Carburetion

« **Reply #25 on:** March 11, 2012, 05:22:40 PM »

not to beat a dead horse but this is why i dont like quadrajets. you have a float issue or something else stuck open take your screw driver handle and tap the float bowl as the fuel is dumping in it should stop! good luck!

« **Reply #26 on:** March 11, 2012, 06:27:09 PM »

Got a copy loud and clear Big J...Come back

What fuel pump are you using? $:-\$

I am thinking several things;

Please forgive the potential blunderings, I have spent the last few hours doing some much needed shop clean up with a very sore knee and have utilized some liquid frosty pain reliever, guess I go to the doctor tomorrow...

If you are using a "performance" fuel pump, you will most definitely need to use a regulator.

If you have to use a jumper wire to get the pump to run to get the pump to start, you have the switch wired wrong (should be a three prong switch with a signal coming from either a momentary toggle on the dash or a lead coming from "I" on the starter solenoid. More on this later....

The pump should run continuously and not shut off on any sort of pressure (unless this is a special type of pump with a cut out switch (don't think I have ever seen one...)..

Rochester carbs need no more than 6 PSI to work right...There is a chance that the needle/seat have a problem, but if you put as much pressure to the carburetor that I am thinking you did, there is no way it will hold it back (most electric fuel pumps can generate over 20 PSI without a problem...

Was this the pump you were using before...Too damn lazy (and a little tipsy) to go back and read the whole thread...

GT

« **Reply #27 on:** March 11, 2012, 07:08:51 PM »

Tis the pump that came with the boat from Ultra, see below. Can't find any markings or anything in owners manual 'yet' still looking. Wiring is stock I am guessing. Where oil pres sender is, there's a T with sender on one side, pressure switch on the other.

Brand new float, needle and seat and chit from Napa.

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« **Reply #28 on:** March 11, 2012, 07:09:24 PM »

All I know about the pump is not to step on it.

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« **Reply #29 on:** March 11, 2012, 07:14:05 PM »

Quote from: BIG JOHNSON on March 11, 2012, 07:09:24 PM

All I know about the pump is not to step on it.

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Hahaha!

You should be good with that setup..

Need to pull the carburetor top and take a look see..

I recommend ALWAYS pulling the carburetor off the boat, taping closed the intake and work on the carburetor on a bench (or like me, on the kitchen table

)..

Did you adjust the float height with the supplied paper gauge? Is there a possibility it did not go together correctly? Was the fuel coming out of the venturis or the accelerator pump ports?

GT

« **Reply #30 on:** March 11, 2012, 08:05:33 PM »

Quote from: GT Jets on March 11, 2012, 07:14:05 PM

Hahaha!

You should be good with that setup..

Need to pull the carburetor top and take a look see..

I recommend ALWAYS pulling the carburetor off the boat, taping closed the intake and work on the carburetor on a bench (or like me, on the kitchen table )..

Did you adjust the float height with the supplied paper gauge? Is there a possibility it did not go together correctly? Was the fuel coming out of the venturis or the accelerator pump ports?

GT

Fuel was coming from venturis. Brass float was set at .25" per instruction sheet. Pops, whom has owned 6 carbureted big blocks, and my marine tech buddy was at the bench with me. It was the correct kit for the carb.. I think I need to put a gauge on it and see what's pushin, or go around that and put a regulator in that line from pump to carb. Is that normal to not have a regulator?

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« **Reply #31 on:** March 11, 2012, 08:48:19 PM »

Quote from: BIG JOHNSON on March 11, 2012, 08:05:33 PM

Fuel was coming from venturis. Brass float was set at .25" per instruction sheet. Pops, whom has owned 6 carbureted big blocks, and my marine tech buddy was at the bench with me. It was the correct kit for the carb.. I think I need to put a gauge on it and see what's pushin, or go around that and put a regulator in that line from pump to carb. Is that normal to not have a regulator?

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Totally agree with checking the pressure at the supply line...And yes, that type of pump has a regulator in it..

GT

« **Reply #32 on:** March 11, 2012, 09:10:08 PM »

Quote from: GT Jets on March 11, 2012, 08:48:19 PM

Totally agree with checking the pressure at the supply line...And yes, that type of pump has a regulator in it..

GT

Float must be too high.

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« **Reply #33 on:** March 13, 2012, 12:44:25 PM »

Fuck this carburetor. Gonna go buy a Holley. I've checked and double checked lowered float... Fuel pushes right past needle unless I push the needle down with my thumb.

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« **Reply #34 on:** March 13, 2012, 12:46:28 PM »

It's hard to go wrong with holly

« **Reply #35 on:** March 13, 2012, 01:57:58 PM »

sorry man ! but there a real b---h to get right!

« **Reply #36 on:** March 13, 2012, 02:40:10 PM »

mine doin the same crap...

« **Reply #37 on:** March 13, 2012, 03:08:36 PM »

Quote from: BIG JOHNSON on March 13, 2012, 12:44:25 PM

**** this carburetor. Gonna go buy a Holley. I've checked and double checked lowered float... Fuel pushes right past needle unless I push the needle down with my thumb.

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x2 im real close 2 this same outcome

« **Reply #38 on:** March 13, 2012, 05:39:44 PM »

$35 Holley pressure regulator and a few brass fittings fixed it. My pump was putting out 8psi and I regulated down to 6 psi.

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« **Reply #39 on:** March 13, 2012, 06:27:11 PM »

Quote from: BIG JOHNSON on March 13, 2012, 05:39:44 PM

$35 Holley pressure regulator and a few brass fittings fixed it. My pump was putting out 8psi and I regulated down to 6 psi.

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« **Reply #40 on:** March 14, 2012, 09:50:40 AM »

Just a kind word of advice to anyone who has no clue and dinkin around with this stuff.. if you pull the top section of the carb off to see how your float is reacting to fuel influx, be sure and hold the piviot point between float and needle when you buzz the fuel pump. If you don't hold it down, the fuel will launch that needle and float off the carb. Gasoline burns like a bitch in your eyes and sizzles in your ear.

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« **Reply #41 on:** March 14, 2012, 10:34:09 AM »

So I'm told this carb doesn't require more than 4.5 psi to keep motor well-fed. Is this adjustment going to change with engina running or need to be adjusted at idle?

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« **Reply #42 on:** March 14, 2012, 01:13:16 PM »

Quote from: BIG JOHNSON on March 14, 2012, 10:34:09 AM

So I'm told this carb doesn't require more than 4.5 psi to keep motor well-fed. Is this adjustment going to change with engina running or need to be adjusted at idle?

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just my opinion but keep it at around 6 PSI (I thought I read you have a closed motor compartment), if the carburetors needle and float can hold it back with the engine off it will be fine...Lower than about 6 PSI and you run the risk of vapor locking the supply line at idle for long periods because of heat build up in the engine bay...

Rochester's have a very close ratio float assy., this is why they don't need the pressure. If you have a spring adjusted type regulator, the regulating valve will go wide open if needed to keep that 6PSI at the needle valve, so further adjustment should not be needed IMHO...I think you fixed it...Now go put that accelerator pump linkage back where it was, fill the fuel tank and the ice chest and go have some fun

....Sheese

GT

« **Reply #43 on:** March 14, 2012, 02:33:55 PM »

Quote from: GT Jets on March 14, 2012, 01:13:16 PM

just my opinion but keep it at around 6 PSI (I thought I read you have a closed motor compartment), if the carburetors needle and float can hold it back with the engine off it will be fine...Lower than about 6 PSI and you run the risk of vapor locking the supply line at idle for long periods because of heat build up in the engine bay...

Rochester's have a very close ratio float assy., this is why they don't need the pressure. If you have a spring adjusted type regulator, the regulating valve will go wide open if needed to keep that 6PSI at the needle valve, so further adjustment should not be needed IMHO...I think you fixed it...Now go put that accelerator pump linkage back where it was, fill the fuel tank and the ice chest and go have some fun ....Sheese

GT

Last thing I did was put accelerator pump back to max setting. Gauge sits at 6psi with motor off and needle holds it back. 7.5 psi is where needle gives way.

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« **Reply #44 on:** March 15, 2012, 08:40:53 PM »

Today's shakedown went awesome. Got only a small list to take care of.

I feel like I got 5mph more outa this thing with the major fuel fix and live timing adjustment. (it was redneck but it really free'd up the motor.)

No one in the guard shack at Elsie so free launch to boot!

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« **Reply #45 on:** March 17, 2012, 01:14:15 PM »

Just for your info, Quadrajets are known for leaking fuel from the bowl thru the throttle plate. There are a set of casting plugs in the bottom of the fuel bowl that over time can leak. The fix is to use 5 minute epoxy and seal them.

« **Reply #46 on:** March 17, 2012, 02:06:03 PM »

Quote from: torquer460 on March 17, 2012, 01:14:15 PM

Just for your info, Quadrajets are known for leaking fuel from the bowl thru the throttle plate. There are a set of casting plugs in the bottom of the fuel bowl that over time can leak. The fix is to use 5 minute epoxy and seal them.

In this case it was pushing the needle open no matter how low float was set. I'll be on the lookout for anything else that may start to leak such as you mentioned.

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« **Reply #47 on:** March 25, 2012, 04:30:02 PM »

Boat runs like a pink scalded dog. Only thing I encountered this past weekend in Parker is when idling, if I smash the throttle and hold it down I get a lil bit of pop-pop noise from exhaust and slight hesitation. If I roll into the pedal, then mash it, its fine.

Here again, before I put the regulator on it was constantly leaking fuel from venturis, so it always had more than ample fuel supply. Will any adjustment of air screws be the fix? I know GT mentioned the accelerator pumps on these are inadequate... I doubt its timing related, could be altitude as it didn't do this at Elsinore on the shakedown cruise. FWIW, the engine will turn 5-5200 rpm with no detonation/pinging and doesn't miss a beat except from idling to stabbed wide open.

Next time out I will back timing off and rule that out and fiddle with the air mixture screws though I have no clue what those screws effect.

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« **Reply #48 on:** March 25, 2012, 04:50:41 PM »

Quote from: BIG JOHNSON on March 25, 2012, 04:30:02 PM

Boat runs like a pink scalded dog. Only thing I encountered this past weekend in Parker is when idling, if I smash the throttle and hold it down I get a lil bit of pop-pop noise from exhaust and slight hesitation. If I roll into the pedal, then mash it, its fine.

Here again, before I put the regulator on it was constantly leaking fuel from venturis, so it always had more than ample fuel supply. Will any adjustment of air screws be the fix? I know GT mentioned the accelerator pumps on these are inadequate... I doubt its timing related, could be altitude as it didn't do this at Elsinore on the shakedown cruise. FWIW, the engine will turn 5-5200 rpm with no detonation/pinging and doesn't miss a beat except from idling to stabbed wide open.

Next time out I will back timing off and rule that out and fiddle with the air mixture screws though I have no clue what those screws effect.

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Need more accelerator pump....One redneck fix would be to slow down the secondaries just a wee bit....In all honesty it sounds as though it is running pretty stout..

To attempt slowing the secondaries it is a bit of a touchy adjustment, so in water testing would be paramount. There is a really small spring in the upper secondary butterfly that has a very small allen screw holding the shaft that has a small roll pin retaining the spring end. If you turn this pin with a small screw driver you are adjusting the secondary spring tension and allows the "fuel to catch up with the air" so to speak.

I have also had some success cutting some transition slots into the upper secondary butterfly, but this gets really touchy, especially given yours seems to run pretty well as it sits.

Fiddle slightly with the tensioning spring but be sure to mark it before you begin so you can get back to where it is now if things don't work out. If memory serves (rarely does) I always used 7/8 of a turn from touch on that shaft....

Good luck, sounds like it's pretty close to me...

GT

« **Reply #49 on:** March 26, 2012, 09:53:51 AM »

Quote from: BIG JOHNSON on March 25, 2012, 04:30:02 PM

Boat runs like a pink scalded dog. Only thing I encountered this past weekend in Parker is when idling, if I smash the throttle and hold it down I get a lil bit of pop-pop noise from exhaust and slight hesitation. If I roll into the pedal, then mash it, its fine.

Here again, before I put the regulator on it was constantly leaking fuel from venturis, so it always had more than ample fuel supply. Will any adjustment of air screws be the fix? I know GT mentioned the accelerator pumps on these are inadequate... I doubt its timing related, could be altitude as it didn't do this at Elsinore on the shakedown cruise. FWIW, the engine will turn 5-5200 rpm with no detonation/pinging and doesn't miss a beat except from idling to stabbed wide open.

Next time out I will back timing off and rule that out and fiddle with the air mixture screws though I have no clue what those screws effect.

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Your pop-pop likely means you're a little lean in the power circuit. To eliminate it, you'll need to richen up the primaries a bit by changing your metering rods and/or power spring. Unless you're lucky and someone has already modified the power spring circuit with an external adjustment (unlikely). Does it have a small allen set screw (plug) on the top of the carb?

The idle mixture screws will only affect idle mixture. Set them for maximum (smoothest) rpm at the desired idle speed.

Sounds like you're real close. Make small changes from here on out. Good luck.

mobboss

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