I'm almost finished with the pony motor rebuild and noticed the hole on the front of the intake manifold. When I disassembled there wasn't anything in it and when you blow air in it, the air comes out where the carb mounts. The parts book calls for a 2F3850 filter and a 3F4343 nut. I will check tomorrow hopefully it is still available. My question is what was the purpose of this? Did it let gas drain out if the manifold if it flooded? I'm also guessing when it is on that it will be close to the back of the dash. Thanks for any help.
Tom

Yes, that is the purpose of the vent, to drain raw gas from the manifold.....no longer available from Cat except for a few pieces. If you can't find one I have been using a vent valve available from McMaster Carr if you need one.

OM, do you happen to have the McMaster item number handy?

Yes, the 1/8" pipe size #2257K11

Thanks OM. I have to hang one on a first year D-4 5t pony carb float bowl.

Tom, if I didn't know any better I would swear that I was looking at my D2 pony motor,not yours. I am at the same stage of rebuild mine that you are at.Will be putting it back in in the next couple of days. Mike D

Thank you for the help OM I got one coming from Mcmaster.
Mike I bet you are like me anxious to here it run. I was real impressed with the engine it seems to be well designed, everything came apart and went together well. My motor had very little wear except for some in the valve guides and they were fairly cheap to replace. I think the main problem with my motor was the valve clearance was to close. I took the block to a automotive engine rebuild shop and they touched up the seats and ground the valve stems to where I have .008" to .009" clearance. I still have to clean up my magneto and install new points and condesor, and paint. Let me know how yours turns out.
TomP

Tom, my engine was a runner, I had started it a few times.But then I had a fuel problem and one thing lead to another. When I checked the oil I found some small bit of metal in the oil,so I changed it and found some big pieces. Started to tear it down and found the rod bearings to be about ready to let loose. Redid the whole thing and about ready to put back in.Mike