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Factory Bosch Carb Pump for PMO 46 Install?
Will the factory Bosch fuel pump for carbs on my 1970T (Zenith carbs from the factory) support PMO 46s for my 3.2 motor install?
Anyone know the delivery rate (gallons per minute) and pressures that it produces and will that support the PMO 46s ? I am under the impression it will. Thanks !
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Robert Callaway PCA | Early S Registry | R Gruppe 1970 T Coupe, 1990 C2 Coupe, 2007 Cayman S 1962 S90 Coupe - Gone, but never forgotten... 1985 Targa - A distant memory... |
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08-28-2022, 08:42 AM
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Location: Marysville Wa.
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Pressure would be the same, 3 to 3.5.
The question is volume to feed the hungry 3.2. Try it and see. Easy enough to update later.
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https://www.instagram.com/johnwalker8704 8009 103rd pl ne Marysville Wa 98270 206 637 4071 |
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08-28-2022, 08:58 AM
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Yep, that's the big concern. I guess I could test the delivery rate with a gas can and stop watch.
Thx !
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Robert Callaway PCA | Early S Registry | R Gruppe 1970 T Coupe, 1990 C2 Coupe, 2007 Cayman S 1962 S90 Coupe - Gone, but never forgotten... 1985 Targa - A distant memory... |
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08-28-2022, 09:02 AM
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Just found this data on the factory Bosch fuel pumps. Shows the factory pump delivers 80 liters per hour, or per my math, 21 gallons an hour. Looking for rate required for the PMO 46s.
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Robert Callaway PCA | Early S Registry | R Gruppe 1970 T Coupe, 1990 C2 Coupe, 2007 Cayman S 1962 S90 Coupe - Gone, but never forgotten... 1985 Targa - A distant memory... |
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08-28-2022, 09:15 AM
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So, looks like I am slowly finding the answers to these questions. Many thanks to Mr. Paul Abbott of Performance Oriented, once again.
Per his website and a quick email, one needs 0.1 gallons/hour fuel delivery per horsepower. So, if the 3.2 at 10.5 compression ratio, twin plugged, puts out, say 250hp (hoping for more obviously!), we would need 25 gal/hr of fuel supply. See here: Performance Oriented Looks like we would be short at 21 gal/hr from the factory pump. Hope this helps someone.
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Robert Callaway PCA | Early S Registry | R Gruppe 1970 T Coupe, 1990 C2 Coupe, 2007 Cayman S 1962 S90 Coupe - Gone, but never forgotten... 1985 Targa - A distant memory... |
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08-28-2022, 12:12 PM
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What about using the MFI pump (same size etc. and bolts right up) which delivers 125 liters, or 33 gallons per hour at 14 psi and then a pressure regulator?
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Robert Callaway PCA | Early S Registry | R Gruppe 1970 T Coupe, 1990 C2 Coupe, 2007 Cayman S 1962 S90 Coupe - Gone, but never forgotten... 1985 Targa - A distant memory... |
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08-28-2022, 06:32 PM
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I am using the stock Bosch low pressure pump original on my '70T with the now installed '79 3.0 engine with 46 PMO's. It works great. No problems with fuel delivery.
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gary 70T coupe forever almost done 88 Carrera Targa diamond blue |
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08-29-2022, 04:26 AM
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Thanks for the intel Gary. Might leave it alone until it's all together and see if it keeps up.
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Robert Callaway PCA | Early S Registry | R Gruppe 1970 T Coupe, 1990 C2 Coupe, 2007 Cayman S 1962 S90 Coupe - Gone, but never forgotten... 1985 Targa - A distant memory... |
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08-29-2022, 06:26 AM
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It's a 914 ...
Join Date: Jan 2008
Location: Ossining, NY
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Re: psi a pump delivers, it's really more about how it's installed. Just looked up early carbed T fuel line routing, and it looks like there is a return line. Easy enough to replace the pump with a higher volume one. With an open/unregulated return line, fuel pressure will be pretty low, like 3 psi or less. This will be true even if you use a high pressure MFI or EFI pump - the pressure comes from the regulator. I've heard that some just run with the open return line. Or you can add a fuel pressure regulator.
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08-29-2022, 07:43 AM
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