Let's say a few lobes are worn down.. What would happen??

I got some funky kind of base coming out my exhaust. Would that cause it?

 

MJ,

Typically, a cam with worn lobes will allow the engine to start and idle almost normally, with no unusual noises. There will be no power output to speak of, and there may be a detectable "miss" or dead cylinder(s) on the affected lobes.

An easy way to check is to remove the rocker covers and measure the valve spring heights at teh reatiners at maximum lifts. Obviously, a dial indicator or depth gauge/caliper is best for this, but for the purposes of checking for severe lobe wear, even a scale with small graduations will work fine. Wear doesn't normally become an operational issue until the maximum lifts are under 0.250", where performance will really start to suffer and be noticable. I've seen cams with lobes at 0.150" start and run normally, but produce power equiovalent to a small four-cylinder. Valve opening event timing retards (but the LCA usually remains the same) on a worn cam, but if you get set up to measure that, your dial indicator will already show the wear of the lobes.

My gues is that if you are getting an exhaust noise, it is more of a valve or ignition timing issue than low lifts. Mixtures can also affect exhaust tone.

 

I had an old 78 Chevy with a 350 that ran great when I had it-pulled the motor and gave it to gramps for his truck. When we pulled out the cam both lobes for the #1 cylinder were gone-looked like it should be cam bearing around it. Oddly though I never heard a difference in unusual sound, never seemed to have a miss, and had plenty of power for a full time 4x4. Go figure?!

 

If an exhaust lobe goes completely flat you'll get popping out of the carberator. Other than that if the lifters have been kept adjusted you wont have any noise.

 

I think you in the same boat with a burnt valve I was changing valve seals put air to #8 and all the air came out of thje TB not sure if the exhaust is burnt and I have a thump/tick sound coming out the exhaust
Does yours shake at an idle???

 

im reading this thread, and my car, the motor especially shakes at idle. you can totally see the motor shaking around, its nothing rediculous but it is visible. also, you can feel the shake its like a slight miss. could this be a burnt valve? would i notice anything different upon startup?

 

When I bought my car the cam had 4 lobes just about gone.. It ran ok till about 3500 rpm then it felt like it hit a wall and wasn't going anywhere (think an electric wheelchair even passed me up) still could spin the tires though

 

What year is your car Mr.Jordan?

 

She's an 87 with 170k's. Good power out of her, just a shakey idle with an exhaust pop. every time the exhaust thumps the engine moves like a miss?? no power loss at all?????

 

BTTT

 

Go read my post on this page. My cam was DEFECTIVE. I'm sure of it, and Summit is sending me a new one. The exhaust lobe on the #7 is almost completely rounded, but the funny thing is that the car drives awesome up till about 5,100 rpms, where it hits a wall, where it should actually pull up to about 6,500 with my setup. I'll put the new cam in Thursday.
Chris