments to see how it goes. I will also try to gather the information on the year of the engine and heads too. it is drivable just have to ease into the throttle and it has plenty of power right on up to highway speeds so I am hoping that its a timing issue...

Thanks again

[69CSF250]

Update on timing, the timing was right at TDC I moved it to between 7 & 8 and took a short ride what a differnce that made all of the backfireing is gone right now but there is a very slight hesitation so I will probably go a little closer to 10* and see how that goes i would have done it yesterday but it wasin the twenties out side. thanks for you rhelp i'll let you know how it goes tomorrow.

[69CSF250]

Another update on timing I set it to 10* and took a short ride throtle response is way better but there is still a very slight hesitation when you punch it, drives great otherwise. next up will be plugs, wires, cap and rotor. Thanks again BobbyFord!

[BobbyFord]

The hesitation you are feeling is because you have a mechanical secondary, double pumper carb on a heavy vehicle with no stall converter. To get rid of the hesitation you are going to have switch the carb to a vacuum secondary carb such as a Holley 3310 or 80508 (same as 3310 but has electric choke). I believe eggman918 may have the carburetor you are looking for (if he decides to switch to 600 cfm).

[69CSF250]

I will be replacing the carb as soon as money permits I was thinking about an edelbrock with an electric choke since I had one on a 400 a few years back that worked really well. not sure of what CFM to persue though. I will keep eggman918 in mind whent the time comes though. Thanks agin BobbyFord I apprisate the aassistance!!