What happens when a cam goes????????
Thread Starter
Safety Car
Joined: Mar 2000
Posts: 4,078
Likes: 27
From: Northeast South Dakota
What happens when a cam goes????????
We're talking about a small block chevy here. This is what it's doing. It's actually in a pickup, not a Corvette, but it's the same thing as far as what we're talking about.
The thing kind of "pops" out of the exhaust when you step on it instead of having that nice V8 "rumble, rumble", and if you step it down a little ways while going down the road, then let off it backfires out of the exhaust, plus it seems like it may be making a little lifter noise now. It is really down on power as well. What do you think. Does this sound like a cam thing????
The thing kind of "pops" out of the exhaust when you step on it instead of having that nice V8 "rumble, rumble", and if you step it down a little ways while going down the road, then let off it backfires out of the exhaust, plus it seems like it may be making a little lifter noise now. It is really down on power as well. What do you think. Does this sound like a cam thing????
Race Director
Joined: Apr 2000
Posts: 17,676
Likes: 201
From: Who says "Nothing is impossible" ? I've been doing nothing for years.
Re: What happens when a cam goes???????? (Dalannex)
I might get corrected here but I think if a cam starts to go ( one or more lobes start to wear down) then it is all over pretty fast.
Thread Starter
Safety Car
Joined: Mar 2000
Posts: 4,078
Likes: 27
From: Northeast South Dakota
Re: What happens when a cam goes???????? (MotorHead)
All electrical appears to be fine, and I'm thinking it's time to tear something apart. It's been a few years since I built a motor for this pickup, maybe it's time again. :rolleyes: Why can't I get excited about doing something like this on a daily driver?????
Burning Brakes
Joined: Oct 2002
Posts: 971
Likes: 0
From: Rockwood TN
Re: What happens when a cam goes???????? (Dalannex)
Cam wore out on my truck and I noticed if you set the timing to factory specs you got valve clatter, but when I replaced the cam I replaced timing set also. So I'm not sure if it was the cam or timing set. Also I had a loss of power when you stomped it you still got the classic quadrajet sound you just didn't go any faster. But a new cam and timing set cured both.
Instructor
Joined: Jun 2002
Posts: 191
Likes: 0
From: Hillsboro OR
Re: What happens when a cam goes???????? (Dalannex)
One of the things I noticed when my cam went is that the cam started moving front to back, and I could hear the timing chain/sprocket hittting the inside of the timing cover. I used a stethascope to track it down. I couldn't hear it in the bock, heads, water pump, etc very well, but could hear it very clearly when I put the probe on the timing cover. My lifters were actually cupped, and the 12 of the lobes were worn down below half of their lift, and one or two were down to perhaps 15% of their lift. I was getting backfiring all the time, very poor running, and of course, the tap tap tap inside the timing cover.
Racer
Joined: Apr 2002
Posts: 324
Likes: 0
From: port jefferson station ny
Re: What happens when a cam goes???????? (Dalannex)
pull your valve cover ( one at a time to avoid excessive oil spray) and start the motor. watch the movement of the rocker arms. If they all appear to be moving up and down normally pull the other cover and watch the other rockers. If you notice a rocker or two not moving up and down the way it should, pull the rocker and see if the pivot ball has worn in the base of the rocker arm. If it has, repace ther ball and rocker. if it hasen't, then you have a worn cam lobe. If it's and exhaust love you will hear backfiring through the intake at idle and at partial trottle. if it's the intake you may or may not hear the same popping in the exhaust. the car should have a miss. try to isolate the miss by pulling plug wires. this way you may not have to pull both covers. good luck. wcj
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Safety Car
Joined: Apr 2001
Posts: 4,795
Likes: 1
From: Regina Saskatchewan, Canada.
Re: What happens when a cam goes???????? (Dalannex)
If a lobe decides to go flat then that particular cylinder will have problems operating. The cases I have seen are when an exhaust lobe goes bad and the valve is unable to lift much. This usually produces a pop through the carb.
Le Mans Master
Joined: May 2000
Posts: 6,493
Likes: 6
From: Bloomington MN
Cruise-In II Veteran
Re: What happens when a cam goes???????? (Stingy74)
I had the factory cam go out on two seperate 305's. I have a very low opinion of 305 motors, but that's another subject. In both of my cases, I got backfiring through the intake. It started out as a pop here or there, then gradually progressed.
AC
AC
Thread Starter
Safety Car
Joined: Mar 2000
Posts: 4,078
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From: Northeast South Dakota
Re: What happens when a cam goes???????? (A C)
As a matter of fact it is a 305, in an 86' half ton 4 wheeler. I rebuilt this motor when I was just out of high school, which was almost 10 years ago, so I don't remember what all I did to it. I am 99.9% sure that the cam and lifters I went with would have been the sealed power factory grind. I suppose I'm going to have to pull some valve covers and check it out. It's a good time to put the old girl in the shop anyway, I lost the ring and pinion last week as well. Gonna have to give it a little TLC. It's only got 270,000 miles on it. :D Shouldn't need any work yet should it???? :lol:
