68 L79 questions
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Cruising
Joined: May 2021
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68 L79 questions
I have pretty much determined my engine to be a real 1968 L79 327/350- with HP suffix (A/C and P/S), built in Summer of 68 (castings are all F,G or H), 2.02/1.60 valve 186 heads(No screw-in studs/guide plates), 151 cam, forged 11-1 pistons, forged large journal crank, long sump pan, standard bore, bearings dated 5/68.
My issue still lingering is the intake combo. I can only find one source that says the engine would have a 3914678 manifold, and it's topped with a 7028207 DA Q-Jet, which sources say is 327/300 only. I know there were plenty of mistakes made through the years, but has anybody ever seen this carb/intake on an L79? How about the big valve heads without guide plates?
My issue still lingering is the intake combo. I can only find one source that says the engine would have a 3914678 manifold, and it's topped with a 7028207 DA Q-Jet, which sources say is 327/300 only. I know there were plenty of mistakes made through the years, but has anybody ever seen this carb/intake on an L79? How about the big valve heads without guide plates?
Dr. Detroit
Joined: Mar 2012
Posts: 10,097
Likes: 4,027
From: New Braunfels Texas
186 Big Valve heads are correct and came on the L-46 350/350 as well. 68' was the first year for the Q-Jet and there is only one Q-Jet manifold available.....low rise, cast iron non-EGR. 1966-67' L-79's had an aluminum intake and a 585 cfm Holley single feed carb.
1968 is also the only year for the large journal 327. I have a 1968 327/300 outside here and it has 186 small valve heads and the same intake and carb.
Jebby
1968 is also the only year for the large journal 327. I have a 1968 327/300 outside here and it has 186 small valve heads and the same intake and carb.
Jebby
Drifting
Joined: Nov 2016
Posts: 1,958
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From: Pittsburgh PA
Carb is def 300 hp version
like said above. 68 L79 used cast iron manifold. I’m not 100% sure if 350 and 300 hp used same manifolds. I’m guessing g maybe they do. So a carb swap would be easy
like said above. 68 L79 used cast iron manifold. I’m not 100% sure if 350 and 300 hp used same manifolds. I’m guessing g maybe they do. So a carb swap would be easy
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Cruising
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"Carb is def 300 hp version"
I got that, but it just seems odd to me that it would have been changed because everything else looks correct- the carb even has the correct date to go with the rest of the engine.
I just saw a post by Lars--"7028207 Chev 68 327/350 MT VETTE 71 46 7036019 AN 2.2973 3.4283"
I got that, but it just seems odd to me that it would have been changed because everything else looks correct- the carb even has the correct date to go with the rest of the engine.
I just saw a post by Lars--"7028207 Chev 68 327/350 MT VETTE 71 46 7036019 AN 2.2973 3.4283"
Last edited by bowtie0069; May 17, 2021 at 03:39 PM.
Melting Slicks
Joined: May 2002
Posts: 2,474
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From: Laporte, IN
HP = 327/350HP
3914678 is a engine block not a manifold
7028207 should be a 7028219 Friend has a late July L79 4-speed original owner his carb is 7028219
Intake 3919803 till June 68 Late June changed to 3927184
3914678 is a engine block not a manifold
7028207 should be a 7028219 Friend has a late July L79 4-speed original owner his carb is 7028219
Intake 3919803 till June 68 Late June changed to 3927184
Dr. Detroit
Joined: Mar 2012
Posts: 10,097
Likes: 4,027
From: New Braunfels Texas
Looks like the L-79 was cam, valve size and compression only.
Jebby
Thread Starter
Cruising
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3914678 is a engine block not a manifold OOOPS! I was doing some cutting and pasting and forgot which item I cut..
7028207 should be a 7028219 That's my main question, but now I've seen 2 places that list the 7028207 being used on the 350 horse.
Intake 3919803 till June 68 Late June changed to 3927184 My manifold is the 184 dated June 20,1968. Every part has June, July, or August casting dates.
7028207 should be a 7028219 That's my main question, but now I've seen 2 places that list the 7028207 being used on the 350 horse.
Intake 3919803 till June 68 Late June changed to 3927184 My manifold is the 184 dated June 20,1968. Every part has June, July, or August casting dates.
Last edited by bowtie0069; May 17, 2021 at 10:07 PM.
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Thread Starter
Cruising
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[QUOTE= there is only one Q-Jet manifold available..../QUOTE] There are many that will disagree with that--like the people with 3919803 intakes. And when you search, you find them with and without the oil filler tube hole, yet they have the same casting number--just like the 186 heads share the same casting number whether they have 1.94 or 2.02 valves, and whether or not they have screw-in studs and guide plates!
Tech Contributor
Joined: Aug 1999
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From: At my Bar drinking and wrenching in Lafayette Colorado
"Carb is def 300 hp version" I got that, but it just seems odd to me that it would have been changed because everything else looks correct- the carb even has the correct date to go with the rest of the engine.
I just saw a post by Lars--"7028207 Chev 68 327/350 MT VETTE 71 46 7036019 AN 2.2973 3.4283"
I just saw a post by Lars--"7028207 Chev 68 327/350 MT VETTE 71 46 7036019 AN 2.2973 3.4283"
Lars
Last edited by lars; May 17, 2021 at 11:12 PM.
Tech Contributor
Joined: Aug 1999
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From: At my Bar drinking and wrenching in Lafayette Colorado
On my carb listing sheet, you will notice that carbs used on multiple cubic inch displacement engines are listed with a "split" application. Carbs that were used on both 396 and 427 engines are shown as 396/427. Pontiac carbs used on 350's and 400's are shown as 350/400. This does not mean there was a 350 with 400 horse... Carbs used specifically on the high performance engines are annotated with "hi perf."
Lars
Lars
Last edited by lars; May 18, 2021 at 10:46 AM.
Instructor
Joined: Feb 2009
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From: asheville nc
My 68 L-79 came with a 7028207 Carb. The inlet stripped out in 1984 when I rebuilt the engine. The only replacement Chevy had was a 1969 350/350hp quadrajet for a Corvette...number 7029207...still on my 50 years owned Vette.
1968 Corvette Assembly manual also shows 7028207 for carb spec.
1968 Corvette Assembly manual also shows 7028207 for carb spec.
Last edited by 68L79; Nov 1, 2023 at 07:43 PM.
Tech Contributor
Joined: Aug 1999
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From: At my Bar drinking and wrenching in Lafayette Colorado
Your information does not agree with the published Rochester specs. Rochester Bulletin 9C-3031 (approved and © by General Motors Corp) shows carb number 7028207 as being 1968 Corvette 327 standard engine (L75) for a manual transmission car. The same Bulletin shows Corvette Hi Perf. L79 manual transmission carb as 7028219, with the Nova L79 carb as 7028229. Right off the official Rochester spec sheet. That's a fact.
In 1969, Rochester Bulletin 9C-3041 (approved and © by General Motors Corp) shows the Corvette standard engine 350/300 carb with manual transmission as 7029203, with the 300-horse automatics getting the 7029202. The 350/350 L46 engine got carb number 7029207, which, in my opinion, is one of the best high performance carbs ever made by Rochester for a Chevy.
If anyone can provide positive evidence that the official, released, published Rochester tech and spec data, as approved by General Motors, is wrong, I'd like to see it so I can make corrections to my historical spec records.
Lars
In 1969, Rochester Bulletin 9C-3041 (approved and © by General Motors Corp) shows the Corvette standard engine 350/300 carb with manual transmission as 7029203, with the 300-horse automatics getting the 7029202. The 350/350 L46 engine got carb number 7029207, which, in my opinion, is one of the best high performance carbs ever made by Rochester for a Chevy.
If anyone can provide positive evidence that the official, released, published Rochester tech and spec data, as approved by General Motors, is wrong, I'd like to see it so I can make corrections to my historical spec records.
Lars
Last edited by lars; Nov 2, 2023 at 12:42 AM.