C-1 Corvette Big Block Conversion
A recent Technical Discussion Board posting mentioned that a C-1 Corvette could be modified/converted to accept a big block Chevrolet engine. Interested, I inquired if the conversion required a straight axle assembly or major modification(s) to the frame? In turn, Mr. Mike Ernst quickly and correctly responded that it was a basic bolt-in conversion using a modified motor mount assembly. I subsequently did a computer search which led to a December 1967 Hot Rod magazine article which described the process and the necessary components for the conversion of '57 through '62 Corvettes for a big block application. At the time, Bill Thomas Race Cars of Anaheim, California, manufactured a kit which consisted of: motor mounts; frame supports; and headers. Also needed was a '57 Chevrolet passenger car cross-shaft bracket (PN 3726096). I then attempted to find Bill Thomas Race Cars, to see if they could still provide the requisite components for the conversion; however, I had no luck. (I believe that this is the same Bill Thomas who created the Cheetah; and if so, believe that he passed away in 2009). Anyway, I am extremely interested in accomplishing this modification on my '61, and this is the million dollar question: "Does anyone know of a source where I can obtain as a minimum, (new or excellent used) motor mounts and frame supports for the conversion?" (Additionally, while the Bill Thomas kit included headers, the Hot Rod article stated that most any type big block header would fit the passenger side of the car without any fitment issues; and that the driver side header required modification to clear the steering box). Thank you in advance for any leads/sources for the required parts! Rob Vanderhoeven
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Rob
SPEAK YOUR MIND, but ride a fast horse. -- Anonymous -
Re: C-1 Corvette Big Block Conversion
Rob, Just curious why you would want to do this. The weight ratio is bad enough with a small block. Add the extra pounds of a big block and steering will suck and traction will be at a minimum. With all the horsepower the new small blocks put out I just wonder what the advantage of a big block would be. Although it would look pretty impressive when you opened the hood! For some other insight to this just search "big block swap in C1 Corvette" has been discussed on other forms.Terry -
Re: C-1 Corvette Big Block Conversion
in 1973, i installed a 427/425 bbc engine in my 57 daily driven corvette. i modified a hurst sbc motor mount to accommodate the bbc engine and the c-i frame motor mount. i used a lakewood scatter shield and modified a 55 chevy pass car z-bar bracket allowing the use of the 57 vet z-bar. headman headers missed the c-1 steering box just barely. i had to remove a small 1 1/2" wide tab just inboard of where the stock 57 heater assembly is located in order to clear the rear of the pass side head. i used the 57 radiator which cooled the contraption adequately. i removed the stock heater and installed a 64 chevy-11 aftermarket heater/air conditioner in its place. i kept the 57 vet rear axle assembly but installed a 4.56 ring and pinion in the differential. a hurst comp plus shifter on a muncie completed the drivetrain. i removed the front crossmember and inserted a pair of 6" channel between the crossmember and the frame of the 57. the mickey thompson tires on ansen alum wheels protruded about 4" outside the rear quarters. back in '73, the car was in hot rod black primer. i drove this beast for about 5 or 6 years while attending WVU. after graduation, we returned to cumberland and bought the farm. the 57 was put in mothballs. in about 2005, i decided to restore the once original 57 250HP powerglide corvette. if you'd like to see what it looks like today, check out the cover of the Fall 2010 RESTORER mag. mikeComment
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Re: C-1 Corvette Big Block Conversion
Without question, a BB in any 53-62 Corvette would make an "awsome" impression! Although, as mentioned above, the weight ratio would be horrible, and in the long run, would likely take away from overall handling, braking and steering. To my way of thinking, the ONLY way to have any chance of this conversion being practical would be to install an ALL ALUMINUM BB. And for an incredible fun factor, open it up to 496.
I have, and have had for many years, a very healthy FI SB400 in the 56. There is no comparrison between the 400 and BB torque. BUUUUUUUT, a SERIOUS SB400 (possibly even an aftermarket block), opened up to 434 with alum heads, would produce about all the power/torque that could be reasonably handled by an experienced driver. The SB400-M20-3.08 posi in the 56 will do just about anything I want it to, and a MAJOR PLUS is that it is a direct bolt in swap for any 283-327, with ZERO modifications required. Makes the KISS principle well defined. Just a thought to consider.
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Re: C-1 Corvette Big Block Conversion
terry and tom are right on. my old 57 with the bbc handled terribly and traction didn't exist. but it was a hoot to get around in. mikeComment
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Re: C-1 Corvette Big Block Conversion
Terry, Mike, and Tom--
Thank you very much for your thoughtful and informed responses! Each one of you brought up some excellent points which I sincerely appreciated you sharing with me; and just as a matter of further discussion, I thought I would provide the following information/rationale for my interest in such a conversion.
Of all the Vettes that I have owned since 1977, I have never owned a big block. As a young man, (I am 61 now), they were financially unobtainable for me; and that remains the same today. While I have never owned a big block Vette, I have owned three (3) big block SS396 Chevelles/El Caminos and loved them. So why am I even considering a big block conversion for my '61, especially since the installation of a new "special high performance" small block would make the car scream? Four basic reasons: 1). I obtained some very nice high performance big block parts in one of my many "horse trading" episodes with my best friend of 41 years. Included in that trade was a pre-production CAN AM aluminum ZL-1 block, and a set of aluminum 074(?) heads. The block, as well as the heads, required work that I estimated would be at least $5000; so, after some consideration, I hauled the heads and block back to his house, but kept the rest of the big block components. 2). My '61 Corvette is nothing more than an "ok" driver quality car. This car which I refer to as Frankenstein's monster was characterized as a '70s/'80s custom by the selling dealer. It has a Colorado assigned VIN; a non-original/incorrect two bolt main "performance built" 350 ci engine; a non-original/incorrect Muncie 4 speed; a non-original/incorrect Hurst Competion Plus shifter; a non-original/incorrect generator to alternator conversion, with a non-original/incorrect tach; a non-original/incorrect AM-FM cassette radio which I pulled out along with a radar detector and threw in the garbage--I then installed a reproduction radio block off plate, but the car still sports a radio antenna; the front nose of the car does not sport '61 Corvette emblems, but instead, a '58-'60 emblem in the nose; the trunk and interior sport non-original/incorrect carpeting; etc., etc. In summation, it is beyond a candidate for a "correct" restoration, and is-what-it-is, a '61 driver/hot rod. 3). Since I drive it locally, to include car cruises, I want something unique/different. That's the story in a nutshell. Again, I agree, the hipo Chevy small block is the way to go for practicality and driveability; but then, I have never been accused of being "practical".
Thanks again guys!!! Best Wishes, Rob
Rob
SPEAK YOUR MIND, but ride a fast horse. -- AnonymousComment
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Re: C-1 Corvette Big Block Conversion
by all means, go for it rob. i've got a 61 bodied 92 ZR1 and its a hoot to drive/autocross/road race/drag race. mikeComment
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Re: C-1 Corvette Big Block Conversion
Well, all I can say, is if you are set on the BB conversion-----------------------------just make it killer!!!!!!!!!!!!
I have been an NCRS member for a VERY long time, but I've always been VERY far away from a numbers correct restoration type person. I like stuff like lawn mowers with a blown HEMI, and I'd like your 61 with a BB. So again, just make it killer if you're going to do it!Comment
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Re: C-1 Corvette Big Block Conversion
a while back I saw a solid axle forget what year with a 427 with a tir power set up on. looked really neat and a hand full to driveComment
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Re: C-1 Corvette Big Block Conversion
Rob, I once had a '57 with a '65 396 425 HP motor. You had to take off gently or risk leaving most of your rear tires at your point of departure. This engine was installed with the Bill Thomas motor mounts. I still have those motor mounts somewhere. I kept them for the historical significance and certainly did not plan to use them again.Comment
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Re: C-1 Corvette Big Block Conversion
I could lighten up the frontend of the 56 even more if I added alum heads, BUT, I have "special" modified 1966 462 heads (we used to call them cheater heads) that I want to keep so that it retains the LOOK of a 57 FI head (double humps are ground off and a pyramid is shaped to look like 539 heads).
Plus, additional bosses were welded, drilled and tapped for staggered bolt pattern, 9-fin valve covers.
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Re: C-1 Corvette Big Block Conversion
Somewhere I have the Bill Thomas catalog, but I swear I cannot locate it!Comment
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Re: C-1 Corvette Big Block Conversion
Way back when, in the mid 60's, I used to "visit" a place called J&G Speed Shop and purchase a few things. A fellow used to be there a lot with his '57 and a 427 stuffed in the front. Raised front, M&H's, it looked great and went in an uncontrolled way. There was another guy who had a '63 coupe painted orange with a 425 HP 409 in it. I believe he used station wagon springs up front. Old skool just looks neat and sounds neat. Have fun Rob!Comment
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Re: C-1 Corvette Big Block Conversion
Mike, Tom, Keith, and Toby--
You do not know how much I truly appreciate your input on this subject! It is this very reason why I subscribe solely to this organization. Through my review of the discussions posted on the TDB, I continue to learn a great deal about these wonderful cars; as welll as get helpful/useful information when trying to accomplish work on them. 1). Toby--If you would be interested in selling those motor mounts, I would love to purchase them. So I don't violate the rules of the TDB, please PM me; or email me at robdianev@yahoo.com. 2). Tom--Those are fantastic photos that you posted of your engine. While aluminum heads are pretty trick, I like your "sneaky" heads. (Your roller tip rocker arms look pretty good as well.) Thanks Again, Rob
Rob
SPEAK YOUR MIND, but ride a fast horse. -- AnonymousComment
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Re: C-1 Corvette Big Block Conversion
Rob,Mike, Tom, Keith, and Toby--
You do not know how much I truly appreciate your input on this subject! It is this very reason why I subscribe solely to this organization. Through my review of the discussions posted on the TDB, I continue to learn a great deal about these wonderful cars; as welll as get helpful/useful information when trying to accomplish work on them. 1). Toby--If you would be interested in selling those motor mounts, I would love to purchase them. So I don't violate the rules of the TDB, please PM me; or email me at robdianev@yahoo.com. 2). Tom--Those are fantastic photos that you posted of your engine. While aluminum heads are pretty trick, I like your "sneaky" heads. (Your roller tip rocker arms look pretty good as well.) Thanks Again, Rob
Here is the whole engine.
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