broken rocker arm
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Teching In
Joined: Feb 2012
Posts: 29
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From: Mississippi
broken rocker arm I was cruising up the interstate the other day and car started backfiring and didnt have any power. Finally got it apart and found a bent pushrod and broken rocker arm. Ive got an lt4 cam with 1.6 roller rockers. Stock push rod length, lt4 valve springs, PRW rockers. Just curious on what might have caused it. Hoping its just a bad rocker and nothing else is hurt.
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Joined: Jan 2013
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From: Las Vegas
Only thing that bends p-rods is the lifters over-adjusted and collapsed. U need to adjust the lifters while at zero lash and while lifter is on the base circle. Zero lash is when u can still roll the p-rod back and forth with your fingers but can't move the p-rod up or down. I've read posts where sometimes new lifters or dry lifters will collapse without the oil and become solid after the adjustment. IMHO the spring is pretty stout and u should try to operate that plunger dry once by hand using a p-rod - its a pretty stout spring.
Sorry for the bad news,
cardo
Sorry for the bad news,
cardo
How long was this setup together for? You been driving it for a decade or broke on the first testdrive?
PRW is rock bottom of the barrel cheap stuff. I honestly know nothing about their quality but I know they are about as inexpensive a part as you can find...................................
If they are heavier than other aluminum rockers that could easily amplify the issues with the LT4 springs being marginal for the heavier LT1 valves.
If you put it together last weekend I would wonder about how you adjusted the valves.
You probably would have been better off reusing the stock lifters and spent more on rockers and springs than what you did.
PRW is rock bottom of the barrel cheap stuff. I honestly know nothing about their quality but I know they are about as inexpensive a part as you can find...................................
If they are heavier than other aluminum rockers that could easily amplify the issues with the LT4 springs being marginal for the heavier LT1 valves.
If you put it together last weekend I would wonder about how you adjusted the valves.
You probably would have been better off reusing the stock lifters and spent more on rockers and springs than what you did.
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Verdad Gallardo Banned
Joined: Jan 2013
Posts: 588
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From: Las Vegas
Jfyi. Well i have my old roller lifters and p-rods in a coffee can sitting in the garage. So i gave it a try today and nothing moved no matter how hard i tried. Placed a piece of wood under the p-rod and pushed down on the lifter (upside down) with my body weight and again nothing. Tried several lifters too. Only result was small dents in the piece of wood from the p-rod.
My prognosis is the spring under the lifter cup is strong enough to ensure the cup doesn't collapse while finding zero lash.
Now something that could also bend a p-rod is if the lifter is adj while on the ramp of the lobe and it then has a lash clearance - which causes the lifter to bang the lobe and p-rod like a solid cam/lifter. But this is just a guess if possible.
Nothing to lose now by trying again Crazyace85 (with new parts of course). Just ensure your on the base circle of the lobe for the lifter your adjusting and to verify zero lash as i said before.
Any comments?
Good luck Crazyace85.
cardo
My prognosis is the spring under the lifter cup is strong enough to ensure the cup doesn't collapse while finding zero lash.
Now something that could also bend a p-rod is if the lifter is adj while on the ramp of the lobe and it then has a lash clearance - which causes the lifter to bang the lobe and p-rod like a solid cam/lifter. But this is just a guess if possible.
Nothing to lose now by trying again Crazyace85 (with new parts of course). Just ensure your on the base circle of the lobe for the lifter your adjusting and to verify zero lash as i said before.
Any comments?
Good luck Crazyace85.
cardo
