Rochester Quadrajet Rebuild - 1986 GMC M4MED

Come along as I rebuild this old carburetor.
It is the original carb. out of a 1986 GMC Sierra.

[@user-dv8mc5cc7p]

Thank you Jay hawker! I am getting ready to tackle my belly acquired Rochester 4me.Your detailed video has given me the confidence I need To go for it. God Bless you too Pete

[@tcapo514]

This is the best damn Quadrajet video I have ever seen. I have watched at least 50 videos and this one is the best by far. The best part is that he doesn't insert any stupid music in his video.😎👍

[@edwardmartin3069]

Just about everything is easier to adjust/tune than a Quadrajet carburetor...BUT, once properly adjusted, Quadrajets provide more power more efficiently than just about any other carburetor around. The carb has adjustments for every phase of engine operations...and...they almost always need some tweaking to get right. Pay no attention to those nay-sayers out there who claim to be Q-jet specialists. Most of them just hate to have anyone de-mystify the art of Quadrajet mastery that they claim to have... I guess they are afraid of being slightly less special... You did a fantastic job of encouraging the common backyard car guy to not be afraid of tackling even the most daunting of chores to take care of their cars....

[@TheJayhawker]

Thanks a lot! I appreciate the kind words.

[@rooster68able]

Saw a guy put a brand new quick fuel 750 on pontiac 400ci dyno 360 hp with carb put back the old quaddrajet same exact power!!! I was surprised same graph lines on dyno down to 1 hp and everything

[@RT4Him]

Enjoyed this very much . Always been so nervous about taking a 4 barrel apart. I like the steps you take from disassembly through rebuild.

[@4xfava]

Thank you, I overhauled mine today using your video for instruction.

[@dantheman1998]

I always had a thing for quadrajets. It's one of the few carbs that are for fuel economy, driveability, and performance. Yeah there are carbs that do each individualy better but this carb had it all

[@briansd2772]

Well said.

[@spyguy7007]

a real carb man , going the extra mile. super job !

[@Cranedewd]

Seeing you look for your carb hammer reminded me of a time my dad and I were characters for a Hollywood Squares type game show at a Boy Scout camp. We were the O’lean brothers. He was Gas and I was Valve. Anyway, we dressed in bib overalls and I had a Quadrajet in one hand and a two pound sledge hammer in the other. Of course the hammer was to adjust the Qudrajet! We taught the auto mechanics merit badge at a winter camp outside Houston and had a blast. This was in the early 90’s and I just lost my dad at the beginning of May. Great memories! Thanks for the video!!

[@TheJayhawker]

Thanks for the comment, sounds like my kind of guys!

[@-ZIO]

Rochester Quadrajet. As in Rochester New York, home of the Quadrajet carburetor. Your Welcome :)

[@kevinpfaff2301]

Great video! Thank you Mr jayhawker

[@jimclarke1108]

Excellent work bud✌

[@DesertRatFabrication]

Great video, thanks for sharing. God bless

[@Texassince1836]

Thats an M4MED specifically. The tan solenoid isn't mixture feedback. When the engine warms up a temperature switch triggers that solenoid which opens a valve allowing some of the accelerator pump shot to leak back into the bowl. The "D" on the end of the model type is for "Dual capacity accelerator pump. Ive got the same one on my '86 and have rebuilt it a couple times in the last dozen years.

[@alexheppner9142]

I was going to say the same thing about the dual capacity accelerator pump. If left unplugged it functions like a regular one.

[@johnwallace5593]

Best video ever thank you sir

[@pq5005]

I just picked up the same one at the junk yard today.

[@briancarsen6315]

Anybody that calls a quadrajet carburetor junk is a fool! Best carb for economy while having decent performance and not having to rebuild it every year. I run q jets on all my chevy engines. They are a bit more demanding to rebuild but worth it. On your carb, you have a little electric connector on it that your pickup probly could plug into the factory harness to meet emissions. This works only when you have the computer hooked up. And it takes info from the HEI and I'm sure yours has extra connectors. That sets the electronic spark control up. Btw...I love your engine color! John 3:16

[@jamesduffus4455]

thats a cold start injector i have the same carb in my parts pile fuel mixture control solenoid replaces needles great vid

[@joanfrellburg4901]

For the idle mixture screws I take them out and put them in a vise between two blocks of wood, then with a hacksaw cut a slot in the middle so you can use a screwdriver OR braze a piece of steel tubing on them so you can adjust them with no tools required.

[@callmenortnortin467]

Quite the detailed rebuild. Lots of less detailed Q Jet rebuilds around .

[@ingles-pasoporpaso8697]

Lovvvveee thissss videooooo!!!!!

[@Texassince1836]

The "green painted parts" are actually Teflon coated for decreased friction.

[@Spiritof_76]

Teflon? Not epoxy?

[@glennpham2763]

When tuned correctly, Quadra Jets are quite effective.

[@rooster68able]

Forgot how many parts were in them they make a holley look like a mousetrap

[@320iguy]

I'm rebuilding a Rochester carb, from an 88 Camaro, and it has a little tab on the upper plate that operates a little valve. It's next to the little valve operated by the throttle rod, I can't find ANY info on it and it doesn't seem to fit the typical gasket set. Also, my needle set has a little plate that operates it rather then spring set. It's like a spring then a little plate sits on it, and that is how it operates. My question is, does this invalidate my gasket set, and should I look for the correct one? Great video, very informative and precise. Cheers!

[@jtp682]

very good video! I need some advice on something. I recently bought an 1986 chevy truck with a V6 4.3. It has a propane system on it and the original carburetor is no where to be found. I have a 78 quadrajet that I just rebuilt and would like to install it. the truck intake manifold is the original spreadbore quadrajet carburetor. Also this engine has the electronic spark control distributor without the vaccum advance. if I put this 78 carb I got on it do you think it will work just fine?

[@octaviofuentes7781]

I miss the part when he put the 3 fallen tubes back on the air horn other than that everything looked good( q jets are good carbs but a lot of people are afraid of them)

[@shortthings8160]

Why afraid?

[@georgegeorgoudis2749]

Hello Sir, God Bless and greetings from Australia. Fantastic video as always. Can I ask, what method did you use to secure the tubes in the airhorn that had fallen off. Was it Loctite, JB weld or some other method. Warmest regards, George (Bonneville 1960).

[@briancarsen6315]

I am curious as well on those tubes. No wonder if didn't run worth a darn... Great video with the play by play.

[@terrellscaife2411]

So what vehicles did they put this carburetor on?

[@callmenortnortin467]

Chuck it on an engine and lets hear that sweet QJet moan, lol

[@gregorydzieciol2662]

Question,in there a difference between any of the sbc timing covers ?which one requires the larger front oil pan seal from the felpro oil pan gasket set

[@Texassince1836]

The difference is the pan, not the cover

[@ilimikadventures5258]

Do you have a guide how to remove carberator from the intake?

[@terrellscaife2411]

Are you familiar with the carburetor on a 1986 Chevy Cavalier 2 L?

[@jtp682]

this is a very good video! I need some advice on something. I recently bought an 1986 chevy truck with a V6 4.3. It has a propane system on it and the original carburetor is no where to be found. I have a 78 quadrajet that I just rebuilt and would like to install it. the truck intake manifold is the original spreadbore quadrajet carburetor. Also this engine has the electronic spark control distributor without the vaccum advance. if I put this 78 carb I got on it do you think it will work just fine?

[@joshbohner1712]

You can delete that spark control system and throw a hei distributor in it with a vacuum advance then you would be good to go with less electronic crap getting in your way

[@TopGunMan]

At 47:17, the power piston assembly should not need to be held down, there is a plastic interference fit bushing that holds it in place.

[@jaedyn121501]

Do you rebuild carbs on the side? I have a 80s carb that needs a rebuild if your intrested

[@curtiswells8129]

Did you do the cad plating?

[@TheJayhawker]

kzbin.info/www/bejne/oaGymYmPprWEhsU

[@hkpoweralajmi5170]

Hi do you have rebuild electric one for my 1984 impala

[@jtp682]

hi there. found this video very helpful.. I was wondering if you can help me figure something out. I bought an 86 GMC V6 to restore but the carburetor was missing. It has the stock spreadbore quadrajet intake manifold. I have a quardrajet off of an 86 chevy 350 and I am wondering if this carburetor will work since it came off of a V8 and not a V6.. Somebody told me this carburetor would be "too much fuel flow", but I dont buy it. Can I use this carburetor on the stock 4.3 L V6? It seems to bolt right on..

[@TheJayhawker]

You may be on the verge of too much but why not try it? I honestly can't tell you what CFM they put on the 4.3's. Otherwise it would be easy enough to get a smaller Edelbrock or Carter and an adapter plate.

[@jtp682]

@@TheJayhawker thank you!

[@callmenortnortin467]

Why would you mess with that brittle accelerator pump seal right directly over an open carb you just put time into to keep it clean?

[@TheJayhawker]

Just being human. Thanks for watching.

[@felipeidarias2963]

Hi, great learning a lot you make it easy to do thanks.

[@ThickGrizzlyPanda]

Can I run that same model Chevy without the sensors on the carburetor?

[@Texassince1836]

Tan(grey) solenoid yes. Blue solenoid no, not reccomended

[@jimmypickle6557]

how much would you charge me if i wanted you to rebuild my q jet?

[@luisgarcia120410]

Can you rebuild mine 😅😭😭😭

[@emerybryant]

what would you charge to do 2 lol

[@emerybryant]

😳 holy shit you made it factory fresh. I dont need that. Just a basic tear down and clean up. 😅

[@ToddASmith-il3zt]

I am not sure I can do this.. need a better work bench

[@jamesroberts1800]

I honestly don't think he used the correct nomenclature for a single part. He only sealed the main well plugs, what about the other 3 ? I won't mention that he should have capped off the idle vacuum air bleed holes (we used double ought buck shot hammered in to do that) in the base plate so the idle mixture screws actually work correctly. Screw where the index is on the choke, what was the tension ? and how many degrees did the vacuum pull off crack it open ? Carbs are best left to the pros and I worked for the "Carb shop" in SoCal way too many years to ever take this video serious. Did he even know that the primary power valve adjustment screw sets the main jet mixture at both cruise and accel ? Certainly seems like a big no from here.....other wise he'd know to never move that screw unless something is very, very, very, wrong.

[@TheJayhawker]

It must be very difficult to be an expert at something and watch an ordinary guy do something not many people do anymore, huh. But let me reply to a few of your statements. If you have never made a public video you may not know that showing every single minute detail looses interest fast. As it was the video was already almost an hour long. Which was why I simply explained to follow instructions on making final adjustments. Also not talking down to people, but instead using language that they themselves can understand makes them feel included. Indeed I did seal all of the plugs, but only showed the main wells. Like I said I sealed everything... As for the pv adj. screw, it was out 3 1/2 turns, it goes back in to 3 1/2 turns....maybe I'm missing something... This carb had very old dried out gas in it everywhere and I wanted everything cleaned out within reason. It seems to me you're very anxious to share your knowledge but you don't share it well. Instead it comes out in the form of degrading put-downs. Perhaps there is a much more constructive way of sharing that knowledge and passing it on to the next generation instead of just trying to be insulting. Maybe you could begin by making your own videos. But instead, if you would like to share some of your knowledge with me, great, I love to learn from guys with experience. I'm learning all the time, I normally don't do mid-80's stuff. It's not where my main interest lies, but rather cars that are much, much older. But I'm willing to learn and to do it. So how about a little mutual respect man? Thanks for watching and God Bless.

[@kenswitzer4133]

I am not a pro but have seen rebuilding these for over 30 year and yes he is clueless.

[@M4MED86]

@@TheJayhawker I have an M4MED on my truck and know I couldn't rebuild one. And because of that,I don't think it's right for me to criticize anyone who does....or even attempts it!Watching you rebuild this thing was very impressive. By the time you took everything apart,there were more parts layin around than a chop shop,but you seemed to put everything back together w no issues. I'm guessin you tinkered w em in the past.😂 Keep up the great work and thank you!👍🏻

[@trailermonkey8687]

@@TheJayhawker Well said Mr. Jayhawker. I would be very interested in learning why we should "capped off the idle vacuum air bleed holes" and if that is something you perform?

[@Bill-xc8le]

Holley's are so much easier to rebuild and tune.

[@TheJayhawker]

I certainly agree, about any other carb. is easier. But in my opinion few are actually better.

[@Bill-xc8le]

@@TheJayhawker I’ve seen a guy at the drag strip run low 11’s with a Quadrajet