Rick B

I am going to look at a 1970 on Saturday, The owner claims it was originally an LT-1. It does not have the original motor, He said that he has the tank sticker but it is elegible. Is there a way to verify that it was originally an LT-1.

SharkAttack

For 1970, the engine block suffix code should be one of the following: CTK, CTR, CTU, or CTV (the last of which means it is an ultra-rate LT-1/ZR-1). If the engine block is not original, request the tank sticker or other documentation. Most of the items listed below can be replaced or altered, so ask a lot of questions, put the burden of proof on the owner, and seek numerous steadfast identifiers. Unfortunately, the engine codes were not incorporated into the VIN number nomenclature until 1972.

Obvious identifiers:

Standard: Holley 850 cfm 4-barrell R4489A (#3972121) or R4555A (#39732123), alternator #1100884, aluminum finned rocker covers, M-21 4-speed manual, big block hood with white or black paint stencil and LT-1 decals, 3.70:1 differential

Not available: A/C, auto transmission

Best of luck!

BlackbirdZ07

The LT-1 should also have a higher redline tach. I'm not sure, but I think it should be yellow at 6300 and red at 6500. That would be a fairly good clue, since none of the other engines offered that year had the high redline tach. In '68 and '69, the 427/435 cars had the high redline tach, but since a solid lifter big block wasn't offered in '70, I believe that tach was only available with the LT-1.

Also, I'm not sure, but the M-21 close ratio 4 speed may have been mandatory with the LT-1. Most of these cars had the low rear end ratios too, like 3.70 or 4.11. Of course, it should have the LT-1/big block hood, and there should be no signs it ever had AC. Good luck!

keytech

If you are looking for it to be a driver then by all means check it out but i wouldn't pay a nickle more than a standard driver is worth if he has pulled the original engine. Aside from living without the air conditioning, any value as an LT-1 is shot. I'll bet the original 850 Holley is also missing, a little tough to find and will be pricey.. Check the tranny numbers, they are on the passenger side toward the rear, should be a M-21. There were some M-22 but they went onto the ZR-1, although the M-22 could be bought across the counter from a dealer so i have heard of them being put in by dealers if requested.

Tank sticker or no, if that original engine is gone then it's just a 70 Vette. I have a 70-LT1 I'm almost finished restoring. you better beleive the parts such as carb, alternator and smog pump are outrageous to replace. Without the original engine it's would be crazy to pay any more than regular 70 driver value.

70ZZ3 96LT4

Rick there is something about the fuel line on only the LT-1 cars. I can't remember exactly what it is at this time. It might be that the LT-1's only have the fuel feed line and no return line. Unlike on my 70 coupe 350/300 which has the fuel feed and return line. I don't know if the LT-1's came with the heavy duty yokes or not. It is easy to take a look at the yokes that go into the differential and see it it has steel caps holding u-joint in. The non-heavyduty yokes had the standard u-bolts. Mayby the previous post person can confirm some of this from his LT-1.


[Modified by 70ZZ3 96LT4, 2:15 AM 10/21/2001]

SharkAttack

Regarding the fuel lines, the base engines will have dual metal lines running parallel with the frame (passenger side, visible from under hood), and the LT-1 models will have only one metal fuel line.

Allan71

The 70-72 LT-1s did indeed use the HD u-joint caps normally reserved only for big blocks. The LT-1s also used a copper radiator and no expansion tank, so the presence of a tank (or holes on the psgr side fender) would mean a base engine no A/C car. The carb was actually a 780cfm vacuum secondary dual feed Holley and a single metal fuel running from the tank to the near the pump should be present. The 70-71 LT-1 also used Transistor pointelss ignition, so look for the amplifier box (or holes where the box was) on the left front side of the radiator (easiest seen by opening the hood and looking from the front of the car through the opening in the hood). Also, there was no Power Steering availalble on the 1970 LT-1 until about May of 70, so an early build car with PS would be suspect since the early 70 LT-1s used a larger 6 quart oil pan that would absolutely not fit with PS (the later cars went back to the normal 5 quart pan). The exhaust pipes on the LT-1 was also 2 1/2 inches whereas all other 70-72 small blocks used 2 inch (same manifolds used on all engines however). The tach redline for is 6500, the L-46 was 6000 and the base is 5300.

Now on the tranny, the LT-1 was just like any other small block Corvette. The car came standard with the M-20 Wide Ratio 4-speed, and the standard rear axle ratio was 3.55 to 1. Unless the buyer checked the M-21 Close Ratio box or another optional ratio with the M-20, the car was delivered with the M-20 and 3.55. Keeping the M-20, you could also order the Performance 3.70 ratio, or the Economy 3.36 ratio. The M-21 Close Ratio 4-speed was availalbe at no extra cost, and this combination gave you the 3.70 axle as standard, along with the Performance 4.11 or Economy 3.55 as options. The majority of LT-1s do indeed have the M-21 with the 3.70 or 4.11s, although many were built with the M-20. In 1972, when A/C was made availalbe in the middle of the year, you were not allowed to order the M-21 on the LT-1 in combination with the A/C, but had to keep the standard M-20 along with the 3.55 axle, and although the 3.36 axle could be had, the 3.70 could not be ordered with A/C. The M-22 tranny was technically an LT-1 option only in 1971 although some debate rages on this. In 1970, it is generally accepted that the M-22 tranny was included and only availalbe as part of RPO ZR-1 and could not be ordered as a seperate option on a standard LT-1. Again, you will hear differing opinions on M-22 usage, but with Chevrolet records showing 25 ZR-1s and 25 M-22s for 70 makes it pretty clear that all 25 M-22s went into the ZR-1s. In 71, it is the LS-6 engine that makes the picture a little foggy. For only the second time (the other year was 66), the M-22 tranny was on the books as a seperate option. Some guys say that it was only availalbe on the LS-6, but some say it could also be had on a standard LT-1. Since the M-22 equipped cars, used a special 12 3/4 inch lightweight flywheel and unique clutch, this would have required many different parts to use the M-22 on the LT-1, this would have complicated the build issue and seems like something Chevy would not have wanted to do, but it is possible. For 72, the only Corvettes to use the M-22 was the ZR-1.

The suspensions on all LT-1s was exactly like the base engine cars, except for 71 where the stiff F-41 setup could be ordered as a stand alone option without having to buy the complete heavy duty car (ZR-1).

keytech

"The M-22 tranny was technically an LT-1 option only in 1971 although some debate rages on this. "

Yes there is debate on this. In 70 for instance there were "officially" the same number issued as were ZR-1's, as part of the ZR-1 package - but did they all go into ZR-1's? The M22 could be bought across the parts counter at any Chevy dealer and supposedly dealers put them in if requested. Still not "factory" but out the dealer door on a new car just the same.