deck height clearance for L48?
Thread Starter
Instructor
Joined: May 2005
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deck height clearance for L48?
does anyone know the deck height clearance on a stock L48? I'm trying to select heads now and need the figure to get accurate results from compression ratio calculators. Also, are the pistons flat top?
Replies are much appreciated. -Jeff
Replies are much appreciated. -Jeff
Drifting
Joined: Jan 2006
Posts: 1,832
Likes: 38
From: Cedar,BC
I'll take a somewhat experienced guess,experts feel free to correct me.
Pistons are anywhere from .020 to.015ish down the hole and they are dished with valve reliefs,assuming the block and pistons are original and un molested.
Pistons are anywhere from .020 to.015ish down the hole and they are dished with valve reliefs,assuming the block and pistons are original and un molested.
Melting Slicks
Joined: Mar 2006
Posts: 3,342
Likes: 7
From: Connecticut
Originally Posted by 77vettejeff
does anyone know the deck height clearance on a stock L48? I'm trying to select heads now and need the figure to get accurate results from compression ratio calculators. Also, are the pistons flat top?
Replies are much appreciated. -Jeff
Replies are much appreciated. -Jeff
I have been tossing the same idea around for my L-48 for quite a while now.
Thanks
Safety Car
Joined: Aug 2001
Posts: 3,683
Likes: 202
From: Waterford Mi
When I rebuilt my motor I did not check the height of the stock pistons but with the flat-top pistons I bought it ended up being about 0.035". With the 76cc heads that really sucked so when I got the Performer heads I went with the 64cc heads.
Thread Starter
Instructor
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I will need to get that dish volume for the calculators. Not sure where I will find.
Will keep posted. I'm working from a few guides, one that has been helpful is "How to Build Max Perfromance Chevy Small Blocks" by SA Design. That and the good people of this forum. Thanks for the replies.
Will keep posted. I'm working from a few guides, one that has been helpful is "How to Build Max Perfromance Chevy Small Blocks" by SA Design. That and the good people of this forum. Thanks for the replies.
Drifting
Joined: Apr 2002
Posts: 1,716
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From: New Baden Illinois
I don't know what the deck height is, but I think the piston volume is either -17.00cc or -12.00cc. The -17.00 sticks out in my mind. By using the calculators, you can sort of back door it to find out the volume, because the L48 was 8.5CR (rated), but was slightly less. Play around with the numbers to find out what volume makes slightly less than 8.5.
Le Mans Master
Joined: Oct 2005
Posts: 9,429
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From: Macon, GA
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Melting Slicks
Joined: Mar 2006
Posts: 3,342
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From: Connecticut
Originally Posted by 77vettejeff
I will be using Dart SS heads with 72cc chambers. 165 runners. I will probably target 9:1 CR. Still planning.
What about a camshaft?
Which one did you decide on?
Thanks
Bob
Thread Starter
Instructor
Joined: May 2005
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I haven't chosen a cam yet. I'm looking to target a CR first. I may have the Darts milled to increase CR while using my stock bottom-end. Not sure. I don't want to be too hard on this bottom-end. I have a 2nd 350 short block where, when the time comes, will be built stronger.
There is good cam selection info in the "Max Performance Chevy Small Blocks" guide. I'm still figuring this out so, any advise is appreciated. Thanks, Jeff
There is good cam selection info in the "Max Performance Chevy Small Blocks" guide. I'm still figuring this out so, any advise is appreciated. Thanks, Jeff
Le Mans Master
Joined: Sep 2001
Posts: 7,739
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From: Unreconstructed, South Carolina
All OE L48 had dished w/ 4 eyebrows with dome volume ABOUT MINUS 12cc. At least two different compression heights were used ... yielding OE deck ranging 0.025" to 0.045" down in hole. You cannot KNOW unless you inspect & measure.
