Straub Bushing Trunion Kits?
Speaking of roller rockers, some manufacturers offer a larger rocker bolt upgrade for more stability. With the trunion being flat milled now rather than plunge cut, would it be possible to have the bolt hole drilled for a larger 3/8" or 10mm bolt? Is there enough meat in the trunion shaft itself?
Only way the larger bolt would help is if the head mounting threads are increased as well. But would assume valve train stiffness is way more than a traditional SBC already which benefit from stud girdles. Has anyone measured the rocker bolt flex/deflection like they do on stud deflection on SBC/BBC?
You could run a larger DIA bolt with smaller DIA threaded shaft... DUH. Perhaps deflection could be limited depending where the bolt is flexing with no mods to the head. And then one needs to figure out at what point the bolt strength doesn't improve deflection due to length and the anchor material (head aluminum). The stud girdle works on a different principle by tying all the studs together for increased rigidy. Would be easier to include longer bolts and a cross top bar that bolts down to all the rockers into the head in the stock locations. A taller VC would be required but its doable. queston still stands... do the stock rockers even deflect that much?
I have checked bolt deflection on the engine stand just rolling the engine over by hand, it was .0005+ with oil, stock rockers and mid 25X hydraulic cam with hydraulic lifter shimmed solid, 140-420 spring on LS3 head. LS7 heads are obviously slightly better. I use a rocker bar just like the old small block Chevy style, it stops the movement. The aggressive cams and higher spring rates make this problem worse.
Kurt
Kurt
Only way the larger bolt would help is if the head mounting threads are increased as well. But would assume valve train stiffness is way more than a traditional SBC already which benefit from stud girdles. Has anyone measured the rocker bolt flex/deflection like they do on stud deflection on SBC/BBC?
I increase bolt size on shaft rockers as that is fairly simple and the 8mm stuff shows issues. I think you could do it on stock stuff, but with rocker bars I have not needed it with hyd engines. The center axle is .730, that could handle 3/8 without issue if you're willing to do the work.
Kurt
Kurt
Speaking of roller rockers, some manufacturers offer a larger rocker bolt upgrade for more stability. With the trunion being flat milled now rather than plunge cut, would it be possible to have the bolt hole drilled for a larger 3/8" or 10mm bolt? Is there enough meat in the trunion shaft itself?
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I have checked bolt deflection on the engine stand just rolling the engine over by hand, it was .0005+ with oil, stock rockers and mid 25X hydraulic cam with hydraulic lifter shimmed solid, 140-420 spring on LS3 head. LS7 heads are obviously slightly better. I use a rocker bar just like the old small block Chevy style, it stops the movement. The aggressive cams and higher spring rates make this problem worse.
Kurt
Kurt
LS heads have different bolt spacing based on valve size and bore it's designed for, and aftermarket heads change from stock often so the bars are specific to the head. I mainly use LS3 heads on my Pro Touring type cars, so that is the only one I produce the bar for. I have made some one off parts for LS7 and Trick Flow cathedral when I used them, but it gets very costly.
I always use the stock rockers on these builds, the LS3 is in the picture.
Kurt
I always use the stock rockers on these builds, the LS3 is in the picture.
Kurt
I have checked bolt deflection on the engine stand just rolling the engine over by hand, it was .0005+ with oil, stock rockers and mid 25X hydraulic cam with hydraulic lifter shimmed solid, 140-420 spring on LS3 head. LS7 heads are obviously slightly better. I use a rocker bar just like the old small block Chevy style, it stops the movement. The aggressive cams and higher spring rates make this problem worse.
Kurt
Kurt
I have checked bolt deflection on the engine stand just rolling the engine over by hand, it was .0005+ with oil, stock rockers and mid 25X hydraulic cam with hydraulic lifter shimmed solid, 140-420 spring on LS3 head. LS7 heads are obviously slightly better. I use a rocker bar just like the old small block Chevy style, it stops the movement. The aggressive cams and higher spring rates make this problem worse.
Kurt
Kurt
Staging Lane
Joined: Nov 2005
Posts: 55
Likes: 0
so I got to see one of the Straub kits up close, I friend bought one, what the hell is the deal with the brass bushings? I put a pair on the trunnion and they rock, do they compress when you press them into the rockers? I was kind of shocked at the slop in them.
TECH Fanatic
Joined: Sep 2005
Posts: 1,584
Likes: 23
From: NYC
I think there is something wrong with the set you bought, because mine were very tight.