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Topic: 1977 L48 - Compression Ratio

in Forum: C3 Engines

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1977 L48 - Compression Ratio (1/8)
1/21/07 9:32am

VTHokie77Vette
Former Member
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Pennsville, NJ - USA

Vette(s):
1977 EX-L48

Joined: 3/13/2002
Posts: 532

Hey Guys,

I was wondering what the compression ratio is for the 1977 L-48. I'm probably going to sell the Jasper remanufactured engine I have to somebody and I'd like to be able to tell them what it is. I could only find 9.0:1 for the L-82. Was it 8.5:1 for the L-48?? Thanks!

VTHokie77Vette2007-01-21 09:33:42

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1977 Corvette EX-L48
383 Stroker, Holley MPFI, MSD Ignition, BTO 700R4, VBP Street/Slalom, Hooker Sidepipes with JCL Spiral Baffles, Corbeau A4s w/ Shark Bar and Simpson 5-Points, 17" AR TTII's, Kumho MX's

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1977 L48 - Compression Ratio (2/8)
1/21/07 10:22am

Gunslinger
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Frederick, MD - USA

Vette(s):
1969 convertible L71 427/435 4-speed black interior

Joined: 9/8/2003
Posts: 3398

The literature I have says 8.5 to 1.

1977 L48 - Compression Ratio (3/8)
1/21/07 10:29am

Adams' Apple

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Duncanville, TX - USA

Vette(s):
#1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas

Joined: 11/8/2003
Posts: 20206

That would be the factory rating. If the engine has been rebuilt, who knows what it has? A larger bore, different pistons, or different heads will change the comp. ratio. As far as you know, it should be 8.5:1, and that's really all you could tell anyone.

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Joel Adams
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1977 L48 - Compression Ratio (4/8)
1/21/07 3:50pm

Chips58
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Australia

Vette(s):
71 Coupe Black on Black

Joined: 5/6/2004
Posts: 535

I've got an L48 and my ratio is currently 10:1! As Joel said, it depends how much work has been done. I have shaved heads and high comp pistons.

1977 L48 - Compression Ratio (5/8)
1/21/07 7:21pm

VTHokie77Vette
Former Member
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Pennsville, NJ - USA

Vette(s):
1977 EX-L48

Joined: 3/13/2002
Posts: 532

Thanks guys. Talking to Jasper years ago they were supposed to be giving me an engine built to the exact specs of the L-48 so I'll tell him its supposed to be 8.5:1...haha. Thanks again!

______________
1977 Corvette EX-L48
383 Stroker, Holley MPFI, MSD Ignition, BTO 700R4, VBP Street/Slalom, Hooker Sidepipes with JCL Spiral Baffles, Corbeau A4s w/ Shark Bar and Simpson 5-Points, 17" AR TTII's, Kumho MX's

(click to see a bigger version)

1977 L48 - Compression Ratio (6/8)
1/22/07 12:20pm

mikeee
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Oviedo, FL - USA

Vette(s):
1977 t-top

Joined: 9/8/2006
Posts: 267

Are any of you with hi lift, long duration, cams ,hi comp. motors having any vacuum problems?

1977 L48 - Compression Ratio (7/8)
1/23/07 6:05am

Adams' Apple

It's the long duration specs that kill vacuum. Anything above around 260-270degs will not allow very much vac. to be made.

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1977 L48 - Compression Ratio (8/8)
1/23/07 3:17pm

mikeee
Former Member
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Oviedo, FL - USA

Vette(s):
1977 t-top

Joined: 9/8/2006
Posts: 267

thanks Joel

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