zgeezer Posted October 5, 2007 Share Posted October 5, 2007 I need some advice regarding a cam swap. I have a 2002 LM7 truck engine with very low mileage. I also have a bare ls1 cam, with less than 20,000 mile on it, out of a 1998 Pontiac. The lm7 cam specifications from Lt1Tech is: .466 Intake lift and .457 Exhaust lift; Intake duration is 190 Exhaust and 191 Intake; the lobe separation is 114 and the timing is 112/116. The same ls1 cam is .500 lift for both Intake and Exhaust; Duration is 209 Exhaust and 198 Intake; lob separation is 119.5 and the timing is 117/122 My use will be as a daily driver. A decent idle is important. The only other modifications with be cold air intake, and Sanderson block hugger type headers. I'll be running the automatic trans that came with the engine. I think an L60E . Rear end is a 3:36 with CLSD. Car weight will probably be 2600#. My advice has run from don't spend any money on this... get a real cam, to Both are smog cams... get a real cam, to Keep the truck cam you'll need the torque when passing and it'll be a smoother ride and get better gas mileage with the truck cam. Ride in my Silverado and you'll see what I mean and, finally, Do it, you can use your stock springs as long as you don't screw with rpm shift levels and its worth 40hp at the wheels. Gas mileage is not really high on my list of priorities. Reliability is. On the other hand, my "design criteria" is to run in the 13s and 105mph. Which I know is achievable withd the LS1. Finally, are there any real pitfalls related to using a used cam. This cam was a pull out from several years ago for some big Crane cam. I'm really cheap. If I can realize hp that can be felt and keep my stock springs I would do this tomorrow. But, what are the down sides to using a 1998 cam in this 2002 engine? If any of you have desktop dyno or some such other program, please share with me your thoughts. g Quote Link to comment Share on other sites More sharing options...
TheNeedForZ Posted October 5, 2007 Share Posted October 5, 2007 Is the 5.3 bored out to 5.7? If it stays a 5.3 then some of the power you expect to gain from the cam swap won't be realised simply because the cam (5.7 LS1) is too much for a 5.3. The LS1 cam is specced to work on an 5.7 engine with 2" intake valves. The LM7 has smaller 1.890" intake valves and the same exhaust valve dia. as LS1. If the LS1 cam is used in the LM7, the whole setup will appear to be exhaust biased which does not help NA power production in general. The other concern is that in 2003, the cam bearing diameters(steps) changed. It is "possible" the 98 cam won't fit correctly in the 02 block if the 02 block caught up with the 03 change. If this engine is to go into a Z and you are allowed to remove the cat. converter...you could consider a complete new cam designed for the new application since removing some exhaust back pressure gives more potential gain that can only be realised with a cam specced to exploit the stronger ecavanging effect. Quote Link to comment Share on other sites More sharing options...
zgeezer Posted October 6, 2007 Author Share Posted October 6, 2007 Is the 5.3 bored out to 5.7? If it stays a 5.3 then some of the power you expect to gain from the cam swap won't be realised simply because the cam (5.7 LS1) is too much for a 5.3. The LS1 cam is specced to work on an 5.7 engine with 2" intake valves. The LM7 has smaller 1.890" intake valves and the same exhaust valve dia. as LS1. If the LS1 cam is used in the LM7, the whole setup will appear to be exhaust biased which does not help NA power production in general. The other concern is that in 2003, the cam bearing diameters(steps) changed. It is "possible" the 98 cam won't fit correctly in the 02 block if the 02 block caught up with the 03 change. If this engine is to go into a Z and you are allowed to remove the cat. converter...you could consider a complete new cam designed for the new application since removing some exhaust back pressure gives more potential gain that can only be realised with a cam specced to exploit the stronger ecavanging effect. I didn't know about a cam journal change in 2003. Mine is a late 2002, so this is clearly something to consider. Thanks for the response. g Quote Link to comment Share on other sites More sharing options...
LS1 240Z Posted October 6, 2007 Share Posted October 6, 2007 i have a 240/242 .600 .610 cam on a 110 LSA and it idles and drives great.. it is all in the tune. Quote Link to comment Share on other sites More sharing options...
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