Vapour Lock

Canuk40 · 09-09-05, 07:55 PM

Hi Guys, I recall previous threads about this modification and was reminded about it by fellow CAV owner Ken Jackson. The problem was that coolant temperatures would spike suddenly after a good blast up through the gears. You could putt along all day, dust off the odd tuner car or other supposed to fast cars and the gauge would stay 80>90c. However stand on it from second through fifth and over she'd go 110>120 and it took a long time to come back.

The rising temps were tamed by plumbing the back of the intake manifold at the blocked off water passages to the front of the manifold. As a result localized boiling doesn't produce trapped gasses, engine block coolant pressures are lowered, the front half of the heads should run cooler as some of the hot water at the back has been bled off and filling the cooling system has to be easier.

Maybe a bit of voodoo but I can say that it certainly worked on Angelos 392W. We decided to go with stainless steel tubing so we never have to go back in after it (all buried under the webers and heat sheild).

Something to look at when your building an engine, it's another of those fiddely jobs that's easier done before the car is together [img]/ubbthreads/images/graemlins/smile.gif[/img]

Canuk40 · 09-09-05, 07:56 PM

Second Pic, nothing to see when it's all together!

Ron Earp · 09-09-05, 08:10 PM

Ian, good to bring this back up for folks that have overheating issues. This first came up about 4 years ago with some folks having the heat problem and Robert and Hershal suggested it to a few that were thinking of going the electric water pump route etc. with their ERAs. as I recall, BLACKJACK had chased heat problems in his ERA for close to a year with no resolution, this little trick did it for him. I drilled and tapped my weber manifold just like that too.

Bill D · 10-24-05, 02:24 PM

Please excuse me for this silly question, but, where does the front tap into? I'm having a difficult time understanding where it terminates in the front. And since I plan to use Webers this post is very applicable

Cheers
Bill D

Ron Earp · 10-24-05, 02:29 PM

Goes to the water neck in most people's builds, or, it can go to the front intake manifold passage too, depending on design. Some tee it into the upper radiator hose.

Best,
Ron

Bill D · 10-24-05, 02:34 PM

OK. Now correct me if I'm wrong Ron. I can plumb the line into the 90º water neck that fits onto the front of the manifold?

Bill D · 10-24-05, 02:45 PM

I think I have it all clear now (I hope). Here is a picture of the setup I plan to get. From the picture I see I can tap into the thermostat housing on hte manifold. Will that suffice?

Thanks for your patience
Bill D

Frank Catt · 10-24-05, 02:57 PM

Be Warned - size matters ! -3 good, -4 MAXIMUM. Too large a pipe will change the flow patterns and just make things worse. I always use dash 3 braided pipe and return to the header tank, as high as possible. All you are trying to do with this system is to evacuate any trapped air or steam in the back of the block, and the most sensible place to send it to ius the header tank. Frank

Canuk40 · 10-24-05, 09:00 PM

Hi Bill, the plumbing goes into the back of the outlet neck on the manifold casting. It's not clear in my pic, sorry. We chose hard piping in stainless because I never want to go in there and work on it again, the tubes are burried under the base plate of the heat sheild for the Webers. That said, I doubt a premium flex line with decent fitting would give you a problem...

Bill D · 10-24-05, 09:20 PM

Thanks Ian. It's all clear to me now!