What is a L81 ?
Thread Starter
Instructor
Joined: Sep 2006
Posts: 154
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From: Upper Darby PA
What is a L81 ?
My '81 has a ZZ4, but the original motor is shrink wrapped laying in the garrage. I'm almost ready to take a wrench to it. isn't the L81 supposed to be a one of a kind ? I have been searching this forum and other sites to get the specs for what's inside the 2 bolt block. I have the usual hp, torque ratings, etc, but no real specs. I can't seem to locate the tech data anywhere. I have read that "maybe" the L81s have forged pistons and performance cams. so "maybe", what kind of heads and cranks do they have ? are they really different, or just a L48with computerized dist & carb ? don't want to unwrap early. just idle curiosity.
Merry Christmas ! Rich
Merry Christmas ! Rich
Thread Starter
Instructor
Joined: Sep 2006
Posts: 154
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From: Upper Darby PA
OK Judd. I see you don't know either. is there anyone out there who has popped open a L81 ? I don't know anyone who has. if the motor bottom is as good as the psuedo data, then maybe some head work, a good intake, and true duals may produce a real performer for very little money. is it a diamond in the rough, or just another compromise coming out of the oil scared 70s ?
Le Mans Master
Joined: Dec 2006
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I pulled the heads and pan off my L-81. 2 bolt main, 74 cc heads, nothing special. Boght a universal crate engine from summit for 1350 delivered. 4 bolt main. Can't rebuild a 350 for that. Nothing beats new with a GM Warranty. Runs great, has 260 HP, and passed smog EASY.
Race Director
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From: State of Confusion
Melting Slicks
Joined: Aug 2006
Posts: 3,429
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From: Kingston Ontario
I had an 81
I rebuilt the motor myself, it was a correct #'s motor so I know the crank was cast, the block was 2 bolt and the pistons looked cast. I believe the heads were 624 casting, alright but nothing you would want to port.Nothing special about the motor. It was the first year for computer controls. Does that answer your question? Yes you could easily get 300hp out of it reliably.
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Burning Brakes
Joined: Aug 2006
Posts: 1,155
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From: San Diego California
I pulled the heads and pan off my L-81. 2 bolt main, 74 cc heads, nothing special. Boght a universal crate engine from summit for 1350 delivered. 4 bolt main. Can't rebuild a 350 for that. Nothing beats new with a GM Warranty. Runs great, has 260 HP, and passed smog EASY.
Race Director
Joined: Sep 2001
Posts: 10,560
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From: Wellington, FL
St. Jude Donor '11 thru '25
My '81 has a ZZ4, but the original motor is shrink wrapped laying in the garrage. I'm almost ready to take a wrench to it. isn't the L81 supposed to be a one of a kind ? I have been searching this forum and other sites to get the specs for what's inside the 2 bolt block. I have the usual hp, torque ratings, etc, but no real specs. I can't seem to locate the tech data anywhere. I have read that "maybe" the L81s have forged pistons and performance cams. so "maybe", what kind of heads and cranks do they have ? are they really different, or just a L48with computerized dist & carb ? don't want to unwrap early. just idle curiosity.
Merry Christmas ! Rich
Merry Christmas ! Rich
Team Owner
Joined: Oct 2004
Posts: 81,241
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From: altered state
St. Jude Donor '05
OK Judd. I see you don't know either. is there anyone out there who has popped open a L81 ? I don't know anyone who has. if the motor bottom is as good as the psuedo data, then maybe some head work, a good intake, and true duals may produce a real performer for very little money. is it a diamond in the rough, or just another compromise coming out of the oil scared 70s ?
You asked, he answered.
Le Mans Master
Joined: Dec 2006
Posts: 8,837
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I don't want to hijack the thread, but it may have run its course anyway. So Big2Bird, I'm considering the new crate engine route for my 80. Did you purchase a short block or long block? Not a turn key for that price. What old vs new parts did you add? I assume your at 8.5:1 compression. How does the throttle feel, compared to the stock engine? I also have to pass the visual and sniff smog police cause I'm in California- but I want the most power possible. If you passsed smog easily, that suggests the new heads and a cam might be a good addition to that inexpensive block.. Thanks for your thoughts. Jim
Burning Brakes
Joined: Aug 2006
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From: San Diego California
Jim, Go to Summit Racing, and check out GM#10067353. It is a long block, and GM warranty for 3yr,50,000mile if installed in a 68-85 GM car.All I did was add an Edelbrock intake, and stock everything else. Runs like a new car, cause it is. The smog guy said he has never seen an old car with such low emissions. He thinks I could have upped the cam and passed. If your ever in Anaheim, e-mail me. Jeff
Team Owner
Joined: Oct 2004
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From: altered state
St. Jude Donor '05
Thanks for the reply Jeff. I'm seriously considering the new long block instead of the cost and no warranty of a rebuild. But I gotta believe that Edelbrock aluminum heads- the 65 or 70 cc, and a slightly more aggressive cam would punch up the hp and tq significantly and still pass CA smog. Jim
