Head chamber size on L-48?
Thread Starter
Racer
Joined: Oct 2000
Posts: 405
Likes: 31
From: Houston, Texas
Head chamber size on L-48?
Planning a rebuild and wanted to know what is the stock head chamber size on 1972 L-48 motor? In regard to compression ratio I have read that 9 to 1 is the limit with stock heads and pump gas, is that true? What could I increase it to?
Thank you
Thank you
Le Mans Master
Joined: Sep 2000
Posts: 9,078
Likes: 7
From: DFW TX
Cruise-In VII Veteran
St. Jude Donor '07
Re: Head chamber size on L-48? (Milest)
First, I don't see a listing for a L-48 in 72. Here's what I have.
- 350 200 hp k code 8.5 -1
LT-1 350 255 hp L code 9.0 -1
LS-5 454 270 hp W code 8.5 - 1
Code is the fifth digit in your vin. I would be you chamber is 76 cc.
- 350 200 hp k code 8.5 -1
LT-1 350 255 hp L code 9.0 -1
LS-5 454 270 hp W code 8.5 - 1
Code is the fifth digit in your vin. I would be you chamber is 76 cc.
Melting Slicks
Joined: Dec 2000
Posts: 2,041
Likes: 0
From: Wichita, KS
Re: Head chamber size on L-48? (Milest)
Your cylinder heads would be one of these casting numbers;
3973487
3998916
3998993
Generaly the cylinder heads are refered to by the last 3 digits of the casting number.
The only ones that I'm familer with are the 993 casting. They are supposed to be 76c.c.'s with 1.94 intake and 1.50 exhaust valves. The 993 heads that I've measured were closer to 84 c.c.'s
9 to 1 is a nice compression ratio for a street motor but you can increase it to more than that if you are careful about your buildup and tuning and still run pump gas.
3973487
3998916
3998993
Generaly the cylinder heads are refered to by the last 3 digits of the casting number.
The only ones that I'm familer with are the 993 casting. They are supposed to be 76c.c.'s with 1.94 intake and 1.50 exhaust valves. The 993 heads that I've measured were closer to 84 c.c.'s
9 to 1 is a nice compression ratio for a street motor but you can increase it to more than that if you are careful about your buildup and tuning and still run pump gas.
Burning Brakes
Joined: Aug 2000
Posts: 852
Likes: 0
From: Katy TX
Re: Head chamber size on L-48? (Milest)
I am running Kieth black flat top pistons with a zero deck block and angle milled 76 cc chamber heads. My compression is 9.4 to 9.5 with this setup and it is fine on 93 octane pump gas. It will not run well on regular (87 octane).
Based on this you should be able to go up to at least 9.5 CR on a non computer controlled engine.
Based on this you should be able to go up to at least 9.5 CR on a non computer controlled engine.
