Intake Manifold Question

T

Timstruck

Member
I would like to put dual carbs on my project and am getting to the point of needing an intake manifold. I have not been able to determine if there is a vacuum port on the aftermarket units on the driver side that connects with the distributor.


Does anyone here have a dual set up with the vacuum port? I'm assuming that I need to have this connected.


Below are two links to what I'm looking for but there's no mention or any pictures of the vacuum port. Also, one of them is not advertised for my year (1937 block) and I'm not sure of the difference.



https://www.speedwaymotors.com/Spee...ifolds,184019.html?OriginalQuery=91015985-PLN


https://www.speedwaymotors.com/Offe...lathead-Regular-Dual-Intake-Manifold,794.html


Thanks for any info and 'yes' I am aware that there's no real advantage to dual carbs :)


Tim
 

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Early ford distributors used manifold vacuum, so it should be easy to add a port if there are none. I find it hard to believe that anyone made a manifold without a vacuum port, but they may exist. If there is only one port "tees", are available that make it easy to connect both the wiper and the distributor. With a little thought and some simple hand tools, it should be easy to add a port to an aluminum manifold if need be.
 
Last edited:
My Offy manifold is the same style as your link with the '32-'48 manifold. It has a port just under the rear carb (on the drivers side) that can be used for vacuum for the early style vacuum brake distributor.
 
I don’t mean to take the thread of the rails but,.....isn’t that a racey ad for back in the day?...Mark
 
I was thinking the same thing!


I don't mind drilling and tapping a hole for the vacuum port as someone suggested above so guess I'll go that route.


Having spent several hours of searching online, I can't seem to find out any definitive reason why some intakes are designated for later years and some for early. I have a 37 block and the link below is the one I would like to purchase. Can anyone tell me why I shouldn't buy it?


https://www.ebay.com/itm/1949-53-Fl...e=STRK:MEBIDX:IT&_trksid=p2060353.m1438.l2649


The price is right. The carbs are more centered than some instead of rearward mounting. I also am using a 12V alternator and not a generator.
 
Timstruck said:
I was thinking the same thing!


I don't mind drilling and tapping a hole for the vacuum port as someone suggested above so guess I'll go that route.


Having spent several hours of searching online, I can't seem to find out any definitive reason why some intakes are designated for later years and some for early. I have a 37 block and the link below is the one I would like to purchase. Can anyone tell me why I shouldn't buy it?


https://www.ebay.com/itm/1949-53-Fl...e=STRK:MEBIDX:IT&_trksid=p2060353.m1438.l2649


The price is right. The carbs are more centered than some instead of rearward mounting. I also am using a 12V alternator and not a generator.
Click to expand...

This link may give you some insight to the differences between early and later intake manifolds.

https://www.jalopyjournal.com/forum/threads/ford-flathead-intake-differences.442152/
 
Timstruck said:
Having spent several hours of searching online, I can't seem to find out any definitive reason why some intakes are designated for later years and some for early. I have a 37 block and the link below is the one I would like to purchase. Can anyone tell me why I shouldn't buy it?
Click to expand...


The early '32-'48 engines sit level in the torque-tube chassis, so the carb base is also level. Ventilation enters the rear of the intake (fuel pump stand) and exits down the front, under the intake, and out the pan, starting in '35.



The late '49-'53 engines sit at an angle because of the new open drive lines and hypoid rear ends, which requires an angled carb base to level the carb. Ventilation enters toward the front of the intake, along with the oil fill. Fumes exit through a road draft tube out of the front of the intake.



Look carefully at early and late manifolds, as they will bolt to all flathead engines, but carb angles and engine ventilation are two issues that need to be considered.


There are some aftermarket intakes that may vary from the norm, like the Navarro tripple I use that has level carb bases but has the late oil fill and road draft provisions at the front.
 
Bob, that explains the differences between pre-48 and the 8BA types, but I have noticed that some of the manufacturers list different manifolds for '32-'41 and '42 - '48 engines. Can you explain that difference?
 
Timstruck said:
I was thinking the same thing!


I don't mind drilling and tapping a hole for the vacuum port as someone suggested above so guess I'll go that route.


Having spent several hours of searching online, I can't seem to find out any definitive reason why some intakes are designated for later years and some for early. I have a 37 block and the link below is the one I would like to purchase. Can anyone tell me why I shouldn't buy it?


https://www.ebay.com/itm/1949-53-Fl...e=STRK:MEBIDX:IT&_trksid=p2060353.m1438.l2649


The price is right. The carbs are more centered than some instead of rearward mounting. I also am using a 12V alternator and not a generator.
Click to expand...

Big difference between '32-'48 and '49-'53 is crankcase ventilation. '49-'53 had a "road draft" tube extending from the left front of the intake manifold down to oil pan level so air moving under the car would set up a slight vacuum in the tube to pull fresh air into the "breather" cap which was on another tube extending up from the intake. This helped evacuate blow-by fumes out of the crankcase at highway speeds. In city traffic, not so much!
'48 and earlier let the fumes find their own way out thru an opening in the left front of the pan and the breather cap on the fuel pump stand. The blocks are a bit different for each system.
Fuel pump push rod lengths also vary.
 
tubman said:
Bob, that explains the differences between pre-48 and the 8BA types, but I have noticed that some of the manufacturers list different manifolds for '32-'41 and '42 - '48 engines. Can you explain that difference?
Click to expand...


Off hand I don't know for sure, but my guess would be slight generator mount and/or fuel pump stand differences.
 
V8 Bob said:
The early '32-'48 engines sit level in the torque-tube chassis, so the carb base is also level. Ventilation enters the rear of the intake (fuel pump stand) and exits down the front, under the intake, and out the pan, starting in '35.

The late '49-'53 engines sit at an angle because of the new open drive lines and hypoid rear ends, which requires an angled carb base to level the carb. Ventilation enters toward the front of the intake, along with the oil fill. Fumes exit through a road draft tube out of the front of the intake.

Look carefully at early and late manifolds, as they will bolt to all flathead engines, but carb angles and engine ventilation are two issues that need to be considered.

There are some aftermarket intakes that may vary from the norm, like the Navarro tripple I use that has level carb bases but has the late oil fill and road draft provisions at the front.
Click to expand...


Thanks Bob. This is what I needed to read.
 
tubman said:
Bob, that explains the differences between pre-48 and the 8BA types, but I have noticed that some of the manufacturers list different manifolds for '32-'41 and '42 - '48 engines. Can you explain that difference?
Click to expand...


The intakes listed for '32-'41 do not have a generator mount.
The '42-'48 intakes are more versatal, having a generator mount.
 
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