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Topic Review (Newest First)
11-17-2010 02:04 PM
Quadrajet [4MV] rebuild 'newbie' needs help

I finally got the gumption to try to rebuild my Quad carb. One reason, because it needed it. Pouring gas out of accelerator pump. And second, because I couldn't afford to pay to have it done.
After looking on Youtube, I found some very informative videos. These videos walked me through the whole process from taking apart to reassembly.
I put it back on my truck, and it fired right up, running smooth as I could hope for. One problem though...years ago the automatic choke went bad on it and I replaced it with a manual-pull cable inside of cab on dash. That was working fine, but when I reassembled carb after rebuild, I left 2 things off of choke linkage. Lockout lever, and cam follower.
Does anyone have a clear picture of how these 2 parts go back on? I know
someone is probably saying that if I could rebuild the carb, I shouldn't have any problem figuring out how these go back on, but I'm wanting to be sure that I don't end up having to take choke linkage off again because something is 'up-side-down'.
Thanks ! !

PS - I agree with Mertz ! !
Actuator rod can be a pain.
12-08-2009 05:42 PM
Mertz I would suggest that you not take apart the choke assembly unless you absolutely have to. Unscrew the screw that attaches the lever to the choke valve and the actuator rod. This will allow you to lift the top off vertically without having to disengage the rod. Make sure that you get the right top gasket. The kit usually comes with several and you need to match it exactly with the one you took off.

Your carb probably doesn't have an APT but I found a great way to set it for those who have one. I mark the depth of the top of the jet on the rod just above the top step with a permanent marker. Drop the APT in without the spring and adjust until the top of the mark aligns with the top of the jet. This will get you very close to having the shoulder of the rod in the correct position in the jet.

I have taken mine apart about 20 times now including several others I had laying around. It really is pretty easy once you do it once or twice and you know the tricks.
12-08-2009 04:22 PM
DoubleVision One thing I do to them all is when I have the carb stripped all the way down I take the main body, place it over a bucket and fill the fuel bowl and watch for leaks. Quadrajets are notorious leakers around the main wells. Many epoxy them and everytime I`ve did it and had it done even by guys who do it for a living like Sean Murphy, they still leaked. The solution is to flip the body over and restake the main wells with a small punch and a hammer, recheck for leaks and that`s it. It`s worked every time for me.
12-08-2009 03:47 PM
poncho62 Make & year GMC/Truck, 1975
Displacement/cylinders NA/8
Carb number 7045586
Primary jet & rod combo NA / NA
Secondary jet & rod combo NA / NA
Idle feed NA
Fuel inlet valve NA
12-08-2009 02:50 PM
jak327 for the bushings do i have to get the kit ($160) or can i use a normal drill bit and drill press to drill out the old bushings and put in the new if i make sure everything is lined up good?

as for the year im just going with what the year of vehicle its in. the carb is probably around 74 or 75 like you say.

12-08-2009 08:01 AM
cobalt327 Your carb is a ‘75-’76 CA emissions from a “Checker or Marine”. The exact type car it was actually used on might not be a Checker OR marine. Depending on what type choke and choke kicker(s) it’s equipped with and front or side fuel inlet would also be an indication of its actual application.

A couple tips:
  • Put a thin piece of metal (like a .045” feeler gage blade) behind the roll pin that connects the acc. pump arm to the air horn to prevent it from butting against the air horn. This will allow you to get a small flat blade screwdriver behind the roll pin to lever it back into position at reassembly. There are 2 sizes of roll pins used, 1/16" and the bigger one, ~3/16", so you will need some smallish punches.
  • Use a wide flat blade screwdriver to remove the needle valve seat. It’s wide and if the blade only engages one side it will bend and split it. Same thing w/the jets- there not too wide, but you want the blade to fit so as to not bugger the slots.
  • Be sure to remove the rubber coated steel washer under the seat- it will almost always stick to the carb body and can be hard to see that it’s there. Use a sharp pick to carefully dislodge it for removal.
  • Prolly the hardest thing is to align the primary rods w/the jets when you replace the power piston into its bore. This must be done basically blind- just be patient and you’ll get it. Don’t forget the plastic insert that surrounds the needle/seat- it goes in before the needles.
  • Check the tiny holes for being blocked that lead from the main fuel bowl to the secondary wells. There is one on each side, about 0.030” to 0.040”, IIRC. Don’t enlarge them (0.040” MAX), just be sure they’re clean.
  • Using the OLD check ball for the acc. pump (under a screw near the needle valve), reform the acc. pump seat by gently giving a firm tap to the check ball using a suitable punch and light hammer. This will ensure a good seal of the new check ball to its seat.
There are many more things that could be mentioned, but these couple things will hopefully help it to go back together easier for you.

Good luck.
12-08-2009 07:19 AM
Hippie It's not "hard" but there are a few tips that you need to know and to try and diagnose your carb over the internet would be a guessing game. Go on eBay and pick up a copy of "Rochester Carburetors" by Doug Roe. I've seen nice used copies for under $10. He was one of the GM engineers that helped design it. It has everything you need to do a good rebuild or performance mods. I bought mine 25 years ago and I don't let it out of my sight.

Another good one is "Rochester Quadrajet Carburetors" By Cliff Ruggles. It's much newer and I haven't seen it that cheap, usually around $20 plus shipping. I just got a copy and haven't had a chance to really get into. So far I prefer Doug Roe's by a slight margin but it hasn't been updated since 1987 and the Ruggles book has some newer info. If you can I recommend having both.
12-08-2009 07:18 AM
poncho62 It's not that hard, if you have done a 2 bbl Rochester, its quite similar....Just lay out your parts so you know how they go back

BTW, I dont think a carb beginning with a "70" is a 77.....Around 74, I think they started with the 170 serial #s...Yours would be older, I believe
12-08-2009 07:02 AM
malc While I had a Quadrajet this book Rochester Carburetors by Doug roe was my bible.
Here´s a picture guide at CHP, and you´ll need a throttle shaft rebushing kit.
It´s not at all difficult, take pictures/notes as you disassemble the carb, and as they say assembly is the reverse.
12-07-2009 11:17 PM
i could use some quadrajet rebuild tips

i could use some quadrajet rebuild tips. ive been told its pretty hard. but i dont have the money for someone to rebuild it for me, so im doing it myself.

i have rebuilt a 2 barrel carburetor before and didnt think it was too bad. but that was the only carb ive ever rebuilt.

so i could use some tips, what not to do, what to do, and so on.

this is a 7045586 quadrajet carberator from a 1977 chevy 350.

the problem im having is its leaking out where the secondary shaft goes through the bowl after the engine is wormed up and down the road a little bit.


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