SoCal Jet Boats
Tech Talk => Jet Pumps => Topic started by: bluthndr on June 14, 2022, 09:28:06 AM
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Good amount of experience with this stuff, just not a lot with boats. Holley 750 vacuum secondary on a 455 Olds in a jet boat. Where would you start for a jet and power valve? I'll get the vacuum gauge out and do it right after a bit. Just looking for a starting point.
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Holley 750 Power valve
https://www.socaljetboats.com/index.php?topic=28742
This helped me years ago
Sent from my iPhone using SoCal Jet Boats mobile app (http://r.tapatalk.com/byo?rid=201)
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Thanks! I'll check that out. Took old 750 Edelbrock off last night and found the spread bore/square bore adapter upside down ♂️. For now I put in a Holley 750 vac sec, with 72 primary jets, a 4.5 power valve, and the light (white) spring for the secondary while I rebuild the double pumper I just got. Gonna check ignition timing and reset it to 12* initial, 34 all in by 2500 and disconnect the vacuum advance, and see where that gets me. Hope to be testing in the water Sat
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Speedway has a vacuum advance block off plate for GM HEI distributors. Waaayyy more accurate spark than a rubber diaphragm trying to hold things steady.
As far as jets, if I remember right, my 750 VS had 74's in the front, and a 6.5 PV. And lightest spring in the secondary diaphragm.
(454, 9:1, Vic Jr. manifold, .575"/.575", 230?/234? roller, 750 vs, logs and snails)
Dan'l
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Ran it with 72s, white spring, 4.5 pv. Ran decent WOT at 4K, but plugged 2 more filters and fought me home? runs good for about 90 seconds - 2 minutes then starts to bog from plugged filters. Didn?t notice right away, but 30 seconds after it died I watched the fuel filter contents fall off the element to the bottom. Spent most of the afternoon resealing the thermostat housing (to find it empty) and then switching to a 4160 from a edelbrock?.