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Old 04-18-2008, 09:08 AM   #41
jim lockwood
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and the added solenoid
What you've got appears to be a '64-'65 unit. If so, the solenoid valve in the picture is not for anti-siphon protection; rather it provides a bypass path for fuel to reach the nozzles during engine cranking.

My guess is there is no anti-siphon solenoid valve and that the only siphoning protection is a small check valve that is (1) integral to the unit (2) in only one of the two siphoning fuel paths and (3) tends to fail.

If that were my unit, I'd replumb the fuel path to provide positive siphoning protection like I described in my earlier posting.

Good luck,

Jim
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Old 04-18-2008, 09:36 AM   #42
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here is what i bought
Matt, you've posted photos of a '63 7375 series FI unit with a modified starting circuit. Instead of a Cranking Signal Valve, your unit now uses a solenoid controlled by-pass around the fuel meter to provide nozzle fuel pressure during cranking.

For this modified starting circuit to work, you'll have to connect one solenoid lead to a terminal with 12 volts only during engine cranking. This same lead will also require a switch that can be used to disconnect the solenoid during engine re-starts. (Otherwise your engine might flood during hot re-starts.) I believe you already have such a switch mounted on the bellcrank boss.

This unit originally came with an anti-siphon "pill" valve inside the fuel meter. It also came with a spring-loaded anti-siphon needle valve in the spider hub. I can not tell if either of these is still present and working, however.

My own experiments with installing anti-siphon solenoids in the '63 - '65 fuel meter-to-spider tubing have been disappointing. Regardless of where it is placed in this tubing, a standard solenoid valve causes a flow restriction in this particular application that changes the fuel supply curve. In my experiments, this change has been significant. However, if you can find a solenoid valve that is full opening (like a tiny gate or ball valve) with no flow restriction when open, I can see how it could be installed in the short feed line without affecting calibration.

Regards,

Jerry

Last edited by jerrybramlett; 04-18-2008 at 12:13 PM.
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Old 04-20-2008, 12:04 PM   #43
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Originally Posted by jerrybramlett View Post
Matt, you've posted photos of a '63 7375 series FI unit with a modified starting circuit. Instead of a Cranking Signal Valve, your unit now uses a solenoid controlled by-pass around the fuel meter to provide nozzle fuel pressure during cranking.

For this modified starting circuit to work, you'll have to connect one solenoid lead to a terminal with 12 volts only during engine cranking. This same lead will also require a switch that can be used to disconnect the solenoid during engine re-starts. (Otherwise your engine might flood during hot re-starts.) I believe you already have such a switch mounted on the bellcrank boss.

This unit originally came with an anti-siphon "pill" valve inside the fuel meter. It also came with a spring-loaded anti-siphon needle valve in the spider hub. I can not tell if either of these is still present and working, however.

My own experiments with installing anti-siphon solenoids in the '63 - '65 fuel meter-to-spider tubing have been disappointing. Regardless of where it is placed in this tubing, a standard solenoid valve causes a flow restriction in this particular application that changes the fuel supply curve. In my experiments, this change has been significant. However, if you can find a solenoid valve that is full opening (like a tiny gate or ball valve) with no flow restriction when open, I can see how it could be installed in the short feed line without affecting calibration.

Regards,

Jerry
thanks jerry for the input, i do have other pics of the unit apart, and yes it is a 63 unit with the solenoid "upgrade"
i will look into that wiring as you described
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Old 04-27-2008, 12:34 PM   #44
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i checked my vacumm today, off the carb going to dist, and my guage bounces for 8-15 vacumm, is this possiable or is this an issue
would that be too low for the fuelie unit?

thanks
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Old 04-27-2008, 03:49 PM   #45
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i checked my vacumm today, off the carb going to dist, and my guage bounces for 8-15 vacumm, is this possiable or is this an issue would that be too low for the fuelie unit?thanks

A manifold vacuum reading that varies from 8" to 15" at an 800 rpm idle speed indicates a serious mechanical problem. Please find another source point to measure and recheck this reading.

There is a write-up on my website in the "Tech Tips" section that discusses camshaft selection for fuel injected engines.
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Old 04-27-2008, 04:38 PM   #46
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...yea the GM TPI setups are great, up to 4800 RPM. They are real good for a low RPM torque motor.
The TPI manifold was designed for the 305, a 350 is pushing the limits, a 327 would probably work just fine. A better solution down that road is a TPI computer running an LT1 manifold modified for a distributor. Torque will suffer a bit with the shorter runners, but the bigger engine will make up for it and high RPM behavior will be much better.

Back to the regularly-scheduled mechanical FI discussion.
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Old 04-27-2008, 09:51 PM   #47
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hey all Mr. Stupid here!!!

i tried another vacuum guage and guess what, i have 12 of vacuum!! at 800 idle

the other guage that i was using was no good, so i guess i should be good for my fuelie setup

thanks
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