Just installed new cap, rotor, wires and plugs in a stock 350 (76). Haven't set the timing as of yet, but attempted not to move the rotor when installing it. I have a definite misfire with a bit of engine knock now. Before the install there was no noise or miss. Could this be a timing issue? Or something else? Thanks for the help.

 

re-check your wires for firing order.

 

Already did that, and they're okay. Just wondering whether timing is the kicker. If not, I guess I'll have to pull the new cap.

 

Could be the timing, if that cap is off a few degrees. Aftermarket caps aren't known for their quaity control!
Check the timing, first!

 

Make sure some one did'nt put the dist in wrong happen to me with my Dodge pick up it was 180 out!I pulled all the wires put it back stock and it did that.

 

There is no way that you could have changed the timing settings by doing what you did,
HOWEVER, if the cap was made wrong (as above), or if it wasn't seated properly when you reinstalled it, you could be off a few degrees.
Also, if the last guy to tune it up left the distributor clamp bolt just a little bit loose, then you could have moved the distributor a few degrees when you changed the cap.

I'd say go rattle everything around, then put a timing light on her and double check.

- Eric

 

Just a shot in the dark, did you gap your plugs and make sure all the wires were secure properly?

 

Are u getting these symptoms while at idle or driving? The misfire makes me think you might have distrubed the points....recheck and regap.

 

Thanks for all of the advice. I pulled and reseated the cap, and she runs fine. It's been awhile since I've done some of this work. Glad there's advice available. Much obliged!

 

After you set the timing make sure you set your idle mixture screws and your idle speed. A tune up isn't complete until you adjust your carburetor.

 

on the underside of the HEI distrb. cap there is a small square thing that fits into a small notch in the distrb. housing. i think they(GM guys), did that for indexing the #1 cyl., maybe it's a reference or something. i'd make sure the cap is on correctly and down in that notch because it is possible to put it all back together with it slightly rotated one way or another.