engine runs ruff idle and pops and backfires out exhaust - Ford Truck Enthusiasts Forums


engine runs ruff idle and pops and backfires out exhaust

Old 06-20-2011, 08:11 PM
68fordshortbed is offline
New User
Thread Starter
Join Date: Jun 2011
Location: Saint Francis Kansas
Posts: 2
68fordshortbed is starting off with a positive reputation.
engine runs ruff idle and pops and backfires out exhaust

I have a 1968 Ford F-100 shortbed i pulled the 360 4speed out and put in a 390 with a C6 when i start it it runs really ruff @ idle and when you slowly push the accel down it starts popping out the exhaust and sounds like its missing. i have the distributor on TDC and on the right slot on the cam but its just dont go away no matter how much we time it or mess with the carburator if you just hit the throttle and let off it does fine but just driving or trying to take off its nothing just pops and backfires im running out of idea of what it could be there arent any vaccume leakes and the wires are fine coil will be replaced tomorrow but other than that im pretty much blank on what it could be. any ideas would be very welcome!
Old 06-22-2011, 12:50 AM
Hypoid's Avatar
Hypoid is offline
Join Date: Apr 2004
Location: Golden, CO
Posts: 2,571
Hypoid has a good reputation on FTE.Hypoid has a good reputation on FTE.
What do the plugs look like?

Do a compression test yet?

Put a vacuum gauge on it?

What is the total advance, and when is it all in?

Did this 390 run before you installed it?
Related Topics
Thread Starter
Last Post
1987 - 1996 F150 & Larger F-Series Trucks
08-25-2015 10:32 PM
1961 - 1966 F-100 & Larger F-Series Trucks
05-02-2015 02:23 PM
1967 - 1972 F-100 & Larger F-Series Trucks
10-15-2013 12:06 PM
Ford Inline Six, 200, 250, 4.9L / 300
01-13-2012 06:29 PM
1973 - 1979 F-100 & Larger F-Series Trucks
09-12-2011 04:59 PM

Thread Tools
Search this Thread
Quick Reply: engine runs ruff idle and pops and backfires out exhaust

Contact Us Archive Advertising Cookie Policy Privacy Statement Terms of Service

© 2018 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.