Noob here and I'll try to keep my long story short. I currently have an early '99-00 lm7 swapped into my beater A body. I am planning on swapping in an 06 lq9 that I have acquired. Like most others I want to make a little (or a lot) more power. My problem is the class I race in requires a "stock" motor. Their idea of stock is pulling 17" of vacuum at 1k rpm. Most cars I run with are all gen 1 small blocks and a lot are stroked and run high compression and use vacuum rule cams and lifters. "Stock" is pretty relative as long as it pulls the vacuum.

My question is about cam selection for the lq9. I know there are a lot of factors involved with vacuum, but cam selection is a big one. My car is 3200-3400 lbs and I've never had the 5.3 over 6k rpm on my recall tach. I'd like to make more low end to get me out of the corners, but I can't wrap my head around all this cam spec voodoo. Would I be better off leaving the 6.0 alone knowing it already makes more power than the 5.3, or is there a mild cam that could wake it up even more and keep the vacuum up to pass tech? I know it will need a tune also, and I'm hoping I can do that through the mail if possible. Thanks for the help.

 

This is when you call a REAL cam guru at either TSP or Cam Motion. They will get you EXACTLY what you need as they know how their cams affect vacuum readings

 

Hello there, what you're wanting to do is open the intake valve after TDC (rather than before like many Performance cams have). You will want something with an intake opening around 7 degrees or later. This is the case with our SUM-8719 Stage 1 Truck high lift. Specs are 209/217 112 +1 .550/.550. You can raise the idle speed to erase the lope entirely if you like.

 

Thanks guys. I was hoping there would be an easy answer. I will call around and talk to the pros.

 

I called around and talked to a few companies and got a lot of "x should work". I completely understand because who buys a cam with their first worry being able to pass a vacuum rule? I think I'll play it safe with one of the stage 1 truck cams that are out there. Thanks.

 

Yes the key to idle vacuum is the later intake opening and the one we mentioned should work well. You can compare cams by putting different ones in the cam timer and seeing how LSA and advance affect this event.

 

Thank you for the help. I plan on getting that cam ordered up this week while you have the sale going on. I've already got some Pac 1218 springs laying around so I believe they will work with your cam. I'm going for the mail order tune route so hopefully it's easy to dial it in without putting it on a dyno. Thanks again.