I just picked up an old 3x2 intake for my 8ba flathead, and there is some odd plumbing underneath it. What is it? the added plumbing in question is it for a PCV? The draft tube has been plugged..
That appears to be what the plan was but plugging the tube in front that the breather went in might not have been wise. You have to have air in so it can flow through and out for proper crankcase ventilation.
Looks like a prank based on the pics cuz it doesn't show where it's going/feeding(?). Coulda been a weird idea that was abandoned. edit: I looked again, is it feeding the plenum? It may have indeed been a shot at some happy gas.
It looks like PCV plumbing, tying both intake planes together for all 8 cylinders to pull on the PCV. The valve can be located in the capped off vertical stand pipe, making the system completely hidden. On 8BAs, ventilation air enters the oil fill tube which would be located in the open port behind the plugged road draft port.
Yes they are plumbed directly into the plenum. There was a third inlet under the junction, but it has been plugged. Not sure why there would need to be multiple inlets into an open plenum.
Ditto PVC plumbing, because the draft tube port is plugged. Someone was doing a neat job of hiding the pcv system. Nice idea! 4TTRUK
I've never seen or heard of a single plane (open plenum) Edelbrock 3-carb 8BA intake, but your's is very different from the #349 I have, mainly in the bottom casting and absence of an exhaust crossover. It looks like you have plumbing into both sides (runners) of the intake, but a picture of the top of the intake with carbs removed would verify manifold design. A PCV valve can be installed directly into the plugged fitting, or into a capped off forward vertical stand pipe, with a 3/8" hose making the connection. What you want is the PCV to draw from the stand pipe (8BA only) to manifold vacuum for proper operation .
A PCV system that was abandoned (probably by a new owner) and plugged with the pipe plug. The freeze plug in the road draft hole adds to this theory.
There are good reasons PCV systems replaced all road drafts in the early '60s. Even "Henry" used them on some military engines during the war.
You can cap the road draft tube, add a 90 degree fitting to it, and plumb that to a handy vacuum port, with a pcv valve. Works great, and keeps the gunk off the bottom of your ride. 4TTRUK
I think it was an attempt to add a crankcase venting system that was hidden. He wanted to keep the engine looking uncluttered and old timey looking. If you think about it, if that plug was removed the vacuum from a running engine would suck crankcase fumes in there and burn them off in the combustion process. Only downside, unless there was some sort of pcv valve installed, is that you could have an explosion if the engine backfired. Not sure what he intended to do for clean air coming into the system though, as he plugged the hole with a freeze plug. Don
8BA's have the air inlet in the oil filler cap. I've been doing some reading on the flathead PVC, and I think I'll end up using it that way.
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