540 c.i. 14-71 blower w/cooler 2% over drive, 6,000 R.P.M. 9.5 lbs boost @ 35 degs. timing in a 3,700 lbs boat. 2-850 cfm DP's w/ no choke horns, primary's :84 jets w/ 10.5 power valve (non referenced) secondary's :88 jets no pv.
http://www.hotboatpics.com/pics/data/500/1949motor1.jpg
Show off!:yuk:And his junk runs good too!
540 c.i. 14-71 blower w/cooler 2% over drive, 6,000 R.P.M. 9.5 lbs boost @ 35 degs. timing in a 3,700 lbs boat. 2-850 cfm DP's w/ no choke horns, primary's :84 jets w/ 10.5 power valve (non referenced) secondary's :88 jets no pv.
Thanks for the run down Dimarco. I'm going to order up some PV's for my junk and get to tuning.
Mark, what power valves were you running on this set-up? I'm still chasing a tune on my heap. I stepped up the blower this summer and almost fried the whole package. I'm running 850 center squirts with plugged power valves and 84's all the way around. It runs good(at 5 lbs. boost) but the mileage is terrible(about 1 mpg)!!!
John,
I had 6.5 power valves.
With no power valves I would think there would be a significant flat spot between the idle jets and coming on the main jets.
Check your idle vacuum and your cruising vacuum and that will help you determine what PV will be best for your setup.
As I recall I had about 10" of vacuum at a cruise speed and I got 2 mpg.
Mark, I haven't experienced a flat spot since I made up bigger squirters(if I remember right I went to .040"'s). I had to machine my own because Holley no longer sold any 4-ways bigger than .035" at the time.
The only time I put a vacuum gauge on her, it did weird stuff. It was in the driveway without any load, but I seem to remember that it had 0 vacuum at idle and the vacuum climbed with the rpms. Does that make any sense? I had the gauge connected to the throttle plate port of the front carb. It's been a while, maybe I'll dip the boat in the river and get some fresh vacuum readings before I tear her down for the winter projects.
2 mpg would be cool, double what I average now!!!
Checking manifold vacuum at the carb base usually works but it sounds like you had the wrong port. It would be the one with the biggest hose connection. Otherwise connect the line right into the manifold.
I was pulling almost 30 inches of vacuum at the base of my carbs, no pv in them and jetting was pretty close to stock on two 800's.
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