Hole in intake manifold - on purpose!

rivcokid

rivcokid

Senior Member
Hi all - Any guesses as to why someone would install a fitting onto the intake manifold that would allow you to unscrew part of it to open a hole in the manifold? I'm trying to get a friend's 1928 roadster pickup to start. It cranks well but never turned over until I removed the top of the fitting. It started once and ran very fitfully for about 10 seconds, then back to not starting.

There are other issues with it, but I'm trying to understand the intake manifold hole. Thanks in advance.
 
If you have a steel tube running under the very right side of the gas tank, or even the fittings designed to hold that tube, it came with a vacuum wiper...
 
The outlet for the vacuum wiper is 3" above the carb/manifold flange and faces outward directly toward the fender. I also have a fitting above that which is on the top of the manifold. I imagined it was for either measuring vacuum or to open and squirt in some starting fluid.
 
Or it could be that a manifold off a car with a vacuum windshield wiper was put on this car that has an electric windshield wiper.

To start your friend's car, I assume you have checked all the usual stuff. Spark, timing, compression, fuel, etc. Opening the hole in the manifold would have nothing to do with the car starting but would make it run lean and not idle.
 
Last edited:
28's had no vacuum port in the intake manifold.

29 and later had a vacuum port in the manifold which has a round boss around the hole.

Many of the manifolds without a hole in the manifold were drilled later by owners or mechanics and would not have the round boss around the hole.

Richard
Anaheim CA
 
Thanks everyone. I'll be back at it on Sunday (after rebuilding the carb) and will see how it goes. There's no hint of a steel tube for vacuum purposes. Will keep playing with it!
 
You must log in or register to reply here.
Back
Top