1971 LS5 Block question
Thread Starter
Intermediate
Joined: Apr 2004
Posts: 36
Likes: 0
From: Manalapan NJ
1971 LS5 Block question
I have a '71 vette I am trying to sell with a block with a casting number 3963512. There is no"P" under this number. The buyer is concerned it may have a replacement block. The date when block was cast looks like l 8 8 or l 8 9. This is on the rear of eng pass side. Is there a date when engine was assembled and where might that be???
Melting Slicks
Joined: Aug 2005
Posts: 2,359
Likes: 15
From: Confusion
Casting date shows 68 or 69, depending which number it is. This is too early for a 71 car to have this engine casting date. On the front of the engine, under the passenger head there is a stamped pad that shows VIN of car and type application for that engine and the assembled date. Is that there????? If so print here all numbers stamped. Just by the casting date my opinion is the block at least is wrong...............B
Thread Starter
Intermediate
Joined: Apr 2004
Posts: 36
Likes: 0
From: Manalapan NJ
These are the markings on the block
Drivers side 3963512 No "P" underneath this number. to the right of this number are the symbols exactly as I have written them.
GM
1
CONV1
On the passenger side, I see 8 8 1(still a prob, car built 01/71), I guess I read them upside down before, this number is directly under the dist, should the cast date be closer to the cylinder head.
On the pad c11s1XXXXX(matches vin)
T0105CPH
Car is a 365hp manual.
I bought car 10 years ago and looks original to my untrained eye.
What do these broach marks look like...
Drivers side 3963512 No "P" underneath this number. to the right of this number are the symbols exactly as I have written them.
GM
1
CONV1
On the passenger side, I see 8 8 1(still a prob, car built 01/71), I guess I read them upside down before, this number is directly under the dist, should the cast date be closer to the cylinder head.
On the pad c11s1XXXXX(matches vin)
T0105CPH
Car is a 365hp manual.
I bought car 10 years ago and looks original to my untrained eye.
What do these broach marks look like...
Last edited by Rayzz; Jun 18, 2007 at 01:44 PM. Reason: add info
Thread Starter
Intermediate
Joined: Apr 2004
Posts: 36
Likes: 0
From: Manalapan NJ
1. You don't need a "P" underneath the casting number ...
2. The casting date is located on the passenger side, lower part of the engine by the starter - sounds like you have some other numbers there.
3. T0105CPH = Tonawanda, January 5th, 454/365hp with 4 speed (LS5 with manual)
4. Broach marks are minute parallel factory finishing marks "carved" into the face of the block before it was stamped.
5. Sounds like your VIN would be around 09000'ish ???
2. The casting date is located on the passenger side, lower part of the engine by the starter - sounds like you have some other numbers there.
3. T0105CPH = Tonawanda, January 5th, 454/365hp with 4 speed (LS5 with manual)
4. Broach marks are minute parallel factory finishing marks "carved" into the face of the block before it was stamped.
5. Sounds like your VIN would be around 09000'ish ???
I thought '71 casting dates were on the to of motor,,,where it meet bellhousing for transmission??
I dont see any # by starter, any more hints yo can give this rookie
Melting Slicks
Joined: Aug 2005
Posts: 2,359
Likes: 15
From: Confusion
Only early 512 blocks from 68 are dated down by the starter, his date location is correct. Sounds like the block is right, only thing is, is it earlier than the tag inside the door assembly date?!?!?!?!?! As long as the VIN on the block matches and the body tag jives, I see no problems..............................B
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
5 Best & 5 Worst Corvette Daily Drivers
Joe Kucinski
The Headlights of Every Corvette Generation Explained
Joe Kucinski
5 Best & 5 Most Overrated Corvette Track Packages of All Time!
Joe Kucinski
Every 2027 Corvette Engine Explained
Joe Kucinski
Designer Imagines A Corvette That Looks More Like a Corvette Than the Corvette
Verdad Gallardo
10 Ugly Corvettes That We Still Kinda Love
Joe Kucinski
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
Thread Starter
Intermediate
Joined: Apr 2004
Posts: 36
Likes: 0
From: Manalapan NJ
actual vin is
194671S106854
build date 01/71 i believe 01/18/71
casting date from left to right (sitting in pass seat) 1 8 8 or 1 8 9
could a block cast in 68 an not be used for that long a time??
194671S106854
build date 01/71 i believe 01/18/71
casting date from left to right (sitting in pass seat) 1 8 8 or 1 8 9
could a block cast in 68 an not be used for that long a time??
Last edited by Rayzz; Jun 18, 2007 at 06:31 PM. Reason: add more info
Account disabled by user request 5 Jan 09
Joined: Jan 2005
Posts: 261
Likes: 1
If it were a 1969 date, then the cast date would be down by the starter.
So I think you have a quandary here ... ???
September or December of 1970 would work well. Any chance that last "8" or "9" is really a "0" (zero) ?????
Thread Starter
Intermediate
Joined: Apr 2004
Posts: 36
Likes: 0
From: Manalapan NJ
I looked at that number more times than I care to today. It could be a 0 but there is a line in bisecting the zero. Anyway the buyer came around again today and we agreed on a price.
Thanks for the help.....
Sincerely Rayz
Thanks for the help.....
Sincerely Rayz
Melting Slicks
Joined: Aug 2005
Posts: 2,359
Likes: 15
From: Confusion
The first digit would normally be a letter, so either I (eye) or L, for September or December. (But there are examples of all numeric codes also ...)
If it were a 1969 date, then the cast date would be down by the starter.
So I think you have a quandary here ... ???
September or December of 1970 would work well. Any chance that last "8" or "9" is really a "0" (zero) ?????
If it were a 1969 date, then the cast date would be down by the starter.
So I think you have a quandary here ... ???
September or December of 1970 would work well. Any chance that last "8" or "9" is really a "0" (zero) ?????
I also thought casting dates after 69 were double digit for the year, example.71, 72, 73
Team Owner
Joined: Jun 2000
Posts: 38,923
Likes: 1,482
From: Southbound
Cruise-In II Veteran
Melting Slicks
Joined: Nov 2004
Posts: 2,672
Likes: 6
From: Nevada City California
They are. I've had 3 '70 LS5's, 2 '71 LS6's, 1 '71 LS5, all had a two digit year code. Something is a miss here.
