How Can You Tell A Real L78 '65 Impala - Impala Tech
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post #1 of 15 (permalink) Old 02-20-2011, 12:52 AM Thread Starter
 
 
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How Can You Tell A Real L78 '65 Impala

I'm sure it's a true 396 4 speed but is it possible to tell if it originally came with a 425 hp 396?

Rain Man
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post #2 of 15 (permalink) Old 02-20-2011, 12:36 PM
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For 1965, unless you have a build sheet, window sticker, or other credible documentation for the car, there's really no way to definitively confirm that the car came with the 425 HP 396. There are however a few things that you can look for that might point you in the right direction. The most obvious of which are matching numbers - do the engine and VIN numbers match? That will at least tell you if it's the original engine to the car.

There were only 1,838 396's installed in all B-bodies for 1965, so even the 325 HP cars are fairly rare as they were still in the process of phasing out the remaining 409 inventory. The 396 was first introduced on 02/15/65, so the casting date should be after this date for either the 325 or 425 engines. The build date of your car should then be sometime between mid February and the end of the `65 model year run. The 425 HP block casting number for `65 will be 3855962. It should also have " Spec. High Perf." cast next to the number. It will be a 4-bolt block with an "IE" suffix in the engine pad stamp. (All were manual transmision only). The casting number will be on the lower right side of the block next to the freeze plug and in front of the starter motor. There were also no dowel pins used on the timing cover for the 425 HP motor.

Hope this at least helps.

Bigblox,

`68 L72 SS 427
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post #3 of 15 (permalink) Old 02-20-2011, 02:51 PM Thread Starter
 
 
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L78 Proof

Quote:
Originally Posted by Bigblox View Post
For 1965, unless you have a build sheet, window sticker, or other credible documentation for the car, there's really no way to definitively confirm that the car came with the 425 HP 396. There are however a few things that you can look for that might point you in the right direction. The most obvious of which are matching numbers - do the engine and VIN numbers match? That will at least tell you if it's the original engine to the car.

There were only 1,838 396's installed in all B-bodies for 1965, so even the 325 HP cars are fairly rare as they were still in the process of phasing out the remaining 409 inventory. The 396 was first introduced on 02/15/65, so the casting date should be after this date for either the 325 or 425 engines. The build date of your car should then be sometime between mid February and the end of the `65 model year run. The 425 HP block casting number for `65 will be 3855962. It should also have " Spec. High Perf." cast next to the number. It will be a 4-bolt block with an "IE" suffix in the engine pad stamp. (All were manual transmision only). The casting number will be on the lower right side of the block next to the freeze plug and in front of the starter motor. There were also no dowel pins used on the timing cover for the 425 HP motor.

Hope this at least helps.

Bigblox,

`68 L72 SS 427
Thanx Bigblox,
As your name implies, I'm also a BB nut. Yes, it has the 962 block and IE stamp but the serial number on the pad is a mystery to me. It has I 598
stamped on the pad. Do you know what that means?
Best, Raymond
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post #4 of 15 (permalink) Old 02-20-2011, 03:25 PM
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Not quite clear on what you're referring to as the serial number on the pad (?) Can you give me the whole sequence of numbers as they appear on the pad? You should have the engine ID stamped on the pad first, followed by the engine VIN #. (Which should match the car's VIN). Where in that sequence do you see the "I598"?
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post #5 of 15 (permalink) Old 02-20-2011, 03:48 PM Thread Starter
 
 
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Hi Bigblox,
I meant to say it is stamped on the pad to the right of the Tonowanda build date.
I 598 occupies the space where the serial number should be.

Thanx
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post #6 of 15 (permalink) Old 02-20-2011, 04:37 PM
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Wow. I don't think I've ever seen or heard of anything like that unless the block has been decked and restamped at some point, but those numbers still wouldn't make much sense. (to me anyway). Is it possible there are more numbers behind the "I 598" that have been machined off or are just illegible?

A hypothetical example of a normal engine VIN sequence for a `65 B-body would be:

15SXXXXXX.

1 = Chevrolet (are you sure your "I" isn't a "1"?)
5 = 1965
S = the assembly plant - St. Louis in my example here
XXXXXX = the car's VIN #.

It's possible this could have been some type of dealer replacement block. Maybe someone else here has some input on this.
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post #7 of 15 (permalink) Old 02-20-2011, 08:57 PM
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A service block woun't come with an engine application code. It was stamped with a two letter service code (forgot what the actual number code is), the date it was built, and the assembly plant code plus a sequence number from the service build sheet so that GM could track it from a QC and inventory control perspective.

Big Dave
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post #8 of 15 (permalink) Old 02-20-2011, 10:23 PM Thread Starter
 
 
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Thanx for the inputs. The service replacement blocks usually had a CE suffix. The engine build date characters used an I to designate both the letter I and the number "one". I suppose the I in I 598 could be the number one. I have also seen rebuilt engines with machine shop stamps on the pads but could it be possible that it's a replacement engine and the dealer stamped the I 598 on the pad? The Tonowanda stamping is very clear with no evidence of being decked. Although the cast date is in line I have a feeling that the block is not original.
Rain Man
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post #9 of 15 (permalink) Old 02-20-2011, 10:32 PM
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Ditto on the CE suffix for the service replacement blocks.

HOW A NOVICE REBUILDS A 66 IMPALA CONVERTIBLE:
http://www.impalas.net/forums/blog.php?u=1432
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post #10 of 15 (permalink) Old 02-21-2011, 06:30 PM
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Raymond, can you post some pictures of the numbers? Vin, cowl tag and engine pad? There may be some other hints. Is there a 598 in the last six of the vin?

Warren
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post #11 of 15 (permalink) Old 02-22-2011, 12:08 PM Thread Starter
 
 
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Warren,

The vin, last three digits 887, does not match with the I 598. The cowl tag body numbers are 65-16637 LOS 21110. The bottom line reads E 2LR 3C. I presume that has to do with options. Can you decipher?
Thanx for your help.

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post #12 of 15 (permalink) Old 02-22-2011, 01:59 PM
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65-16637 LOS 21110
E 2LR 3C

65 ==> year made
16637 ==> Impala SS 2 door Sports Coupe
LOS ==> assembled in LA, CA
21110 ==> Sequence number for internal use not associated with VIN
E ==> RPO code A01 Tinted Glass
2 ==> Options Group Number Two
L ==> RPO code M20 Manual Four Speed Transmission, close ratio (M21 or M22)
R ==> RPO code U80 Rear Seat Speaker
3 ==> Options Group Number Three
C == RPO code B70 Padded Dash

Big Dave
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post #13 of 15 (permalink) Old 02-22-2011, 09:30 PM Thread Starter
 
 
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Thanx much Dave for decipering the option codes. Now if I can decipher my '66 L78 Chevelle codes.

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post #14 of 15 (permalink) Old 02-28-2011, 11:11 PM
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Raymond, the next thing would be to get the stamped transmission and rear axle dates.

Warren
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post #15 of 15 (permalink) Old 03-28-2011, 02:23 PM
 
 
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What is the status of the car? Is it an original project, or has it been gone through? I would check for spring tags. L78 cars got specific springs, and if the springs are original this is a great way to confirm its authenticity. We know it's an original 4 speed car, but the cowl tag won't tell us anything about the engine. Does the car have a tach in it, and if so is does it go to 7K with an redline of 6K RPM? If yes, check the date on the tach in relation to the body build date. Obviously it should precede the build date of the car. Original radiator in it? What does it have for tailpipe hangers out back? L78 cars used a specific style tailpipe hanger. Firewall piercings are another thing to check. There is other stuff to check too. Would help if you could post some pictures up of these details. Hopefully it turns out to be a real L78.
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