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Rough idol

Chevk587

Whiskey bent & Hell bound
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hey guys just did a head gasket so had everything apart dun dun dun lol anyways I'm very sure I got all the grounds on everything is connected properly when I first start the truck everything runs fine for about 5mins then all of a sudden it sounds like it's missing or timing is off ! I replaced the ignition modual the other night be cause it would run the cut off and not start then is key off crank again and it would fire up then die again just curious if anyone has had a problem like this or can point me in a direction thanks 87 blazer tbi 5.7
 
Like Billy Idol?
Tell us about how you adjusted the rockers.
 
Like Billy Idol?
Tell us about how you adjusted the rockers.

Went thru each valve at the dwell area of the cam tightend them while spinning them til I got a drag and did a half turn it runs fine has power when it's running right I'm not sure the valves are the issue...
 
Maybe not but I am tempted to believe a valve because it showed up later. Takes a while for the lifters to pump up. You used eoic?
 
You would think it would be all the time then when it first starts runs great / normal then all of a sudden timing changes starts running rich I can smell it it's really strange ...
 
You would think it would be all the time then when it first starts runs great / normal then all of a sudden timing changes starts running rich I can smell it it's really strange ...
Eioc ?? Sorry not sure what that is ?
 
If it runs rich are you sure you have the coolant temp switch plugged in? Thermostat at least a 180deg?
 
As 80' 427 says but also, have you driven it? The idle air stepper motor sets itself when you drive at a constant speed (around 30mph from memory) for a while. Could be worth trying.
 
Smell is also a poor indicator of mixture. A missfire will not burn the fuel in a cylinder causing the exhaust to smell rich when in reality is may be too lean to burn.
 
When you timed the motor di you disconnect the wire going to the computer. I think it's a green and black one. On mine it's right behind the glove box. It takes all the timing out from the computer.
 
When you timed the motor di you disconnect the wire going to the computer. I think it's a green and black one. On mine it's right behind the glove box. It takes all the timing out from the computer.

Yeah I did mine is tan and black next to the steering .
 
I had a dist. That went bad about a year ago. It would run fine for about an hour under a load and then start surging and losing all power. Eventually it would die but 20 mins later it would start back up and run like a dream for a little bit and do it again. And I replaced everything trying to figure it out
 
I had a dist. That went bad about a year ago. It would run fine for about an hour under a load and then start surging and losing all power. Eventually it would die but 20 mins later it would start back up and run like a dream for a little bit and do it again. And I replaced everything trying to figure it out
So you replace the distributor and it was fine after?
 
A high knock sensor count will just keep the ignition from advancing fully. You won't get max performance but it won't retard it so much that is doesn't run properly.
 
This may be way too simple but I had a rough idle after letting my truck sit off and on for about two years. After replacing the plugs and wires, it would run fine for the first few minutes but after it warmed up, the rough idle returned. Turned out that I had a fouled PCV valve. Best $4 I spent.
 

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