mikem350

OK, looking at a car locally. No hood or engine. Any way to tell from the trim tag or anything else if a genuine LT1? Assuming the vin is no help for 1971.
TIA, Mike

76CSRvette

I don't know much but the engine is what pretty much make it an LT1. But there is the trim tag (can be changed for $12) The tach redline is 5600 (also can be swapped) I know more will chime in with better info but there is a lot of threads on how to find out if it an lt1

AirBusPilot

Redline is 6500.

ralphspears

single fuel line from the tank to the fuel pump

76CSRvette

https://www.corvetteforum.com/forums...l-lt1-car.html
https://www.corvetteforum.com/forums...-tomorrow.html

20mercury

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"

69Pman

At this point, just ask the owner.
I'm going out on a limb here but I always thought that the LT-1 motor was what made it an LT-1. Without the motor, it's just another cool corvette.
I understand this response isn't what you're looking for but overall, it's something to think about.

mikem350

Have to ask the owner again to explain his reasons. This car went thru extensive changes, including a frame swap, rear end swap, complete front clip due to a wreck, several engines, trans, etc.

Thanks for all the info...very interesting!!

Easy Mike

Not without original GM paperwork with the car. The LT-1 was an options package and included several things in addition to the engine. Any and all of the various pieces could have been added by a prevoius owner in the past.

Based on what you've posted about the car, are you certain you want it?