limige

car started acting funky and picked up a ticking noise, almost sounded like and exhaust leak but i knew it wasnt... so i picked up some pro mags and studs to go with the 230/236 cam that's in there (was running stockers) about a month ago. i figured i'd install them and look for a bad lifter.. i reused the stock lifters as well, didn't think there were any issues with OEM's...

well i pulled the valve covers and everything looked ok on the drivers side, but on the passagers side i found my problem. one pushrod went through the rocker arm, two other rockers blew out the bottoms and one had a peice busted off.

so what's the most likely reason?
lifters not getting oil up top?
valve springs in-adaquite? (comp 941's)
or stocker rockers not strong enough for the cam/spring combo?


what do you guys think???

mike

kyle97

How many miles were on the stock rockers? With a higher lift cam you put different stresses on the rocker arms than with the stock setup. It's possible that the stock rockers had certain weaknesses ground into them from miles of running with a lower lift cam, and the new cam exploited these weaknesses. Most cam instructions I've ever read say its required that you put new rocker arms on for this reason.

limige

rockers had over 100k on them for sure..

limige

limige

so what are the chances it could've been valve float?

limige

i checked the pushrods, they appear to be slightly bent, maybe .005-.010 i almost appears they may have been rubbing the guideplates?? i did a visual check and rolled it over by hand when i assembled it, they didn't appear to be hitting but i've read about the gmpp being the ones to use.. mine are comp cams flat plates with slots. comp cams hardened pushrods 7.200 length.


could the guideplates deflecting the pushrods cause this or just using stock rockers on a cam/spring combo do this?? someone has to have some insight what may have happened or what to look into?

luckyou03

wow i never thought i'd see a stock rocker do that

njenson

wow, you would think you might have noticed that kind of a problem right away huh

Z95m6

Just looking at your pics you can see your rockers are on at a huge angle. You need to get some better guide plates.

TobyZ28

What symptoms was the car exhibiting before you knew what it was?

396D1SS

The stock rocker arms can not handle that amount of spring pressure. I have had the same thing happen to me before.

limige

well i didn't know what it was until i pulled the valve covers, i suspected bad lifters. never expected this...mind you the car has been driven very little since the rebuild/cam install.

i've been chasing down vaccum leaks and lean issues, changing injectors and playing with the program, so when the car acted up i didn't realize it was mechanical at first. then it started ticking, thought it was a collasped lifter. boy did i get a suprise..

Buttercup

Don't use anything but the proper GMPP or adjustable guideplates on the LTx heads.

The stock rockers are self aligning and shouldn't use any guideplate, especially improperly spaced guideplates!!! This can cause excessive wear.

I didn't think the stock rockers were slotted enough to allow for that much lift??? If the rocker was running out of travel the pushrods will bend and try to push straight through the rocker like this. What does the underside of the fulcrum (at the end of the slot) and the stud look like?

You sure the valvesprings aren't binding?

TraceZ

^^ that was my first thought.

RedLT4Mike

This brought to mind a corney joke seeing as there is
PENETRATION involved... http://www.safbe.com/forum/viewtopic.php?p=651#651