road draft tube

Air passing over the draft tube causes as vacuum which pulls air out of the motor. The oil filler cap allows air to enter the engine, the cap should be position on the filler tube so that it catches the air from the fan.
 
On the carb setups I have done we plug the road draft hole and insert a PCV valve and plumb it into the manifold. Still keep the fill tube and vented cap in front. Works great
 
Conversion of the 8BA/8CM style of engines that have the road draft tube located at the front of the engine is very simple.. To convert the engine to a closed crankcase with a PCV, remove the draft tube, use the block fitting from a '63-65 Ford trunk Y block V8 or a '63-67 CSB V8. This type of fitting will take the place of the draft tube and accept a 3/8" hose and PCV. Vacuum can be picked from the intake manifold below the carb. Make sure you use a vented cap on the oil fill tube.
The vacuum will draw air through the filler cap, blow-by will be sucked into the intake, acting as an upper cylinder lube. In some cases the carb can be leaned out to allow for the added richness of the blow by.
The PVC application should be close to the CID of the engine. The size of the PCV is important because on acceleration the valve must close so there is vacuum for the vacuum advance in the distributor.
 
Hey blucar I just read your post about a conversion of road draft tube to pcv. I'm interested, I've got a 1950 F-1 with a stock 8BA, if you or anyone out there in the BARN could give me a list of what I need to do this I would do it tomorrow. I'm not clear on the piece that goes in the block. My draft tube dumped out right next to crank shaft pulley, made for a good mess on front of engine. Mine didn't extend down under the engine. Any help would be great.THANKS Jim
 

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