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Maiden track trip with low lash solid roller cam in my LS2

3K views 17 replies 8 participants last post by  fabio 
#1 ·
Doing an experiment on using a solid roller with the stock non-adjustable rocker arms and shimming them up to set my lash. After putting some miles on the car and checking for hot lash which settled in at .000" cold and .009-.011" hot I finally got to the track.

Old best with a 230/238 .620"/.602" 113+3 hydraulic cam was 1.61 60ft, 7.25@94mph 1/8th, and 11.46@116.7mph 1/4 mile. For that run the car was really well dialed in with 27* timing and 12.9:1 air/fuel.

New cam is a 239/247 .636"/.620" 113+3. This cam will behave like approximately a 234/242 hydraulic cam due to hot lash according to Kip at Cam Motion.

DA was within 100ft of my previous best, but I was still tuning and fuel was rich at a fluctuating 12.0-12.4:1. I think with some more tuning and some more low end timing I can eek another tenth out of it. On a different run with some higher shift points it went a touch over 118mph but the run wasn't quite as good (11.42 ET)




Slightly slower pass:




Overall I'm really pleased with it. What the slip doesn't show is how much smoother the power delivery feels, how it's stable enough to pull to 7000 rpm, and how quick it feels like it revs from a mid RPM hit on the highway.
 
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#3 ·
I was trying to play with shift points but it seemed to like commanded shifts at 6900rpm 1-2 and 6800 2-3. My trans is built well so it hits those pretty close and firm. Converter is a tight Yank SS3600.


No other changes aside from the cam, lifters, and pushrods.

Valvesprings are the exact same ones I had on the old cam. Brian Tooley Racing Platinum .660" using some old Patriot Gold brand titanium retainers. I just had the machine shop check the pressure and they were still like new.

Pushrods are Brian Tooley off the shelf LS pushrods. Stock rocker arms I pressed out the needle bearings and installed the trunion kit. I cut the pedestals into sections so I could shim them 2 rockers at a time.







My worksheet showing how thick the shims are under each:

 
#5 ·
It's a blast for sure. The cam still has power similar to the told one down low but once it hits close to 5000 it's like someone lit a match under its ass.

My favorite past time is hitting the curvy backroads and this thing just loves being held in 2nd gear at 4000-5000rpms through a turn then hammer down on the exit.
 
#7 ·
It wasn't the warmest. In the high 40s to low 50s with strong cold winds from the Northwest. I spent most of my time in the car, darn near hot lapping it then tuning then running again. I made 7 passes from 1pm to 3:30pm or so.

Eventually the car will get a set of adjustable roller rockers and I will be able to see if it picks up any with the addition of those from less friction and being able to set a slightly tighter hot lash to regain some of the cam size.
 
#8 ·
Shoot, I'll take drag racing in 40's and 50's over salt covered truck any day. That's when my car typically runs it's best. :thumbsup:

What kind of DA do you all normally see out there?
I'm usually at, or sometimes even below, sea level.
 
#10 ·
That's no joke. Well the cold air got us down to ~445ft. Normally it's 1000ft when it's "good" and most of the time 2500-3000ft due to heat and humidity.

Nice job!
I've had great luck with Cam Motion with the current custom SR and previous HR for my 355.
I can't say enough good things about them. I got my first cam from him for my 99 Silverado as a test mule for his "drop in" replacement 5.3 truck cams. When I went to switch from ls1 to ls2 my Comp cam wasn't looking pretty so I got one of his cams and some new lifters for it then a couple months later he proposed this little experiment to me since he liked the write up I did on his truck cam.

Ran it last November then did the cam swap and hit opening day at the track yesterday.
 
#12 ·
Spring specs are 155 lbs @ 1.780", 380 lbs @ 1.180", 400 lbs @ 1.130, coil bind @ 1.070"

I just installed them on the heads with no shims and did not get an actual measurement for install height.
 
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