new guy from Austin
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Intermediate
Joined: Jul 2018
Posts: 32
Likes: 11
From: Austin, TX
new guy from Austin
New member here in Austin, TX. Looking for help in evaluating engine stamp codes as I am in the market for an LT1. Previous cars include 1966 roadster and 1970 roadster. Looking hard now for my next C3!
Bill
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Welcome and I'm moving this over to the C3 General section for some assistance with your question.
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Safety Car
Joined: May 2008
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From: Lafayette Louisiana
Hi and welcome!!! This is a great forum!
Here is a LT-1 List I have complied mostly from this forum that I hope you might find useful. 1/2 the FUN is the hunt, I always say.
Good luck to you!5-21-2018 Here is a great list I saved from a posting here:
There are a few things that only a LT-1 would have , some are pretty easy to change out and some are not very easy at all.in no piticular order.
1st. No 1970 or 1971 LT-1 had A/C
2nd. Emission sticker on fire wall behind master cylinder should have letters AX on upper left corner for a 71.
3rd. All LT-1's are 4 speeds. (M20 was std , M21/M22 were optional)
4th. Tach has 6,500 RPM red line on 1970 & 1971 and on 72's w/o AC
5th. All 71 LT-1's came with A.I.R. system. If removed should still have manifolds with holes for the tubes, Car may have headers and if so ask to see old manifolds.
6th. LT-1's had copper radiator W/O a overflow canisiter on the passanger side fenderwell. There should also be no holes whers one had been mounted.
7th. All 70 / 71 LT-1's had Tranisitor Ign. system. That may have been removed. But if it is removed look for the 3 holes on the front face of the driver side inner fender well where the Amplifer box was mounter.
Take a flashlight and look in front of the front wheel or open hood and look at it from the front side. 2 holes on bottom and 1 on top. No TI on the 72 LT-1
8th. Should have a Winters snowflake intake manifold with casting # 3959594
for 1971 and 1972, per NCRS, 1970 should be #3972110. Both manifolds are aluminum (my addition).
9th. LT-1's had a Holley carb. so there is only 1 fuel line , no return line like a quadra-jet carb. Look along frame rail on passanger side for the single line. Also the fuel tank is different. There should be no nipple on the passanger side, side wall for a return line.
If you lay on your back under the rear wheel you can reach your hand up and feel for an indention on the passanger side. If there is a nipple that is capped off , then beware.
Also the single fuel line on a LT-1 was not the same line that was used to feed fuel on the 2 line set up. So if someone removed the return line the look of the 3/8 line is still different. Not a big difference but if you can look at a car with a 2 line set up then you can see what you do not want to find.
10th. LT-1's had solid lifters , but if the car does not then that is not to big a red flag. Many people do not like them and may have replaced with HYD. lifters during a rebuild.
11th. The hardest to fake and most expensive would be the 4 bolt main block. No # on the outside of the block can verify this.
Only way to verify is to remove the pan or have a lighted optical viewer and remove the drain plug.
12th. LT-1's use 2.5" exhaust pipes like the big block cars. But the manifolds were still 2" set up. So the pipes flair from 2 to 2.5" about 6 inches from the manifold. The exhaust hangar at the trans is also different. Look on line at the Corvette Central site and you can see both 2" and 2.5" hangars.
13th. As I recall the highest rear end gear was 3:36 if trans was a M20
And id Trans was a M21 or M22 the 3:55 was highest gear
M20 3:36 Economy
3:55 Standard
3:70 Performance
M21 / M22
3:55 Economy
3:70 Standard
4:11 Performance
14th. The 71 /71 LT-1 Aluminum valve covers should have a rubber oil cap not a twist in. These covers are very hard to find. All the catalouges sell the twist in cap style.
15th. LT-1's have the same heavy duty half shaft retainers as big block cars. look at the rear end side yokes, there should be caps with bolts. Base cars used U bolts with nuts.
16th. The rocker arms have a letter O stamped in them.
17th. The balancer on the crankshaft is an 8" unit not a 6"
18th. Original LT-1 hood would not have the holes for 454 number emblems since LT-1 decal and stencil was used.
That is all I know of. and you could not fake all of this and sell a car for a mid 20's price and be worth the effort / expense.
So until someone finds the lost records from St Louis anyone buying a no base model car will be going out on a limb at little unless you are buying from the original owner.
Sounds like a very nice Corvette, if you decide to pass, please post a picture! Even if a "fake" LT-1, it might be a great deal if priced accordingly. IMHO, the key is to pay fair market price for what it actually is!
19th Great check list for a LT1. You could add No p/s in 1970 with a CTU engine. CTU had the 6 qt. oil pan. Also, plastic fan shrouds on LT1s. 6-21-18
20th. Lots of places to find this (the key is of course: is it an original stamp?)
1970 CTK, CTR, CTU CTV(ZR1)
1971 CGY(ZR1), CGZ
1972 CKY CKZ(ZR1) CRS CRT
Here is a LT-1 List I have complied mostly from this forum that I hope you might find useful. 1/2 the FUN is the hunt, I always say.
Good luck to you!5-21-2018 Here is a great list I saved from a posting here:
There are a few things that only a LT-1 would have , some are pretty easy to change out and some are not very easy at all.in no piticular order.
1st. No 1970 or 1971 LT-1 had A/C
2nd. Emission sticker on fire wall behind master cylinder should have letters AX on upper left corner for a 71.
3rd. All LT-1's are 4 speeds. (M20 was std , M21/M22 were optional)
4th. Tach has 6,500 RPM red line on 1970 & 1971 and on 72's w/o AC
5th. All 71 LT-1's came with A.I.R. system. If removed should still have manifolds with holes for the tubes, Car may have headers and if so ask to see old manifolds.
6th. LT-1's had copper radiator W/O a overflow canisiter on the passanger side fenderwell. There should also be no holes whers one had been mounted.
7th. All 70 / 71 LT-1's had Tranisitor Ign. system. That may have been removed. But if it is removed look for the 3 holes on the front face of the driver side inner fender well where the Amplifer box was mounter.
Take a flashlight and look in front of the front wheel or open hood and look at it from the front side. 2 holes on bottom and 1 on top. No TI on the 72 LT-1
8th. Should have a Winters snowflake intake manifold with casting # 3959594
for 1971 and 1972, per NCRS, 1970 should be #3972110. Both manifolds are aluminum (my addition).
9th. LT-1's had a Holley carb. so there is only 1 fuel line , no return line like a quadra-jet carb. Look along frame rail on passanger side for the single line. Also the fuel tank is different. There should be no nipple on the passanger side, side wall for a return line.
If you lay on your back under the rear wheel you can reach your hand up and feel for an indention on the passanger side. If there is a nipple that is capped off , then beware.
Also the single fuel line on a LT-1 was not the same line that was used to feed fuel on the 2 line set up. So if someone removed the return line the look of the 3/8 line is still different. Not a big difference but if you can look at a car with a 2 line set up then you can see what you do not want to find.
10th. LT-1's had solid lifters , but if the car does not then that is not to big a red flag. Many people do not like them and may have replaced with HYD. lifters during a rebuild.
11th. The hardest to fake and most expensive would be the 4 bolt main block. No # on the outside of the block can verify this.
Only way to verify is to remove the pan or have a lighted optical viewer and remove the drain plug.
12th. LT-1's use 2.5" exhaust pipes like the big block cars. But the manifolds were still 2" set up. So the pipes flair from 2 to 2.5" about 6 inches from the manifold. The exhaust hangar at the trans is also different. Look on line at the Corvette Central site and you can see both 2" and 2.5" hangars.
13th. As I recall the highest rear end gear was 3:36 if trans was a M20
And id Trans was a M21 or M22 the 3:55 was highest gear
M20 3:36 Economy
3:55 Standard
3:70 Performance
M21 / M22
3:55 Economy
3:70 Standard
4:11 Performance
14th. The 71 /71 LT-1 Aluminum valve covers should have a rubber oil cap not a twist in. These covers are very hard to find. All the catalouges sell the twist in cap style.
15th. LT-1's have the same heavy duty half shaft retainers as big block cars. look at the rear end side yokes, there should be caps with bolts. Base cars used U bolts with nuts.
16th. The rocker arms have a letter O stamped in them.
17th. The balancer on the crankshaft is an 8" unit not a 6"
18th. Original LT-1 hood would not have the holes for 454 number emblems since LT-1 decal and stencil was used.
That is all I know of. and you could not fake all of this and sell a car for a mid 20's price and be worth the effort / expense.
So until someone finds the lost records from St Louis anyone buying a no base model car will be going out on a limb at little unless you are buying from the original owner.
Sounds like a very nice Corvette, if you decide to pass, please post a picture! Even if a "fake" LT-1, it might be a great deal if priced accordingly. IMHO, the key is to pay fair market price for what it actually is!
19th Great check list for a LT1. You could add No p/s in 1970 with a CTU engine. CTU had the 6 qt. oil pan. Also, plastic fan shrouds on LT1s. 6-21-18
20th. Lots of places to find this (the key is of course: is it an original stamp?)
1970 CTK, CTR, CTU CTV(ZR1)
1971 CGY(ZR1), CGZ
1972 CKY CKZ(ZR1) CRS CRT
Last edited by 20mercury; Jul 25, 2018 at 06:19 PM.
Good luck with your search!
Drifting
Joined: Aug 1999
Posts: 1,451
Likes: 84
From: Round Rock TX
Have an original owner 5 Star Bow tie car, that’s not for sale. Make sure you get the smog pump and other special parts. The stamp on ours has suffix CTU. I would recommend the new NCRS color judging manual to help in making sure it’s right when you find one.
