Okay this is weird. I have a 1995 F150 eddie bauer edition truck with a 5.0 liter. Its been bored out and has a new high dollar cam and has been running fine for over 6months. My father and I went to change the stock rocker arms to roller rocker arms, these are the same ones they use in the cobra motors, I talked to crane and comp cams and they said it shouldnt do anything drastically to the motor. They even have the ford emblem stamped on them and a genuine ford part number on them. We switched them out and now it sounds like a freaking race car. It idles high and so low that I think the motor is dead. It sounds like it has a vacuum leak when its idleing but when you drive it, it doesnt act like it has one. All we took off were the intake manifold, the sparkplug wires, and the valve covers. can anybody help me out here?

 

You should do a compression check. My bet is that the rockers are out of adjustment. You may need only shims, you may new new rods and shims.

Keep us posted,
Mike

 

Sometime the roller rockers are machined so that the pushrod contact point is lower than the stock units because of the additional material in the rockers. The answer is as mickeyswoods says; either shims or shorter pushrods.

A question that pops into my head is, did you bleed down the lifters while changing the rockers? Also, did you torque the new rockers to the specs outlined in the instructions?

The reason I am asking is that if you properly bleed down the lifters, then tighten the rocker bolts until the slack is out of the pushrod, you should only be able to torque the bolts another 1/4 to 1 turn until they bottom. If you can turn them more that 1 full turn, you need shims or shorter pushrods.

 

whats the ratio? they should have come with shims..

 

We did put shimms in. It came with .02 and .035, we used the smaller ones. Yes it was torqued to spec. The roccker arm ratio is 1.7, they have 1.65, stock is 1.6 but they dont make them anymore.

I have been told that the older computers can only adjust the fuel ratio so much, 3 millisec and up to 32 lbs of psi to be exact, and they I might need a higher fuel pressure regulator because since we put the rocker arms in it doesnt start on first turn like it use to. The problem isnt the shimms or the pushrods and its running on all eight cylinders just fine. Its just that it has this intermiten loop when it idles but runs like a race horse when you drive it. Any more ideas fellas? Thanks for all the feed back