Like the topic says, what would be the symptoms of tightening rocker arms too tight?

I have 1.52 roller tip rockers in my car and over the winter I had to readjust the valve lash yet again. When I did this, I went a little more than 3/4 or a turn, but less than a full turn. So I think they are ok.

But anyways, the reason I ask is because since my 88GT has been back on the road, it has been having little "quirks" here and there. It has had to really "search" around for an idle a few times. Sometimes it wants to stumble a little after you first get on the gas (~1900rpm). It has also given me a little shudder at 45mph.

So my best guess would be that maybe my rockers are too tight. Some other possbilities could be my ignition module or possibly even my wires. But I'm not really too sure.

Any input would be greatly appreciated.

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1987GT *for sale*, or trade, PM me for details.

This is a so so way to tell.

Check the compression on all the cylinders. If the valves are not closing due to "too" tight conditions, the compression will suffer. I have seen people go way too far and you get ZERO compression.

On a slightly aged 2.8 you should see between 125 and 145....I would think if you are running around 90-115 compression, you might be in to tight.

On 3.4 engines the compression runs about 150-160 on all the motors I have installed.

Loyde

if you tighten them too far one of a few things happens...

you hope the car only runs like crap.
you burn valves.
you bend push rods.
you break rockers.
you get the idea....

If the rockers won't hold their adjustment something fairly serious is wrong. There is nothing that would make a good hydraulic valve train need repreated adjustments like that. If the valves are hanging open into the combustion phase they will burn very quickly. A burnt valve means a complete head rebuild or replacement.

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11-Sept-01, The day the world as we knew it ended.

Factory lifters are supposed to have about 3 turns of travel in them. If you went too tight you would likely have a pronounced skip at idle at the very least.

Well I'm going to do a compression test today or tomorrow. That will probably help me diagnose my problem a little better.

I'm still not sure it it's the rockers though. It idles fine and it revs just fine. My power is very good.

Ogre, it's not that my rockers arms aren't holding their adjustment, it's that the first time I did it (I had to take it apart because I collapsed a lifter) I adjusted them wrong (I confused the 1-3-5 side with the 2-4-6 side), so there was alot of noise in the valve train still.

AkursedX, from my experiences I have learned this - the book calls for 1 1/2 turns on the rocker arm adjustment nut to set valve lash - I have yet to do this and have compression.... more often it is around 3/4 of a turn from the point of being slightly snug.. snug them, check the compression on that cylinder, and adjust accordingly, 1/8 of a turn at a time ... just a suggestion.

When i tightend them to much my Idle went up like another 1000 rpms... that also caused like it it me shakey at stops and stuff....

Kyle

Comp Cams Roller tip 1.52 are 1/2 turn --------

quote Originally posted by GT GT 87: Comp Cams Roller tip 1.52 are 1/2 turn --------

A good place to start diagnosing this is to check that theres a little bit of slack between the rockers and the rods. do this by making sure the lifter is sitting on the lowest point in the cam. Do this for all cylinders and start tightening approprately from there. If the rockers are tight, you should experience erractic iddle which may worsen at high speeds as oil pressures goes up..Good luck