Carb question
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Joined: Aug 2015
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Carb question
I just picked up a 75 vette and am confused on the carb that's on it. It appears that the previous owner put on dual exhaust and cut out the cat. It also looks like they have disconnected all of the emmisions crap as well. Now the carb that is on there has a has a hose on it that is plugged with a bolt and it just doesn't feel or look right, some of the levers are loose and not functioning properly, and so forth. Should I replace the 1975 carb with a pre emmisions carb or an aftermarket one. Not sure if it makes any difference at all, I'm not mechanic. I know my car is slow but all 75's are..lol. It seems to run ok as it is but would like it to run better.
Last edited by nick0187; Aug 4, 2016 at 09:24 AM.
Safety Car
Joined: Oct 2007
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Likes: 267
From: Austin Texas
Corvette of the Year Winner 2017
2016 C3 of Year Finalist
slow down, ask questions determine what you have, before you start changing things.
learn everything about your car, know what each and every **** is, and what it should do.
step 1 determine what carb. you currently have.
what is your goal ? daily driver? Restore to original ?
supply pictures about any questions, and you will get lots of help here.
like a picture of the current carb. and congratulations on your new car !
learn everything about your car, know what each and every **** is, and what it should do.
step 1 determine what carb. you currently have.
what is your goal ? daily driver? Restore to original ?
supply pictures about any questions, and you will get lots of help here.
like a picture of the current carb. and congratulations on your new car !
Thread Starter
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Joined: Aug 2015
Posts: 66
Likes: 1
Haha.. Alright, you are definetly right. I'm just excited to get it up and running as good as it can. I'm looking for a fun car to drive, not a show car necessarily. I'll have to take a few pictures and maybe a video of the carb once I get home tomorrow. Thanks for the reply. I appreciate all the help and advice from the experts here.
Instructor
Joined: Feb 2016
Posts: 182
Likes: 27
From: Somerville Alabama
Looks like it says L48 on the hood, the base engine.
If carb is original it would be a Rochester Quadrajet, name will be on side.
When not running the linkage on passenger side (right) will be loose until engine is started and provides vacuum to it.
Is the plugged hose (medium-size) at front, going left toward valve cover? There would normally be a PCV valve in left valve cover.
Or... make sure the distributor vacuum (thin hose) is connected to front left top of carburetor.
A picture will help tremendously, both with and without air cleaner, to see how original or changed it is.
Diagram link: http://i29.photobucket.com/albums/c2...onsRouting.jpg
If carb is original it would be a Rochester Quadrajet, name will be on side.
When not running the linkage on passenger side (right) will be loose until engine is started and provides vacuum to it.
Is the plugged hose (medium-size) at front, going left toward valve cover? There would normally be a PCV valve in left valve cover.
Or... make sure the distributor vacuum (thin hose) is connected to front left top of carburetor.
A picture will help tremendously, both with and without air cleaner, to see how original or changed it is.
Diagram link: http://i29.photobucket.com/albums/c2...onsRouting.jpg
Le Mans Master
Joined: Apr 2011
Posts: 6,284
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From: Hermosa
Should I replace the 1975 carb with a pre emmisions carb or an aftermarket one. Not sure if it makes any difference at all, I'm not mechanic.
If you want to learn how to rebuild it get this book.
https://www.amazon.com/Rebuild-Modif...=cliff+ruggles
If not then you can send it to someone who knows about the q-jet.
Lars Grimsrud or Cliff Ruggles are both experts on them.
http://www.cliffshighperformance.com/
Last edited by REELAV8R; Aug 11, 2016 at 01:16 PM.
Le Mans Master
Joined: Jul 2006
Posts: 8,117
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From: charlotte north carolina
I was once told to attach one return spring below the throttle shaft axis, and one above-obviously in opposite directions. It reduces the wear on the shaft bore (or bushings if the carb has been repaired).
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Tech Contributor
Joined: Aug 1999
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From: At my Bar drinking and wrenching in Lafayette Colorado
That's a really nice, original carb in rebuildable condition. Other than the severely bent accel pump rod, it's pretty much unmolested, and will run really well once rebuilt and correctly set up. No need to replace that one. If you need help with the rebuild, drop me an e-mail for info.
Lars
V8Fastcars@msn.com
Lars
V8Fastcars@msn.com
Thread Starter
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Joined: Aug 2015
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Thanks for all of the insight, keep it coming..lol. I'm brand new to carbs and it seems a bit overwhelming at the moment. I watched a video on rebuilding the quadrajet and it seems quite difficult. How much would it cost to have somebody fix it up and rebuild it?
Advanced
Joined: Sep 2013
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From: Ottawa Illinois
Lars is your man
He is the master for your carb. Do not pass go. Do not hesitate to remove said carb and send it. He will make it look and run better than new. He sends you instructions on how to pack it for shipping. He rebuilt mine....well actually a replacement we found on eBay....since my original had been "brutalized" in its previous life. Not sure if Lars kept it for a door stop...
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From: At my Bar drinking and wrenching in Lafayette Colorado
Lars
Last edited by lars; Aug 12, 2016 at 10:28 AM.
Le Mans Master
Joined: Apr 2011
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From: Hermosa
Actually, the '75 carbs do not have the APT (adjustable part throttle) feature - they have the adjustable plug/needle insert in the anaerobic chamber hole location, which can be adjusted similar to the APT. This was a 1-year feature, and the carbs were changed to the "real" APT in 1976. The other unique thing about the '75 is that it was the only year that the Vette used the rear pulloff in addition to the forward pulloff. The rear pulloff was quickly realized to be unnecessary, and was not used after 1975 except on trucks.
Lars
Lars
Dr. Detroit
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From: New Braunfels Texas
Drifting
Joined: Sep 2010
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From: Laguna Niguel California
Yes, send the carb to Lars, and no, the '75's don't have to be slow. It's still a 350 small block with plenty of potential. It's pretty easy to double the factory's horsepower rating, and even more. It's only money, how fast do you want to go?