Car sounds and runs like poo

[stevesLX]

--------------------------------------------------------------------------------

O.K. I will make this as short as possible. Last Thursday I decided to put my roller rockers back on. These are GT40P heads with non adjustable rockers. I also changed out my lifters because I had a couple that were one reason or another were not pumping up. All I did when I changed the rockers was pulled the factory one off and I put my rollers on. I did not go thru the whole base cicle of the cam deal or nothing since these are non adjustable and I was doing a one for one swap. So I drive the car on Friday and it sounds like crap. So this weekend I put my factory rockers back on and it still sounds like crap. But the car still had plenty of power both low end and top end. So I tear it all back apart and low and behold I guess I didn't tighten down my lifter girdle because the 2 bolts that hold it down were about 3 threads shy of coming out. So just to rule the lifters out I put my other ones back in minus the coulpe that wouldn't pump up and put it all back together last night and start it and its still noisey. I have always had some valvetrain noise but this is super noisy and you can hear a louder tick that is consistent with the lope of the cam. You can only hear it at idle. So I go and drive the car and hammer it down and once you get up into the higher RPM's like 400o or higher it starts jerking and missing real bad. So I am clueless as to where to start now. I ran the car with the valve cover off on the side that seemed to be super noisy and really can't pin point where its coming from. But it just seems funny that after the lifter girdle was lose and I put the rollers on all my problems started. And now I fix all that and its still not better. So I just pulled my valve covers off and started with #1 and went thru the whole valvetrain and tightened everything down on the base circle of the cam and started it and it still sounds the same. So I just tore it all the way back down to the lifters and everything looks normal so I dont know what to do.

 

[stevesLX]

Nobody out there has any ideas

 

[68keyblr]

you still have to do the base circle thing! You have to torque them to 18-20 ft-lbs, arriving at the prescribed torque between 1/4 and 1 full turn.

If you're not on the base circle then you won't get the proper torque.

 

[stevesLX]

I did the whole base circle thing yestarday and was getting 3/4 of a turn and it still sounds no different. I cant move any of the rockers up and down like if you were trying to see if they are collapsing or not. However I can move a few of them side to side. They dont move but a smidge each direction but it appears as if all my lifters are pumped up.

 

[408gt91]

Did any of the lifters turn when the lifter girdle came loose?

 

[cenok is family]

Did any of the lifters turn when the lifter girdle came loose?

+1. and make sure all the "spider" lifter hold down thingys are on correctly and not upside-down.

 

[stevesLX]

Yes the dog bones are all on correct and from what I recall none of the lifters turned. The girdle that holds the dog bones in place was just lose it did not come completely off. I pulled the cam today and it seems to look O.K., but then again I really dont know what to look for.

 

[jtfairlane]

By the very fact that people are referring to "base circle of the cam deal" and the "base circle thing" does not give me high hopes that anyone is doing this right.

StevesLX:

You are saying you have non-adjustable, bolt-down, pedestal style rocker arms. Is this right? If so, do the following - (this procedure is ONLY for pedestal mount rockers, no adjustable stud mount)

Adjust your rockers one cylinder at a time.

Watching your lifters, turn the motor over by hand until both lifters are at the lowest point in their lifter bores. They are both low (retracted into the lifter bores) at TDC of the compression stroke and again on the exhaust stroke. You want to turn the motor over for 1 full revolution of the entire intake, compression, power, and exhaust cycle (in other words, you hit TDC at least twice) to make sure the lifters are at their lower point. This is because they will be slightly lower at TDC on the compression stroke than they will be at TDC on the exhaust stroke, and you need find the lowest point, so finding TDC only once is no guarantee it won't be lower on the next revolution until you double check.

Once you are on TDC of the compression stroke (lifters at lowest point in their bores), you can install the rockers for THAT CYLINDER. One at a time, slowly tighten the bolt until there is no clearance between the rocker tip and the valve stem tip. Now, using a torque wrench, torque that rocker bolt to 18-20ft/lbs. Your torque wrench should reach 18-20ft/lbs between 1/4 to 1 turn of the torque wrench. If you can't make at least 1/4 turn of the torque wrench before reaching 18-20ft/lbs, OR you have to go more than 1 full turn before reaching 18-20ft/lbs, than you will have to shim the pedestals OR install longer pushrods, respectively.
Do that for both rockers, and then move on to another cylinder, repeating the WHOLE process over again.

This is the correct way to install bolt down pedestal mount rockers.

 

[stevesLX]

O.K. I appreciate that and I will try that. Now as far as being lower on the compression stroke VS the exhaust stroke my cam is .512 lift on both intake and exhaust so I beleive the lowest point will be the same on either or. Now just to make sure that I am doing top dead center on the compression stoke correctly. The exhaust valve will go fully open and then closed and then the intake valve will go fully open and then closed. That should now be TDC for that cylinder, correct or not.

 

[Flavadave4]

Reassemble the rockers and tighten them when they are at the lowest point like JTfairlane said......thats the only time when they do not have a load on them.

 

[jtfairlane]

O.K. I appreciate that and I will try that. Now as far as being lower on the compression stroke VS the exhaust stroke my cam is .512 lift on both intake and exhaust so I beleive the lowest point will be the same on either or. Now just to make sure that I am doing top dead center on the compression stoke correctly. The exhaust valve will go fully open and then closed and then the intake valve will go fully open and then closed. That should now be TDC for that cylinder, correct or not.

No, you're wrong. The amount of lift your cam has makes no difference. The fact that it is a single pattern cam (same lift for both I and E) makes no difference. The lifters are going to be SLIGHTLY further into their bores at TDC on the compression stroke than on the exhaust stroke, no matter what your cam specs are. I usually use my fingers and feel the top of the lifter compared to the top of the bore at TDC, I rotate again until next TDC and feel again, you should feel a slight difference.

The above method is only really needed if you are having a hard time figuring out which is TDC Compression vs TDC exhaust.

You are correct about the intake valve, though. If you see the intake valve open and then close for that cylinder, then you are coming upon TDC for the compression stroke for that cylinder.