my 390 runs great and runs smooth until you stand in them she starts barking through the carb until you back out of it then ease back into it then it will scream back to life. The timeing is set at about 9 degrees btdc. Just did a tune up and still does it not sure what to do with it. Driving me nuts.

 

Vacuum advance working properly?

 

You checked the timing with the Vaccuum advance disconnected right? Does sound like a VA issue.

 

Sounds like a lean condition, Vac or Mech secondaries? Accelerator pump may not be suppling enough fuel. Or it may be just a carbon build up causing the problem.

 

Not sure what the problem is took to vac advance off and that made it worse. triied to run the timing at 12 tdc and that didn't work.

 

What would the vacuum advance have to do with it? When he stands on it the vacuum all but disappears anyway. Only the centifical advance is still working.

Power valve bad, low float level, partially plugged main jets, centrifical advance not working (it sounds like this is it if the removal of the vacuum made it worse) bad coil, bad condenser. I've seen all of the above cause your symptoms.

 

1966/67 F100

If you have a smog pump on that engine, you will also have an anti-backfire valve: C6AZ-9B289-C.

The same valve was also used on 1966/67 passenger cars with 289/352/390/410/428 engines.

 

When mine didn't work it back fired.. just like it backfired when the Crane Xri wires were binding and it wouldn't advance correctly. Although I did overlook the through the carb part so My bad!

And it's spelled centrifugal mr,

 

did you figure out your problom? if not here's something that I encountered with my truck 70' f 250 2wd 360fe. from a stop sign if I accelerated slowly, like there was an "egg" under the gas peddle, it would be fine, also fine at cruise rpm conditions. but if I tried to accelerate from a stop even slightly hard it would pop like crazy thru the carb, wicked bad...crazy...If I was cruiseing along at highway speed and tried to gas it to pass or accelerate..same thing real violent until I let up and gingerly brought her up to speed. I went nuts, changed intake gaskets twice, carb base plate gaskets, new timing chain & gears, rebuilt the carb, bought a new carb, plugs wires cap points etc.....nuts... i was going insane and then..... I talked to a retired ford mechanic from the late 60s early seventies....he said of all things...check the LIFTERS!!!!!! what??? lifters? It didnt tap or miss, it was real smooth great oil pressure, I thought it was nuts but hey I did all this other stuff, why not the lifters. I did them and it ran perfect....unbeliveable....here they were screwing up under heavy load but were ok at light load conditions. I hope this helps, if not, good luck!!!!!

 

Last time I was in school was 1965, when you've been away from school as long as I have and are spelling better than am, then you can give me grief.

 

the little dots under the word whilst your typing is a heads up your ****ing up, option click and it'll give you a tip..... Like that show (Are you smarter than a 5th grader)

enough scratching each others eyes out already were here about Fords® and folks who drive them.

 

Have not got it figured out yet. It does not pop under a load, used it the other day to tow a mini-van on a trailor it did just fine no popping. It only pops when empty and I hammer the throtle to pass another car or if I just want to stretch her legs for a second.

 

I had popping in mine. I had to adjust the accelerator pump/squirters to my engine. This is pretty easy if it's a Holly 4v. You have 30-50cc acc pumps, and a lot of squirtes size to control feed. The Power valve may be set to low if it works fine under load. Hook up a vacumn gage and drive it. When you nail it, see where your manifold vacumn drops and runs at. As the load is increased this will be lower. You normally want the power valve to be open under these conditions. Try a power valve the is 2 above your no load reading and see if this helps.

Popping through the carb is normally to much timing for the amount of fuel. The poer valve will have a big impact.

I had a Pantera that had the same problem with a 351. The car was so light I ended up with a 10-12" power valve. Where a std was around 5".

 

Had 5 different 5th graders and was smarter than all of them, even though 3 went on for college degrees and the other 2 are working and supporting themselves. I have spell check on this PIA machine, but I'm old and forget to use it sometimes (most of the time). Oh yeah and all but one of those 5th graders grew up to be Ford owners, the youngest daughter was but traded down to a Chevy (Suzuki) Tracker from her Ford pickup, but then she was born under the sign of Aquarius.