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humanpotatohybrid wrote:
Remind us what transmission you have again? The R700 conversion?

Do you have the mechanical pump? If you slowly go from steady power to intermittent bursts, that sounds like it could match to how the mechanical pump delivers fuel. In that case, is your fuel filter clean? The ceramic filters don't really look dirty, they just need cleaned periodically. The fuel pump was designed to always try to deliver much more fuel than needed to prevent this situation.

What's your fuel level like when this happens? Full, or less than 1/2 a tank? Have you checked the fuel tank condition? (I don't remember if you did) Sometimes the internal fuel line in the tank gets a pinhole at the ½ or ¼ full point causing a variety of expected issues only at low fuel levels.

64avanti wrote:
Points to a fuel prob.
The old timers will tell you- Most ignition problems are carb related!

Super car, BTW.

HH56 wrote:
I need to do research on the exact OD solenoid action for 55-6 units but with no electric lockout switch, in theory solenoid will get power any time the car is going over cut in speed. With the lockout knob pulled out though, there should be an internal mechanical block to keep the plunger from being extended so the car cannot go into OD. Without the plunger being extended there is a set of contacts inside the solenoid that will not be closed so there should not be any ground available so impossible for ground to reach the ign cut out circuit and cause issues.

If the knob is pushed in, the car will go into OD and the solenoid internal ground contacts will close when plunger nears the maximum extension. Ground will get as far as the kickdown switch but go no farther so again no ign cut out issue. If you floor the gas, kickdown switch will pass the ground and make the engine miss a few revs but at the same time the solenoid will also drop out immediately and open its contact to cut off ground as the plunger retracts so the engine will not die. That entire process only takes a few milliseconds. In one of the OD writeups I believe it said the engine cut out process is supposed to be over within 1-2 engine revolutions at 60mph and within a "few" spark pulses at a lower rpm.

On the fuel filter, as was mentioned earlier the ceramic filters can look clean and pass air freely if you blow thru them. In practical fact, if varnish has deposited in the pores it can restrict fuel flow. Depending on how much restriction has occurred will sort of determine at what speed the engine starts getting starved for fuel.

You can try soaking the elements in acetone or carb cleaner to see if that will dissolve the varnish but in some cases it won't and the elements will need to be changed. If you cannot find the small ceramic elements the filter will need to be converted to a paper element.