Bought a Series 3 V12 because I wanted to tinker with it. First drive, it overheated badly. It can’t be that hard. I’m going to mess with it until it behaves. Also, that emission garbage , that is no longer needs, detracts from beauty of that lovely motor. I thought posting here might lead to some answers that are not being shared. I started out tearing into the thermostats, tested them and figured out they are actually working. Not the problem. But, every part I have like looked into has led to discovery of terrible prior mechanic’s work that was shoddy at best. I’ve torn out the air pump and associated plumbing. Same for the gulp valve. Replacing all steel water pipes and new hoses.

now I am looking at vacuume lines that are clearly misdirected and there are no diagrams or info to use for correction. So, I’m tearing it out also. I think I need one vacuum line to the distributor, which was swapped out for a DG Barrett unit. That may be good news if I can find documentation and support for how it operates. I will post the results of these changes and if they actually do help with the cooling problem which I now think was related to incorrect timing of the distributor. Any information anyone might have about this would be lovely to learn.

 

More. Not only did I take out the vacuum lines, I learned they were plumbed in a way that could not have been any use. The heat valve on the Right side of engine, where four of the vacuum lines run up to various parts and bits leads me to believe that the system was compromised by some prior mechanic. Nothing in the current arrangement led to a vacuum SOURCE. If there is no vacuum source, there was never any vacuum on this entire circuit of tubing. More, one of these lines led to the Distributor, but again, without a vacuum source, it was never doing anything. So... I have capped off all of this. The only Vacuum source from the rear of the Left Manifold was going to the Gulp Valve, which I have removed. So, I capped it also. So, without any vacuum lines connected to anything, I am going to see what actually happens I run the engine. I am just completing the installation of all new cooling hoses and pipes. Then we can run it.

 

As you likely discovered the vacuum source is a tap in the intake manifold. The "heat valve" when cold retards the ignition timing and opens the warm air vents to help the engine heat up faster and run better when cold. If you've removed all that plumbing the specs for the ignition timing will no longer apply so you'll need to figure out how best to set that.

 

Another thought is you may want to try to keep the gulp valve. When you lift off the throttle abruptly the sudden increase in vacuum will create a slug of very rich mixture flowing through the intakes as the Stromberg diaphragms don't react fast enough to adjust the mixture properly. The gulp valve, as the name implies, adds a gulp of air to that mixture to lean it out. Without that extra air you'll probably get some back firing or minor explosions in the exhaust, none of which will do the engine any good.