Hot Rods Missing at highway speeds

I have a problem with 1951 mercury flathead, starts great and idles good, when I start moving and get rpms up engine starts missing. It happens just about the time to shift gears, in high gear with peddle to the floor it looses all power until I let off the gas a little, but still bucks and jerks at 3/4 throttle. I have new plugs, points, roter, cap, condenser, fuel filter, electric fuel pump. Timing seems good, blew fuel line out. Anybody have any ideas.

 

Are you running a stock distributor?, that could be the culprit.

 

Yes stock distributor, I'll have it checked thanks.

 

Fuel delivery? Carb?

 

I have gone through everything on the fuel system, even took gas cap off to see if vented cap wasn't working.

 

What carburetor are you running?

 

Original, teapot holley 885ffc.

 

First item to discuss would be the electric fuel pump location. It should be mounted within 18 inches of the fuel tank and as LOW as possible. Electric pumps will push gas around the world, but about 18 inches is the max to pull gas.

***uming the location is good, then is the issue only in high gear, or in all gears?

If all gears, could be either fuel delivery or ignition.

If only high gear, almost certain to be fuel delivery.

Has the carburetor been rebuilt, and if so, was one of the wafer fuel valves used? Or, one of the two ball fuel valves? We have seen fuel volume issues with both.

Jon.

 

Missing in high gear cruzing, but at the peak of rpm just before changing gears, carb was rebuilt and I belive it was a wafer valve.

 

Fuel pump is mounted right at the fuel tank with filter between tank and pump.

 

did it happen before or after the new points? i have found some of the points they sell now have a very weak return spring/strap, which causes point float. i have even bought points that did not have the spring with it.

 

I still have old points I will try them again only takes a few minutes thanks

 

Going to test vacuum advance also. Make sure that is working.

 

you can tell right away when the points are out by opening with your finger tips. there should be resistance. compare to old points and if they are weaker switch the springs.

 

You didn't mention coil. They can do what you describe when they are bad or going bad.

 

I just got a new coil trying that next, thanks

 

Distributor might be off on spark mayby need to pull it and set it back to #1 cylinder make sure your cables are not gone. Check this at night and see if you see any spark p***ing somewere check them cables then points and then coil. Make sure the carb is getting the fuel wen you hit the gas pedal with engine off see the squirts. I forget the name. Accel pump or something like that in the carb. Check all your connections

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I'll check all these things tonight. Thanks

 

nice merc. my dad sold mine in 1971 for $25 while i was floating off vietnam.