Engine Noise

[67Camaro RS/SS 350]

I just installed a set of AFR 195 64cc heads and upon firing up the motor, I have this noise:


I run a comp 270H and Rhoads variable duration lifters. These lifters require adustment like a solid lifter. I used a .020" feeler gauge, which is the street gauge. The first fire up I had noise on both sides of the motor. Yesterday I readjusted the valves and now it's only on the drivers side. I used an engine stethescope and it's definately coming from the drivers side valve cover. At first I thought it a rocker hitting the rocker drippers that are on the top of the valve covers, but I ran the motor with the covers off and it is still there.

[Taylor1969]

You can adjust them when the engine is running. Take the valve cover off and figure out where the noise is coming from and then adjust the rocker until the noise softens.

[67Camaro RS/SS 350]

Can you adjust a solid lifter with the engine running? Rhoads variable duration lifters are adjusted like a solid lifter, not hydraulic.

[Jim Nilsen]

I ran rhoads lifters for years and they are hppiest if you adjust them while running. A couple of degrees on the wrench can make all of the difference.Mine were always the best at 1/8 to 1/4 turn after the pushrod stopped spinning.

The noise on the drivers side may be what you want on the pass side. they will sound like mechanical solid lifters when adjusted right.
You will also notice that when everything is set correctly your vacuum will be the highest so put a vacuum gauge on the motor while adjusting if you can.

I was pulling 18 to 21 in. of vacuum at idle with a 280 Magnum cam from Comp Cams and never ran a choke summer or winter and had the only car on the block that started at -25 degrees one winter. The car would be like a stocker with gobs of torque until 2500 rpm and then it was like a turbo kicked on. Lots of people thought I shifted but I was still in 1st until 60mph.

I was tempted to put them in the engine I am going to run but didn't want to go thru the breakin with the fuel injection system being an out of the box program to start and am I glad I waited now.

Goodluck and hope you can handle the slight ticking at idle.

[67Camaro RS/SS 350]

The instructions say to adjust them using a feeler gauge, like a solid lifter. I thought doing it running was a hydraulic thing? Before the head swap, the engine made 18" at idle and that was with a 76cc chamber. Will the vacuum change if the compression ratio changes?

[Jim Nilsen]

The instructions say to adjust them using a feeler gauge, like a solid lifter. I thought doing it running was a hydraulic thing? Before the head swap, the engine made 18" at idle and that was with a 76cc chamber. Will the vacuum change if the compression ratio changes?

I would do them according to the instructions they put out now. My lifters were on the car when they first came out and I know they have made small revisions over time. It would seem that if they were all the way out with lash like a solid they wouldn't have room to pump up or down, but that was then and this is now 27 yrs later.

I too had 76cc heads and mostly had 21 in. of vacuum at idle.

Vacuum is more effected by the cam duration and overlap than by compression.

[67Camaro RS/SS 350]

That's cool. I am hoping I got the issue figured out. I pulled the drivers side valve cover and there is a mark. It appears a rocker was making contact with the cover. I don't understand that because it didn't before the head swap. I even went to a shorter pushrod.