I've been testing to determine why some '58 - '63 FI units are hard to start cold. Since these units are equipped with a Cranking Signal Valve, I used to assume the CSV was always linked to the problem. I was wrong.
I don't fault anyone for being suspicious of their CSV. It's a very clever design (in theory) that just doesn't hold up well under real world conditions. However, I've found CSV's almost always fail "open" rather than "closed". Then could they still function but shut off the signal boost too soon? Well, I guess it's possible. I've seen that happen myself, but I think it was a once-in-a-lifetime event for me.
Could the engine be generating an especially low vacuum level during cranking? Yep, that's possible, but it's unlikely. I've tested an engine with a 50% leak-down rate, a 30-30 cam, and a slow starter. It still managed to generate a 1" manifold vacuum during cranking, and that's enough to start if.... YOU HAVE TIGHT CLEARANCES IN THE GEAR PUMP.
Unfortunately, the gear pump is the culprit in most of these hard cold starting cases. At the slow speed of cranking, you've got to have extremely tight clearances between the gears and the pump center housing / end plate to generate a good nozzle spray. I'm talking on the order of less than .001" clearance. Otherwise the pump just won't send enough gas pressure to the nozzles to make the engine start.
There isn't any way to repair a worn gear chamber now. There are no replacement gears and center housings available with the necessary close tolerances. The good news is that some are on the way, probably. I'm not making them, but Gail Parsons is planning to do so. I'll post more news when I have it. No, I don't know when they'll be ready for sale.
I've given poor advice to some about this hard starting problem in the past. I apologize for that. I know better now, I think. You just can't eliminate the problem unless you convert your unit to a '57 / '64-65 type solenoid design using engine fuel pump pressure for starting. But... a temporary cheap fix is to keep a can of ether near the car just for cold starts.
I don't fault anyone for being suspicious of their CSV. It's a very clever design (in theory) that just doesn't hold up well under real world conditions. However, I've found CSV's almost always fail "open" rather than "closed". Then could they still function but shut off the signal boost too soon? Well, I guess it's possible. I've seen that happen myself, but I think it was a once-in-a-lifetime event for me.
Could the engine be generating an especially low vacuum level during cranking? Yep, that's possible, but it's unlikely. I've tested an engine with a 50% leak-down rate, a 30-30 cam, and a slow starter. It still managed to generate a 1" manifold vacuum during cranking, and that's enough to start if.... YOU HAVE TIGHT CLEARANCES IN THE GEAR PUMP.
Unfortunately, the gear pump is the culprit in most of these hard cold starting cases. At the slow speed of cranking, you've got to have extremely tight clearances between the gears and the pump center housing / end plate to generate a good nozzle spray. I'm talking on the order of less than .001" clearance. Otherwise the pump just won't send enough gas pressure to the nozzles to make the engine start.
There isn't any way to repair a worn gear chamber now. There are no replacement gears and center housings available with the necessary close tolerances. The good news is that some are on the way, probably. I'm not making them, but Gail Parsons is planning to do so. I'll post more news when I have it. No, I don't know when they'll be ready for sale.
I've given poor advice to some about this hard starting problem in the past. I apologize for that. I know better now, I think. You just can't eliminate the problem unless you convert your unit to a '57 / '64-65 type solenoid design using engine fuel pump pressure for starting. But... a temporary cheap fix is to keep a can of ether near the car just for cold starts.
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