Intro and help....455 w/ Edelbrock problem
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Intro and help....455 w/ Edelbrock problem

  1. #1
    Member bparsel's Avatar
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    Default Intro and help....455 w/ Edelbrock problem

    Hey everyone,

    Nice to find a little jet site here! I've just been searching and reading but havent really found what I'm looking for. Any help would be greatly appreciated!

    I'm running a 455 and just recently switched out my rochester carb for an Edelbrock 750 performer. The boat is idling great and running just ok at W.O.T. however I have absolutely no mid range, it just bogs sputters and almost dies. So I have to take it to wide open to get it to come out of the water. I have spent a few days fiddling with it and I'm still down about 10mph on the top end and still no mid.

    I'm running the orange standard spring on it. Anybody running this carb on their 455? if so what spring combo are you running and how did you get it tuned in? I'm about ready to junk the the thing!

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    Senior Member 74 HOWARD 21RC's Avatar
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    what was wrong with the Q-jet??

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    Senior Member jetboatperformance's Avatar
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    Welcome To PB , sounds to me as if your boat is "running out of fuel" either due to pressure or volume (or both) , a fuel pressure guage would be a helpfull tool in your diagnosis. When you switched did you "upgrade" the rest of the fuel system ? what pump and what type filter ? Also does your boat have a bow tank or saddle tanks and if saddle tanks are the isolated from each other Lots of good help info and advice here post up and folks will help. Re that carb I was told years back that They Edlebrock "targeted that unit to the 350 chevy application , there are "track packs" (small parts selection) available to change metering rods and jets , also might be prudent to take a spark plug reading Tom

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    "Try it Now!" Tahiti Boss21's Avatar
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    bparsel, i agree with fuel prob. I took my edelbrock carb out of the box, bolted it on, and it's been trouble free for 8 years now
    1992 Eliminator Daytona 21'

  7. #5
    Member bparsel's Avatar
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    Quote Originally Posted by 74 HOWARD 21RC View Post
    what was wrong with the Q-jet??

    I rebuilt the Q Jet and the boat ran fantastic except it wouldnt start on its own, needed either and had a very rough idle. I changed it due to a fuel leak-down issue that I couldnt get resolved.

    The strange part about it being a fuel delivery issue is that it the problem actually seems like the rear 2 barrels are opening way too soon. Almost like as soon as the boat comes off idle the rear barrels are opening. I want it to be set up so that they only open with the last 1/4 throttle. Also the boat was running a solid 72 on gps last year with the q jet, this year with the Edelbrock Im only running 60 and it actually runs faster when I back it off to 3/4 throttle and let it lean out a little.

    I have ordered a "Calibration Kit" for it but wanted to see if other guys were running them on a 455 what spring combos they were running to help give me a headstart.

    The gas tank is mounted under the rear bench seat. This boat is a '74 Glastron Carlson CV21

    I appreciate everyones info so far!

  8. #6
    NW Spectraholic Malcolm's Avatar
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    I wish I could help ya. I tried an Edelbrock once. Fought it for weeks on the river (in it's defence it wasn't brand new, but was very clean inside). Finally put the Q-jet back on. Now years later I graduated to a Holley 750 DP and a RobbMc 110 fuel pump. The stock style 455 pumps tend to peter out around 4500 rpms with the Q-jet's small bowl, but the Holley with more volume holds on past 5000. Should be similar with the extra capactiy of the Edelbrock I'd think.
    Malcolm

    75 Spectra 18
    77 Spectra 19 project

  9. #7
    Member bparsel's Avatar
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    Thanks Malcolm, I posted this topic on IBOATS originally as well and the consensus of the advice was to sell the edlebrock and buy a holley. Pretty much everyone concede that if the Edelbrock didnt work straight out of the box I was in for a huge headache trying to get it dialed in. I feel like it will work but I've already spent 4 days trying to get it dialed in with absolutely no change.

    The boat runs flawlessly on the trailer, the issues only occur in the lake under a load on the jet.

  10. #8
    Toesnsandnabiernhand BO Duke's Avatar
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    Cool Hey Guy's

    I also have a OLDS 455 ,.040 over and run a MECHICAL pump with Torker Intake with 1 inch spacer plate and a Holley 750 DP and also made 3" Exhaust spacers off the logs and put a O2 sensor(air/fuel) Mixture Gage and Dialed
    the Holly Right IN. Also run a Corvette Fuel Filter in line .They are supposted to be less REstritive is what I was told. 7lbs of fuel pressure is what I run with a K&N marine Spark Arrester. I do have all my CARB settings for
    a HOLLEY 750DP aplication. JETS, Power valve, (But like the other guy's said a Gage from Summit, Jegs is PRICELESS for chasing fuel PROBLEMS)
    GOOD LUCK!!!
    Team No BS Crew

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    Senior Member fleetimus's Avatar
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    I ran a 750 Edelbrock on my Olds for years. Only problem I ever had was a vacuum leak. A plug came out the side of the carb. Check for a vacuum leak somewhere.

  12. #10
    Member bparsel's Avatar
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    Bo - I am running an inline fuel filter, the bore is stock on mine but it's cammed with race heads on it and I'm also running a spacer plate. Wish I would have bought a HOLLEY right now!

    Fleet - I'll do a doublecheck and see if I overlooked a possible leak. DO you remember what color springs you had in it?

    It's so frustrating when it was tearing a$$ up the lake last year but wouldnt start! Now it starts great but won't tear a$$!!!! ARGH!!! And I'm also burning way more fuel.

  13. #11
    Senior Member fleetimus's Avatar
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    I had it setup with the lightest springs. Also, be sure you are not running more that 6 psi of fuel pressure. They DO NOT like too much fuel pressure.

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    Default Low float setting

    Just about every Edlebrock AVS I've ever messed with had low float settings out of the box. Check the level, AND the float drop, very important to keep fuel in the bowl at WOT..............Ray
    LOUD BOATS SAVE LIVES

  15. #13
    Boat Nut sleekcrafter's Avatar
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    Messed with one a few years ago in an inboard.....the air plate on the secondaries would not uncover the verturie, ended up drilling the balance weights to make it open, and uncover the venturie. I ran one on my 468 for a few years too, could never make the HP a Holley would, but was a very driver friendly carb.
    Upper Midwest Power Boat Association
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  16. #14
    NW Spectraholic Malcolm's Avatar
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    Just to confuse the issue a little more...

    I was playing with an 800 Q-jet years ago at Shasta (Fleet should remember). Ended up taking the primary needes clear out of it to make it go. With them in it would rev up to 2000 and die. With them removed I could at least get on plane and go places. That was the straw that made me go Holley.
    Malcolm

    75 Spectra 18
    77 Spectra 19 project

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