73 L48 piston swap
Thread Starter
Pro
Joined: May 2001
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From: usa
73 L48 piston swap
I have a 73 L48 4 speed car, the L48 being an 8.5 to 1 compression ratio, Iam sure it has dished pistons. I have a set of stock bore 350 flat top pistons. any Idea what the compression would raise to ?
Team Owner
Joined: Jan 2006
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From: Crossville TN
Somewhere around 9.0, I think. You should still be able to run on "mid" grade of fuel without pinging. If you have the engine torn down, are you considering any other modifications while you are at it? Better cam and aluminum heads [to match with cam] would be best, if you can afford it.
Le Mans Master
Joined: Mar 2008
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From: Oxford MA-----You just lost the game!!!!
I don't know if I'd bother putting new pistons and rings in without boring it, to get the bores perfectly round again, in which case, your stock bore size pistons won't do you much good obviously. But, for all I know, your stock bore may be in good enough shape for such a swap, might just need a dingle ball hone, so that's up to you.
If your current shortblock has decent compression, an easier (probably more expensive, though) way to increase compression would be to use a thinner head gasket, and some heads with a smaller combustion chamber. You can get pistons pretty cheap, though.
http://www.northernautoparts.com/Pro...uctModelId=380
Scott
If your current shortblock has decent compression, an easier (probably more expensive, though) way to increase compression would be to use a thinner head gasket, and some heads with a smaller combustion chamber. You can get pistons pretty cheap, though.
http://www.northernautoparts.com/Pro...uctModelId=380
Scott
Thread Starter
Pro
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From: usa
no just thinking about this coming winter, have this piston and rebuilt rods, car is numbers matching still so I'd like to keep it stock looking.and keep the block stock.
just a clean up and bearing job.
kinda thought that would be a bit higher closer to 10 to 1.
if I decide to go modified I have a 454
just a clean up and bearing job.
kinda thought that would be a bit higher closer to 10 to 1.
if I decide to go modified I have a 454
Team Owner
Joined: Jan 2006
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From: Crossville TN
L-48 has 76cc heads; dished portion of piston is 5-7cc. So, it would be a 7-8% increase in C.R. Not that much gain for a lot of work. I sure wouldn't tear an engine down just for that change. But, if you changed heads, cam, headers, the gains would be significant.
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Surely can't hurt...but nothing dramatic. I remember back in the 70's/80's I installed quite a few 11.0 domed pistons in these engines for folks who wanted to keep the old heads. Got you into the 10'ish range and worked OK. There weren't as many good heads available back then of course. Today,,,swapping heads would be a lot easier and yield much better results.
As mentioned, if you want to do it right...boring the engine and getting cylinders perfect is important. Cast flat top pistons are cheap...so doing it right won't cost too much. If wanting to go mega cheap and you have the pistons...throw a quicky hone on it and drop them in and keep your fingers crossed.
JIM
As mentioned, if you want to do it right...boring the engine and getting cylinders perfect is important. Cast flat top pistons are cheap...so doing it right won't cost too much. If wanting to go mega cheap and you have the pistons...throw a quicky hone on it and drop them in and keep your fingers crossed.
JIM
Last edited by 427Hotrod; May 5, 2013 at 02:41 PM.
Le Mans Master
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From: melbourne florida
2023 C3 of the Year Finalist - Modified
not very much benefit for the effort. small chamber heads and a cam are a better route, if you want it to look stock you can paint the aluminum heads.
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Le Mans Master
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From: Hermosa
7T1vette L-48 has 76cc heads; dished portion of piston is 5-7cc. So, it would be a 7-8% increase in C.R. Not that much gain for a lot of work. I sure wouldn't tear an engine down just for that change. But, if you changed heads, cam, headers, the gains would be significant.
I've cc'd both the pistons and heads on a stock l-48. You'll be better off changing heads and pistons to get any kind of compression.
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