3/4 of an inch lift
04-03-2004, 12:43 AM
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3/4 of an inch lift Has anyone ever had a cam with a 3/4 of an inch lift? I was wondering because that's what my auto tech teacher is running on his 468 big block and was just wondering if it's possible or has ever been done on an LS1. thanx.
-Brent
-Brent
04-03-2004, 03:32 AM
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Usually cams of that lift are generally solid roller lobes. However, there are a some "race" hydraulic roller profiles that do have similar lift with the proper rocker arm ratios.
To answer your question, yes, there have been cams with that much lift (even more in some setups) used on the LS1.
To answer your question, yes, there have been cams with that much lift (even more in some setups) used on the LS1.
04-03-2004, 07:43 AM
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Are you sure he said "3/4" lift" and not "3/4 cam". That may just be an old school saying. Back when the hot rod world was fairly new and there were not that many cams the selections were refered to as a stock cam or a race cam. Then when modified cams started hitting the scene they would be refered to as 3/4 race, which is to say that cam is about 3/4 of full race.
04-03-2004, 08:11 AM
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3/4 inch (.750) lift at the valve is used on many highend, especially big block, race engines. Some of the higher end NASCAR classes are over .750 lift regularly. Pro Stock 500 inch, 10000 rpm engines are probably over 1.0 inches by now.
Page 271 of Comp's online catalog shows .520 lobe lift cams for Mountain Motors which give .988 at the valve with 1.9 rockers. They have a few(!) lobes that don't make the catalog which are "bigger" yet.
As for LS1 engines, I'm not sure LS heads can be made to flow effectively much above .700 lift. The race versions used in the C5R probably do.
Whenever you are at those kind of lifts and the high rpms that style of engine turns, controlling the valve train becomes a MAJOR challenge. I suspect a 1.0+ lift 10K rpm PS engine has valve spring life measured in seconds, not minutes.
Page 271 of Comp's online catalog shows .520 lobe lift cams for Mountain Motors which give .988 at the valve with 1.9 rockers. They have a few(!) lobes that don't make the catalog which are "bigger" yet.
As for LS1 engines, I'm not sure LS heads can be made to flow effectively much above .700 lift. The race versions used in the C5R probably do.
Whenever you are at those kind of lifts and the high rpms that style of engine turns, controlling the valve train becomes a MAJOR challenge. I suspect a 1.0+ lift 10K rpm PS engine has valve spring life measured in seconds, not minutes.
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04-03-2004, 08:53 AM
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Originally Posted by michael101
Are you sure he said "3/4" lift" and not "3/4 cam". That may just be an old school saying. Back when the hot rod world was fairly new and there were not that many cams the selections were refered to as a stock cam or a race cam. Then when modified cams started hitting the scene they would be refered to as 3/4 race, which is to say that cam is about 3/4 of full race.
04-03-2004, 09:05 AM
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Gordon's (GTS SS) old SR LS1 cam is almost 3/4"...
http://www.futralmotorsports.com/modifications.htm
But yes, it's common in race big blocks to have a cam with that much lift.
http://www.futralmotorsports.com/modifications.htm
But yes, it's common in race big blocks to have a cam with that much lift.
04-03-2004, 10:28 AM
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Originally Posted by michael101
Are you sure he said "3/4" lift" and not "3/4 cam". That may just be an old school saying. Back when the hot rod world was fairly new and there were not that many cams the selections were refered to as a stock cam or a race cam. Then when modified cams started hitting the scene they would be refered to as 3/4 race, which is to say that cam is about 3/4 of full race.
