engine miss

Help Support 7173Mustangs.com:

John J

VIP Members
Joined
May 26, 2013
Messages
1,411
Reaction score
26
Location
michigan
My Car
1973 red convertible 351 4 V
My engine has a miss that I can't figure out. I have new autoilite 42 sparkplugs and new ignition wires. I also have a 1406 Edelbrock carburetor. I just changed the fuel filter. I was going to play with the timing next. Is there something else I should look at?. My car is stock except for the carb.

John J

 

Don C

Fords Forever
Joined
Jan 1, 2012
Messages
7,913
Reaction score
696
Location
Springfield, OR
My Car
1971 Mustang Sportroof M code
Was it missing before you put the new plugs and wires in?

 

Mikes73

VIP Members
Joined
Jun 9, 2012
Messages
1,323
Reaction score
8
Location
oklahoma
My Car
1973 mustang sportsroof - 351c 2v - fmx trans.
Did you check the float levels on the carb when you installed it or make any rod/spring/jet changes to the carb?

 

Don C

Fords Forever
Joined
Jan 1, 2012
Messages
7,913
Reaction score
696
Location
Springfield, OR
My Car
1971 Mustang Sportroof M code
Did you check the points for correct gap/dwell? How about the distributor cap and rotor?

 

c9zx

VIP Members
Joined
Sep 30, 2010
Messages
5,341
Reaction score
273
Location
Mustang, OK.
My Car
1972 Mach 1 Q code
2007 GT
1969 Cougar Eliminator B302
CSX 7000 Shelby Cobra FIA
2020 Edge ST
2002 F250 V10
If it is a constant miss, (dead miss) I'd move the inductive pickup of the timing light to all 8 plug wires to see if spark is occurring reliably on all 8 cylinders. If you have consistent  spark at all 8, I'd suggest doing a compression test to find the bad cylinder. Once you identify the bad cylinder, pull the valve cover on that side and check to see if something has gone wrong with the pushrod, rocker arm, valve spring, etc. If that is all good, do a leak down check to determine the source of the compression leak (intake, exhaust, rings).

If it is an intermittent miss,

 

c9zx

VIP Members
Joined
Sep 30, 2010
Messages
5,341
Reaction score
273
Location
Mustang, OK.
My Car
1972 Mach 1 Q code
2007 GT
1969 Cougar Eliminator B302
CSX 7000 Shelby Cobra FIA
2020 Edge ST
2002 F250 V10
Did you check/set the gap on the new plugs? What did the old plugs look like?

 

waterlife

Well-known member
Joined
Jan 12, 2015
Messages
551
Reaction score
2
Location
MARLBORO NJ
My Car
1972 Mustang Convertible
With car running, pull 1 wire at a time off the cap, when you hit the wire that when removed does not change the engine idle, do a compression test

 
Last edited by a moderator:
Top