matt rem Posted December 1, 2004 Report Share Posted December 1, 2004 How much lift can you use in the LQ9 with out having the pistons hit the valves? I have just heard no more than 550. Is this true? Link to comment Share on other sites More sharing options...
SSLink Posted December 1, 2004 Report Share Posted December 1, 2004 I am using the LPE GT2-3 cam and it specs at 207/220-.571/.580- 118.5 LSA. Plenty of clearance. Duration is just as important as lift. Big duration holding the valve open at high lift longer makes it more likely that the cycling piston will make contact. Have your heads been milled any? You should always check clearance on a cam or rocker install but I'm thinking that even with our flat-top pistons you're going to have to be up close to .600" lift with pretty big duration to have any issues. Link to comment Share on other sites More sharing options...
matt rem Posted December 1, 2004 Author Report Share Posted December 1, 2004 Well that sounds better, I thought there are cams around here with alot more than 550. What do you think of the a 210/218 531/531 LSA 112? I have 1.8 rockers so it will be 551 on the lift. I really don't want to do a stall so I don't want to get to crazy. Link to comment Share on other sites More sharing options...
SSLink Posted December 1, 2004 Report Share Posted December 1, 2004 That combo should give you no clearance issues. You will lose a little bottom end (I think Marc W. may be running that same cam...check with him) and you will have to retune for it to idle right. With no stall I would personally opt for a 114 or higher LSA which will give you better off idle pull (and a smoother idle). You're on the right track keeping intake duration at 210 degrees. In our big, heavy trucks low to midrange torque is more important than top end horsepower on the street. Link to comment Share on other sites More sharing options...
BigTex Posted December 1, 2004 Report Share Posted December 1, 2004 I have 1.8 rockers so it will be 551 on the lift. <{POST_SNAPBACK}> With 1.8 rockers, that cam will have .562 lift, which is still no problem. Link to comment Share on other sites More sharing options...
matt rem Posted December 1, 2004 Author Report Share Posted December 1, 2004 I was just thinking of this problem I might have, with these rockers if you tighten down the valve covers just alittle to tight the #3 exhaust hits the valve cover. Will the more lift cause the rest to hit? Link to comment Share on other sites More sharing options...
misterp Posted December 3, 2004 Report Share Posted December 3, 2004 ...I have 1.8 rockers so it will be 551 on the lift... <{POST_SNAPBACK}> More important than effect on lift is the effect on effective valve duration and valve opening/closing events; not only do you get more gross lift, but the cam will act like it is delivering more duration that it actually has. I know *zero* on the dynamics of LQ9 heads (I last played with old Pontiac heads) but it is not unusual for some to experiment with putting 1.7's on the intake side and 1.8's on the exhaust side trying to get insight as to how the heads behave with their chosen exhaust system (or intake system) and form an idea of how to proceed next in their cam selection. But outside of this you are just engineering around the cam designer's intent. Use the rocker arm ratio called for by the cam designer, or switch cams. Mr. P. Link to comment Share on other sites More sharing options...
marc_w Posted December 3, 2004 Report Share Posted December 3, 2004 Hey Matt, got your email today... Yeah, about the rockers contacting.......... I'm not too familiar with that. Maybe you need spacers? I don't think they're too expensive. TSP or Thunder has them. I can't say for sure if you'll have issues when you put that cam in. I'm thiking you "probably" will. Link to comment Share on other sites More sharing options...
marc_w Posted December 3, 2004 Report Share Posted December 3, 2004 DOH!! They ARE expensive. Link to comment Share on other sites More sharing options...
matt rem Posted December 3, 2004 Author Report Share Posted December 3, 2004 Thanks Marc, I don't know what I am going to do, I may just yank the converter and then change the cam. It will open my options. Just don't know how I am going to like the loose feel of the converter, my moms trailblazer feels so loose that it won't move ( because it has no power). Or get a custom grind for something I want. I never thought of the 2 different ratio rockers on the valves, I know my oval race motor had that combo on it. I quess the spacers are a nice piece. Whats another 260 bucks after I have gone this far! Link to comment Share on other sites More sharing options...
matt rem Posted December 3, 2004 Author Report Share Posted December 3, 2004 Hey Marc, My Dynatechs haven't been on a week and I too have a leak already, I am checking it out tonite, Any quess what is leaking? Link to comment Share on other sites More sharing options...
ACDenali Posted December 4, 2004 Report Share Posted December 4, 2004 I just bought a Comp grind TR224/224 581/581 112lsa for my Denali. It has the LQ4. Link to comment Share on other sites More sharing options...
matt rem Posted December 4, 2004 Author Report Share Posted December 4, 2004 Are you doing a stall with your cam? Link to comment Share on other sites More sharing options...
ACDenali Posted December 4, 2004 Report Share Posted December 4, 2004 Yes, 2600stall. Also LS1 Edit tuning. Link to comment Share on other sites More sharing options...
marc_w Posted December 6, 2004 Report Share Posted December 6, 2004 Dyna's - Mine was leaking at the center connection under the tranny there... I couldn't get that thin clamp to seal well on it's own. I used some exhaust sealant tape (more like putty) that's mainly used for 2-stroke exhausts. I loosened the clamp, pulled the connection apart a bit, applied a little of the putty, and (forcefully) slid it back together. It seems to have worked great. Mine still sounds like it's leaking every now and then at a cold idle, but the power is definitely there. I don't have any black streaks on the exhaust, no water dripping, and I can't feel any air puffing out anywhere, so it might just be normal noise. Here is a link to the stuff I used I hope the link works... Link to comment Share on other sites More sharing options...
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