L48 piston question(s)
Thread Starter
Instructor
Joined: Apr 2006
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From: Wallaceburg Ontario
L48 piston question(s)
Does anyone know if the 1979 L48 came with flat top, flat top with valve relief or dished pistons? I ask because I'm considering an Edelbrock Power Package (cam, intake and heads) for my Vette's stock 350. If I were to go with the 410 hp/408 torque set up, what size headers/exhaust will I need? I'd like to put the compression ratio between 9:1 and 10:1 (in other words, pump gas friendly).
Thanks in advance,
- Chilli
Thanks in advance,
- Chilli
Le Mans Master
Joined: Sep 2001
Posts: 7,739
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From: Unreconstructed, South Carolina
Originally Posted by Chilli
Does anyone know if the 1979 L48 came with flat top, flat top with valve relief or dished pistons? I ask because I'm considering an Edelbrock Power Package (cam, intake and heads) for my Vette's stock 350. If I were to go with the 410 hp/408 torque set up, what size headers/exhaust will I need? I'd like to put the compression ratio between 9:1 and 10:1 (in other words, pump gas friendly).
Thanks in advance,
- Chilli
Thanks in advance,
- Chilli
Thread Starter
Instructor
Joined: Apr 2006
Posts: 174
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From: Wallaceburg Ontario
Thanks, Jackson. Does anyone have any idea what my new CR would be if I used 64 cc heads with the head gaskets Jackson mentioned, assuming the block has NEVER been milled (and what the maximum cam lift would be that I could use with said CR)?
- Chilli
- Chilli
Le Mans Master
Joined: Sep 2001
Posts: 7,739
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From: Unreconstructed, South Carolina
Originally Posted by Chilli
Thanks, Jackson. Does anyone have any idea what my new CR would be if I used 64 cc heads with the head gaskets Jackson mentioned, assuming the block has NEVER been milled (and what the maximum cam lift would be that I could use with said CR)?
- Chilli
- Chilli
http://www.campbellenterprises.com/R...o%20calculator
Suggest you'd be better served with iron small chamber heads (ie vortec) and thin 0.015" shim gaskets (ie felpro 1094 vol 3.2cc).
Drifting
Joined: Jul 2002
Posts: 1,995
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From: Garland Texas
I just finished an engine close to this combo. Flat top pistons with 4 relief, squared and deck the block to achieve .015 below deck, 64cc iron eagle heads, and a Fel-pro .039 comp head gasket. Ended up with 9.8 compression and .055 quench.
Mike
Mike
Melting Slicks
Joined: Mar 2006
Posts: 3,342
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From: Connecticut
Originally Posted by gerry72
No. Not even close to hurting the engine. Besides, you'd be more concerned with rpm than just the torque number.
410 hp/408 torque was all that was posted
What RPM do you calculate to produce 410 hp/408 torque?
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Safety Car
Joined: Aug 2000
Posts: 3,711
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From: San Antonio TX
Originally Posted by Bob Onit
Sorry
410 hp/408 torque was all that was posted
What RPM do you calculate to produce 410 hp/408 torque?
410 hp/408 torque was all that was posted
What RPM do you calculate to produce 410 hp/408 torque?
Melting Slicks
Joined: Mar 2006
Posts: 3,342
Likes: 7
From: Connecticut
Originally Posted by gerry72
it comes out to 5300 rpm. That is the rpm you need with 408lb/f to get the 410hp. I know where you're coming from but it's not relevant to his question, which was a concern of overstressing the block from torque and that's the question I answered.
Thats the stock redline for the 1973 L-48
Instructor
Joined: Oct 2003
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From: Frederick MD
Compression is where the power is at, but with crappy gas and expensive gas prices.... 9:1 - 9.8 compression and 300-350 hp is a pretty good place to be for a street car. Any more and you're gonna have to get flat tops.
Thread Starter
Instructor
Joined: Apr 2006
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From: Wallaceburg Ontario
Originally Posted by Bob Onit
Sorry
410 hp/408 torque was all that was posted
What RPM do you calculate to produce 410 hp/408 torque?
410 hp/408 torque was all that was posted
What RPM do you calculate to produce 410 hp/408 torque?
- Chilli
Melting Slicks
Joined: Mar 2003
Posts: 2,512
Likes: 49
From: Franklin IN
Pardon the dumb question.......
Originally Posted by tracdogg2
I just finished an engine close to this combo. Flat top pistons with 4 relief, squared and deck the block to achieve .015 below deck, 64cc iron eagle heads, and a Fel-pro .039 comp head gasket. Ended up with 9.8 compression and .055 quench.
Mike
Mike
Thread Starter
Instructor
Joined: Apr 2006
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From: Wallaceburg Ontario
I believe quench is the total distance between the piston's outer top edge at TDC and the bottom surface of the head. This distance (I think) is made up of the deck height added to the head gasket height. I could be wrong, because according to my math, the above mentioned quench should be .054, not .055. The outer EDGE of the piston is used in the measurement because a dome (aka "pop up") or dish does not factor into the quench equation. Please, anyone, correct me if I'm wrong because I VERY recently asked this same question on a different site.
- Chilli
- Chilli
Safety Car
Joined: Aug 2000
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From: San Antonio TX
You are correct. Ideal for a steel rod engine is .040 (though you can go lower but don't be surprised to see witness marks once you get close to the .020s) and .060 for an aluminum rod engine. Though setting up ideal quence is a blueprint operation that you can do only after some preliminary machine work. Few people bother.
Le Mans Master
Joined: Sep 2001
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From: Unreconstructed, South Carolina
Originally Posted by Chilli
According to the Edelbrock site, the 410 hp comes at about 5600 rpm while the 408 torque comes in at 4500 rpm.- Chilli
Originally Posted by gerry72
You are correct. Ideal for a steel rod engine is .040 (though you can go lower but don't be surprised to see witness marks once you get close to the .020s) and .060 for an aluminum rod engine. Though setting up ideal quence is a blueprint operation that you can do only after some preliminary machine work. Few people bother.
... Although I like 0.030"-0.040" quench w/ steel rods.
