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carbs


kaybyrd's Avatar
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03-15-02, 01:11 PM   #1  
carbs

I just rebuilt the carb on my 79 chevy blazer, full sized, 4wd. Lots of folks have told me that to rebuild a quadrajet was foolish. It's running rich again, and cannot be adjusted past it. Even had a real mechanic check it when I was done, said all was good, but also stated that I prob should get a new one. What kind, and not expensive. I be po' right now.

Any thoughts?

Oh, 4 barrell, 350.

Thanks.

Kay

 
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03-15-02, 01:15 PM   #2  
Joe_F
The problem may not be with the carburetor. The timing, ignition and mechanical conditions of the rest of the vehicle must be in order. A car with a worn timing chain or other mechanical troubles will not run right even with a good carburetor.

That being said, if you rebuilt it and it checks out, it probably needs adjustments. Whoever told you rebuilding a Q-jet was a bad idea probably has no clue how to rebuild one, so discount that person's opinion. A Q-jet is the best carburetor for a street vehicle, hands down.

The mechanic should have put the truck on a gas analyzer and adjusted it accordingly to lower the emissions and tune it for performance. If he doesn't have access to it, choose a shop that does and go from there on getting it to run right.

Also make sure the choke is working right. I suggest you pick up a shop manual or Doug Roe's book on Q-jet carburetors to guide you. Both excellent references.

 
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03-15-02, 01:21 PM   #3  
After I rebuilt the carb I took it through inspection in Memphis, TN (I know live in Miss. where if the horn works, you pass). About a year before that I had the lifters replaced, timing chains, gears, etc. Had a pro do that one. Wasn't sure how to do that, plus lived in an apartment and didn't think they would appreciate me doing this in the parking lot.

I rebuilt it because the float was bad and was diluting the crankcase. It's not doing that now, but it does run rich. Fuel is getting into the crank case, but not nearly as bad. Takes a few months before I can even smell a trace in the oil, by then it's oil change time anyway.

Guess I needed to go back to school and learn to work on carbs, huh.

Kay

 
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03-15-02, 06:05 PM   #4  
If you're getting fuel in the crankcase, it's probably due to a break in the diaphragm of the fuel pump. The float on most Q-jets is not hollow, and won't fill with gas. The needle valve could stick, but that usually causes massive flooding. I bet you just need a fuel pump.


"Who is John Galt?" - Ayn Rand (Atlas Shrugged)

God bless!

 
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03-15-02, 06:13 PM   #5  
cheese,

i'm glad you said something about that. i changed the fuel pump not too long ago, and guess i didn't get it screwed in good an tight because one of the bolts backed out somewhat. i retightened it, but did not realign the rod inside. now it makes a clicking noise.

thank you, thank you!

kay

 
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03-15-02, 08:58 PM   #6  
Carb

Kay first let mr say I am not a big fan of the Quadrajet I like and can tune the Holleys to a T. Having said that there are 2 large problems with the Qjet 1. When you rebuild them you must install a neopreme filler into that center part that is in the bottom of the main body called the main jet well.

It has allways been a big problem with the Qjet. The Standard Carb rebuild kit used to put one in but that was a long while ago. You can still buy them and fit it up into the center space before you install your throttlle body, the lower part with the round moveable plates.

the symtoms are gas leaking out of the main jet plugs into the vac passages causing an overly rich condition. 2. the Primary throtle shaft wears badly causing an uneven and unresponseve adjustment to idle settings. A carb shop can put bushings in for less than $100.00.

Do you remember putting a thick black rubber, looks like a triangle with corners cut off up into the bottom center well before puting the main body together with the throtle body?

Almost all the Qjets I have rebuilt had leaks in this area. They ran rich no mater what jet or nedle setting you used.

On everyone that we check today the primary throtle moves up and down You might want to check this. Only when it gets real bad will gas leak out. This most often causes a lean condition with poor idle.

One thing to remember is back when the muscle cars ruled the road one of the first things done was to replace the Qjet with the much more tuneable Holley. I know some will disagree with me but I saw all those new Qjets piled up in the coner of the shops I worked in. In alot of cases the shop owner would just give them to anyone who would haul them away.

One large problem is the Q jet is a 750 CFM Carb while you can get a 600 to 650 CFM holley. If you were runing let's say a 427 big block tricked out you would want a 750 CFM Holley.

I have a tricked out 350 and will never come close to using all of my 650 CFM that my Holley 4175 list 8100 has to offer.

Any good Holley manual can teah you to tune a Holley. I learned a long time ago the little tricks of how to do it, and fliping through the Holley book at advance Auto I could not believe my eyes. Right there in black and white were the tricks I had taken a lifetime to learn.

I hope I helped you some. If you chose to go Holley let me know and I can help you mucho! Marturo

 
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03-15-02, 09:22 PM   #7  
Nope, don't remember the triangle deal. This is the first carb I've rebuilt since school. That one I had an instructor right over my shoulder so that doesn't count. It was a hard one, too. Shouldn't have tried that one first, came out of a Chev Luv aka Isuzu pup with a Chevy logo.

Okay, if I were to go Holley, how do I choose the size? My brother in law put one on his car, and it never ran right. Something about it being too much for his Firebird.

Something else that I might point out, this is not only our family station wagon, it is also my mud truck. I don't do a lot of serious mudding in it because I get tired of fixing the things I tend to break. New brakes, tie rods, repacking bearings and ujoints I can do today with my eyes closed. Usually, I take it in to have the joints replaced since it is a major pain in the tail and I don't have the patience. I also have the front and rear end serviced at the shop. Anyway, I do need gas mileage better than 5 mpg, but know that running 33's on it uses more fuel. I do more pulling people out of the mud, than getting myself into it. Don't know anyone who's big enough to pull my truck out, and where I go isn't exactly legal or wrecker friendly.

I use the truck mainly to run to Sam's and to take out of town trips. We use the Cavalier for simple around town trips. This makes this truck complicated for me. Lords knows I'd love to lift it, and throw some real mud tires on it, but like I said, family station wagon, hauling bikes and grills, and the like.

All this needs to be figured in on the carb and what I'm looking at. Hate to go less powerful and get myself stuck somewhere trying to unstick someone, but don't want to get worse gas mileage than I already do. Currently I'm lucky to get 10 mpg, maybe better on longer trips.

Thanks and sorry for the long message.

Kay

 
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03-15-02, 11:12 PM   #8  
1979 Chevy Blazer

The part # is 0-80128 Spread Bore Part # Street legal.
Or the parts store will call it LIST R80128. It comes with #58 main jets. This is where the rubber meets the road. You will get a Mr.Gasket 4 hole base gasket not one that has a big cut out. You want the primaries seprate than the secondaries. You will buy the Secondary Diaphragm spring kit P/N 20-13 you will have the heaviest spring a black. I use the short yellow you might not.

Your main jet that cmmes with it is a 122-58 or size 58. I use a 122-62 or a size 62. Unless you have put a hotter cam in like I did your Power valve will not need changed.

Please get the HaynesTechbook (HOLLEY Carburetor Manual. I got mine at Advance Auto. The ISBN # is 1 56392 069 7 any book store will be able to get that #.

Did you learn about reading spark plugs?

You must change the secondary spring or the Carb will only every be a 2 barrel. Lawers have made the world safe for the Companies eg. Go buy a remmington rifle today and the trigger pull will be over 10 lbs Most rifle shooters use 3 or 4 lbs but then you changed it. Holley puts a spring in that won't let the secondaries open, you change it to yellow,but then you changed it. When we go to court all the lawyer for the Company has to say, in case of an accident is, YOU CHANGED IT and they win. See how that works?

Ok so now that you understand that, you see now why you hear, well I bought a Holley for my car, and it never ran right.

You may or may not have to change your main jets. You will have to change your secondary spring.

You will need to buy a pureolator fuel pressure regulator and set it on 3 PSI. it installs in the rubber fuel line after the fuel pump before the carb. If you have steel line all the way up from pump to carb cut with tubing cutter leave 4 inches of steel from carb and cut out at least 8 inches of steel line and replace with rubber fuel line. Put the fuel regulator in the center of the rubber line. Allways use a good can type fuel filter before the fuel pump not after.

When you get your Holley jetted and the right secondary spring installed you will have beter gas milage and more power than you will believe that 350 had in it.

I get all my holley needs at http://www.summitracing.com 1- 800-230-3030 Their sales people are great and if you don't see it they can get it. they also have a great Tech line.

Please get the book right away. If I told you that you could change jets by removing 4 screws and then your looking at them. Well could you do that with the Qjet you just rebuilt? This is why I like Holley so much everything is compartmentlized for ease of tuning. Once you get it right thats it. One more note and this is very important. At one time there was a company Standard Motor Products. Makers of the famed blue streak electrical parts and the best Carb rebuild kits for the Rochester Carbs +.

Some years back they were bought out. I did not know this and my son had his first truck. Of course when it came time for a tune up we went down to the Auto parts store and Dad said get the Blue streak points Cap & roter button. He did the tune up himself and was so proud.

We took it on a test drive and all was well at first then it started missing and we hardly got it home. I opened the hood with it running and watched the Distributor cap wobbleing around. Shut it off I yelled. I took the cap off and what the#%&$
the rotor button tip had come foward cutting a grove all through the contacts and cap.

Over the years in the shop I had bought spares for Chevys that I knew I would own and need in the future. When I compared my NOS ( New Old Stock) with this new BS they had glued the metal part of the roter button instead of the brass rivet they had used in past.

My point I am sorry to say is the once great Standard Carb rebuild kits today are no better than the cheap Tomco Carb kits of yesteryear. Holley makes the best Renew Kit on the market today. This is not just my opinion but that of many Mechanics today. I miss the Blue Streak and those heavy duty Standard Carbs kits and have written them many times to no avail. Good night all Marturo

 
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03-16-02, 08:09 AM   #9  
chadtoolio
Back to the original post..

Have you rechecked the float level????

If set to high it can let fuel spill right over the top of the fuel reservoir and down the throttle bores..

Or even a bad float..

A rich running vehicle can even contaminate the oil with fuel and when the sucks the vapors out of the crankcase via the pcv valve it can cause it to run slight rich. If not, still wouldn't be bad to change the oil...

Good luck

 
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03-16-02, 09:42 AM   #10  
Float Level

I agree with you on the float level, but I think Kay probley checked that right. This problem with the lower main jet area in the area below the jets is legendary.

Qjets have this problem, and before the well filler was a standard part of any quality rebuild kit, we made the ourselves with thick neoprem.

I have installed and tuned hundreds of Holley carbs with great results. This has to be your decision Kay. You can recheck the float level and install a well filler and probably get the Qjet back to what it was before.

Look the guys & Gals who trust me with their engines on the restored 67 to 72 Chevys are well aware that the Holley is not the standard carb for their cars & trucks. They also are car and truck affectionados. The last thing most want to do is put a non standard part like a Holley instead of the Qjet.

However we want to drive them and have fun. The amount of money you will spend to get the shaft bushings fixed, a lack of a quality rebuild kit and the allways even stufed leaking wells. Well you do the numbers and I haven't even touched on the fact that the Rochester Qjet is and has been out of business for a long time.

Kay I realy thought one car daddy from the daze would have come out of the shadows by now. Just say yes I owned a 1969 SS Chevelle with a 396 4 on the floor, and took that D&%$ Qjet and tossed it for a HOLLEY and blew the doors off of those FORDS & MOPARS. Where are you guys and Gals ???????


I am hanging out here and to think I worked FLA NY GA OH I raced Motocross in the late 60s early 70s AKA Mike the MAD MAN. I probably worked tuning your Bike or Muscle Car until you could not stand it. OK I stand pat. Marturo

 
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03-16-02, 09:50 AM   #11  
chadtoolio
Whos yo Daddy?

Not a 69 chevelle, but have a 82 olds with a smallblock olds motor, high rise intake, ceramic coated headers, and a HOLLEY double pumper!

Well at least before I cracked the ring lands on the number 3 piston....

Very tunable to any situation, millions of trick parts.

But requires some experience and time to get them right, but the best carb by far.

And yes, it did have a Q-jet on it first!

Is that better Marturo Baby! LOL

 
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03-16-02, 10:56 AM   #12  
Who loves ya baby?

Chadtoolio
Ya Made my Day
Hey I saw your post on the brake fluid. Do the BMWs come standard with dot 5 Silicone now? We used it in the Porsches because Dot 4 would boil out. I have been using it in every complete Hydralic rebuild for about 10 years now!

82 Olds nice ride. How long before you get her rolling again?

Hmmmm I wonder how he cracked those ring lands, Bet I know, slaying a ford yeah! LOL.

Marturo

 
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03-16-02, 11:02 AM   #13  
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We still use dot 4, and as for the olds, she's been running with a stock 307(boo) since the piston incident..

Need another vehicle so I can take her off the road and get some motivation. LOL

I cracked the piston when I overheated one day 110 degrees outside, going to the dragstrip..

 
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03-16-02, 11:25 AM   #14  
Ugh!

Hey Kay
Are you still here? Throw a wrench over at us, let us know what you think. Oh I bet shes out puting that holley on. I wonder what she ment by, she goes mudding & she better not end up with less power. Hey Kay I have a Cousin over in Memphis, I will give you his name and Addy, you can whop up on him. If that Holley dose'nt work better than that ol Qjet.

He is a Mechanic somewhere in Memphis, you know how mechanics are. Get um mad they throw tools at the boss, and were lookin for another job LOL

We both did some dirt track racing, back in Little Rock in the early 70s. What a lot of fun we had riding our bikes under Memphis, there is a whole tunel system under that City.
Marturo

 
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03-16-02, 03:40 PM   #15  
Joe_F
Get some books at the library and learn through those.

Also, you should put the truck on a gas analyzer and see what is coming out the other end.

Holley carbs are leakers and fuel dumpers over time and you'll lose fuel mileage on an already voracious engine. A Q-jet has much smaller primary bores and gives better fuel economy than any Holley.

Not to mention Holley blow power valves...not a problem in Q-jets .

The issue Marturo speaks of regarding leaking is easily fixed.

That being said, I agree with Chad and Cheese on what they mentioned.

And Marturo too, except for the Holley bit .

 
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03-16-02, 05:55 PM   #16  
not throwing wrenches over here.

Hey guys, before I start changing the carb on the truck, i still want to check and see if the rod in the fuel pump is off. Like I said earlier, I retightened the fuel pump after a bolt came loose and then it started sounding like a rod knocking (quieter tho) in the engine. It's the fuel pump. May go ahead and replace it again, it's only $10. It's been raining here, I have no garage so it will wait until the rain stops before I check that. I may just be dumping extra fuel into the carb from the pump. Would be nice if that's all it is.

Will consider the other carbs after I know for sure what's going on with what I've got. I really love my truck for many reasons, but am not into the mudding thing as much as some are. Earlier I said that I'd love to jack her up, and send her into no-man's land, BUT it's what the family uses to travel with. There are 6 of us, 4 kids, 2 of which are teenagers. It's the only thing big enough to hold all of us and our essentials. This is why I don't want to put a fuel hog carb (extra power for mudding), but don't want to put a sissy carb (station wagon mode) on it either. I also hate to have to keep replacing what I break. I'm rough on it when in the mud. Nothing like that feeling guys! Nothing, well...that's not all true. It's a high better than any drug or drink.

I don't mud much, here in Southaven it's illegal and you will get arrested or shot. More likely shot if youre on someone elses land. The last place I went mudding was Austin Peay bottoms (Memphis). Tore the fool out of my truck pulling a buddy out of the river. He couldn't help (truck transfer case jammed in not working in any form or fashion) and was a newer truck with no tow hooks or spots underneath. Hate jerking people out especially when I'm hooked up to suspension. It's odd to me down there. Seems half dry, half wet, then pure wet. What's under the mud is the same, hard some spots and deeper mud in others. I end up walking in the mud testing the "waters" more than I actually do driving.

Another thing about the mud tires I have besides them being 33's, I set them on 12" rims to get my width (no extra height for clearance, just more tire to ground, hence a bit more traction). This has gotten me out of getting stuck like some I pull out. They're tall, but too skinny when it comes to traction. This effects the fuel mileage, too. Traction equals friction, friction equals resistance.

You guys are great. Love all the input. I may actually have a clue after sticking around here!

Kay

 
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03-16-02, 08:54 PM   #17  
Kay...that fuel pump shouldn't be making noise. There's not much you can do to align the pushrod for the pump. Makes me wonder if your pump is wrong, or broken. Does the truck run like it's rich, or you just have gas in the oil?

Oh... my 2 cents on the holley issue: I really like a Q-jet. They are quite dependable, and can be real performers. Seems like holleys always need to be fiddled with, but then again...I've never really learned that much about holley's, and can't relate to you any experience with them. My Q-jet on my '85 chevy truck lasted for 200,000 miles, started sticking on the secondaries, so I pulled it and rebuilt it, and it runs like a new one...maybe better, lol! Also, I can squeeze 19-21 mpg's on the highway!!! That is thanks to the small primaries joe mentioned. The secondaries are huge and will suck the gas, but they only open when you need them. Normal driving habits will rarely open the secondaries. This way...you get POWER when you want it, and economy the rest of the time. That is called a spreadbore design. Squarebore is where the primaries and secondaries are the same size. The spreadbore holley that marturo mentioned might be a good carb, I don't know. I'm stickin' with my Q-jet! No offense marturo!!....just a result of my experience.


"Who is John Galt?" - Ayn Rand (Atlas Shrugged)

God bless!

 
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