Hello forum, I have read through the forums and have taken some advice but still need little more thoughts on the vacuum advance on the distributor. I have a 1978 ford 4X4 with a new manufactured rebuilt 460. Motor sounds and runs great other than the pinging when the vacuum advance is hooked up. I have the truck timed at 12 btdc. It pings during mid-throttle. I have tried timing it all the way to 8 btdc.. (power loss).. Also with the vacuum advance off it runs smooth (just not as powerful start-offs) BUT... if i hook up the vacuum advance (port side not manifold) it misses just off idle. Now im lost. Ive tried everything ive read in the past threads.. even backed the vaccum 3/32 out about 7 turns... it stopped the pinging.. but sluggish again.. Ive tried turing it back ina couple turns and it pings again. any thoughts on why this is happening to my new motor and new edelbrock 750??. When i ordered the motor, I had them put in a RV cam.. I was told it was just a slight increase from stock cam..(if that matters) Im still assuming it should be timed about 11 or 12.. Ive exhausted my puzzling attempts. Any comment would be appreciated. thanks!

 

Put a timing light on it that measures advance. There could be something wrong with the ignition vacuum advance canister. A couple of people on the forum know those ignitions and can offer some troubleshooting directions.

 

The book for your carb tells how to make adjustment to the "power mode". If you richen it a little it should help.

Dennis
1999 F-350 Powerstroke
1977 Highboy 429 4-speed 35"s
1972 Ranger on a 1978 F-250 4x4
frame 466 Pulling Truck

 

If your vacuum advance is not new I would check that first to see that it will hold a vacuum. I recently had mine leaking and it caused a part throttle ping because of the vacuum leak.

 

Thanks for all your feedback. My vacuum advance was new.. holds vaccum.. I found i had to adjust the vacuum advance (3/32) out 7 turns.. it stopped the pinging.. My motor is a fresh rebuild from spokane s&s engines. (250 miles on it so far) I am still getting about 7 MPG. Im easy on the gas and driving 55-60 mph sheesh! NEW motor...NEW 750 edelbrock carb.. NEW edelbrock 460 proformance aluminum intake.. Im exhausting my otions here. 170 miles to a 25 gallon tank is a bit depressing for all the money I have spent to make sure it can run its best to help out the mileage.. oh yes.. not to mention dual exhaust, open chrome air cleaner... Guess I am just stuck with 7 MPG.. Id hate to see the mileage when i get enough guts to kick in the 4 barrels for any length amount of time... or haul my camper up a hill.... SSSLLLUUURRRPPPPP.. gulp gulp gulp... I might as well keep a pocket full of quarters and thow them up on the dash each second I make a pass when "get on it" Ill call it my "passing gas fund" any thoughts on why i am getting 7 MPG?? shouldnt it do better than that? Thanks!

 

7mpg gallon sounds right for a 6000lb 4x4 with box frontal area.