Replacement Carb Suggestion for 390

[joeflsts]

I just bought a 1970 F100 4x4. The previous owner told me it was a 390, however this truck was built with a 360 (according to VIN). This truck is relatively good condition, has a little rust, and needs paint. Recently it developed a hesitation at low RPM but will clear up when I accelerate. I have changed the plugs, and vacuum advance but that hasn't cleared it up. I intend to do the following:

1. Change Points & Condensor
2. Change Wires
3. Change Distributor Cap

It has an older 4bbl Holley on it and the plate has the following stamped: C60F N A 6DA

I'm seriously considering buying a new carb (so I can drive now) and rebuilding this one. Can someone suggest a good replacement carb for a 390?

I am very new to this and appreciate any help.


Joe

[knightfire83]

Welcome to Fordification joeflsts !!

I couldn't find any info on the carb. numbers you posted I think they might be the wrong ones. I found a site that shows where the correct ID numbers are located: http://www.holley.com/TechService/ListNumber.asp

Everyone has their own brand that they like to use ex: Holly, Edelbrock, etc. Personally I have had nothing but problems with Holley's so I run Edelbrock.

The best results I ever have ever had is with Quadrajet on GM vehicles, when you learn to rebuild and properly tune them they give incredible results. But this isn't applicable to your situation.

Any brand you go with you will need 600-625 cfm for a mostly stock 360/390 engine, a 750 cfm would be overkill unless you like to drive to the gas station regularly. A new carb. runs about $200 unless you can find one used on craigslist or a swap meet, but then you still don't know if it works or needs rebuilt.

I bet with your ignition tune up as you previously described it will get rid of the hesitation you are experiencing. Don't forget to also replace the rotor in the distributor. In addition double check the tightness of the nuts holding the carb to the intake manifold (they like to work loose over time.)

Another thing to consider is getting rid of the points all together and get electronic ignition for better performance and reliability. You can find this by getting a used Duraspark setup off a 75+ FE equipped Ford vehicle, a Petronics kit, or a MSD ignition box.

You may want to measure the stroke on your engine to see exactly what size engine you have. After 30 some years it may or may not be the original motor. A 390 is a direct bolt in when replacing a 360 and they are physically the same on the outside. The only difference is the piston stroke via~ a different crank and rods.

Hopefully others will chime in with additional information about troubleshooting your Holley.

[joeflsts]

Welcome to Fordification joeflsts !!

I couldn't find any info on the carb. numbers you posted I think they might be the wrong ones. I found a site that shows where the correct ID numbers are located: http://www.holley.com/TechService/ListNumber.asp

Everyone has their own brand that they like to use ex: Holly, Edelbrock, etc. Personally I have had nothing but problems with Holley's so I run Edelbrock.

The best results I ever have ever had is with Quadrajet on GM vehicles, when you learn to rebuild and properly tune them they give incredible results. But this isn't applicable to your situation.

Any brand you go with you will need 600-625 cfm for a mostly stock 360/390 engine, a 750 cfm would be overkill unless you like to drive to the gas station regularly. A new carb. runs about $200 unless you can find one used on craigslist or a swap meet, but then you still don't know if it works or needs rebuilt.

I bet with your ignition tune up as you previously described it will get rid of the hesitation you are experiencing. Don't forget to also replace the rotor in the distributor. In addition double check the tightness of the nuts holding the carb to the intake manifold (they like to work loose over time.)

Another thing to consider is getting rid of the points all together and get electronic ignition for better performance and reliability. You can find this by getting a used Duraspark setup off a 75+ FE equipped Ford vehicle, a Petronics kit, or a MSD ignition box.

You may want to measure the stroke on your engine to see exactly what size engine you have. After 30 some years it may or may not be the original motor. A 390 is a direct bolt in when replacing a 360 and they are physically the same on the outside. The only difference is the piston stroke via~ a different crank and rods.

Hopefully others will chime in with additional information about troubleshooting your Holley.

Thank you! I got the numbers off a tag (FOMOCO) that was attached to the carb itself. I decided to replace the carb with an Edelbrock and it is on it's way. I do plan to measure the stroke and I'm pretty sure this is a rebuilt motor. The blue paint still look relatively new the heads, intake, and valve covers. I'm working tonight to replace the points, condenser, plug wires, rotor and cap.

Thank you again.

Joe