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This winter I'm switching down to a smaller camshaft. 230/246 .634/.634 115+4 LSA
What i currently have on the car C6Z06 is
BTR 4
PSI1515ML (ti retainer) with T&D roller steel adjustable rockers & smith brothers bushings.
Johnsson 2116LSR lifters
I've just seen some info that the T&D rockers require a lot more spring than i actually have?
What I'm thinking is:
Keep the T&D rockers, upgrade to BTR .650 max lift springs (shim for increased seat and open pressures)
(good to have adjustablity with the tight window of preload on the 2116LSR lifters .035" Pre-Load + or -.005". Or if 150lbs seat and 450lb open is enough, possibly grid the cam on a .650 lift lobe instead?) or
Run stock rockers with CHE trunnions, and keep PSI1515ml springs. (light and nice, but harder to get correct preload with off the shelf pushrods)
IMO your springs are more than you need even considering the rockers keep in mind is a four degree advance which will lower the max rpms
However there’s no wrong reusing them, if buying new then 380 lbs open pressure is still generous imo.
By the way lmk if you decide to sell or swap your T&D rockers for Smith Brothers solid Bronce trunnion upgraded LS7 rockers plus cash
IMO your springs are more than you need even considering the rockers keep in mind is a four degree advance which will lower the max rpms
However there’s no wrong reusing them, if buying new then 380 lbs open pressure is still generous imo.
By the way lmk if you decide to sell or swap your T&D rockers for Smith Brothers solid Bronce trunnion upgraded LS7 rockers plus cash
Oh really? BTR seem to suggest 150lb closed, and 450lb open pressure is required, basically their SP002 kit. Dunno if thats for aluminium rockers, or steel though. Starting to feel like im trying to invent the wheel again, instead of just running parts that most people use.
I know the smaller cam will not be quite as rev friendly, but i drive my car mostly on the street, and on the road course. I think a smaller camshaft will make the car more fun on the street, and even generate better laptimes with more torque down low for the track.
Im using titanium intake, and Ferrea 2042p stainless hollow stem exhaust valves btw
I use 140 seat 380 open on ls7 with Texas speed stage 3.5 Cam shifting 7300 and is all good.
By the way my friend pretty much did cam down size too for road corse went with the Cam Motion Titan cam and he loved it coming of the turns makes big torque check it out.
I use 140 seat 380 open on ls7 with Texas speed stage 3.5 Cam shifting 7300 and is all good.
By the way my friend pretty much did cam down size too for road corse went with the Cam Motion Titan cam and he loved it coming of the turns makes big torque check it out.
Thanks man! But what did he have before if thats a downsize cam? Thats very close to the BTR stage 4 that im getting rid of. BUT; if you only do track driving and no street driving, im sure its awesome!
140 seat and 380 open with roller rockers? Or did I misunderstand something.
Thanks man! But what did he have before if thats a downsize cam? Thats very close to the BTR stage 4 that im getting rid of. BUT; if you only do track driving and no street driving, im sure its awesome!
140 seat and 380 open with roller rockers? Or did I misunderstand something.
He had 247 intake duration before
below is LS7 spring specs what I see is too much unnecessary spring pressure for the cam you mention you are going to which has a lower rpm operating range due to the 5* advance and lower int duration.
we use 525 open pressure for 8000 shift points on llsr using T&D Machine adjustable rocker arms only thing I do different is I pay extra to put a grove across the center to lighten them up this is using .092 wall double tapered push rods.
The ls7 is a rev happy engine in stock form as you may know going past 7k often no problem so for same or similar rpm operating range you just want to compensate for the added valve nose weight added as far as i understand you are also using a hydraulic cam as well so why adding unnecessary spring pressure is my argument, here’s the ls7 spring specs
Installed height = 1.995"-2.00" (without seal/spring base).
Spring base thickness = .048"
Net installed height = 1.952"
Seat pressure = 113.0lbs
Open pressure = 312.4lbs @1.352" (.590" lift)
Open pressure = 316.6lbs @1.342" (.600" lift)
Coil bind = 1.304" (.644" lift)
The Btr stage 4 is like a max effort street cam
the cam I suggested is a stage 3 or comparable and works real nice on the street in in his own words and still makes good power and great torque.
By the way how do you plan to turn the motor to adjust the valve lash?
He had 247 intake duration before
below is LS7 spring specs what I see is too much unnecessary spring pressure for the cam you mention you are going to which has a lower rpm operating range due to the 5* advance and lower int duration.
we use 525 open pressure for 8000 shift points on llsr using T&D Machine adjustable rocker arms only thing I do different is I pay extra to put a grove across the center to lighten them up this is using .092 wall double tapered push rods.
The ls7 is a rev happy engine in stock form as you may know going past 7k often no problem so for same or similar rpm operating range you just want to compensate for the added valve nose weight added as far as i understand you are also using a hydraulic cam as well so why adding unnecessary spring pressure is my argument, here’s the ls7 spring specs
Installed height = 1.995"-2.00" (without seal/spring base).
Spring base thickness = .048"
Net installed height = 1.952"
Seat pressure = 113.0lbs
Open pressure = 312.4lbs @1.352" (.590" lift)
Open pressure = 316.6lbs @1.342" (.600" lift)
Coil bind = 1.304" (.644" lift)
The Btr stage 4 is like a max effort street cam
the cam I suggested is a stage 3 or comparable and works real nice on the street in in his own words and still makes good power and great torque.
By the way how do you plan to turn the motor to adjust the valve lash?
Thanks for taking the time and properly answering my questions.
Yes indeed, I'm still using a Hydraulic camshaft, with Johnsson 2116LSR lifters. No reason to go too high on spring pressure, just putting strain on everything.
I probably wont run the engine past 7k, since as you say the max HP wont happen much above 6500-6600, if i don't pick another camshaft.
You still think 405 open and 140 closed is enough i assume, that i get with the PSI1515ML springs.
Planning to turn the engine over via the balancer bolt, how so? Although it will be to measure required pushrod lenght and then add preload of 0.035". Feeling some education coming my way
These are the rockers I have: Steel LS7 NHRA LEGAL DIRECT BOLT ON, made for the Eliminator drag race program in mind where stock heads is a regulation (?)
See attachment.
Thanks!
The springs you mention have the pressure the rockers are very familiar and are great, as for the balancer bolt wrench I had to make my own sense I’m not sure any is available nor do I know anybody else ever manage to get a wrench in there.
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Spring and rocker help
Thats very close to the BTR stage 4 that im getting rid of. BUT; if you only do track driving and no street driving, im sure its awesome!
