# Use of 1.85 RR on exhaust only



## doww301 (Oct 30, 2011)

The cam I'm getting ready to install is a BTR stage one N/A for ls2. Specs are .610/.573, 223/230 on a 115+2 LSA. The current law in California says that I don't have to smog because I live in a rural county with a population of only 25,000. So, I'm going to be using JBA shorties and JBA catless mids while keeping my catted ones stored in the garage in case the law ever changes and I have to smog. I have a brand new set of BTR modified trunion 1.7 rocker arms on my shelf as well as a set of SLP 1.85's. I was thinking that I could use the 1.7's on the intake and use the 1.85's on the exhaust only-this would bring my exhaust valve lift to .623. My valve springs are BTR .660 doubles which spec out at 155 lbs @ 1.780", 380 lbs @ 1.180", 400 lbs @ 1.130, coil bind @ 1.070". With this setup the math says I should have .100 of room on the intake side til coil bind and .087 on the exhaust side (assuming correct installed height). My main concern is that adding .050 onto the exhaust side with the 1.85's could considerable shorten the life of those valve springs and possibly those lifters as well. So, would this be a potentially bad plan and I should abandon ship and sell the 1.85's, or could this work and be reasonably safe. Any sharing of knowledge on this would be greatly appreciated!


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## svede1212 (Nov 1, 2005)

I wouldn't do it. Besides increasing lift you increase duration and tip acceleration. That cam already has a pretty large intake/exhaust split. Usually 4-6 degree difference in the norm. A BandAid on one that doesn't have correct valve events isn't the way to approach it. I'd just get a better cam. The Torquer V2 or StreetSweeper HT are great cams in a LS2 and are designed to have the correct valve events. With a proper tune you can retain near to stock gas mileage and drive ability with big HP gains. Being a A4 a higher stall converter is usually recommended too.


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## doww301 (Oct 30, 2011)

*Thanks*

Thanks Jerry!


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