qyadrajet running way rich..how do i fix this?

[soup0027]

quadrajet running way rich..how do i fix this?

angine is running way too rich. 305 merc with a NEW quadrajet 4 barrel. Idles good and steady. I know the carb is not adjusted right. Took it out and when you get on it it bogs way down. Now if i have the spark arrester and hatch off it gets goin a little better as its getting more air. I pulled the plugs and they are black. Confirmed firing order has all new ignition parts, idles perfect. what do i adjust and how do i do it. Im thinking the float is out of whack.

 

[OldSkool]

There should be 2 adjusting screws in the front of the carb down low by the base. They may have plastic caps over them. Remove the caps and start the engine. While it is idling carefully screw the adjusters in until the engine begins to run a little rough. Now back the screw out until the engine begins to run smoothly again. Do the same to the other adjuster.

Check out this site for more adjusting tips.
http://vetteworks.tripod.com/qjet.htm

These adjsutments require a degree of mechanical ability so take care when doing them.

 

[techmitch]

There should be 2 adjusting screws in the front of the carb down low by the base. They may have plastic caps over them. Remove the caps and start the engine. While it is idling carefully screw the adjusters in until the engine begins to run a little rough. Now back the screw out until the engine begins to run smoothly again. Do the same to the other adjuster. This should help set the carb and remove the bog down caused by sudden over fueling.

These are for adjusting base idle mixture only. i recommend that you start with checking your base timming and the mechanical advance operation. After that if you still have the same problem I don't know if you have vacuum or mechanical secondaries on that carb. but maybe an adjustment is in order. Please keep us posted on your progress.

 

[soup0027]

the base idle is fine, one thing i do want to question is adjusting my secondaries (large plates?) it has vacuum secondaries but there is a little screw behind the linkage that i think can be adjusted. read somethin about how you can adjust it to change the timeing in which it opens up...somethin like to match the primaries. running it at wot with the hatch off i look down at it and both the choke plate and secondary are open all the way. like i said with the hatch of it runs better so its hard to see a problem. what effect would adjusting that little phillips head behind the secondary linkage?

 

[techmitch]

Three questions:

What was the problem that led you to replace your carb.?

Did your original carb. have vacuum secondaries?

Do you know for a fact that your base timing is correct and that the mechanical advance is operating properly?

 

[JVM225]

I had a similar problem with one of my re-manufactured carbs.
One of my carbs was shot so I figured why not get two nice re-manufactured ones. I had good intentions.
One of the re-manufactured carbs was so bad that I put the good original back on and returned it. The other re-manufactured was bogging out. I had a friend keep an eye on it while I ran the boat. He saw where the rod that opens the secondaries was hanging up. We stopped the boat, gave it a little twist with a needle nose pliers, and it runs perfectly now.
So much for re-manufactured carbs. They looked real pretty, but that's where it ended.
The funny thing is that the company I got them from advertises how they set them up for your motor and actually run them on a motor before they ship them to you. It's a load of crap!

 

[soup0027]

needless to say there has been an ongoing issues to get this thing to run right. long of the short it just started kinda running crappy and ive been scratching my head and replacing parts ever since. i will check timing but dont know how it woould become off in the first place. i did a full tuneup plugs wireds cap rotor coil fuel pump and then the carb last and now i cant seem to get it right. the carb i got is a replacement of my old the only noticeable differences were the switch over to electric choke which seems to be working and the j hook on top of the carb other than that the same.i think the carb gasket might have been thicker than the original one. this evening i checked float level and its good.n i will check timing. what should it be set to at base idle....800 rpms or somethin that how much before tdc?

 

[KRB64]

Not to make lite of your situation but maybe you need to change the boat's name to something less ironic?

I know these things are very frustrating, been there done that. Seems like I'm usually chasing the wrong trail though and find out I was way off from what I thought the culprit was.

Good luck.

 

[Lady Ashley SR560]

had a qjet on my 69 firebird... If i remember correctly.... some of the carb needle/seats adjust oppisite or backwards compared to most carbs.

 

[1956olds]

Hate to say it but mabey it will be cheaper in the long run to find a " good" mechanic that can troubleshoot ,some just point and click (parts changers ) and can cost a lot more money than necessary.

 

[myersb]

Re: quadrajet running way rich..how do i fix this?

Are you sure it is firing on all cylinders? Did you check all the plugs? Were they all black. The only reason I am asking this I came across this problem last year with a friends boat. Same problems other than number 1 cylinder was dead. It idled fine but when running wot the engine just seemed to bog. Found a blown head gasket. Repaired and now the boat runs fine.

As for your new carb. Are you sure it is a direct replacement. You could remove the secondary metering rods and check to see if they are the same as the original.They should have numbers stamped on them.

Can you give us a little more details on the history of the changes?

 

[testlab]

I was reading this and thinking back to when I used to modify a lot of GM small and big blocks in the 80s. Never had much luck with reconditioned carbs as often the core part it was rebuilt from had different jets, rods or other tinkering done. The recon shops didn't flow test them or set up the metering (usually).

You may need to pull it apart and compare the jet sizes with what was fitted as standard for that engine (of the exact same spec).

I think myersb is right.

 

[Monaco II]

Over the last year I've been tinkering with my carb, purchased a rebuild kit, mostly because of a bog when hitting the throttle really hard, i.e. pulling up a skier. I found that adjusting the air valves helped a lot in my case, these are the valve/flaps above the actual secondaries. This is an adjustment on mine is 1/2 a turn and on some 3/8 turn depending on your model. My understanding is loosen the allen screw (set screw? this screw is facing down) while holding the adjustment screw (otherwise it will turn out from the spring pressure) loosen screw (count the # of turns if you are like me) then turn it in until you feel the spring tension start, then go in an additional 1/2 to 3/8 turn. This helps to hold the secondary's from opening too quickly (but I'm sure with too much tension they would have a poor result as well). Would seem that this may take some fine tuning to get correct as "feeling the spring" is difficult. I understand that this can also be adjusted to a certain tension, but I haven't gone that route yet. I found a utube vid on it from a kid and it's helped me alot, of course the rest of your carb needs to be adjusted correctly first. There's nothing like knowing your boat inside and out. Good luck.

 

[soup0027]

so i think ive figured out and fixed the problem. i checked the float level...all good. checked timing...all good. I pulled the secondary mettering needles out of my old carb to check the size. Than i pulled the ones out of the new carb, and they were noticably wayyy smaller. So since i new it was running way too rich so i switched them out. I dont know how they rebuild these but the sizes were way off and the carb was running way to rich on the secondaries....now it runs much much better. does this sound like a reasonable fix. i didnt write down the sizes but assumeing the the old ones are bigger and create a leaner mixture thus the better performance..?

thanks for everyones help

 

[testlab]

That sounds exactly like what I was mentioning above. It used to happen all the time and its not surprising since the same carb can fit a multitude of engines - so I guess they clean them up, replace what needs it and put them on the shelf.

The correct size means better performance. Too small = too rich and poor performance; too big = too lean and overheating, detonation and other nastiness.

 

[sprink56]

If the secondaries are opening too quickly you might have a faulty choke unloader or dash pot...it's the small round gizmo on the starboard side of the carb. You might also have a vacuum leak.

You might try this site out as a resource :http://www.cliffshighperformance.com/

Cliff Ruggles is a Q-Jet expert and supplies custom parts and re-build kits for marine Q-Jets. i was having a similar problem on the starboard engine in my Formula. Installed the marine kit specific to my carb and it has instant throttle response from idle to 5000 RPM.

Good luck with this.