L71 Which way to build????
Thread Starter
Team Owner
Joined: Mar 2002
Posts: 44,681
Likes: 1,830
From: Huntsville AL
L71 Which way to build????
I'm bringing my 69 / L71 back to life after years of being dead. This car came to me with the motor missing. I have rounded up the correct Tri-Power intake, Rect Port Heads, 4-Bolt block and 7/16 Dot rods. Now here is the hard part: Do I rebuild back to 435hp / 11:1 Compression GM specs or go the route of lower compression and more up to date cam set up? Bring on all thoughts. :chevy
Pro
Joined: Mar 2001
Posts: 500
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From: Michigan
Re: L71 Which way to build???? (Mr D.)
I am missing my tripower manifold and carbs! It was trashed long ago, has a rec port '70 454 vette manifold and holley. I will buy the tripower someday when I stash aside $1,500 t0 $2,000. Lucky you! I do have proper block and heads though.
When I rebuilt the block last a couple of years ago, I lowered the compression ratio to 9:6 to 1 so I would not have pinging problems. It used to have 12:0 to 1 and you had to be a chemist mixing fuel additives. The last I drove it at the high compression was about 18-20 years ago, it was fast. But as it is now, it is still fast, but not as it was. But more drivable on pump gas.
Dwayne
:cheers:
When I rebuilt the block last a couple of years ago, I lowered the compression ratio to 9:6 to 1 so I would not have pinging problems. It used to have 12:0 to 1 and you had to be a chemist mixing fuel additives. The last I drove it at the high compression was about 18-20 years ago, it was fast. But as it is now, it is still fast, but not as it was. But more drivable on pump gas.
Dwayne
:cheers:
Thread Starter
Team Owner
Joined: Mar 2002
Posts: 44,681
Likes: 1,830
From: Huntsville AL
Re: L71 Which way to build???? (BigBlockVette)
Nice ride BBV, I know what you mean about the pump gas thing. I have read a few post from BB owners saying they have no problem with pump gas and 11:1 compression. I will do my homework before I move forward. :chevy
Drifting
Joined: May 2000
Posts: 1,573
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From: Ga.
Re: L71 Which way to build???? (Mr D.)
I vote for lowering the CR to about 9.5 to 1...that way you can enjoy the car and not worry about finding good gas all the time....I don't think you will miss the hp too much.
but you could build the short block with 11.0 to 1 and then run 842 aluminum heads which allow you to run a higher cr without fear of detonation on a lower octane....
but you could build the short block with 11.0 to 1 and then run 842 aluminum heads which allow you to run a higher cr without fear of detonation on a lower octane....
Drifting
Joined: Nov 2002
Posts: 1,692
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From: Loveland, CO
Re: L71 Which way to build???? (Mr D.)
I just finished the buildup on my L71. I used a Summit Speed Pro kit which uses 11 to 1 comp. pistons. I hope to get by with pump gas at the Denver altitude, which I understand effectively reduces your compression by about 20%. Of course the gas companies know that you don't need as much octane at altitude, so they drop the ratings by a few points here. I did lighten up on the cam a bit. The stock cam is pretty radical for street use, so I switched to a little less duration Comp cam.
