Holley 470 Truck Avenger Settings
Like most other odd fire mods, that stuff about "bolt on, out of the box performance" does not apply to you. This is what I've run. YMMV.
1970 225cid short block, stock pistons/crank/rods/etc.
Comp Cam 252H kit
Melling hi-vol oil pump, stock spring!!! (don't put the hi pressure spring kit in)
Offenhauser 360 aluminum 4bbl intake
Holley 470 Truck Avenger
FLAPS mechanical fuel pump
FLAPS fuel pressure regulator, I think 2psi to 7psi range, IIRC
GM even fire HEI modified for odd fire
Setting #1, sea level (Pensacola FL)
Main jets: 52
Power valve: 2.5
Secondary jets: 57
Secondary spring: Purple
Pump cam: orange (I think - whatever it came with)
Setting #2, Midwest (Oklahoma City/Kansas City)
Main jets: 48 (Really would like to try 47, but couldn't find a set.)
Power valve: 2 stage, 5.5"Hg/10.5"Hg, part #125-211
Secondary jets: 57
Secondary spring: Silver
Pump cam: orange
Random install notes:
Don't forget to set the secondary throttle stop before you install the carb; DAMHIK.
Out of the box, I had fuel weeping from the top of the secondaries. Crank the float down 1/8 to 1/4 turn.
Do not use anything other than the blue Holley brand gaskets. Buy extra fuel bowl and metering block gaskets and stick them in your recovery kit so that you won't have to fall back on FLAPS brand in an emergency.
The choke was a bit of a PITA for me to tune; there is a small idle screw that is located under the choke and extremely difficult for me to get hold of. I don't have any words of widom to ease tuning it other than to mention not to forget to set it. It's easy to overlook.
I have recently switched to a two stage power valve. I like it so far. I think the PVCR on the 470 are a bit large for the Dauntless. The two stage power valve seems to let the fuel ease in a little slower. Prior to that, I had to run a 2.5" and larger main jet or else I was getting bog. I knows others have had good results using a lower PV and smaller jets, but this is what I ran and it made a nice brown plug. I do think the two stage PV is pretty good, though, and comes in smoothly at 10.5"Hg with a bit smaller jet than the single stage.
Also of note: I dont' care what the Holley tech site says, it is possible to blow out a PV on a late model Holley. I leaned out the jets a little too much one night in the garage and got a violent backfire through the carb when I revved the throttle. Symptoms following the backfire included extremely rich idle, couldn't kill the engine closing off the idle needles, stumbling off idle, black smoke/soot, raw fuel droplets out of exhaust at idle. Even on the phone, Holley claimed it wasn't possible and that I must have some other problem. Changed out the PV and it ran well again. I think a really bad PV could possibly flood this engine.
Semi-related: With my GM HEI, I ran a NAPA vac advance unit for '75 Buick Apollo w/231. In contrast to what others have reported using the 2g, I could not get enough advance out of the Holley port vacuum located passenger side of the metering block. I ended up playing with initial between 10 and 12deg BTDC, for a total of 32deg to 34deg. You'll probably end up using the lightest mechanical spring in your kit. My experiences using the metering block port is that you're basically going to need all your mechanical no later than around 2500rpm. I'm hypothesizing that this may have something do do with lower overall manifold/port vacuum as compared to the 2g, but haven't done any side-by-side testing. YMMV.
Last edited by jayhawkclint; 03-26-2009 at 01:57 PM.
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