Hard Starting/Backfires

[jwebb]

Engine was running fine and now very rough. What could be the cause(s) of labored cranking, backfiring through carb and running very rough? Distributor wasn't moved intentionally, plug wires not touched, vacuum line connected to carb...Something inside the distributor?? HELP!!

[GoDadGo]

Was your distributor locked down tight?
What is your initial timing set at and where is it set now?
Could it have vibrated and is now over advanced which would cause labored starts along with other problesms?
Also, if you are running a Holley Style Carb, often one back fire will blow the power valve(s) creating rough running issues.
Start by checking the initial timing.

Hope This Helps!

[scottiec]

Im with GoDad.

Get a timing light on it. Check all your plug wires.

[mike223]

You might want to pull the valve covers and make sure you haven't lost any rocker arms.

Comp Cams instructions for installation of polylocks ("hold polylock with wrench and tighten setscrew") will not reliably lock them in place.


They typically need to be a little tighter than you can get them by tightening the setscrew alone.

Learned the hard way...

[jwebb]

No idea of how, apparently a senior moment, firing order was wrong!

[GoDadGo]

No idea of how, apparently a senior moment, firing order was wrong!

Maybe You Are A Closet Chevy Guy Or Mopar Dude!

Congratulations!

[Big Blocker]

OK . . . OK . . . we'll give you the benefit of the doubt - this time. Very easy to transpose early firing order with later firing order. Depending on which cam you have it could be either; 1-5-4-2-6-3-7-8 - or - 1-3-7-2-6-5-4-8.

Glad it was something we have all done (although, maybe not admitted to it).

Doc