upgrade L48
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Intermediate
Joined: Apr 2012
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From: hot springs village ar
upgrade L48
putting 64cc cast iron heads, L82 cam and edlebrook performance intake on the engine. how much will I increase the hp? all parts were free so don't tell me to go buy this or that.
Pro
Joined: Feb 2012
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Just off the hip I'm guessing around 275 HP if the carb is tuned and your timing is done right.
Safety Car
Joined: Oct 2000
Posts: 3,593
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From: Southern Indiana
I would say even if your engine only has 8.5 compression that those heads will detonate with any timing.
I would recommend some .041 thick Felpro head gaskets to help out some.
Otherwise go for it!
I would recommend some .041 thick Felpro head gaskets to help out some.
Otherwise go for it!
Le Mans Master
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From: Oxford MA-----You just lost the game!!!!
Keep the shiny side up!
Scott
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From: hot springs village ar
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Thread Starter
Intermediate
Joined: Apr 2012
Posts: 37
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From: hot springs village ar
L48 upgrade
putting on 1987 64cc cast iron truck heads, L82 cam, low rise edlebrook performer alum. intake with a 650 holly carb....what hp should I get. parts are free so???
Le Mans Master
Joined: Oct 2010
Posts: 6,916
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From: melbourne florida
2023 C3 of the Year Finalist - Modified
here we go again. the N.H.R.A rated the L-82. at 300+ horsepower. you have less compression and cam. small chamber heads will give you compression, close to 9.5-1 . the L-82 cam is the same as the 350/350 cam except it is retarded 4 degrees. with that cam advanced 4 degrees and the heads with a thin gasket you will have north of 300 horsepower. that will be a nice package with a manifold headers and the ignition set up correctly.go for it. there were thousands of motors built with the 350/350 cam that was a great street cam and still is
Le Mans Master
Joined: Mar 2008
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From: Oxford MA-----You just lost the game!!!!
Keep the shiny side up!
Scott
Pro
Joined: Aug 2000
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From: Vancouver B.C.
Guessing around 300 to 315.
I think L48 was available in 1970,and it had 10:1 compression with the .390/.410 lift cam. Also this cam was rated at 195 degrees duration at .050. Very small cam. Factory spec'd this engine at 300 HP.
Going with 64 cc heads will yield you about 9.3:1 compression with fish pistons. Shim gasket maybe 9.5:1. Plus if theses heads off a truck are vortecs, they will flow much better than old camel humps.
This coupled with more agressive L82 should yield higher HP than a stock 1970 L48. If factory figures can be relied on.
I know you said not to comment on parts, but if I could I would go with another cam. I always found the L82 cam to be a little lazy on the bottem end. Just my comment. For small $$$ you could get a better cam.
Good luck
I think L48 was available in 1970,and it had 10:1 compression with the .390/.410 lift cam. Also this cam was rated at 195 degrees duration at .050. Very small cam. Factory spec'd this engine at 300 HP.
Going with 64 cc heads will yield you about 9.3:1 compression with fish pistons. Shim gasket maybe 9.5:1. Plus if theses heads off a truck are vortecs, they will flow much better than old camel humps.
This coupled with more agressive L82 should yield higher HP than a stock 1970 L48. If factory figures can be relied on.
I know you said not to comment on parts, but if I could I would go with another cam. I always found the L82 cam to be a little lazy on the bottem end. Just my comment. For small $$$ you could get a better cam.
Good luck
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Intermediate
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From: hot springs village ar
Thread Starter
Intermediate
Joined: Apr 2012
Posts: 37
Likes: 0
From: hot springs village ar
Le Mans Master
Joined: Oct 2010
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From: melbourne florida
2023 C3 of the Year Finalist - Modified
as a cam gets more radical the low end gets weaker generally. its a good combo for the investment. and those net figures factored in the lousy exhaust system a set of headers and a good exhaust do wonders for those numbers. do some bowl work on the heads that will help too
Pro
Joined: Aug 2000
Posts: 610
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From: Vancouver B.C.
As mentioned above. There is a difference between factory gross and net HP numbers.
L48 rated at 185 HP is the probably net mid '70s rating when it was really smogged and choked.
1970 L48 10:1s Gross HP -300
1971 L48 8.5:1 Gross HP -270
1972 L48 8.5:1 Net HP - 200
The 1971 and 1972 L48s are virtually the same engine. Only difference is on how the engines were rated.
There is potential in the L48, don't get put off by the net smogged 185 rating, you can liven it up.
Generally most talk HP in gross numbers. Net or rear wheel much better indicator, but more variables involved.
L48 rated at 185 HP is the probably net mid '70s rating when it was really smogged and choked.
1970 L48 10:1s Gross HP -300
1971 L48 8.5:1 Gross HP -270
1972 L48 8.5:1 Net HP - 200
The 1971 and 1972 L48s are virtually the same engine. Only difference is on how the engines were rated.
There is potential in the L48, don't get put off by the net smogged 185 rating, you can liven it up.
Generally most talk HP in gross numbers. Net or rear wheel much better indicator, but more variables involved.