holley 4412 500 cfm

[64 200 ranchero]

what would be a good power valve besides the 2 stage style, i am looking on getting the best performance without running so rich that im just wasteing fuel with no added power like i am now, i dont care about getting the best milage i just want more power useing less gas

 

[bubba22349]

will depend on the amount of vacuum you have.

 

[CZLN6]

Howdy:

Power valves are basically a vacuum operated switch. Vacuum drops below a given point and the PV opens. The amount of fuel is determined by a power valve channel restriction which is built into the metering plate. For most operating conditions a power valve is chosen that is two numbers lower than the vacuum range of normal driving.

the power valve channel restriction (pvcr) can be tuned in several ways. The simplist is to insert a piece of wire into the holes, bent so it will not disappear into the oriface. IIRC the typical channel restriction on a 4412 is .062". A guitar string of a specific size works well in tuning the fuel of the PV circuit. Start with a .010" E string and go from there to lean out the PVCR. YOu really need a very sensitive A/F meter to get it right, but leaner is a good place to start.

Adios, David

 

[xctasy]

The 500 cfm Holley suffers from being set up to replace a 352 to 390 cubic inch V8-s 2-bbl Autolite, Carter or Rochesters found in Fords, AMCs, Chrysler and GM V8 replacements from the Holley catalouges. Holley make sure it is set up rich to avoid lean out conditions in applications from 160 to up to 220 hp net.

To suit our i 6's, it has to run much leaner under wide open throttle, but not a whole heap leaner generally. The power valve channel restrictions of two 62 thou holes is way too much for a 150 hp engine, and could be knocked down to as little as 16 thou each with a 2.0 power valve. This what was used on 2.0 and 2.3 liter Pinto engines when amped up from the stock 230 to 280 cfm carb to a 4412 500cfm.

For our sixes, some where between the stock 8.5 power valve and 62 thou holes, and 2.0 power valve and 16 thou holes will be i6 nirvana. jet sizes stock were quite big at 71 to 73. On a little 150 hp engine, it was down to 65 call size.

So a 65- 73 jet will do, and power valves should be 2.0 to 8.5, with PVCR down to 16 but ideal size is probably equal to 62 thou minus 10 thou to get in ball park.

 

[64 200 ranchero]

well the most vac i can get is about 17ish in gear on most days, i will try the guitar string, i also tried replacing the accel pump discharge valve to a 28 like wsa111 said but, my carb already had one, now is this because i am at a lower elevation 117 feet above sea level, thanks for the help

 

[64 200 ranchero]

i replaced the stock jets with 68's the engine liked that alot, i took the choke out since i had no use for it and i replaced the accel discharge nozzels from the stock style to the tube style, im thinking the 5.5 pv and .010" may be a good place to start, thanks for the info

 

[CZLN6]

Howdy Back:

What size discharge nozzles did you use? To determine a vacuum threshold when choosing a PV, I recommend that you hook up a vacuum gauge so that you can watch it as you drive through a normal days trips- noting high, average and lows. Lows are not the WOT, which should be zero vacuum. A 5.5 PV will open at around 5.5" of vacuum and lower. 5.5 PV is probably a good place to start.

I don't recall what tranny, cam and rearend gear you are using?

Lower elevation- richer. Higher elevation- leaner. Most factory set-up on carbs is at or close to sea level.

Adios, David

 

[64 200 ranchero]

i used a 28 nozzle, im running a 67 c4 with a shift kit and H servo, im not sure of the cam, it was installed before i bought the engine and the guy who sold it to me didnt know, it has a lope to the sound and my vac reading is around 17-18 at idle in drive, i have a vac gage in the car ill watch it and find out the readings, my rear gear is 3.55, im running the stock 65 head with an adapter for the 2b, thanks

 

[64 200 ranchero]

i put the guitar string in the power valve, it seemed to help, then i put the 65 jets in and i think it lost some torque, throttle response is exelent but after it go's into second it lag's a little, then in third it picks up again, the 68's seem to have more power in 2nd