more noisy rockers...

[txstang84]

Hey guys, I saw a reply to a noisy rocker question someone had quite awhile back...anyway, I'm having the same problem with the same circumstances...stock length pushrods with rockers pulled from a '95 Cobra, on GT-40 heads. I bought new stock length 5.0 pushrods (6.272") and I've got tons o' noise coming from my valvetrain. During assembly, the rockers went down without a hitch..."0" lash + 1/2 turn on all 16...now they sound like a pissed off sewing machine on steroids.

Getting to the meat of the question, a posted reply by (edit: 90MustangGt) said that I need special pushrods from Crane for the Cobra rockers...I ck'd Jegs, and they sell them for $80 (or $130 for heat treated)...but they're 0.117" longer?? That seems like alot of extra length to be putting into a non-adjustable valvetrain...

I'm running '95 Cobra rockers on stock GT-40 heads with a Lunati 51014 cam (284*int/292*exh total, 218*int/226* exh @ 0.050", 0.500" int/ 0.510" exh) in a freshened/balanced stock bottom end. The thing runs very well, but just like everyone else in the 'stang world who has noisy rockers, it's annoying as hell...please advise, any help is appreciated.

 

[v8only]

did you make sure it was on the base lobe of the cam b4 checking rocker adj? Noisy rockers = bad adj., I've been through this a dozen times literally between my car and my bro's car. I'm running gt40p's and 1.7's rr's cobra style stock pushrods, he's running gt40's with 1.6's and a tfs cam, upgraded pushrods but stock size. Our cars are finally adjusted perfectly, and you can barely hear them if at all.

go to the crane side and read up on the adj procedure. Even a non rebuilt head will need a shim hear or there, I find it strange you turned up perfect on all of them.

 

[txstang84]

Oh yeah, I made damn sure that I adjusted them on the base circle...they started off quiet, then since April, they've just gotten terrible. Noisy rockers does not always mean bad adjustment; but presumably more than 90% of the time, that's what it is. Since they are pedestal mount, and they are torqued down properly, my only recourse for "tightening" the rockers is to get longer pushrods or lashcaps-which is out of the question as far as I'm concerned. I could loosen them with shims, but quite obviously that would only make my problem worse.

And yes, I've already gone to the Crane website to review, for the 100th time, proper adjustment procedures even for pedestal mount rockers. As far as you thinking it strange that all 16 rockers came out perfect lash, I submit to you, truth is sometimes stranger than fiction. Not to poke fun or anything of that nature. The heads are stock, but they have been through a simple rebuild (i.e. shimmed springs, 3 angle v/j, and 0.004" cleanup surfacing). At any rate, I was also surprised-pleasantly of course-upon seeing that all rockers went down so well...but now, they're noisy, and I've ck'd them a couple times already. The only "play" I can find is side-to-side clearance on the rocker trunnions.

But, the rockers went back into their exact stock positions, and when the original engine they were on was pulled apart, they made no noise whatsoever. Obviously some people will no doubt make mention of the differences from block to block...again, I will reitterate that lash was ck'd to be 0 lash + 1/2 turn on all 16 rockers from the base circle...rocker by rocker.

Edit: Oh, btw, the noise is only really bad around 1800 and up...idle is barely discernable

 

[txstang84]

Is it possible that my oil pickup is a hair too far from the pan? When I drove it home from work, I was listening to it, and sounds almost like it does it worse when I'm decelerating

 

[fastranger347]

ive tried every adjusting method known to man, and 3 sets of rollers over a course of ten years and my conclusion is that once you deviate from stock spring pressures and use aggressive cam profiles, the lifters are just gonna be noisy period, and yes they are slightly louder on deceleration

 

[emagdnim]

ive tried every adjusting method known to man, and 3 sets of rollers over a course of ten years and my conclusion is that once you deviate from stock spring pressures and use aggressive cam profiles, the lifters are just gonna be noisy period, and yes they are slightly louder on deceleration

I had the exact same problem with the ramp rates on my comp cam nx264 cam and stronger springs. Impossible to get the back to stock silent. I even bought new pushrods, roller rockers, and lifters.

 

[txstang84]

...get this...

I just got my PMS in the mail yesterday, and before hooking it up, I brought the timing back down to 10* for the tuning purposes...I did have it at 14* initial, and now the noise has quieted down. It's still there, but nowhere near as bad

The tuning is a whole other story though...I put another thread there about how I can't get it to idle anything lower than 1500rpm. I guess I'll just have to turn off idle control for the time being, and let the A9L do it's own thing.