Big Block L71 numbers match?
Thread Starter
5th Gear
Joined: Jun 2015
Posts: 5
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Big Block L71 numbers match?
Hello! I just joined the corvette forum today in hopes to find out some information about the 68 corvette I own.
The block # is 3935439 Heads# 3919840 in my corvette black book this tells me it is a L71 427 435hp. I also read in this book that except for the year 1955 the vin# did not reveal witch engine the corvette had until 1972.
I have heard many different ways in finding out which engine originally came with the car, can anyone shed some light on the best way to determine this?
Thank you
Jon
The block # is 3935439 Heads# 3919840 in my corvette black book this tells me it is a L71 427 435hp. I also read in this book that except for the year 1955 the vin# did not reveal witch engine the corvette had until 1972.
I have heard many different ways in finding out which engine originally came with the car, can anyone shed some light on the best way to determine this?
Thank you
Jon
Race Director
Joined: Oct 2000
Posts: 12,667
Likes: 3,123
From: Shamong, NJ
The "439" block was used for 390, 400 and 435 engines, but the "840" heads were only used on the 435.
On the front passenger side of the block, is a machined pad that should have two sets of letters and numbers, stamped into it. One set should match the your VIN, and the other set will be an engine assembly date and engine identifier code. If it is a 435, the identifier (or suffix code) will be "IR", and read something like this, T0202IR. The "T" is for the Tonawanda engine plant, "0202" would be the moth and day the engine was assembled, and "IR" is the suffix code that identifies an engine as a 435.
The rear end will also have an ID code stamped into it. The code used on 68 big blocks, was different than small block rear end codes. This could identify a big block car, but not which big block came in the car.
Beyond that suffix code, or original paperwork, there really isn't any way to know what engine originally came in a pre-72 Corvette. There are a lot of little clues that identify a big block car, but everyone of them can easily be changed.
On the front passenger side of the block, is a machined pad that should have two sets of letters and numbers, stamped into it. One set should match the your VIN, and the other set will be an engine assembly date and engine identifier code. If it is a 435, the identifier (or suffix code) will be "IR", and read something like this, T0202IR. The "T" is for the Tonawanda engine plant, "0202" would be the moth and day the engine was assembled, and "IR" is the suffix code that identifies an engine as a 435.
The rear end will also have an ID code stamped into it. The code used on 68 big blocks, was different than small block rear end codes. This could identify a big block car, but not which big block came in the car.
Beyond that suffix code, or original paperwork, there really isn't any way to know what engine originally came in a pre-72 Corvette. There are a lot of little clues that identify a big block car, but everyone of them can easily be changed.
Team Owner
Joined: Sep 2006
Posts: 31,237
Likes: 4,328
From: Westminster Maryland
Hi Jon,
Welcome!
gb62 did a pretty nice job explaining the whole 'stamp pad' / 'what engine came in my car?' information for you.
If you're interested in knowing more about the 'originality' of your 68 you might consider purchasing the 1968-1969 Technical Information & Judging Guide from the NCRS site.
It's a very large detailed book about 68-69 cars and you might find it quite interesting.
It can be found at the 'store' on the NCRS site and can be bought without becoming a member.
It's always fun to see new CF members cars… how about a couple of pictures?
Regards,
Alan
Welcome!
gb62 did a pretty nice job explaining the whole 'stamp pad' / 'what engine came in my car?' information for you.
If you're interested in knowing more about the 'originality' of your 68 you might consider purchasing the 1968-1969 Technical Information & Judging Guide from the NCRS site.
It's a very large detailed book about 68-69 cars and you might find it quite interesting.
It can be found at the 'store' on the NCRS site and can be bought without becoming a member.
It's always fun to see new CF members cars… how about a couple of pictures?
Regards,
Alan
Thread Starter
5th Gear
Joined: Jun 2015
Posts: 5
Likes: 0
Thanks for the response. Ok so your saying that the vin# is on the block prior to 1972?
The "439" block was used for 390, 400 and 435 engines, but the "840" heads were only used on the 435.
On the front passenger side of the block, is a machined pad that should have two sets of letters and numbers, stamped into it. One set should match the your VIN, and the other set will be an engine assembly date and engine identifier code. If it is a 435, the identifier (or suffix code) will be "IR", and read something like this, T0202IR. The "T" is for the Tonawanda engine plant, "0202" would be the moth and day the engine was assembled, and "IR" is the suffix code that identifies an engine as a 435.
The rear end will also have an ID code stamped into it. The code used on 68 big blocks, was different than small block rear end codes. This could identify a big block car, but not which big block came in the car.
Beyond that suffix code, or original paperwork, there really isn't any way to know what engine originally came in a pre-72 Corvette. There are a lot of little clues that identify a big block car, but everyone of them can easily be changed.
On the front passenger side of the block, is a machined pad that should have two sets of letters and numbers, stamped into it. One set should match the your VIN, and the other set will be an engine assembly date and engine identifier code. If it is a 435, the identifier (or suffix code) will be "IR", and read something like this, T0202IR. The "T" is for the Tonawanda engine plant, "0202" would be the moth and day the engine was assembled, and "IR" is the suffix code that identifies an engine as a 435.
The rear end will also have an ID code stamped into it. The code used on 68 big blocks, was different than small block rear end codes. This could identify a big block car, but not which big block came in the car.
Beyond that suffix code, or original paperwork, there really isn't any way to know what engine originally came in a pre-72 Corvette. There are a lot of little clues that identify a big block car, but everyone of them can easily be changed.
Thread Starter
5th Gear
Joined: Jun 2015
Posts: 5
Likes: 0
Thanks!
Hi Jon,
Welcome!
gb62 did a pretty nice job explaining the whole 'stamp pad' / 'what engine came in my car?' information for you.
If you're interested in knowing more about the 'originality' of your 68 you might consider purchasing the 1968-1969 Technical Information & Judging Guide from the NCRS site.
It's a very large detailed book about 68-69 cars and you might find it quite interesting.
It can be found at the 'store' on the NCRS site and can be bought without becoming a member.
It's always fun to see new CF members cars… how about a couple of pictures?
Regards,
Alan
Welcome!
gb62 did a pretty nice job explaining the whole 'stamp pad' / 'what engine came in my car?' information for you.
If you're interested in knowing more about the 'originality' of your 68 you might consider purchasing the 1968-1969 Technical Information & Judging Guide from the NCRS site.
It's a very large detailed book about 68-69 cars and you might find it quite interesting.
It can be found at the 'store' on the NCRS site and can be bought without becoming a member.
It's always fun to see new CF members cars… how about a couple of pictures?
Regards,
Alan
Race Director
Joined: May 2006
Posts: 18,710
Likes: 2,574
Vin
Yes the VIN is on the block prior to 72 assuming nobody has machined the pad and wiped it out. Starting in 72 the full VIN had a digit which indicated what engine was in the car from the factory.
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Thread Starter
5th Gear
Joined: Jun 2015
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Instructor
Joined: Jul 1999
Posts: 138
Likes: 1
From: Brick New Jersey
Don't be to quick in dropping your tank. I also wanted to know if the build sheet was still on the tank of my 68. I bought an inexpensive cable lens mounted video inspection camera. It was something like $50 at Harbor Freight. Romoved the gas tank fill boot and snaked the video camera along the top of the tank on both sides. Unfortunetly the build sheet wasn't on my tank. A whole lot easier then dropping the tank !! Tom.
Last edited by tomdoc; Jun 4, 2015 at 07:51 PM.