I have a second gen Cav, 3.1.. I recently put a crane cam in, nothing Rad, also put in 1.6 roller rockers from comp cam,, problem is this is the second set of pushrods that I have bent, 4 the first time, now two more folded, I am sure I adjusted them right, ran great for about hundred miles then started popping through the intake, tore it apart and more bent pushrods, anybody have any idea what the bleep I am doing wrong??? maybe chrome moly pushrods????? thanks for any help,,
Check to be sure the rocker arms are not bottoming out in their available travel due to the greater valve lift. If they can bind at the end of their travel, you will bend pushrods regularly. Post pics here if you like and I can tell you more about what to look for.
Bill Hahn Jr.
Hahn RaceCraft
World's Quickest and Fastest Street J-Bodies
Turbocharging GM FWD's since 1988
www.turbosystem.com
Not sure how to check, the intake is off, and I can see the rods, I guess rotate the engine by hand, what does a binding spring look like?? thanks
Not spring bind...rocker arm bind. We used to run into this on the old small block Chevys when we'd put in bigger cams. Long-slot rockers could be had for those motors to alleviate the problem.
Pull off a rocker arm and examine it for binding because of the addtional lift. They can only travel so far before something physically binds, like the end of the rocker arm slot on the stud it pivots on.
Bill Hahn Jr.
Hahn RaceCraft
World's Quickest and Fastest Street J-Bodies
Turbocharging GM FWD's since 1988
www.turbosystem.com
Quote:
also put in 1.6 roller rockers from comp cam,
Haven't seen roller rockers yet that can't rotate enough for a mild cam, but anything's possible.
Need to ensure no valve spring bind and spring retainer not hitting top of guide. I'm not a V6-60 guy so I don't know max lift on stock heads / springs off the top of my head. With valve at max lift, should be able to pass at least a .060" feeler gauge between coils of the spring.
-->Slow
Hmm. OK. I see the OP's mention of the roller rockers now. Yes, they typically would be expected to clear the mild cam, but that fact that he replaced them brings something else to mind now...
What rocker arm / valve adjustment procedure did you use, Martin?
Bill Hahn Jr.
Hahn RaceCraft
World's Quickest and Fastest Street J-Bodies
Turbocharging GM FWD's since 1988
www.turbosystem.com
I found out a much easier way to adjust the 1.6 rockers .....
I was told to tighten them down til you can spin the pushrod, but how hard are you suppose to try to spin the pushrod?
So ..... Tighten them till they contact the valve stem and the pushrod, then pre-load the lifter by an additional 2 complete turn with the rocker lock nut.
But I would also advise chrome-moly pushrods, thats what I have ..... granted it is a 2200, still the same concept.
Two turns is more than I've done; I'll usually go for one. But this comes from my old V8 days, admittedly...the standard for these engines may well be different.
Yep, this is why I ask...I'm wondering if the OP used the correct procedure. If he's got them too tight, it might bind at high RPM and bend the pushrods.
Bill Hahn Jr.
Hahn RaceCraft
World's Quickest and Fastest Street J-Bodies
Turbocharging GM FWD's since 1988
www.turbosystem.com
To set the rockers turn the cam on the bottom of the cam lobe not the peak of the cam lobe?Does it matter?I know some motors just torque it down but others there is a procedure.
Typically, this type of adjustment is done with cam on base circle (valve closed). This refers to when we are "adjusting" the clearance (actually, the lifter preload) to a particular specification.
Yes, in some engines this is pre-set via the parts design, and you can just tighten the rocker arm pivots to a torque spec.
Follow the correct procedure for each engine, and also refer to cam/valvetrain manufacturer's recommendations.
Bill Hahn Jr.
Hahn RaceCraft
World's Quickest and Fastest Street J-Bodies
Turbocharging GM FWD's since 1988
www.turbosystem.com
Well with the stock rockers on the 2200 you can just torque them down and their all set, but with the 1.6 roller rockers, you need the arftermarket studs and locks.
You want to torqu the rockers with each cylinder at top dead center.
The easiest way to figure this out is using two people . . . . . Remove the spak plug for cylinder 1 and have one persone plug the hole with their finger, have the second person spin the crank pulley.
When the cylinder reaches the compression stroke there will be pressure behind the finger in the spark plug hole and air will force out behind the finger.
After this happens, shine a light in the spark plug hole and move the cylinder to its top most position on that stroke.
Next mark the crank pulley to you know where top dead center is.
Follow the same procedure for the rest of the cylinders.
If you have a repair manual you can just follow the firing order and move the crank 1/2 rotation and torqe the next cylinder down.
Once all rockers have been toqued rotate the crank assembly manually and listen for binding on the rockers.
Thats about it!
Thanks guys, I believe I may have over tighten them, went by GM shop manual,
