A friend of mine has a 1968 Chevelle that he can't get to run. I went over this past weekend to check it out. He is the second owner, his brother-in-law bought the car new in Cheyenne, Wyoming. He doesn't have the build sheet. I have known these people from the early 60's so I don't think they are wrong. Anyway, they claim this 396 came from the dealer with a 425 hp 396 and 4 speed. I have two questions-how many were delivered like this and what size is the original Holley? I am fairly sure the power valve is causing the problem and would like to get a carb kit but the parts house said they need more info. The only 425 hp in that year that I can find was the Corvette. Can anyone shed some light on this?
1968 Chevelle-396 c.i.-425 HP?
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A friend of mine has a 1968 Chevelle that he can't get to run. I went over this past weekend to check it out. He is the second owner, his brother-in-law bought the car new in Cheyenne, Wyoming. He doesn't have the build sheet. I have known these people from the early 60's so I don't think they are wrong. Anyway, they claim this 396 came from the dealer with a 425 hp 396 and 4 speed. I have two questions-how many were delivered like this and what size is the original Holley? I am fairly sure the power valve is causing the problem and would like to get a carb kit but the parts house said they need more info. The only 425 hp in that year that I can find was the Corvette. Can anyone shed some light on this?
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I remember something about a 390hp/396 in 66 but like Tom said, highest hp 396 in 68 was 375hp.
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Your best bet is to get the list number off of the carb and match it to the list on www.holley.com Direct link:
http://www.holley.com/TechService/Library.asp
Chevrolet by the numbers and many other technical references show the highest 1968 Chevelle Motor being the L78 375hp . The engine pad suffix code should be EG. Any higher and it was dealer add-on and not factory.
http://www.holley.com/TechService/Library.asp
Chevrolet by the numbers and many other technical references show the highest 1968 Chevelle Motor being the L78 375hp . The engine pad suffix code should be EG. Any higher and it was dealer add-on and not factory.
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Is there any info at all...window sticker, sales contract, dealership invoice...? Did the dealership sell any other 425 hp rated cars?
Any dealership advertisement? There were certainly cars sold with 396 425 hp ratings, but probably no mechanical difference between the 425hp rated motors and 375 L78
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I've had two L78 375 hp Chevelles. They certainly weren't putting out any 425 hp, even with headers and tuning. Not really dogs, but certainly not up to the killer hype that you read in magazines. Our 360 hp 4 speed 455 Lemans would literally run away and hide on our L78 Chevelle. Our L72 powered Chevelle made considerably more power too. Back in those days the numbers were just that and were meant more for advertising than reality. It's pretty coincidental that the hp figures just happened to come out in 25 hp increments. The L78 just needs a lot more camshaft than stock to get enough air through those big ports to make decent power. The super stock cars fly.
???
The L78 and L72 share the same camshaft, heads and intake... If the smaller engine needs a lot more camshaft to make decent power, then how can the larger L72 make considerably more power?
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The extra cubic inches and bigger bore unshrouding the valves seem to allow more air through the heads making things more efficient. I haven't heard of a better reason for the L72 engines to work so much better. I'm just going from my own hands on experience. My conclusions might be wrong, but something works better with the bigger engines. Back when Dick Harrell was converting the Fred Gibb COPO Novas, He did a little comparison test. The L78 car ran mid 13s and the L72 427 conversion car went 12.0s. Quite a difference for 31 cubic inches.
Mike, I will get that number hopefully by this weekend. Thanks for all of the replies. I know all of my books only show 375 hp but he swears his is 425. He is gone all week but I will definitely ask about any paperwork plus post the number on the pad. JWA, thanks for the Holley link. It will be added to my 'favorites' list since this isn't the first time this has happened. I don't see how those little silver tags can disappear so easy.
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Keith has it right about the value of unshrouding of the intake valve, this has been well documented.
All sorts of horsepower legends abound in the musclecar world. Some can be backed up at the drags, others are best left as legend or overblown marketing hyperbola. Some of it is just emblem and sticker engineering.
Orlando, are you still interested in the Frontier dealer license frames?
Thomas
All sorts of horsepower legends abound in the musclecar world. Some can be backed up at the drags, others are best left as legend or overblown marketing hyperbola. Some of it is just emblem and sticker engineering.
Orlando, are you still interested in the Frontier dealer license frames?
Thomas
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I've owned a fair number of these cars over the years and can't imagine any case where a stock 360 horse 455 Lemans would run within a second of any stock, properly tuned/in decent shape L78 equiped car. Most anything with an L78 was a formidable oponent back then. Although the only L78 engine I have presently is on an engine stand instead of in a car, I presently have a 427/425 Biscayne and don't see anything in it's performance to suggest that there's any more horsepower difference between the two than what would be reasonably expected from the additional 31 cubic inches. As far as the L78 camshaft it's MORE THAN adequate to propel a properly set up car way down into the 11's, whether installed in a 396 or 427. Of course this is ALSO the same camshaft that was installed in the LS6 engines in the '70 Chevelles and El Caminos, AND the '71 LS6 Corvette.
Back to the original topic of this thread, Chevy ABSOLUTELY, POSITIVELY did not put a 396/425 rated engine in a Chevelle from the factory. I'm guessing that somebody stuck a 425 horse air cleaner sticker on one somewhere back then and over the years as memories faded it became factual. Who knows what some somebody in a dealership may have done with a 427 horse sticker easily obtainable from the parts room, or a Corvette air cleaner lid? In any case the engine would have been the same and if somebody had attempted the Corvette exhaust manifold swap, which of course wasn't good for anything like 50 HP anyway in the real world, it would not only be noticeable, but fabricating and hooking up the pipe on the right side would have been difficult to say the least.
Since the 396/425 horse engine in the Corvette was EXACTLY the same as all the 396/375's (with the exception of the Z16 in '65 which had a hydraulic camshaft) EXCEPT for the different exhaust manifolds on the Corvette there has been a good bit of confusion over the years.
Back to the original topic of this thread, Chevy ABSOLUTELY, POSITIVELY did not put a 396/425 rated engine in a Chevelle from the factory. I'm guessing that somebody stuck a 425 horse air cleaner sticker on one somewhere back then and over the years as memories faded it became factual. Who knows what some somebody in a dealership may have done with a 427 horse sticker easily obtainable from the parts room, or a Corvette air cleaner lid? In any case the engine would have been the same and if somebody had attempted the Corvette exhaust manifold swap, which of course wasn't good for anything like 50 HP anyway in the real world, it would not only be noticeable, but fabricating and hooking up the pipe on the right side would have been difficult to say the least.
Since the 396/425 horse engine in the Corvette was EXACTLY the same as all the 396/375's (with the exception of the Z16 in '65 which had a hydraulic camshaft) EXCEPT for the different exhaust manifolds on the Corvette there has been a good bit of confusion over the years.
1965 was the only year for the 396/425 engines, available in both Corvettes and any of the full size cars (Impala's Biscaynes, Bel Air's, Caprice). The 427 was introduced in '66. The top Chevy engine in '66 was the 427/425 available only in Vettes and the full size cars. There was also a 427/390 engine for Vettes and full size cars. Top engine for Chevelles (excluding dealer installed or COPO's) was the 396/375 through 1969.
While true that the 396/425's and 396/375's engine specifications were the same, exhaust manifolds excluded, there is no evidence that any 396/425 rated Chevelles left the factory in any year.
Dan
While true that the 396/425's and 396/375's engine specifications were the same, exhaust manifolds excluded, there is no evidence that any 396/425 rated Chevelles left the factory in any year.
Dan
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3964spd, did they really put a 427/ 425HP in the impala's and caprices? i don't ever recall seeing one. come to think of it, i'm not sure i've seen any 427 impala before '68. anyone have any opinions on this?
back to the point, people confuse things over time. a car that was a 396/ 325HP becomes a 396/ 425HP as the years go by. there's probably more bad information in the hands of the public about classic cars than anything else.
back to the point, people confuse things over time. a car that was a 396/ 325HP becomes a 396/ 425HP as the years go by. there's probably more bad information in the hands of the public about classic cars than anything else.
Oh Yeah... Lots of 427 powered Impalas and Caprices, etc... I have even seen several 66/67 4-doors and station wagons with factory 427s (usually 390 HP, not 425HP)...
In '66 alone, IIRC, there were about 1800+ L72 425HP full-size cars (I forget the number). I seem to recall no factory L72 in '67 (or something like 6 ) for some reason... These also were the sole "factory" application of the "427 TurboJet" Flags, which are virtually identical to the "396 TurboJet" flags used on 65-67 396 powered cars (except the Corvette, which used a unique emblem)...
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Which of the following best applies to you
1. I have been around Chevelles for many years and feel that I have enough experience to definitively conclude that GM did not sell a 425 hp rated 396 despite supporting GM documentation
2. I have been around Chevelles for many years and have not heard of GM selling a 425hp rated 396, but know that almost anything was possible back then and would consider the possibility if the proper supporting documentation was made available**
3. I am a crazy old geezer and can give a rats a$$ about whether or not gm sold 425hp rated 396 Chevelles
** supporting documentation entails window sticker, GM published documentation, dealership advertisements, original owner statementsq
1. I have been around Chevelles for many years and feel that I have enough experience to definitively conclude that GM did not sell a 425 hp rated 396 despite supporting GM documentation
2. I have been around Chevelles for many years and have not heard of GM selling a 425hp rated 396, but know that almost anything was possible back then and would consider the possibility if the proper supporting documentation was made available**
3. I am a crazy old geezer and can give a rats a$$ about whether or not gm sold 425hp rated 396 Chevelles
** supporting documentation entails window sticker, GM published documentation, dealership advertisements, original owner statementsq
2A. I have been around Chevelles for many years and have heard of GM selling a 425hp rated 396, but ...
Yeah, another of those subjects we really shouldn't bring up???
I had heard from a few people (20-25 years ago) that some early '66 cars had "425HP" "decals"... Not sure how true, this was years ago, when no one really cared much. The cars were standard L78 cars, just with a 425 HP DECAL on the air cleaner... So, even if its "factory" applied stickers, were they truly 425HP cars? Just because someone at the factory applied the wrong decal, maybe a mistake, maybe they didn't read the memo reducing the HP "rating" to 375HP, maybe they had a hangover and grabbed the wrong decal, maybe they were a lowely secretary/worker or even a salesman trying to keep a sale (someone wants the 425HP, and the salesman doesn't want to lose the sale, so he writes it up as such... the secratary typing the window sticker probably doesn't know the difference, types in (on the window sticker) what it says on the order form (the RPO gives the price, she probably doesn't know about HP ratings and probably doesn't care). If the car shows up at the dealership, the smart salesman would also swap out the decals before the customer arrived...
Further more, Chevrolet really didn't build ANY "425HP" cars or "375 HP" cars, they built L78s and L72s and etc that were advertised as 375 and 425HP, etc... were these ratings accurate, or was it just the marketing department playing around with values close to actual???...
My father "ordered" a new '58 Bel Air hardtop, 348, 315 HP ("Interceptor"?) with 4.56 gears... The salesman hand wrote the order (I have the carbon copy)... the car had the engine my dad wanted, but pretty sure the "engine name" the salesman wrote down was not the "official" name given to the engine ("Police Special" 4-barrel or "Super Turbo Thrust" with 3X2s?)... Does that make it one-of-one because someone had the wrong name?
If I get a job at the Honda assembly plant tomorrow, and sneak in (and slap on ) a few "450 HP" and "427 Turbo Jet" Decals on some Oddyssey or Civic, is that going to change what was really offered or available? Or could it be said that Honda made a 425HP 427 in 2008... Ultra rare options, but it came from the factory that way... Probably alot harder to fudge or fool with the window sticker nodays (probably all computerized)...
I have heard numerous stories of assembly line workers loading up "unauthorized options" on a fellow assembly line worker's (or a family members) car as it was being built... Stuff would accidently appear in the car... I have even heard the story of an assembly plant manager having a 427 dropped in his '66 malibu station wagon as it rolled down the line... No idea if any of these happened, or how often...
IMO, it has to do more with what was "officially authorized"...
Whew! I gotta lay off the Pepsi
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Guys, I have a little time to kill before I go work out
So supposing such a car exists, (smile), we have an L78 with:
a factory applied 425hp decal...maby applied in error
an original GM 425hp window sticker...maby an error
corresponding 425 hp dealership advertisement...maby an error
corroberating statements from independent original owners and dealership owners..maby both are liars or mistaking
Early official GM published documentation rating the L78 425...maby a misprint
What do we make of all this information surrounding one particular car (if such a car exists)?
A standard L78 that was labeled in accordance with a buyers request?...quite possibly
A standard L78 with 6 verification errors that coincidentally identify it as a 425hp? possible, but as a scientist, I would have to say very unlikely...
If such a car exists, I would have to side with said vehicle being a special order car in accordance with a special request that is merely a standard L78 with unique history and very cool documentation identifying it as a 425 hp car...
Is it really a 425 hp car? Its probably no more of a 425hp car than a standard L78
Does this one isolated car mean that GM officially built 425hp rated Chevelles? Well, dependes on who you ask and how he/she interprets the given data
So what would be the significance of such a car? Well, the answer to this depends on who you ask. To some people it means absolutely nothing, to others, it can be considered a benchmark car and an icon reflecting a time when people could request and take delivery of whatever their heart desired...
If you ask me, I would be absolutely delighted to own such a car. As a collector, I believe that these cars bring collections to life...that is if such a car exists (smile!!!)
Is a standard L78 with unique history and documentation worth more than its counterpart L78 Chevelle...Well that depends on who you ask...As a collector, personally I would drop the extra coin to own a unique piece of american muscle car history
Again, that is if such a car existed (he, he, ha, ha, smile, smile, smile)
So supposing such a car exists, (smile), we have an L78 with:
a factory applied 425hp decal...maby applied in error
an original GM 425hp window sticker...maby an error
corresponding 425 hp dealership advertisement...maby an error
corroberating statements from independent original owners and dealership owners..maby both are liars or mistaking
Early official GM published documentation rating the L78 425...maby a misprint
What do we make of all this information surrounding one particular car (if such a car exists)?
A standard L78 that was labeled in accordance with a buyers request?...quite possibly
A standard L78 with 6 verification errors that coincidentally identify it as a 425hp? possible, but as a scientist, I would have to say very unlikely...
If such a car exists, I would have to side with said vehicle being a special order car in accordance with a special request that is merely a standard L78 with unique history and very cool documentation identifying it as a 425 hp car...
Is it really a 425 hp car? Its probably no more of a 425hp car than a standard L78
Does this one isolated car mean that GM officially built 425hp rated Chevelles? Well, dependes on who you ask and how he/she interprets the given data
So what would be the significance of such a car? Well, the answer to this depends on who you ask. To some people it means absolutely nothing, to others, it can be considered a benchmark car and an icon reflecting a time when people could request and take delivery of whatever their heart desired...
If you ask me, I would be absolutely delighted to own such a car. As a collector, I believe that these cars bring collections to life...that is if such a car exists (smile!!!)
Is a standard L78 with unique history and documentation worth more than its counterpart L78 Chevelle...Well that depends on who you ask...As a collector, personally I would drop the extra coin to own a unique piece of american muscle car history
Again, that is if such a car existed (he, he, ha, ha, smile, smile, smile)
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