I suffered a rocker arm end cap failure that spit out the needle bearings. Could only account for 1/3 of the bearings even after sweeping the oil pan with a magnet.

https://ls1tech.com/forums/general-l...rain-plug.html

We installed a fresh set of WS6 Store / RPMSpeed rockers but the car continued to have driveability issues. New plugs, wires, O2's and the car seemed to run well except for backfiring at higher TPS/rpms.

Went back into it today and found that the pushrod was slightly bent on the offending rocker and a needle bearing in the pushrod hole. Replaced it, buttoned it back up, test drove it, and the backfire is still there at higher throttle and rpms.

I can't think of anything else to do but pull the head and inspect the lifter(s). I'm open to any other suggestions, but nothing else comes to mind.

 

Is it backfiring out the intake or exhaust?

 

When you changed rocker arms, did you check pushrod length?

 

Out the exhaust.

No we didn't. The valvetrain is all stock and original.

 

Time to check your push rod length. The push rod cups are not on the same plane as your stock rockers, with the new rockers. I�m only talking thousandths, but that�s all it takes. I�d guess you need a slightly shorter pushrod.
Measuring your pushrods properly will tell you what you need.

 

Well, if you're right and the geometry is off with the new rockers, and the stock pushrods are too long for these rockers, then potentially all the pushrods could be bent, not just the one on the bad rocker. Another factor in favor of this possibility is that there was no backfiring while driving with the bad rocker. All the driveability issues started after the new rockers; the car ran perfect when the bad one was still in there.

 

Posts like this make me want to punch the computer screen.

OP, you've likely got something else going on. May be something simple, if you have access to hptuners or similar i would run a scan and see what all the sensors are doing, fuel trims etc to see if you can get a lead on the issue.

 

Do a compression test on the hole that had the bad rocker

 

I'd do um all, backfiring out the exhaust is a sure sign you got a dead hole.

 

lmao.

 

Check the valve springs while you're at it. A weak or broken spring will cause a backfire issue also. Slightly bent valve is also a possibility considering you had a bent pushrod. Along with a compression test here is how I check for a bent/sticky valve.
Pressurize the cylinder, Remover retainer and spring, Use a small pair of vice grips ( I tape up the teeth to protect the valve stem) and clamp them on the tip of the valve firmly and then depressurize the cylinder. The valve should rotate and slide up/down freely.

 

i read this last night, and thought somebody has their engines mixed up, or thinks OP is running a set of solid lifters or something...

 

Yep I have EFILive and did a scan. Fuel trims, everything else is normal. I ran the car in open loop, closed loop, MAF unplugged, and it backfired in all conditions with enough throttle and rpms.

 

From PM: [QUOTE=tech@WS6store]The rocker arms are made to be an exact bolt on fit. That's how i did with mine. Unbolted stock rockers, bolted new rockers down, and that is that. i can double check physical alignment and measurements tomorrow. It sounds like you may have lingering effects of the original rocker failure or possible issues from the orig needle bearings causing abnormal wear or issues.

 

Spark issues will show up around there also and can cause that, so can fueling. What does actual afr show per bank?

 

Why would a post like this, make you want to punch your computer screen? Chill bro...stop punching stuff.
Op changes his rockers, and now has backfiring out of the exhaust.
FIRST inclination is that the valves aren�t closing. Remember that we are working with a non-adjustable valve train. I like the guys at WS6Store, and I buy from them, but maybe something is a little off? I understand variances from hydraulic lifter preload, I really do. Install too long a pushrod in your engine, go out and run it hard and you�ll likely have the same issues.
And your suggestion is to run a diagnostic, when this is clearly a mechanical issue?
Maybe my SUGGESTION to have the op check his pushrod length is out of line?
Call me crazy, but that�s where I�d start...

 

Ummm....... That and the fact that the rocker arms look to be stock rockers with a trunion upgrade so they should be no different than what he took off.

 

Agreed, they should be no different....but is it too much to ask to simply check pushrod length to make sure? Takes all of what, 20 minutes?

 

It would not hurt but pointing at just that as an issue and ignoring the rest is tunnel vision.

There are many causes of his issue, some of which may still be related to his original problem.

 

I�m not ignoring anything guys. I simply SUGGESTED to START with measuring pushrod length, to ENSURE that the rocker geometry, and cup location is kosher.
I never said that�s absolutely the problem, I simply said that�s where I�d start. You know as well as me that it�s virtually Impossible to diagnose issues like this over the net. It�s probably not the issue...but it could be...it�s a free easy simple step, and that�s where I�d start. AND THEN I�d look at at other issues once I ruled this out.