Re: Stewart

Posted by HH56 On 2021/7/17 15:35:47

There is no diagram I am aware of and the single carb is different than the dual so any photos I take would be only partially correct. Maybe someone will see your post and oblige with a few photos.

Unless someone does have a photo of a single carb application best I can do is describe what I remember. There is a port on the rear of the carb base or throttle plate which gets a tee fitting. The power brake check valve goes in one port on the tee and a 1/4" steel tube for the main wiper supply connects to the other. I do not remember which port gets the power brake check valve but the check valve and brake hose being fairly large does need to be positioned to miss the distributor assy, coil, and the oil sender as it heads to the firewall.

The steel tube extends over to the right head and bends toward the firewall as it lays near the top of the head. It lays fairly close to or maybe right under the rocker cover and as I recall there is one clamp around the tube near the rear which uses one of the 3/8" threaded holes on the side of the head for its mounting bolt. I think it is the front hole and the ground strap to the body uses the other hole. The tube extends past the head a bit more toward the firewall and bends up a couple of inches where it connects to a hose going to one of the inlet ports on the side of the wiper balance valve. Don't remember which balance valve port is which but if they are not marked I believe the washer installation diagram in the parts manual shows the proper connections.

If the engine is stock there is another 1/4" steel tube from the aux vacuum pump in the crankcase. That vacuum port exits the block about in the middle and slightly above the oil pan. Via an elbow it connects to an inline check valve. The other end of the check valve continues the vacuum line path with the tube also going toward the firewall and then bending upward just past the block or head to come up beside the tube from the carb. As I recall the clamp for that tube is on the bellhousing area and maybe uses a bolt shared with the clamp for the trans cooler lines. Cannot remember too much of the detail there. Another rubber hose connects that tube to the other inlet port on the balance valve.

If the Olds or the old PI modified pump without the aux vacuum pump has been installed that tubing may have been removed. If it is still present and connected to the balance valve make sure the path is blocked off in some fashion so intake manifold vacuum cannot leak past the check valve into what would be an open hole in the crankcase. As I recall one common blocking method for the PI pump install to keep the stock look was to insert a solid dowel or steel ball in the rubber hose so it was completely blocked to prevent any possible vacuum leak. Some who had the PI pump mod went old school and installed a fuel pump with a vacuum section to replace the crankcase pump. They utilized the old aux tube by disconnecting and removing the elbow, plugging the block port, and adding necessary fittings on the check valve to extend the tube up to the point where it can connect with a short hose to the new fuel pump vacuum port.

The 1/8" steel vacuum advance tube originates on a port on the right side of the throttle plate toward the front of the carb. As I recall the tube is just more or less free floating between the carb and the distributor advance connection although there might be a clamp near the coil hold down bracket to control vibration.