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1/2/15 8:38pm - Original Message: '1979 L48 Quadrajet rebuild'
wonl2
Former Member
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taylors, SC - USA

Vette(s):
1979 Corvette Dark Green all original 60,000 miles

Joined: 12/7/2014
Posts: 3
I'm looking to rebuild the Quadrajet carb on my 1979 L48. I see so many places to buy the rebuild kits and the prices range from $27 to $75. I want to do this right the first time with a quality kit. Where can I find a rebuild kit that has quality parts? The carb has 60K miles. Will the new rebuild kits allow for the use of 10% ethanol gas. I have been using pure gas. Just wondering.

Thanks for all responses.

Phil
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1/2/15 10:29pm - Reply: 'Re: 1979 L48 Quadrajet rebuild'
Adams' Apple Lifetime Member
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Duncanville, TX - USA

Vette(s):
#1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas

Joined: 11/8/2003
Posts: 19454
If you have a NAPA auto parts place close, get the kit from them, and get a new float, also. You'll need the carb number to get the correct kit. You can find the Quadrajet ID number on the vertical edge of the carb, driver side rear.
 Most any kits these days will be ethanol resistant.


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Joel Adams
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1/3/15 10:55am - Reply: 'Re: 1979 L48 Quadrajet rebuild'
Sarge81 Lifetime Member
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WEST SENECA, NY - USA

Vette(s):
1981 Blue Ice Met. w/pearl ghost flames TKO500 5speed. LS1 Swap 3.45 Dana 44.

Joined: 12/3/2001
Posts: 2376
Being a common issue with Rochester carbs, especially 4 spd. cars you might want to also check your primary throttle shaft for slop in it. If you grab the throttle linkage where the throttle cable goes to, try to move it forward, backward, up n down. If there is excessive play you'll want to do or have a bushing kit installed. Otherwise you'll have a vacuum leak there and you'll never get a solid carb adjustment after a rebuild. 
Another thing to do is use a straight edge on all the flat mating surfaces to make sure there is no major warpage. 


____________________________________

GEN III 5.7L "LS6" Engine swap
TKO500 5 spd.
3.54 Dana 44
'69 "N11" Sidepipes
Borgeson Steering Box
Born 8/1981
Sequence #3975




Click here to see more pics of my Vette on CarDomain.


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1/5/15 1:04am - Reply: 'Re: 1979 L48 Quadrajet rebuild'
daveo76
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Vancouver, WA - USA

Vette(s):
1976 Silver/Firethorn. L48, 4spd. Original 2 bolt, vortec heads, 9.4:1 CR, Speed Pro Cam: 224/224@0.050, 112 LSA, Eagle Steel Crank.

Joined: 8/25/2005
Posts: 831
I had really good luck with Cliff's High Performance.  Their kits are designed to work with today's ethanol fuels and they are not as generic as the parts house kits - more closely matched to your q-jet's model number.  As Sarge mentions, you should definitely think about re-bushing the primary throttle shaft.  Cliff's has the kits for doing that and I think they're also available on e-bay.  


Cliff also has a good book on rebuilding q-jets.  I used it along with Doug Roe's book on Rochesters.  





|UPDATED|1/4/2015 11:04:14 PM (AZT)|/UPDATED|


____________________________________

 

1976 Silver/Firethorn.  L48, 4spd.  Original 2 bolt, vortec heads, 9.4:1 CR, Speed Pro Cam: 224/224@0.050, 112 LSA, Eagle Steel Crank.
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1/6/15 1:44am - Reply: 'Re: 1979 L48 Quadrajet rebuild'
daveo76
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Vancouver, WA - USA

Vette(s):
1976 Silver/Firethorn. L48, 4spd. Original 2 bolt, vortec heads, 9.4:1 CR, Speed Pro Cam: 224/224@0.050, 112 LSA, Eagle Steel Crank.

Joined: 8/25/2005
Posts: 831
Sarge81 said: Being a common issue with Rochester carbs, especially 4 spd. cars you might want to also check your primary throttle shaft for slop in it. If you grab the throttle linkage where the throttle cable goes to, try to move it forward, backward, up n down. If there is excessive play you'll want to do or have a bushing kit installed. Otherwise you'll have a vacuum leak there and you'll never get a solid carb adjustment after a rebuild. 
Another thing to do is use a straight edge on all the flat mating surfaces to make sure there is no major warpage. 


Hey, Sarge - what is it about the 4 spd cars that exacerbates this problem?  I've never heard that bit of trivia but I've lived it since my car is a 4 spd and the shaft was pretty sloppy.  




____________________________________

 

1976 Silver/Firethorn.  L48, 4spd.  Original 2 bolt, vortec heads, 9.4:1 CR, Speed Pro Cam: 224/224@0.050, 112 LSA, Eagle Steel Crank.
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1/6/15 7:30am - Reply: 'Re: 1979 L48 Quadrajet rebuild'
Sarge81 Lifetime Member
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WEST SENECA, NY - USA

Vette(s):
1981 Blue Ice Met. w/pearl ghost flames TKO500 5speed. LS1 Swap 3.45 Dana 44.

Joined: 12/3/2001
Posts: 2376
daveo76 said:
Hey, Sarge - what is it about the 4 spd cars that exacerbates this problem?  I've never heard that bit of trivia but I've lived it since my car is a 4 spd and the shaft was pretty sloppy.  



With manual transmission cars your constantly "on and off" the gas when shifting gears. 
Automatics your foot is more steady on the gas since the transmission is doing the shifting for you, hence less wear on the primary throttle shaft. 

On Rochester carbs the throttle shaft is steel and the base plate the shaft sits in is aluminum. That's where these bushing kits come in handy. The shaft will then sit in a brass/bronze bushing instead of the softer aluminum.

Every Rochester 4 barrel I have rebuilt since the mid '80's up until a few years ago, I found the manual trans cars had considerable amount of slop in the primary throttle shaft vs. automatic trans cars. 
Of course the secondary throttle shaft never seem to wear out simply because they never really open and close constantly during "normal" driving. 




____________________________________

GEN III 5.7L "LS6" Engine swap
TKO500 5 spd.
3.54 Dana 44
'69 "N11" Sidepipes
Borgeson Steering Box
Born 8/1981
Sequence #3975




Click here to see more pics of my Vette on CarDomain.


Lifetime Member #26
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1/6/15 11:40am - Reply: 'Re: 1979 L48 Quadrajet rebuild'
daveo76
Standard Member
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Vancouver, WA - USA

Vette(s):
1976 Silver/Firethorn. L48, 4spd. Original 2 bolt, vortec heads, 9.4:1 CR, Speed Pro Cam: 224/224@0.050, 112 LSA, Eagle Steel Crank.

Joined: 8/25/2005
Posts: 831
Interesting, makes sense. Thanks for the info.

____________________________________

 

1976 Silver/Firethorn.  L48, 4spd.  Original 2 bolt, vortec heads, 9.4:1 CR, Speed Pro Cam: 224/224@0.050, 112 LSA, Eagle Steel Crank.
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1/6/15 1:15pm - Reply: 'Re: 1979 L48 Quadrajet rebuild'
Adams' Apple Lifetime Member
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Duncanville, TX - USA

Vette(s):
#1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas

Joined: 11/8/2003
Posts: 19454
Sarge is right, plus, manual trans cars usually have a little stouter return springs on the carbs, which adds to the accelerated(pun intendedTongue) wear on the shaft bores.
The main thing to remember about shaft bore wear is....Rochester/GM never intended for these carbs to still be running 25-30 years later. Back then, 10 years was a good run, if they lasted that long. So why bother using bushings there to start with? Even now, with throttle bodies on infected cars, there are shafts running in bare, untreated aluminuminum, or even magnesium in some cases. Wacko

____________________________________
Joel Adams
C3VR Lifetime Member #56    
My Link


(click for Texas-sized view!)
             NCRS

"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"
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1/6/15 7:19pm - Reply: 'Re: 1979 L48 Quadrajet rebuild'
F4Gary Gold Member
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Grapevine, TX - USA

Vette(s):
1972 LT-1 convertible with factory air.

Joined: 8/26/2006
Posts: 869
Adams' Apple said: Sarge is right, plus, manual trans cars usually have a little stouter return springs on the carbs, which adds to the accelerated(pun intendedTongue) wear on the shaft bores.
The main thing to remember about shaft bore wear is....Rochester/GM never intended for these carbs to still be running 25-30 years later. Back then, 10 years was a good run, if they lasted that long. So why bother using bushings there to start with? Even now, with throttle bodies on infected cars, there are shafts running in bare, untreated aluminuminum, or even magnesium in some cases. Wacko


What's an infected car?   LOL


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1/7/15 12:13pm - Reply: 'Re: 1979 L48 Quadrajet rebuild'
Adams' Apple Lifetime Member
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Duncanville, TX - USA

Vette(s):
#1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas

Joined: 11/8/2003
Posts: 19454
Uh.....the kind with fuel infectors, of course.....Confused

LOL


____________________________________
Joel Adams
C3VR Lifetime Member #56    
My Link


(click for Texas-sized view!)
             NCRS

"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"
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1/7/15 12:56pm - Reply: 'Re: 1979 L48 Quadrajet rebuild'
Sarge81 Lifetime Member
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WEST SENECA, NY - USA

Vette(s):
1981 Blue Ice Met. w/pearl ghost flames TKO500 5speed. LS1 Swap 3.45 Dana 44.

Joined: 12/3/2001
Posts: 2376
My car suffers from the fuel infectors syndrome. It was born with one of them there 4 bbl fuel mixers on top the motor, then it suffered a slow progression of fuel infection. Poor thing.  All in all fuel infection isn't such a bad thing. I accept it for what it is. I miss the days of vapor lock, sticky chokes, ethanol messing with it and other associated problems...........NOT!!! LOL

____________________________________

GEN III 5.7L "LS6" Engine swap
TKO500 5 spd.
3.54 Dana 44
'69 "N11" Sidepipes
Borgeson Steering Box
Born 8/1981
Sequence #3975




Click here to see more pics of my Vette on CarDomain.


Lifetime Member #26
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1/9/15 2:25pm - Reply: 'Re: 1979 L48 Quadrajet rebuild'
73shark
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Overland Park, KS - USA

Vette(s):
1973 Orange Metallic Coupe (orig owner), L82, 4 spd (WR), PS, (A/C & PW (I installed from wrecked 73)), leather, AM/FM Stereo, ran with '65 FI unit earlier & will again some day.

Joined: 7/9/2003
Posts: 394
wonl2 said: I'm looking to rebuild the Quadrajet carb on my 1979 L48. I see so many places to buy the rebuild kits and the prices range from $27 to $75. I want to do this right the first time with a quality kit. Where can I find a rebuild kit that has quality parts? The carb has 60K miles. Will the new rebuild kits allow for the use of 10% ethanol gas. I have been using pure gas. Just wondering.

Thanks for all responses.

Phil

Unfortunately the carb isn't the only thing susceptible to ethanol damage. Any plastic,rubber, or aluminum part can also be damaged as alcohol is a weak acid. Plus you will get better mpg with pure gas.



____________________________________

1973 L-82 4 spd

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