Holley Tri Power Carburetor Technical Information

HP Trends provides Ford tri-power tuning information and sells restored FE Ford tri-power systems, carbs, and tri-power parts.

One misconception of the FE tri-power is it is over carbureted for 390 and smaller displacement FE's. One must realize 2v and 4v carbs are flowed differently. 2v carbs are flow tested at a pressure of 3" and 4v carbs are flow tested at 1.5". To make an accurate comparison of a 2v VS 4v carb take the total cfm of the 2v and divide by 1.414. Example: Total cfm rating of most FE tri-power carbs (List #2436/2437) is 1030 cfm. 330 cfm primary + 350 cfm each outboard = 1030 cfm divided by 1.414 = 728 cfm.

1030/1.414 = 728

As one can see if comparing the tri-power system to a single 4v intake system the tri-power is equal to a single 4v intake with approximately a CJ carb that is 730 cfm. Ford did the homework, and rather well at that!

A common mistake in setting up any intake system is the "bigger is better" approach to carburetion. The FE tri-power is just as effective on a big cubic inch FE as it is on a 352. NHRA Super Stock FE Fords are turning in excess of 8000 rpm with a 730 cfm CJ carb, the tri-power is more then enough to feed any healthy street/strip FE. To obtain the best performance out of an intake system, particularly multi-carb set ups, Concentrate on fuel delivery with good tuning.

*Make sure the carb idles within the idle circuit.

*Select the proper size powervale.

*Correctly adjust the idle mixture screws.

*Insure all adjustments are to spec, accelerator pump gap, etc.

*Select proper size discharge nozzles, pump cams, and index holes for optimum performance.

*Select correct size jets based on spark plug readings or dyno information.

Although these are just the basics you'd be surprised how many over look this and what a difference just the simple basics will add to performance and driveability. A well tuned FE tri-power is a great performer with excellent street manners when properly tuned and adjusted.

Main body metering passages

1. To discharge nozzle from acc.pump.	10. To timed spark port
2. To main air bleed.	11. Fuel bowl vent
3. To main discharge nozzle.	12. To main air bleed.
4. To Idle air bleed.	13. To main discharge nozzle.
5. Used w/auxiliary air bleed.	14. To Idle air bleed.
6. Not use (not drilled).	15. Dowel for metering block.
7. Dowel for metering block.	16. Used w/auxiliary air bleed.
8. To curb idle transfer slot.	17. To curb idle transfer slot.
9. To curb idle discharge.	18. To curb idle discharge.

Metering block metering passages

1. Acc.pump discharge.	13. Fuel bowl vent
2. Main air bleed from main body.	14. Main air bleed from main body.
3. Main passage to discharge nozzle.	15. Main passage to discharge nozzle
4. Idle air bleed from main body.	16. Idle air bleed from main body.
5. Air bleed to main well.	17. Air bleed to main well.
6. Main body dowel.	18. Timed spark passage.
7. Main air well.	19. Main body dowel.
8. Idle feed restriction from main well.	20. Idle feed restriction from main well.
9. Idle fuel from main well.	21. Idle fuel from main well.
10. Idle transfer to main body to curb idle adjusting screw.	22. Idle transfer to main body to curb idle adjusting screw.
11. Curb idle discharge.	23. Curb idle discharge.
12. Powervalve channel restriction.	24. Powervalve channel restriction.

Accelerator Pump Cams

The accelerator pump cams come in various shapes and sizes and are coded by color. Not only does the shape and size determine the capacity and rate at which fuel is delivered from the accelerator pump to the accelerator pump discharge nozzle (squirters) but the index hole affects this as well. Below is a list of different pump cams sized from smallest to largest by pump shot capacity in relation to index hole position.

Note: Brown pump cams only have one index hole and are used on 50 cc accelerator pumps and various other pump cams have three index holes.

Index hole #1	Index hole #2
White	Black
Blue	White
Red	Red
Orange	Blue
Black	Orange
Green	Green
Pink	Pink
Brown