I have a Holley rebuilt Q-jet carb in my summit racing basket ready to buy it. I was seaching through post in here looking for more info and I read this post from "Lars" about this nightmare of a mess he found in a holley rebuilt q-jet. I have picked up in here that he is the carb god so I sure dont feel good about buying this carb now. What the heck can I do? I just need a good performing carb to fit my stock spread bore intake. stock motor, 4-speed. Anybody have ANY suggestions?

 

i recently installed the Jet Performance Stg.2, quadarjet on my L82, it works perfect, smooth idle and excellent throttle response, you may want to talk to these people also.

http://www.smicarburetor.com/product.../productID/836

http://www.jetchip.com/JET_Carburetors.asp

 

Lars has stated on this Forum that the track-record for "factory" rebuilders to put a Q-jet together correctly is poor...they'll probably work, but not well. If you presently have a Q-jet, you could rebuild it yourself so it would be correct (at least, per expert advice and instructions via blogs or manuals). If you choose to purchase one, try it to see how it works (performance, fuel economy) and if it isn't right, then disassemble and correct it. At least you should have all the parts (hopefully).

 

The Jet Performance carbs have a good reputation, but I agree with 7T1vette, build your own! If you don't have one, get an old core off ebay for $15. Buy "Rochester Carburetors" by Doug Roe, read and rebuild. Then get Lars' quadrajet papers to tune it and you will be in great shape with the satisfaction of doing it yourself.

God bless, Sensei

 

I found a paper by Lars that is a must for tuning q-jets.

search for "How to Tune a Q-Jet by Lars"

 

I bought a q-jet from "Mountain Man carbs" in Arkansas(in think) after I stripped out the fuel line threads on mine. He advertises on fleabay. I spent @ 15 min on the phone with him discussing what I have & the rebuilt carb was set up pretty darn close to what I needed. Price was reasonable and I was happy with the results.

 

thats the bummer.. I dont have the original carb. The engine came with a junk holley on it that had too much stuff inside rusted into dust. Another holley I had laying around I had rebuilt and it poured gas from the back barrels and filled up the cyliders with gas and hydro locked the motor. All the gas leaking has messed up my painted intake 2-3 times now. Even if I could find a core, I dont have have a dozen carbs laying around to rob good parts from. Also I have never tried to put one back together and I dont think I would be able to even notice all the problems Lars found in the holley built one he wrote about. I think my 71 had a 750cfm but the only new spreadbore holleys I can find are 650's and dont use the original type choke thats on my intake. I'm going to check that link thats above and see what they have.. any other suggestions? Is there another carb god in here that is still in business? Somewhere it was said that Lars retired and he didnt answer a message I sent so I guess this is right?

 

You can also look up" Qjets by Cliff" on the internet. Cliff is very talented, you can call him and go over the problems you have. He can tell you what to do, send you parts or you can send the carb to him for repair. Al

 

I second the motion for Cliff. Top notch guy, he"ll have a good core for you to use, and set it up just right.

 

I have had a Holley 4175 that I bought new, quadrajet spreadbore replacement carb, on my 78 L-82 for 23 years and it runs perfectly at idle and on the road with the original jets but the lightest spring for the vacuum secondaries. Very easy to work on if you need to replace/tune the primary jets and looks real easy to rebuild but still not necessary after 23 years.

 

Well I still cant find much on a spreadbore holley, they are 650cfm and my stock q-jet was 750cfm, dont want to go down do I? Plus they have electric chokes and I have the type that is a coil spring mounted on the intake, it looks new and works good with a heat gun on it. I am reading up on SMI & Cliffs like you all suggested. I'm also looking at cores on ebay, Does anybody know what numbers or identification I should search for that would be correct for a 71 454 manual w/ac? Not a correct dated correct for judging or anything, just correct enough for what I need? again, factory stock street only driven car. I want the motor to run strong but smooth, stable, dependable ect.

 

Lars tuning paper shows , 71 454 MT vette , correct carb as # 7041205
like this one.

http://cgi.ebay.com/ebaymotors/1971-...Q5fAccessories

http://www.corvettefaq.com/c3/QJetTuningPaper.doc

 

Read the description of that Ebay carb carefully. You will see it is a re-stamp, not an original "rare" carb. Also, it is sold "as is". It will probably sell for alot more than it's worth to someone who isn't paying enough attention (which is the seller's plan).

 

Pat,

I have a remanufactured Q-jet I ran on my '73 L82 4spd for a little over a year, until I found my original. I don't know how it would work on a big block, but if you're interested send me a pm ( disregard the price, make me an offer!). It ran fine on my car and was purchased new.

Here's the link

http://forums.corvetteforum.com/c3-p...tml?highlight=

Chris

 

I seen that one on ebay said restamp.. whats that mean exactly? just the date is removed and restamped to another or all the numbers are removed and restamped? so can that carb be off anything at all and only have restamped numbers on it saying its something else or is that just a date code thing?

 

It is a trick to dupe people. Notice how throughout the description it is called "very rare" and refers to the date stamp making it for a '71 HP big block yada, yada, yada. Then very subtly, it slips in "this is a restamp" to cover the seller when the truth comes out.

This carb could be any Quadrajet (some were actually put on 6 cylinder vehicles). Quadrajets were used on a wide veriety of vehicles and were engineered for that particular vehicle. Any can be made to work for another application. The proceedure is to use it on the new vehicle as it was originally set up/ jetted and adjust from there (Lars' method) although Ruggles suggests immediately going through the idle circuit and re-engineering the carb for its new application, which is a lot of work and often not needed.

But everyone agrees that what you do NOT want to do is take a carb from one application and jet/ rod it like a carb that was engineered for another. This does NOT work, and is exactly what this Ebay carb seller has done; he took a core who's original application is now a mystery, and put in '71 big block rods and jets. This will most likely be a tuning nightmare, because the carb was not engineered for that rod/ jet combo and there is no way to know what the original set up was. You really have no choice but to go through the intire carb, checking and record all parameters (all restriction/ bleeds/ bypass etc. sizes) to figure out what you have, then modify them and select an applicable starting jet/ rod combo. There's very little chance of you getting this done right at your local garage, and it would be expensive.

The only application you would really use a carb like this for is an NCRS trailer queen for shows, but even then, the re-stamp is so bad it is obvious (numbers sitting high/ low and unevenly spaced). The bad thing is that an un-informed buyer will probably get ripped off by this guy.

God bless, Sensei

 

Qj came out in '67 and across the boards by '68, and ran without EGR until '73, when that was introduced across the board, if you have a EDR carb, trying to use it on a non EGR application, I have been told you need redo the 'off idle transferr circuit'....that is two of the brass metering stems/capillaries? in the carb top if you trace them they go into the little slots in front of the primary butterfly....I don't totally understand why that has to be that way, BUT know that the brass tubes need drilled out a tad to supply more fuel.....

the reason is that EGR essentially feeds in inert gasses in place of air, so that means you needed less fuel, so that circuit is what was leaned out....

so doing what we hotrodders typically want to do, run without EGR, that carbs have a terrible off idle stumble, which is greatly compounded by any throttle shaft leakage from wear....

this was all explained to me years ago by a major rep carb guy....