Quote:
Originally Posted by Formulajones
There are different versions but if that's the more common street series it should have 72 front jets and a 6.5 power valve.
Since you're in the Carolinas you're near sea level. I'd like to know what vacuum your engine produces at idle to be sure, but if I had to guess you should be making 12-13 inches at idle easily enough when tuned properly.
So the power valve in my opinion opens a bit too late. I'd like to have an 8.5 in there so it's getting into the power circuit a bit sooner and helping the transition.
From there, being a 455 and at sea level, I'd also bet the 72 front jets are probably a tad lean. Considering I run that size jet in SBC's here at 5000 feet elevation, I think a 455 might be a pinch thirstier than that.
I'd likely bump that to a pair of 74's and try it. Rear jet should be 80's, I'd leave that alone for now.
Squirter should be a .031 in that carb, probably okay for the time being. Getting the power circuit working sooner may be enough to cover the big hole you're creating when whacking the throttle and you may not have to touch the squirters.
The calibration I'm seeing on that carb is more suited for a 350 out of the box, you're going to have to change some things for optimal performance and good drivability. Start with the power valve and front jet and report back.
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A lot of good carb advice here. The car is not a drag car with a monster camshaft and needs either a less than 5.0" power valve or 3.5" power valve.
Larger trucks with Holley cars used LARGER NUMBER POWER VALVES because they wanted ADDITIONAL FUEL to the engine SOONER, not later.
So a 10.5" Power Valve in a truck was installed for a reason.
Same deal for the recommendation to use a 8.5" Primary Power Valve in the carb. More fuel SOONER when you WOT the throttle at lower speeds.
As posted the carb is lean. 74s or even 76 jets is more common on 455 sized engines on the Primary side.
It would be nice to have the actual "List # off the airhorn of the carb and the build date code.
Tom V.