after firing/ popping thru exhaust

[richp85elco]

I was breaking in my cam today with open headers and the car was afterfiring, so I tried playing with the timing advanced it and retarded it but either way it was still happening. After running it too retarded for a while it was running really hot so I shut it down. I suspected it could have been a vacuum leak, and sure enough I forgot to plug the vacuum fitting in back of the manifold. So I plugged the fitting and advanced the timing but it was still afterfiring... This time the car never reached 220 so I continued with the break in at 2000-2500rpm. After 20 minutes the headers were not red, car was still below 220 degrees but it kept afterfiring, even at idle. It was doing it as soon as the car fired up so I doubt its a flat exhaust lobe( I hope), Cam, lifters were lubed, used brad penn 30w break in oil and a bottle of comp additiive. Preload on the lifters was 3/4 of a turn, comp suggested 1 full turn, I wanted to air on the safe side. engine was pre oiled had good oil pressure just under 60 at 2000 rpm

I am using a brand new holley 600cfm w/ electric choke un-adjusted, the choke was not connected at this time, no leaks that I know of. Also I did not have a regulator on the holley fuel pump that outs out 7psi 80g/h. Is this normal when running a car with open headers? there were no vacuum leaks, so could the carb be running way too rich from the factory? This is the first time i've done any of this

 

[84sbcregal23deg]

no not really normal. should clear up pretty quick after initial startup. what kind of distributor are you using? also are you positive the firing order is correct? also what kind of base timing do you have? check for cracked plugs too and make sure none of them have closed gaps.

 

[Longroof79]

Just a quick question regarding the choke. Do you have power (12 volts) going to the choke? You mentioned that the choke wasn't hooked up. The reason I ask is because if there isn't power to the electric choke, it will not relax the bi-metal element and therefore will not open the choke butterfly...thus creating a rich condition.

Holleys do tend to run a bit rich on start-up. I have the same carb on mine currently.

 

[CHRIS.O]

How did you adjust your lifters, I know what your settings are but how did you do it? Also are you sure the distributor isnt a tooth off, it can still run, all be it poorly and you would probably notice it.

 

[chevy2480]

Are you sure you got fireing order right even with a wires wrong it could run. Also a bad plug could do that just because there new doesnt mean there good

 

[richp85elco]

Distributor is from skip white, plugs are gapped at .044, I didnt have 12v going to the choke but the choke valve was open, as a matter of fact it wont close all the way now will the heat make it stay open. For lifter preload I did the ICEO method got to zero lash and tightened 3/4th turn. When I installed the distributor I got it to line up to a tower and go all the way into the oil pump then I used that one as my number 1 and set the firing order from there. ..dam I think the firing order is wrong my haynes book said 1846.... i just looked it up isnt it 18436572? Im at work now so I have to double check that tomorrow morning but im pretty sure i have 4 and 6 firing right after each other. I had the initial ming at 14 but i moved it all over the place trying to make the popping go away and then I had to rush to work so I am unsure where its at right now.

 

[chevy2480]

Distributor is from skip white, plugs are gapped at .044, I didnt have 12v going to the choke but the choke valve was open, as a matter of fact it wont close all the way now will the heat make it stay open. For lifter preload I did the ICEO method got to zero lash and tightened 3/4th turn. When I installed the distributor I got it to line up to a tower and go all the way into the oil pump then I used that one as my number 1 and set the firing order from there. ..dam I think the firing order is wrong my haynes book said 1846.... i just looked it up isnt it 18436572? Im at work now so I have to double check that tomorrow morning but im pretty sure i have 4 and 6 firing right after each other. I had the initial ming at 14 but i moved it all over the place trying to make the popping go away and then I had to rush to work so I am unsure where its at right now.

18436572 would be the correct fireing order. As far as valve adjustment i always found it easy to adj by spinning pushrod to i feel resistance then go a 1/4 turn always had quite valve train but thats me.

 

[dream on mcss]

Wait, you said you replaced the cam. Are your sure you lined up the timing marks right?

 

[richp85elco]

So sure enough in the morning went to check the firing order and I had it just as I had taken it down on my notes.

( notice anything wrong) I probably should have double checked because when I was setting the preload on the lifters I distinctly remember the number three lifters come up at the wrong time as I was following the firing order. Im amzed I got the motor up to 3000rpm with no problem it had good throttle response and felt strong and it was only running on 6 cylinders I need to change the oil before I fire it up again but if it felt strong running on 6 it'll feel even better on all 8! Just hope the cam is ok it didnt have the smoothest start up

Heres a blurry pic

 

[CHRIS.O]

Your cam will be just fine, they are tougher than people would lead you to believe. Sure the oils we use contain less zinc and all that but you will be just fine with a quality oil and additive. The only way your gonna wipe one is improper adjusting of valves, too tight. Or if you use crap oil and dont run it long enough. Mistakes happen on the plug wire haha, I have had my fair share of, "why wont it run right" moments. Goodluck and I hope she runs like you want her to.