I would be checking the Distributor to make sure the Advance is actually working properly. This can be verified by using a Timing Light and watching the Timing. Marks  move as the RPM increases. Also how much initial Advance are You using. Should be 10-12 BTDC. Factory Specs are very Conservative. The Jets in my 390 are #57. The fact that You changed Carbs and are still having same problem makes Me lean towards a problem with Ignition. I've done 3 of these using the 390 and a stock 57+ Distributor with Pertronix 2. Other than changing the Jets to 57 or 58 this Setup has worked fine "out of the Box". Did some adjusting  afterwards but initially it was very driveable as installed.

  

As suggested, you need to verify if the advance is working properly..also when doing so check to make sure your crank shaft balancer is o.k. When the rubber deteriorates in old balancers the marks may have slipped..   


Paul

"Jarhead

I'm sorry! It isn't an Ignitor III distributor. It's an actual '56 Ford distributor that has been rebuilt with a longer shaft to eliminate the wobble and a lower bearing to keep the shaft running true to the Ford block. All the guts and coil are Petronix Ignitor III. Distributor is built by FBO Systems in Oregon and has both vacuum and mechanical advance and is supposed to make the Y-block able to accept all of today's technology including the modern fuel formulations. I've installed John Mummert's manifold with the new Holley 390 CFM and it still hesitates or "bogs" at takeoff or when trying to pick up speed. Everyone says it's a carb. adjustment but no one can get it adjusted right."

Three things for Tip-In Hesitation -

1) Improper vacuum signal (ported) to DIST and/or defective/improperly adjusted vacuum advance,

2) Defective/improperly adjusted carb accelerator pump,

3) At speed, trans doesn't go into passing gear (2nd)

Or you are using a taller runner or single plane intake which will require a longer accel pump shot.

For the HOLLEY, you can buy one of their manuals that details the setting up of one properly.

MUMMERT makes three alum intakes I believe, 1) the 4V for FORD, 2) a shorter intake for the BIRD (hood clearance), and 3) a 4V with no heat riser provision. BLUE THUNDER also has a model.

Once you establish correct dist operation/advance, it must be in HOLLEY accelerator pump shot/duration. This can get fairly complicated so you need the manual for reference unless you are experienced.

Description and Source of FBO DIST - http://4secondsflat.com/Ford%20Y-Block%20Distributors.htm

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Prior to changing Carbs and Distributors were You experiencing any problems as far driveability etc? Or did You only start having any Problems after changing Carb and Distributor? You might try setting the Timing using a Vacuum Gauge instead of timing Light. Hookup vacuum Gauge to direct engine Vacuum.The Lower outlet on the 390 Carb is direct Vacuum. Slowly advance the Distributor until Vacuum reading starts to drop. Move Distributor in opposite Direction until Vacuum starts to drop.Set Distributor haflway between the 2 and lock Distributor down. Take it for a Ride and see if there is an Improvement. Its possible the Damper has moved and setting Timing with a Light is no longer Accurate. Setting Timing with Light may make timing retarded because Damper is no longer correct.  Mechanics and Speed Shop Employees would not think of this as a possible explanation for poor Driveability if they are not familiar with the Y Block  As I suggested prior You should use a Timing Light to verify the Distributor Advance is actually working.

  

Isn't the FBO a completely new distributor body  ?  Sure seems so on their web site.


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

I was just looking at FBO Website. Looks like a Quality Product made in USA.If You check some of the Items that were suggested and still no Improvement maybe U should check with FBO and see if they have any suggestions regarding their Distributor. If You were not having Problems before changing Carb and Distributor its One or the Other which is causing the Problem and I think its Ignition related not Carb. Let us know what You find when doing some checks as suggested. Did You check the Jet Sizes? They need to be around 58. New 390 Holley Carbs come with #51 from the Factory.

  

Not to hijack the thread, but there’s a core charge on the FBO distributor, so there’s something they’re reusing. If their name had come up a week earlier, I’d had stopped in and seen them. I was driving thru Cottage Grove, OR.

On the carb side, you might go back and look at some earlier post on setting the secondaries on Holley carbs. I don’t know if it applies to the 390, but it might if it’s a 4160 series. I think it was a post by Greenbird56.



miker
55 bird, 32 cabrio F code
Kent, WA
Tucson, AZ

Maybe the main Shaft? The Housing they sell is for sure New.They were offering them on Ebay for awhile with only a $25,00 Core charge. The fact that He can't even really drive it is not something I have had a problem with having done 3 of these Swaps. Upsize the Jets to 58. Set the Timing at around 8-10 initially and they can at least be road tested and run well  and then I would fine Tune them.He has had 2 Carbs on this and still no Improvement. I am very interested to know the final Outcome when He figures out what the Problem is.

  

I went back and reread the whole post. The only time I had a Holley with a BIG bog, just short of not driveable, it was the main jets. The carb had been shipped (it was a new 4160 vacumn secondary) with the mains 10 sizes small. Like 55 instead of 65. Hard to remember, that was 1968. Problem solved. So maybe worth pulling the bowls and checking the jets. Doesn’t seem QA has improved lately.

miker
55 bird, 32 cabrio F code
Kent, WA
Tucson, AZ

When these 390's are shipped new they seem to have 51 main Jets. Probably because they can be used on everything from 4 Cylinders up to small V-8's. They are all supposed to be wet Tested at Holley. The last new One I bought in the Spring had a definite  Fuel Smell so I assume it was tested. It only had 51 Main Jets. 58's seem to work well for my Stock Engine. Anyway He has had some Suggestions given. Look at the Basics first..