Miss over 40 mph
 

My uncle touring has a miss over 40 mph. He said if was only over 40 mph. Thoughts and suggestions. Stock 1930

Re: Miss over 40 mph
 

Getting too lean?
What happens if he opens the GAV?

Point bounce? (whatever that is...)

Doug

Re: Miss over 40 mph
 

Check point and rotor to cap gaps.

Re: Miss over 40 mph
 

Point bounce = weak point arm spring. Actually the weak spring will not allow the points to close when the engine reaches a particular RPM. Also check to see if the point gap has increased.

Re: Miss over 40 mph
 

open the GAV a bit.. Easiest to try :)

Then I'd go with the ignition advice above (don't forget the condenser and coil as they will also exhibit some issues at higher rpms, especially as they get hot), a well as to check for good strong flow to the carburetor from the fuel tank..

Re: Miss over 40 mph
 

In no particular order:

1. Air/fuel mixture too lean:

a. Restricted fuel supply
(1) Plugged fuel filter (if installed)
(2) Gas cap not venting
(3) Plugged fuel tank outlet
(4) Carb float set too low
(5) Carb passage(s) restricted or plugged

b. Vacuum leak:
(1) Between carb and inlet manifold
(2) Between inlet manifold and block

2. Ignition:

a. Coil:
(1) Weak
(2) Polarity reversed

b. Distributor body:
(1) Rotor-to-body gap unequal
(2) Body cracked

c. Points:
(1) Not gapped correctly
(2) Corroded
(3) Spring weak or broken

d. Failed or weak condenser

e. Spark plugs:
(1) Incorrectly gapped
(2) Cracked insulator
(3) Fouled
(4) Wrong type or heat range

Re: Miss over 40 mph
 

add to list : sloppy bushes in distributor.
Any more wanted?

Re: Miss over 40 mph
 

All good info. Could also be reversed coil polarity.

Re: Miss over 40 mph
 

Check the spark plug wire strips on the distributor. Some spark plugs are shorter than others and need longer plug wires. if the wires are too short and contact the distributor cap , the number three wire can burn through the cap and cross fire to the number four wire inside the cap. I had this problem. My car would run ok at low speed but miss at highere rpm. I happened to be looking under the hood one night with the engine running and saw the sparks flying between the edge of the cap body and the number 3 plug wire strip when I reved the engine. Check the distributor cap body for melted spots under where the wire is contacting the cap. this usually only happens if the plug wires are too short and touching the cap body. Just a thought.