well I fired my engine up for the first time the other day and after sorting out some problems it was running real rough and wont idle down. Well I went through and changed all the wires and checked the firing order a couple of times. Blocked off all the vacuum ports and changed the ignition module and wiring for news ones. Im getting ready to pull all the plugs and check the gap and im gonna pull the bowl off the carb and clean out the jets and such. But im still not sure thats why its running rough. I went through and ran it as I adjusted the valves (hydraulic lifters) and set them 1/2 turn after clicking stopped. But its still running rough. hopefully cleaning the carb and gapping the plugs will help but for some reason I dont think it will.
Its also got a brand new dis. cap. Please help.

well I gapped the plugs to 45 and cleaned the carb and still no better than before. I finally got the idle high enough to stay running and I got the timing set and it made it run better but its still rough and shaking the whole car. While timing it I heard a valve start tapping agian so Im gonna order a new rocker arm nut set and change them all and reset all the valves hopefully it helps.
still looking for opinions and suggestions

Carb base gasket or manifold intake gasket vacuum leak could cause the high idle. Do you have a good ground between the block, chassis and firewall? Battery is charged and alternator working? (electronic ignition really needs 12 plus volts). Fuel pressure is good? Float height isn't too low? Choke fully open? Wiring to the coil and distributor solidly connected (no corrosion, fraying)? Timing is advancing as you rev the motor (nothing stuck)?

I fought this once. I did wires, module, cap, rotor, vac lines, tore through the carb -- turned our to be a weak (but not failed) coil. I hate to suggest throwing parts blindly at a problem, but if you have a spare maybe it's worth dropping it in.

I know you said you changed the wires but it sure sounds like it could be a dead cylinder. While at idle, pull each wire one at a time and see if it changes anything. If you get one that doesn't you know it's that hole. Try swapping wires with another cylinder to see if it follows the wire. If it does not, verify spark to that plug.

I tend to agree that it sounds a lot like a vacuum leak. You can try spraying carb spray at the base of the carb and along the sealing surfaces of the intake - don't forget the rear. It could also be leaking because of a cracked intake gasket at one of the ports and thus pulling crankcase gases and even oil from the lifter valley.

If none of this or the other guy's suggestions seem to bring you any clues, try running a compression check and make sure you don't have a stuck valve or broken ring, etc. A leak down test would do the same for you but most guys don't have leak down testers. I would have to borrow one.

Just trying to throw some things on the table to give you some ideas to check.

Good luck and let us know what you find.

When I pulled the plugs I noted what each one looked like and all of them looked exactly the same so this is making me think that its not a dead cylinder or the problem is coming from a single cylinder. I took off all the vacuum accessories and pluged it up and the PCV hose going to the base of the carb I pluged up. Its not that im having a high idle its that I have to set the idle high just to get it too idle. Im thinking its either the valves or the coil might be bad, Im gonna see if I can borrow a coil from my brother and see if that helps it

I'm struggling for ideas. Do you have 12-15 degrees of static timing advance? Did you check the carb? I agree that you've likely eliminated that it is coming from one cylinder. Try the coil, see what you get. Chase your grounds and power wires really well.

would a bad ground cause something like this? The only ground wire I have to the engine is one from the battery that also bolts to the fender. Im gonna try the coil it seems like it might be a likely suspect but Im also gonna have to get new rocker nuts since some arent locking and working loose.

I found my Accel Super Coil and I can get an external coil cap from my brother so I think im gonna try that and see what happens.

The bad ground can cause rough running, if it wreaks havoc with your ignition. The theory is that a good ground ensures a 0 voltage signal. Of course, your battery/alternator system is producing 13-14 volts. But the key here is the "difference" in voltage between ground and positive -- a full 13 or 14 volts. Now, imagine a week ground at the block. It does not create a true 0 voltage (at least compared to battery 0 volts). And, your distributor's ground connection is though physical contact with the engine block. So the difference is not the 13-14 volts you want, but something less. The ignition system really needs 12 volts or more to operate. With the weak ground described above, the ignition is now seeing something less the than required 12 volts and doesn't want to function well.

Is this a common failure? Probably not. But remember, these cars had ground straps from the valve cover bolts to the fire wall to ensure a good ground. I watched a guy go swap out a carb, distributor, battery, and alternator on an engine rebuild once because the engine was breaking up and misfiring. He replaced all of this to no avail. Turned out the only negative battery connection he had was the starter cable, nothing to the fender or fire wall. Point is, it's an easy thing to eliminate.

Having said that, I still think since you can swap the coil you should try it. Also, your comment about the rocker nuts -- if these are backing off they will cause rough running (I've seen that to).

well I replaced the rocker nuts, some were loose already and they werent locking very well went to fire it up and well what do I hear still valve train tapping very loudly we are now guessing a colapsed lifter but this is hard for me to imagine but it does sound fairly possible also when we started it it had a bad back fire and was running even worse and would back fire out the carb with it running and die. Well this is getting to be a nightmare and is driving me nuts.
Would a colapsed lifter cause a backfire? How would I tell if it is a lifter?
any input is appreciated

im also guessing that there might be too much preload causeing the backfire?

Did you do a cam break-in? Run the car at 2,500 rpms for 20 minutes.

yes but I ran it at 2200 rpms...but shouldnt make a difference.
Update, I Checked the cam it is fine no wiped lobes...First lifter I pulled out, no 8 exhaust, couldnt compress it....Guessing its my culprit?

yes but I ran it at 2200 rpms...but shouldnt make a difference.

Just checking :thumbsup: . What manufacturer of cam and lifters are you using?

they are the summit brand of which I believe is a renamed comp cam?

they are the summit brand of which I believe is a renamed comp cam?

I've had two comp cams in my 454 that were noisy, at first I thought something was wrong and had a couple of "seasoned" people listen to it and they said it was normal. If you can post sound or video clip.

Changed out the lifters for sealed power ones and wow made a big difference but it still is noisey but its not a real loud tap like before. Its running a whole lot better but its still kinda rough. Im thinking that theres still a miss. My dad thinks that something is out of balance like the balancer isnt working right or something like the flywheel or the torque converter is bent or out of balance. Its also not idling in gear either...

Your adjusting the rockers while running? I'd make sure your backing them up far enough and long enough to let the lifter pump up. It's possable to back it up and hear clicking, but not letting them repump could result in keeping the valve open.