Hi Guys.

I have a 57 Bird with a 312 and a Fordomatic tranny. Holley 4160 465 CFM carb. I have a bog on acceleration from a stop position. I have new plugs, rotor and wires a year old. The car in idle runs smooth as silk. When I pull away from a light the car bogs and runs rough. Once up to speed it seems OK. If I punch it once at speed she takes off without hesitation. I have checked the front float level. Its right at the bottom of the sight hole. Gas trickles out when car is gently rocked. I had an issue late last year with advance plate sticking (slight rust) in an advanced position. I cleaned it up and lubricated it. It now moves smoothly in both directions. How stiff should the spring be? It takes a bit of effort to move it. I am wondering if the vacuum is strong enough to advance the plate. Vacuum reading is at 18.5 inches at idle in drive. I have advanced the distributor - car runs better but begins to ping and hard start when hot indicating to far advanced. If I retard a it bit it starts bogging again. Its such a fine line. This is cheating a bit - running it at advanced condition. Is the advance spring too tight? Is this something I can adjust without making it worse. My vacuum advance diaphragm is not leaking - I took it off and hooked up to my shop vac to test it. Carb air mixture screws are adjusted 1 1/2 turns out from closed position.



Any ideas?

Nate, check your accelerator pump. With the engine not running look down into the primary side of the carb with the choke plate open, advance the throttle by hand and look for two streams of fuel squirting from between the primary venturi. If one or no streams carb needs to be cleaned. If really heavy streams you may need to adjust the accelerator pump for a little less flow. This is an easy check so is worth a try. Mike

1956 Fairlane Victoria (ORREO)

 

Overlooking Beautiful Rimrock AZ

It could be the accelerator pump diaphragm rupchured or dried out and not giving your carb a big enough squirt to the nozzles. With the engine shut off look down the carb and open the throttle and see how fuel flows from the squirters.

Hi Guys thanks. I should have mentioned the carb is 1 year old. Squirters seem to be working fine. Nice clean jet of fuel when working accelerator.

Try a little more advance. I think that solved my hesitation problem

54 Victoria 312;  48 Ford Conv 302, 56 Bird 312
Forever Ford
Midland Park, NJ

You need a timing light to check and see if the timing is advancing during acceleration with the vacuum unplugged from the distributor and the port plugged on the carb. You do this with the car parked and in neutral. Mark say the 12 degree on the crankshaft damper and set it there. Rev the engine alittle to see if the mark moves an inch or more with the timing light. If it's not moving enough it can bog untill the timing catches up. This is a chronic problem with older distributors needing a little care. The weights may be stuck in the distributor ( I have seen this many times ) and once the've been fixed it's unbelieveable how much better the engine will run ( if that's the problem???) Ideally a good spot to see is if the timing moves to about 36 degrees on the damper at about 3000 rpms and settles in around say 10 to 14 degrees at idle. At least this will be a good starting point.

-Gary Burnette-

It may be a little lean on the primary side.  Our alcohol laced gasoline doesn't burn as well as real gasoline, so you need to burn a little more of it to get the same power you used to get.  It is pretty well known that fuel mileage with E85 is slightly more than half what it is with E10.  That tells me it isn't as efficient. 

John - "The Hoosier Hurricane"

I had this problem and just had to dial in the vacuum, timing and air/fuel mix.  Here are two things to try, first hook up the vacuum gauge to a port under the crab and disconnect and plug the vacuum advance on the distributor. Start the motor. Turn the distributor slightly to increase the vacuum reading on the gauge at about 800 rpm. If the Adjust the RPM to stay at 800 as you adjust the timing. When the vacuum gauge is at it's highest vacuum at 800 rpm, retard the timing just enough to drop the vacuum ONE INCH, and set the distributor clam in place.

Then adjust the idle mixture screw such that the motor almost stalls, then back it out very slowly until the maximum vacuum reading is achieved. Go another 1/2 turn in that direction to ensure the vacuum drops then back to the maximum vacuum setting with the screw. All the time maintaining 800 rpm with the idle set screw.

After the mixture is set, go back and recheck/fine tune the timing.

Another thing you can try is more of a truck thing but still is a good read and will help you.

http://m571.com/yblock/distributortuning.htm

1958 F100 292

"Nothing is particularly hard if you divide it into small jobs."

"Chop your own wood, and it will warm you twice."

-Henry Ford

I’ll add that the accelerator pump adjustment on the carb also needs to be checked.  If you have any free play in the accelerator pump arm linkage with the throttle in the idle position, then a flat spot or hesitation will also be present.  Accelerator pump arm adjustments are performed with the throttle in the wide open position, not the idle position.

 

To perform the accelerator arm adjustment on a 4150/4160 Holley, you will open the throttle all the way (WOT).  Push the pump arm lever down and then adjust the pump override spring to obtain 0.015” clearance or freeplay between the pump arm itself and the diaphragm lever.  A proper adjustment at this point keeps from bottoming out the accelerator pump diaphragm while at the same time insures that the linkage is properly preloaded so that fuel can be delivered as soon as the throttle is moved off of the idle position.

Lorena, Texas (South of Waco)

Hi Gents.

I have advanced the timing by turning the distributor clockwise just a tiny rotation. The car runs significantly better. It takes off a lot better from a standing stop with a lot more zip. I also noticed when in a park when I rev the engine, it revs really clean as opposed to sounding like a tractor. There is no pinging at this point even under hard acceleration, but it is early in the season with cool temperatures at about 50˚. The only thing I noticed is the delay when I go to start the car. There is a slight delay when I turn the key - almost a hard turn over condition, but it fires immediately. Will this damage the engine? If I retard the timing the problem goes away but the hesitation/sluggish performance returns.



Thanks for help...were getting there!