Marine tech buddy of mine says I oughta clean or rebuild my quadrajet if its never been done. Guaranteed shit be floating or caked in there. I never messed w/ an automotive carb before.. another buddy of mine has a good Holley 750 for the taking, I just don't know how to tune the damn things.

So the question, am I better off rebuild the q-jet, or slap on the Holley and figure it out?

On side note, I think the boat runs rich to begin with, I always smell fuel. There's a tiny pump with its own linkage that sprays fuel down the hatch when you crack the throttle, I'm gonna back the setting off on the linkage and see what happs. If I mash throttle four times in a row quickly, I can almost turn the engine off.

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well if it aint broke dont fix it! in all the quadrajets i have dealt with , you leave them along. when they go bad. put a holley on.

really??  tell that to the guy who said yah! i can do this it looks easy!!!!

Only thing that scares me is screwing around with a perfectly good boat engine that starts and runs bitchin for what it is and its size.

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dont touch it. unless its to add a blower. 

Gonna pull carb and rebuild this week. Decided against my buddie's Holly, ain't nothin wrong with mine and no sense in trying to get more power, 400hp but a heavy turd that won't dry out anyway.

Pops says his '89 Hallett gots same carb as mine and he may/may not have a brass float and coffee can full of jets, anyway.. anything specific I need besides a rebuild kit w new gaskets, accelerator pump, needle n seat, metering gizzy blah blah..? Hope Napa or someone sells it so I can get it quickly, no dice at O'reilly. Does Rochester sell kits or Fo aftermarket? Never piddled with a carb I've only owned diesels and fuel injected and the last boat just ran so never dicked with it.. Seems like it runs rich cuz I smell a little unburnt fuel here and there, maybe supposed to be like that? Pops says go down a jet size and try out.

Spark plugs that came out looked good but were gapped around .0025, I set mine to 45 cause that's what pops said and he's got gray hair so I sometimes listen.. could the shy gap cause a "rich" running condition?

Sorry lots of jumbled questions just wanna get as much done as I can while waiting for my Eff'd up upholstery to be finished.

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Pulled carb and rebuilt today. Got the kit, Napa.

Good thing I took it apart, original float was disintegrating.

Turns out the main jets are not serviceable, kinda sucks but oh well. Put in a new brass float, accelerator pump, gaskets and whatever else could interchange with the kit.

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Rotten Chesters use different size metering rods, not jets....

Do you need to fatten it up?

Talk to me Goose...

No, was looking to lean it a shade. Thought I may have found my problem with the sunken float.. I backed off the accelerator pump one hole on its linkage to not dump so much fuel each time I flick throttle.

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Leave the accelerator arm where is was and go up one metering rod size...Does it run fat at WOT? that is really rare for a q-jet...Sounds like the plug gap was too tight and possibly to little timing...What ignition? What plugs?

The accelerator pumps on these are actually a bit inadequate, so in this case more is better, it will not cause it to run fat unless the check ball is FUBAR.

Where does it run fat? I love these carburetors, very tunable and they can run good, just need a little finesse.....

We will get through this bud, I got your back....      

GT

I almost always smell raw fuel when I come to a stop or if idling and a breeze from the stern. Boat runs fine.

Maybe just how carbs are? I dunno chit, but it always smells gassy with no drips and it FOCKING EATS FUEL.

Maybe I'm overthinking without enough understanding.

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I will tell you that idle fat has absolutely NOTHING to do with jetting....Purely idle mixture adjustment....

Get everything back together and I'll get you the 411. 

GT

Not HEI.. gonna set plugs to 35 thou.

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Does it have points? Or electronic? Gonna go out on a limb and assume electronic. It actually has a GM HEI coil from a late model style ignition system which could very well be .045", but .035" will run regardless.

GT

crate motor is a 93 marine power 454 sport-pac rated @ 390 HP... That's really all I gots. Internet seems of no help and engina owners manual just says its a Delco EST ign..

Edit: the manual does state .035 for plug gap, though I was advised by Google and a boat tech buddy to go .045..

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You should be at a .035" plug gap and 36*BTDC timing at 2500+ RPM.   

The two idle mixture screws should be adjusted to achieve a proper fuel mixture at idle, idle speed should be approx 850-900 RPM in the water and engine warmed up with the choke completely off then open (counter clockwise) both idle screws about a turn and a half (will run fatter than all hell) then slowly turn closed (clockwise) until the engine idle begins to fall off, then back out 2/3 of on turn. Do this a few times for each screw backing it out 1/2 turn each and go back and forth (left and right).

Altitude and fuel quality both have an effect, so keep that in mind when going to different lakes.

Good hunting.

GT

FWIW, previous guy had screws 2.5 turns out.

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A good starting point is 2.5 turns out, I guess I should have clarified that the turn and a half was after an initial starting point of the 2.5 turns, if it is too lean when you go to do your turns in it will die out and you get frustrated...

Good luck!

And does this thing really need a choke on it? It's got the heat riser dealy but even when its cold out the choke flap is almost wide open on it...

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GT, got your ears on?

Ok an update. Got the carb on and was gonna fire it to ensure it will start. On mine I have to use a jumper wire to the fuel pump to bypass the oil pressure switch to prime the carb. I jumped it and the pump sang and never built pressure to shut off. I look down the hatch and its dumping fuel down the throat! My float is set correctly and I think the pressure from the pump is forcing through the needle and bypassing everything. There is no pressure regulator, does this mean I need to add one?

This should definitely explain why I smell raw fuel at idle, not accelerator pump pushing too much..

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