What are the symptoms of a too tight and a too loose rocker (other than being loud)? I am trying to hunt down a low rpm stumble. I just installed a CC503 cam and supporting valve train components. Thanks

 

Could this be cam surge that I am having?

 

"could be" cam surge but I am not sure what you are experiencing. That is a pretty small cam for cam surge but if everything is not in order and the tune is not sialed in exact even a Hot Cam cam have cam surge.

Start by checking absics and making sure there are no exhaust leaks, plug wires on right plug (this has happened to alot of people so CHECK), rips in elbo between MAF and TB, dirty MAF, etc.

If the rockers are too tight, it will have a slight miss at idle or low RPM as the valve springs are battling againts the lifter preload and the valves can be hed off there seats and not sealing properly. Rea djust them to 1/8 past zero lash (3/8 stud) or 1/16 past zero lash (7/16 stud) and see if that fixes it.

Some people adjust the rockers 1/2 at one engine point and the other 1/2 at another engione point. While this "might" work, I have always done 1 cylinder at a time. Bring #1 up to TDC on compression stroke so you KNOW these lifters are on the base circle then adjust the #1 int/exh valves. Rotate 90 degrees and do cylinder #2, etc.

Just go through the firing order (1-8-4-3-6-5-7-2) and rotate the engine 90 degrees (1/4 turn) as you go from cyliner to cylinder.

Too loose can do some weird things also and might be setting off knock sensor.

get these problems ironed out and if the problem persists, get some data logs of the engine doing what ever it is doing and post them up. there are alot of smart people here that can use that data and tell you where else to look.

Lloyd

 

Thanks for the reply Lloyd. I adjuated the lifter preload with the enginre running and set it to 1/4 preload. I have checked for vacuum leaks by spraying wd40 around the intake and vacuum lines. The reason i think it is cam surge is that it starts when the engine warms up. I know that 1/4 turn is lets say from 12 o'clock to 3 o'clock. What is 1/16 past zero lash? Thanks again

 

1/8 would be half of that (12 to 1:30) and 1/16 would be 1/2 of that (12 to 12:45).

If you have them at 1/4, you will not have any problems at low RPM. Depending on what you considered "zero lash: to b and what "zero lash" actually is, they might actually be slightly tighter than you think but either way, it will not give you any problems at low RPM. You can move on to the rest of the list and see what you find.

Be sure and dbl check the plug wires. I made that mistake years ago and I was SURE they were correct . . . . . . until i ran out of other iodeas and decided to check for the hell of it then realized I was chasing gremlins that were not there. It is a simple mistake made by everyone at some point if you work on enough cars.

Other than that and the rest of the list, get the data logs and someone on here can help ya decipher where to go next.

Lloyd