LS7 ZL1 Tuning Help
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Heel & Toe
Joined: Oct 2010
Posts: 17
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LS7 ZL1 Tuning Help
Just got my engine back from the shop and installed, 454 LS7 12:1 compression, 100 octane gas, comp cam zl-1 nostalgia cam. I took it out for a short ride as set on dyno. Total timing 37 degrees, 20 - 22 @ 850 rpm, idle vacuum 3.5 @ 850 rpm. 850 dp with both power valves blocked off jet sizes increased form 78 to 88. Gotta say sounds wicked at idle and runs great when getting on it but part throttle {holding steady speed} seems like its loading up on fuel and sounds unhealthy. Any advice on where to start to get better cruising characteristics if thats possible. Dyno showed 538 foot pounds at 3500 rpm and 576 hp @ 6500rpm so I dont mind trading some of those # for driveabilty.
Race Director
Joined: May 2006
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Removing power valves and increasing jet size is fine for wot driving not cruising. The whole point of the power valve is to richen only when you get on it. Put size 80 jets back in and the 65 power valves. If you need more gas increase the jets 2 numbers at a time but you may not have to make any changes. Due to the characteristics of the intake and carburetor a 69 L88 with an 850 DP ran 82 on the drivers side and 78 on the passenger side for the primaries and 80 on the drivers side and 82 on the passenger side for secondaries. Just pointing that out for comparison purposes, the 88's are way too rich.
Last edited by MelWff; May 21, 2011 at 04:38 PM.
Race Director
Joined: Nov 2002
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From: Taylor Michigan
Mechanical pump I presume. Put the carburator back to the condition when it came out of the box and if your running a VC can, its not necessary with that kind of HP.....the lash on the cam that I use is 24 and 26 and tune it like a L-88 as there is nothing mysterious about a LS7
