Anyone have any advice on camshaft replacement. 83 K5. When I put the new engine in I didn't break in the cam. (2500 miles ago)It runs okay unless I am pulling my trailer. It is gutless under load. Does this sound like the cam? I have adjusted the carb, set the timing and at idle the vacuum gage reads a steady 18. I drove it around and it ran alright until I hooked up my trailer(2500lbs) it barely made it up hills. I had the gas pedal to the floor and it wouldnt keep up with traffic. Then unhook the trailer and it drove okay, it still lacked power going up hills but I kept up with traffic.

 

I would suspect more of a carb issue than cam. What for a carb do you have on it? Have you rebuilt it completely?

 

It is the original carb, freshly rebuilt. I took it apart and checked the float, and the areas that normaly leak, filled up the bowl and let it sit for a while. The only thing I found was the adjustment was way out. The primarys were so rich that when I turned the idle adjustment screws there was no effect. I leaned out the primarys, after making the small tool to gain access to the weird screw at the top of the carb. I adjusted the carb using vacuum readings and it was running great. I drove it all over and throttle response has never been better. Then... I hooked up the trailer and as I crested a large steep hill there was a super slow truck in front of me and I couldn't get any speed after that. I unhooked the trailer and it runs okay exept for up a big hill, it is very subtle but I can feel the lack of power.

 

How's your timing advance?

 

The timing is set at 8 btdc. I followed the procedure of setting the timing using the sticker under the hood. It has new wires, plugs, the distrubutor was new when I put the engine in. I am pulling my hair out on this thing. I have been out of work for 8 months and I have a job starting next week. I got to get this thing dependable. I appreciate your help.

 

Are you sure the timing is coming in correctly under load?

If the cam is the direction you want to go, you could either verify the lift/duration & timing or just swap it out with something better.

 

How to check the timing when it is under load? Yesterday I measured the lift at the pushrods and there was no evidence of any flattening. I also checked for slop in the timing chain and there was none.I am happy about that. Today I am going to start all over. Since the problem is seeming to be either ignition or carb I a going to buy a 40.00 computer code reader. Both the carb and the dist are attached to the computer maybe this will tell me something.

 

It really isn't something you can check too readily without having it on a dyno. I would pull the distributor and make sure that the vacuum advance dashpot and timing weights/bushings/springs are working properly.