Rebushing Marine Qjet?

Discussion in 'The Venerable Q-Jet' started by MrSony, Aug 8, 2018.

  1. MrSony

    MrSony Well-Known Member

    I've heard conflicting answers, ranging from "it's a qjet, so yes. Duh." to "marine qjets don't wear like automotive ones do, not nearly as much time on them, etc".

    What say you guys?
  2. Cliff R

    Cliff R Well-Known Member

    We install bushings in them here. Common sense dictates that it is better to tighten things up in that area and add a bronze bushing so side play stays tight for the life of the unit.

    The factory tolerances were a little too loose for my liking anyhow.

    We do a LOT of them here, and a good percentage of them were just done somewhere else. Biggest problem I see is using the wrong parts in them, incorrect settings, not getting them cleaned out good, and crappy accl pump seal. The "soft" blue seals don't make the grade, neither does installing the small N/S assembly from a "generic" rebuild kit......FWIW......Cliff
  3. carmantx

    carmantx Never Surrender

    I agree with Cliff. We add bushings to every Marine unit. Most are worn and would leak. It is a fix for the life of the carb in most cases.
  4. techg8

    techg8 The BS GS

    It's a rare qjet that wouldn't benefit from the bushings in my experience.
  5. MrSony

    MrSony Well-Known Member

    This quadrajet also is missing the fast idle linkage... being as it's a marine carb, does it need it? Did it have it? I've seen some of the "reman" marine carbs with and without it, but for all we know they just painted a normal qjet black.
  6. carmantx

    carmantx Never Surrender

    From my experience, some had fast idle cam and some did not. So yours may be one that did not have the cam originally.

    GRNDNL Wannabe

    are they 750's or 800's?....They any better than non-marine q-jet's...
  8. MrSony

    MrSony Well-Known Member

    Most were based off of chevy style qjets, so I'd assume 750, I'll check mine, but it's just a guess.
  9. carmantx

    carmantx Never Surrender

    Like all Quadrajets, the marine units were calibrated for a specific application and use. They were 750 cfm capable. They are the best unit to use for a marine application. Calibrations are much different than auto use Quadrajet.
  10. Cliff R

    Cliff R Well-Known Member

    "I've seen some of the "reman" marine carbs with and without it,"

    I haven't seen a single Marine replacement carb from the companies selling them that was worth two squirts of duck poop. I get them sent here all the time and refuse to work on them. Instead we have the poor soul who invested in them get a real Marine Quadrajet core (or we'll get one for them) and build those instead.

    The main reason is that 0riginal Marine units are set up much different than their automotive counterparts and use different main components, calibrations, tuning parts, etc. Keep in mind that a Marine engine is working very hard most of it's life, and they weren't subject to emissions either.

    They will not use a distributor with vacuum advance, very few had PCV, and it's extremely rare to see a working fast idle cam and linkage on them. That is simply true because the operator had full control of engine speeds with Morse controls, so little to no need for fast idle at cold start-ups as the person starting the engine sets the warm up RPM. It's also dangerous to have fast idle on a Marine engine as there may be scenarios where you would need to fire up the engine and move the boat very quickly so wouldn't want to wait for it to warm up enough so the fast idle cam dropped out of the way so you could engage the Marine gear......Cliff
  11. TORQUED455

    TORQUED455 Well-Known Member

    I still recall the engineers at Rochester Products shaking their collective heads when after going through the special plating design and procedures for marine carbs and then the end user (Mercury Marine for one) would blast the outside of the carb with black paint! Nothing like adding paint to linkages etc and expect to keep the carb working well. Warranty must have been real fun under those circumstances.

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