Replacement carb for 1979 L48
Race Director
Joined: Feb 2001
Posts: 11,130
Likes: 1,984
From: Grapevine Tx
2018 C3 of Year Finalist
2016 C3 of the Year Finalist
There is rebuilt and then there is REBUILT. A major difference.
One company may consider "rebuilt" as cleaning it and throwing a new gasket/seal kit in it.
A good rebuild service will also measure for warp/leakages, validate it functions as should/make adjustments as needed, tune to your specific engine specs, etc. Probably 3-4 hours of billable work.
If someone offers a "rebuilt" carb for $100 + exchange then that means they spent about 20-30 minutes on it.
Sending a carb to LARS or anyone that is intimately knowledgeable of the operation and gotchas is money well spent. (disclosure: I do not know LARS as I do my own work but lots of positive threads here about his work)
One company may consider "rebuilt" as cleaning it and throwing a new gasket/seal kit in it.
A good rebuild service will also measure for warp/leakages, validate it functions as should/make adjustments as needed, tune to your specific engine specs, etc. Probably 3-4 hours of billable work.
If someone offers a "rebuilt" carb for $100 + exchange then that means they spent about 20-30 minutes on it.
Sending a carb to LARS or anyone that is intimately knowledgeable of the operation and gotchas is money well spent. (disclosure: I do not know LARS as I do my own work but lots of positive threads here about his work)
Why not just send either carb to Lars?
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,114
From: Crossville TN
If the carb is original to the car and has not been rebuilt by some "shop", the carb is likely in its original configuration. That being the case, rebuilding it YOURSELF with a good quality rebuild kit is very doable.
It the carb has been sent to a rebuild shop, you have no idea of what parts got used to rebuild it. These shops don't usually just rebuild YOUR carb; they replace your carb with a rebuilt unit of [approximately] the same configuration. A correctly rebuilt carb is what you want.
If the carb has been altered, sending it to Lars is a good idea. He knows what parts are correct for your carb and can refurbish it to correct configuration. YOU cannot do that. Hence, my alternative recommendations...
It the carb has been sent to a rebuild shop, you have no idea of what parts got used to rebuild it. These shops don't usually just rebuild YOUR carb; they replace your carb with a rebuilt unit of [approximately] the same configuration. A correctly rebuilt carb is what you want.
If the carb has been altered, sending it to Lars is a good idea. He knows what parts are correct for your carb and can refurbish it to correct configuration. YOU cannot do that. Hence, my alternative recommendations...
Race Director
Joined: Feb 2001
Posts: 11,130
Likes: 1,984
From: Grapevine Tx
2018 C3 of Year Finalist
2016 C3 of the Year Finalist
If the carb is original to the car and has not been rebuilt by some "shop", the carb is likely in its original configuration. That being the case, rebuilding it YOURSELF with a good quality rebuild kit is very doable.
It the carb has been sent to a rebuild shop, you have no idea of what parts got used to rebuild it. These shops don't usually just rebuild YOUR carb; they replace your carb with a rebuilt unit of [approximately] the same configuration. A correctly rebuilt carb is what you want.
If the carb has been altered, sending it to Lars is a good idea. He knows what parts are correct for your carb and can refurbish it to correct configuration. YOU cannot do that. Hence, my alternative recommendations...
It the carb has been sent to a rebuild shop, you have no idea of what parts got used to rebuild it. These shops don't usually just rebuild YOUR carb; they replace your carb with a rebuilt unit of [approximately] the same configuration. A correctly rebuilt carb is what you want.
If the carb has been altered, sending it to Lars is a good idea. He knows what parts are correct for your carb and can refurbish it to correct configuration. YOU cannot do that. Hence, my alternative recommendations...
If it were me, I'd send it to Lars regardless.
Le Mans Master
Joined: Oct 2007
Posts: 7,441
Likes: 964
From: Tennessee/Rhode Island
Tech Contributor
Joined: Aug 1999
Posts: 14,370
Likes: 6,361
From: At my Bar drinking and wrenching in Lafayette Colorado
Update on Phil's carb:
Phil ended up sending the carb out to me. The carb had the following issues:
After a complete teardown, the carb was run through the hot tank for cleanup. These dirty, original, unmolested carbs are always the best carbs for rebuild, and the carb cleaned up so nicely it almost looked new.
I did a slight re-jet of the carb to better match his application, and then corrected all the setup issues with a nice performance calibration. The carb really ran well on the test engine, with all air/fuel numbers hitting right on the desired specs.
Phil reports that he simply installed the carb on his engine and that it fired and ran immediately, coming down off cold fast idle as the engine warmed up and running perfectly. He's now verifying timing and tuning, and has a nice running Vette - nice job on the install and setup, Phil!
Lars
Phil ended up sending the carb out to me. The carb had the following issues:
- Very loose secondary spring windup. This would have caused a horrible tip-in stumble going into the secondaries
- Very high fast idle - fast idle set to 1550 rpm
- Accel pump rod installed in wrong hole - lean accel pump shot that would have caused a stumble
- Lean jetted for application
- Accel pump diaphragm collapsed - inoperative
- Extreme low float level - extreme lean condition
- Low APT setting - lean
- Choke shaft seals broken causing dirt ingestion into carb
- Idle mixture screws fully backed out beyond operating range in an attempt to fix the lean conditions caused by the above issues
- Secondary airvalves jamming and binding against airhorn casting
- Significant sooting in throttle bores indicating engine timing issues
After a complete teardown, the carb was run through the hot tank for cleanup. These dirty, original, unmolested carbs are always the best carbs for rebuild, and the carb cleaned up so nicely it almost looked new.
I did a slight re-jet of the carb to better match his application, and then corrected all the setup issues with a nice performance calibration. The carb really ran well on the test engine, with all air/fuel numbers hitting right on the desired specs.
Phil reports that he simply installed the carb on his engine and that it fired and ran immediately, coming down off cold fast idle as the engine warmed up and running perfectly. He's now verifying timing and tuning, and has a nice running Vette - nice job on the install and setup, Phil!
Lars
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Thread Starter
Advanced
Joined: May 2016
Posts: 95
Likes: 7
From: Tolland Massachusetts
Phil's carb after rebuild by Lars.
Update on Phil's carb:
Phil ended up sending the carb out to me. The carb had the following issues:
After a complete teardown, the carb was run through the hot tank for cleanup. These dirty, original, unmolested carbs are always the best carbs for rebuild, and the carb cleaned up so nicely it almost looked new.
I did a slight re-jet of the carb to better match his application, and then corrected all the setup issues with a nice performance calibration. The carb really ran well on the test engine, with all air/fuel numbers hitting right on the desired specs.
Phil reports that he simply installed the carb on his engine and that it fired and ran immediately, coming down off cold fast idle as the engine warmed up and running perfectly. He's now verifying timing and tuning, and has a nice running Vette - nice job on the install and setup, Phil!
Lars
Phil ended up sending the carb out to me. The carb had the following issues:
- Very loose secondary spring windup. This would have caused a horrible tip-in stumble going into the secondaries
- Very high fast idle - fast idle set to 1550 rpm
- Accel pump rod installed in wrong hole - lean accel pump shot that would have caused a stumble
- Lean jetted for application
- Accel pump diaphragm collapsed - inoperative
- Extreme low float level - extreme lean condition
- Low APT setting - lean
- Choke shaft seals broken causing dirt ingestion into carb
- Idle mixture screws fully backed out beyond operating range in an attempt to fix the lean conditions caused by the above issues
- Secondary airvalves jamming and binding against airhorn casting
- Significant sooting in throttle bores indicating engine timing issues
After a complete teardown, the carb was run through the hot tank for cleanup. These dirty, original, unmolested carbs are always the best carbs for rebuild, and the carb cleaned up so nicely it almost looked new.
I did a slight re-jet of the carb to better match his application, and then corrected all the setup issues with a nice performance calibration. The carb really ran well on the test engine, with all air/fuel numbers hitting right on the desired specs.
Phil reports that he simply installed the carb on his engine and that it fired and ran immediately, coming down off cold fast idle as the engine warmed up and running perfectly. He's now verifying timing and tuning, and has a nice running Vette - nice job on the install and setup, Phil!
Lars
Team Owner
Joined: Jan 2007
Posts: 53,648
Likes: 878
From: Southern Cal Ca
St. Jude Donor '22
Update on Phil's carb:
Phil ended up sending the carb out to me. The carb had the following issues:
After a complete teardown, the carb was run through the hot tank for cleanup. These dirty, original, unmolested carbs are always the best carbs for rebuild, and the carb cleaned up so nicely it almost looked new.
I did a slight re-jet of the carb to better match his application, and then corrected all the setup issues with a nice performance calibration. The carb really ran well on the test engine, with all air/fuel numbers hitting right on the desired specs.
Phil reports that he simply installed the carb on his engine and that it fired and ran immediately, coming down off cold fast idle as the engine warmed up and running perfectly. He's now verifying timing and tuning, and has a nice running Vette - nice job on the install and setup, Phil!
Lars
Phil ended up sending the carb out to me. The carb had the following issues:
- Very loose secondary spring windup. This would have caused a horrible tip-in stumble going into the secondaries
- Very high fast idle - fast idle set to 1550 rpm
- Accel pump rod installed in wrong hole - lean accel pump shot that would have caused a stumble
- Lean jetted for application
- Accel pump diaphragm collapsed - inoperative
- Extreme low float level - extreme lean condition
- Low APT setting - lean
- Choke shaft seals broken causing dirt ingestion into carb
- Idle mixture screws fully backed out beyond operating range in an attempt to fix the lean conditions caused by the above issues
- Secondary airvalves jamming and binding against airhorn casting
- Significant sooting in throttle bores indicating engine timing issues
After a complete teardown, the carb was run through the hot tank for cleanup. These dirty, original, unmolested carbs are always the best carbs for rebuild, and the carb cleaned up so nicely it almost looked new.
I did a slight re-jet of the carb to better match his application, and then corrected all the setup issues with a nice performance calibration. The carb really ran well on the test engine, with all air/fuel numbers hitting right on the desired specs.
Phil reports that he simply installed the carb on his engine and that it fired and ran immediately, coming down off cold fast idle as the engine warmed up and running perfectly. He's now verifying timing and tuning, and has a nice running Vette - nice job on the install and setup, Phil!
Lars
Melting Slicks
Joined: May 2011
Posts: 2,753
Likes: 119
From: Springfield Missouri
I have a quadrajet that fit my 76, rebuilt from Holly, ran for about 300 miles,taken off when my carb was sent back from being restored. PM me if you are interested. I am NOT saying it is the correct carb for your, since there is age difference and carbs change from year to year and even sometimes changed during a year run. I can send pictures if interested, just Pm me your phone number.
You can not beat the way Lars rebuilds the carbs!!!!!IMO
You can not beat the way Lars rebuilds the carbs!!!!!IMO
Last edited by lvmyvt76; Feb 9, 2018 at 10:00 PM.
Le Mans Master
Joined: Oct 2007
Posts: 7,441
Likes: 964
From: Tennessee/Rhode Island
Update on Phil's carb:
Phil ended up sending the carb out to me. The carb had the following issues:
After a complete teardown, the carb was run through the hot tank for cleanup. These dirty, original, unmolested carbs are always the best carbs for rebuild, and the carb cleaned up so nicely it almost looked new.
I did a slight re-jet of the carb to better match his application, and then corrected all the setup issues with a nice performance calibration. The carb really ran well on the test engine, with all air/fuel numbers hitting right on the desired specs.
Phil reports that he simply installed the carb on his engine and that it fired and ran immediately, coming down off cold fast idle as the engine warmed up and running perfectly. He's now verifying timing and tuning, and has a nice running Vette - nice job on the install and setup, Phil!
Lars
Phil ended up sending the carb out to me. The carb had the following issues:
- Very loose secondary spring windup. This would have caused a horrible tip-in stumble going into the secondaries
- Very high fast idle - fast idle set to 1550 rpm
- Accel pump rod installed in wrong hole - lean accel pump shot that would have caused a stumble
- Lean jetted for application
- Accel pump diaphragm collapsed - inoperative
- Extreme low float level - extreme lean condition
- Low APT setting - lean
- Choke shaft seals broken causing dirt ingestion into carb
- Idle mixture screws fully backed out beyond operating range in an attempt to fix the lean conditions caused by the above issues
- Secondary airvalves jamming and binding against airhorn casting
- Significant sooting in throttle bores indicating engine timing issues
After a complete teardown, the carb was run through the hot tank for cleanup. These dirty, original, unmolested carbs are always the best carbs for rebuild, and the carb cleaned up so nicely it almost looked new.
I did a slight re-jet of the carb to better match his application, and then corrected all the setup issues with a nice performance calibration. The carb really ran well on the test engine, with all air/fuel numbers hitting right on the desired specs.
Phil reports that he simply installed the carb on his engine and that it fired and ran immediately, coming down off cold fast idle as the engine warmed up and running perfectly. He's now verifying timing and tuning, and has a nice running Vette - nice job on the install and setup, Phil!
Lars
Advanced
Joined: Mar 2015
Posts: 79
Likes: 3
From: winter fl
Carb 1978 L48 tuning
That Holley is easier to modify as compared to the Quadrajet but if you like to just drive a well running car the Quadrajet works best. I do run Holleys on other cars but the Quadrajet is the best carb for "set it up and forget about it" closed hood drivers. They work great when clean and adjusted right. California emissions calibration may be a bit too lean but nothing that could not be fixed when it is apart.
Send it to Lars is my advice. I carried mine to him years ago and it still works great.
Send it to Lars is my advice. I carried mine to him years ago and it still works great.
Last edited by gjjcvette; Oct 10, 2020 at 08:06 AM. Reason: typo
Burning Brakes
Joined: Oct 2012
Posts: 1,152
Likes: 252
2 year old thread but I will throw my opinion in anyway. There are a ton of variables but generally speaking, for a weekend driver, my experience is that you can count on a carb to stay in good condition for about 5-8 years before it needs to be looked at again. Daily driver is more like 4-5 years. YMMV.
Last edited by Dynra Rockets; Oct 10, 2020 at 08:28 AM.
Thread Starter
Advanced
Joined: May 2016
Posts: 95
Likes: 7
From: Tolland Massachusetts
I sent the Quadra jet carb from my 1979 Corvette to Lars for rebuild. I was absolutely satisfied by his work. He gave me some helpful advice. We bolted it on following his instructions and up she fired. He has a test engine on which he tests every carb to ensure It is working correctly. I give him two thumbs up. I was directed to him by members of the forum.
