Rough idle on fresh rebuild

[allworknoplay]

I just finished the install of a rebuilt 22r in my truck. While going through the initial break in and adjustments i have been unable to identify why it has a shake/vibration to it. I have adjusted timing twice, done the lean best adjustment on the rebuilt weber carb, adjusted my valves, and fixed a pretty significant vacuum leak at the base of the carb. I haven't driven the truck yet but it idles and revs fine, sounds good, but there is a slight vibration to the motor that seems to get amplified through the body. To the point that I am a little nervous to take it out on the road to continue the break in.

I have checked for any points of contact on the frame or body, engine mounts are good, checked that my grounds are connected, pulled individual plug wires to verify each cylinder is firing, all to no avail. I have been doing tons of reading and still have a couple more things to check out tomorrow when I get back to the truck.

More suggestions are welcome, but my biggest question is regarding the cam that I have. The back story on the engine is that I bought it off a guy who had it rebuilt by a shop for a project that never got completed. It is a zero mile engine that I could verify with receipts from the shop and inspection of everything where I was able to see there was still assembly lube on everything. He said that his mechanic friend talked him into a "stage 1 cam" from a place called Skunk2 Racing. The guy I bought the engine from was definitely less knowledgeable about motors than even me, but said the cam is only supposed to have a slightly longer duration and shouldn't be aggressive.

So my questions are..is it possible this could be the affect of the cam? Do i just need to drive it to wear everything in? As I don't know anything about the competence of the assembler, am I supposed to be setting some sort of dwell or cam timing? Obviously I am hoping that I am overlooking something super obvious but I can't help but expect the opposite.

Thanks, Nick

 

[Toast]

Hey dude, so it's def possible that whoever did your cam didn't do it right. If they didn't replace the rocker arms then it's wrong.

 

[allworknoplay]

Ok, I definitely didn't look at it from that angle. I still have the guys info, so I will ask him some more info in addition to inspecting it. If it boils down to something like that I guess I will be giving engnbldr a call to order up what I need to replace the cam.

 

[KLF]

Replacing the cam doesn't require replacing the rockers, unless they are worn out and flatspotted. Mine are original and I'm on my 3rd cam. But I did replace the tappets last time.

My engine ran rough when I first got it running after the rebuild. Run it for a couple hundred miles, change the oil, and check the valve clearances. Run It for another 1500 miles, do it again. It will settle in.

 

[allworknoplay]

I did some research on the cam that is "supposedly" in my truck. It's a Comp Cams 87-119-6 camshaft, and the specs on their website show an intake and exhaust valve lash setting of .010 for both. I set mine to factory specs of .008 and .012. I won't get a chance to adjust it until tomorrow, but I hope this has some effect on the rough idle. This is something I should have had all figured out before my start up but it honestly never occurred to me. I only know enough about engines to get myself in trouble.

Thanks to you guys chiming in. I will update my progress.

 

[allworknoplay]

Do you guys think I could have a bad harmonic balancer? I replaced my front main seal before installing the engine because the guy I got it from had tweaked the rear seal putting it in and I wanted the piece of mind. I had to be pretty rough with the pulley and stuff to get it off but didn't note any damage. But I've never dealt with a bad balancer before and wouldn't exactly know what I would be looking for.

 

[allworknoplay]

I adjusted my valves to the specs designated for my cam = no change. Tomorrow I am going to put my old "knockoff" weber carburetor from my old engine onto this new motor to see if there's a difference. I know it functions well and the jets are a size smaller. I have my fingers crossed.