Accurate LT-1 Identifiction by way of relay?

[Gary Schisler]

Bob, since I am actively looking for a nice 72 I read your article with interest. Am I missing something here? Isn't an LT1 by definition NOT a base engine? If you have the base engine you don't have an LT1 or if you have an LT1 then you don't have the base engine? Any help here?

thanks, Gary

[Gary Schisler]

whoops!

Sorry, I re-read the post and just now saw the comments at the end about the emissions sticer and state issued tag. Gary

[Bob Booth #33372]

Terry...I looked but couldn't find...

...the post in the archives that I described. In fact, I couldn't find ANY posts at all. Usually it comes up showing the posts similar to this board, but all I could get was the "search" window, and no matter what key word I typed in, it would come back "...nothing found matching the criteria...". In any case, I'll continue to look for it. I remember that it was about 1/3 the way down the list and it was in response to a person trying to troubleshoot his wiper door system. For the life of me I can't remember his (the responder) name but I remember that he was referred to the original poster as very knowledgable about vacuum systems by another person who responded. And it was a very long and extremely detailed response.

Also, I am working on getting those numbers from my car for you (currently at home with the flu). I hope to search for the tank sticker this weekend and I just have to crawl under the car to get the rest.

Regards, Bob Booth

[Joe L.]

Re: Accurate LT-1 Identifiction by way of relay?

Bob----

As far as I know, the location of the w/w door vacuum relay (GM #5638427) is TOTALLY unrelated to which engine was originally installed in your vehicle. Your emissions label, which is likely original, probably tells the true tale. Otherwise, you might look for tachometer redline. A redline of about 5,000, or so, indicates a base engine; a redline of about 5,800, or so, indicates an LT-1. Also, keep in mind that LT-1s used a different hood, so if yours has a non-LT-1 hood which appears original, that's another clue.

[Bill Baird]

Re: Accurate LT-1 Identifiction by way of relay?

Base engines are typically redlined at 5300 rpm, while LT-1's are typically redlined at 6500 rpm (except the '72 LT-1's with air, which I think were redlined at 5800 or 6000 rpm).

Bill Baird

[Bob Booth #33372]

Accurate LT-1 Identifiction by way of relay?

Hello all,


Nice to be back on the board, but probably not for long so I'll try to slip in a quick question. In the archives I was reading a post from a gentleman who was trying to help someone with a w.s. wiper door problem on his shark. He stated something to the effect of; "...you say that the relay valve is located under (in) the right side fender so I assume that it's a '71 or '72 LT-1...".


Does this mean that only '71 or '72 LT-1's had their wiper door relays in the fender? Is this a way to tell an LT-1 from other models? If so, because mine is also located there, my '72 is one of those very-rare-and-yet-rarely-wanted LT1's that came with a base 350! (or at least that's what the emissions decal in the engine compartment says). My car has a state issued VIN and I know almost nothing about history of the car. Could it be that it was originally an LT-1? But how to explain the emissions decal?


Thanks,


Bob Booth

[Terry M.]

Re: Accurate LT-1 Identifiction by way of relay?

Sorry Bob,


I believe all 1972 Corvettes had the vacuum relay valve for the windshield wiper door mounted by the windshield washer reservoir. 1969 and 1971 were some there and some by the brake master cylinder, but I don't think the engine had anything to do with the location of this valve. However, neither did serial number in 1971. I think 1969 changes with serial number (early & late kind of thing.) All 1970 is by the brake master cylinder.


I wish I had seen that post - I would like to know the basis of these claims. I really don't know what made the difference in the location of the relay valve - other than the available parts at the time of assembly. Perhaps the person who posted that is on to something - I would like to hear from them.


Terry