Need help on determining LS6 motor

[Ole Greenie]

Here are the pictures for the throllt and TV cable hook-up.







TV cable isn't completely true but I could not bring it into 100% in line due to the throw of the linkage. Not much room...

[406 Q-ship]

If that is an LS-6, it is one of the last run service replacement engines. It has a high rise square port intake on it, it doesn't mean the heads match but by the way you describe how it runs I believe that the heads are square ports too. It is a really late replacement service engine because GM dropped the low rise "corvette" intake in the very late 1980's and went to the intake used on the L-78/L-72 intake (high rise). I bought one of the last run LS-6 service engine in 1989 and it had a high rise L-78 style intake mainfold in it. Casting numbers on the service engine replacements can get weird and will not necessarily match old casting numbers. Check the front pad for the engine code would be the best option but not an end all. My LS-6 did have the 7.4 cast into it like the later GM blocks.

[Ole Greenie]

Originally Posted by 406 Q-ship

If that is an LS-6, it is one of the last run service replacement engines. It has a high rise square port intake on it, it doesn't mean the heads match but by the way you describe how it runs I believe that the heads are square ports too. It is a really late replacement service engine because GM dropped the low rise "corvette" intake in the very late 1980's and went to the intake used on the L-78/L-72 intake (high rise). I bought one of the last run LS-6 service engine in 1989 and it had a high rise L-78 style intake mainfold in it. Casting numbers on the service engine replacements can get weird and will not necessarily match old casting numbers. Check the front pad for the engine code would be the best option but not an end all. My LS-6 did have the 7.4 cast into it like the later GM blocks.

Thanks for that great information. The stars further align knowing that the person I bought this motor from (actually bought his truck and swapped motors) in 2001 said he installed it about the timeframe you had mentioned. Of couse it was a few years ago now so "that year" runs into the next in listening to him, but everything lines up correctly.

so I have a high rise intake. I also know I cant run less than 91 octane in it unless I further retard the timing.

Although a nice new LSX conversion is appealing, I think I will stick with the nostalgia of the BB LS6. I don't know of any others around here or on this board. Thanks again!