quote:Originally posted by bdud:quote:Originally posted by PanteraDoug:
My difficulty at the moment is engineering in a PCV system with the Webers off of a vacuum manifold.
There isn't enough volume of vacuum left to pressurize the brake booster. Just getting the PCV system to work means finagling with internal restrictions in the line to the pcv and loosing 2 in-hg at idle.
Problem is there are no pcv valves that close 100% at idle. They are all open a little.
Doug, check out this product, http://mewagner.com
I also did not want to bleed off vac at idle because I have a large duration cam and I cannot find a "performance" pcv. I have bought quite a few, some have just a small hole and are rated at different vac levels. There are also people who threaded a screw on the top of a regular pcv valve to adjust it. I bought one of these valves but because of the cold weather and bolting on other parts, I am not sure when I will get to test it. Try it risk free for 30 days and you can get an inline adapter and it can be mounted in any direction / orientation.
I already investigated this one. If you read the information you will note that they do no claim the valve to close 100% at idle. That is the issue for me.
What I currently have is an Allen set screw that is drilled with an orifice of .060" or so (maybe I used 2mm?) that is installed in line to the PCV valve.
What it does is instead of me having 14" at idle it reduces the leak to only 2". That leaves me with 12" at idle.
Considering that I have 74 degrees of overlap with this camshaft that is a very strong vacuum signal. Even 12" would be good.
IF there was a PCV valve that fully closed that would solve much of the problem. As far as I can determine there is not. These valves are $2 parts and the quality of the construction is as cheap as you can get. The design intent is there with them but the execution in building them is not.
The combination of low VOLUME of vacuum signal (not strength) created by the IR (individual runner) manifold and a 5/8" vacuum tube to the brake booster creates an issue that even a one gallon storage tank in line does not fix.
I am still in progress with this vacuum refinement. Too cold to run the engine right now. Got up to 18 this morning. Webers don't like that.
The issue was complicated by a non-functioning check valve at the booster. I've replaced that but still haven't pressure tested the booster itself to see if the internal diaphragm is shot (kaput). Considering this is the original booster to the car, that is a distinct possibility and if it is rotted out could be the problem right there?
I may have to take my own recommendation and send this booster to Harmon brakes and let him rebuild it?
At the moment, this is a very, very complicated issue and I need to backtrack to identify basic problems that I may have overlooked.
The availability of the vacuum pump is comforting and the fact that there is no one anywhere that I can find that has run a PCV system with a Weber set up makes me a trailblazer. That is a task which I detest but often find myself immersed in.
I thank everyone for the input. Hopefully I will be able to remember all of these options but I suspect that it may be just that scenario of the elephant hiding in the bowl of M&M's and everyone else sees it but me?
Confucius say, "never set a cannon to kill a mosquito!" Well ok, but he never said anything about a machine gun? Ask Ted Nugent.