340 six pack setup help

[topbanna70]

So I have rebuilt my six pack and have them installed and have the car running but as its running once it gets to operating temps it gets a backfire in the exhaust and the guy who rebuilt them said that sounds like a valve issue im trying to find someone to adjust the rockers but im wondering if anyone on here knows what a 340 should be set to any help would be greatly appreciated.

 

[rklein71]

Check the spark plug wires, you can run the engine in the dark, you will see sparks if the plug wires are bad. This can cause backfiring as well. Easy test.

 

[topbanna70]

It has new wires on it and all the connections are good.

 

[rklein71]

Bad spark plug?, I ran a six pack for 25 years in my 69 Barracuda and any backfiring I had was always ignition related. Make sure you have a good ground from the engine to the body as well. No ground really plays havoc with electronic ignitions.

 

[topbanna70]

The plugs are brand new ngk's I think it may be valve related cause it's not a big backfire it's more of a muffled sound

 

[rklein71]

Could be valve related....just suggesting things to look at that are a little easier.

 

[topbanna70]

Do you know what they should be set to you chance?

 

[rklein71]

See attachment

 

[topbanna70]

Thank you now I just have to find someone who has messed with adjustable rockers before

 

[Daves69]

Start with a compression test and maybe a leakdown test.