Crankcase pressure

clay · Posted: Tue Nov 25, 2014 10:20 am Post subject:

That would work. But he still would have to install baffles of some sort or we both know what would happen after that😄. Clay

aharris05 · Posted: Tue Nov 25, 2014 1:05 pm Post subject:

af2 · Posted: Tue Nov 25, 2014 6:56 pm Post subject:

There is a tube that goes in first before you put the outer tube on. That keeps the dipstick from fluttering around and maybe touching the crank.

Edit!!! Here you go...

http://www.summitracing.com/parts/nal-3951600

af2 · Posted: Tue Nov 25, 2014 7:06 pm Post subject:

And if Smoke will let me put some funny stuff on how people don't know.

http://www.stevesnovasite.com/forums/showthread.php?t=136258

Knarley Darley · Member Joined: 22 Apr 2004 Posts: 1247 540238.26 points

The evac tubes in the headers will actually pull vacuum in the crank case which promotes ring seal, and increases power. Another fairly inexpensive thing you can do is get a electric GM smog pump, and plumb that into a valve cover. And Ditto Clay on the baffles.

Big Dave · Posted: Fri Nov 28, 2014 6:34 pm Post subject:

Wonder if those guys would want to buy a set of NOS muffler bearings I don't need since I started building BBC instead of the SBC with the confusing dip s***k issue?

Big Dave

af2 · Posted: Sun Nov 30, 2014 5:28 pm Post subject:

Knarley Darley · Member Joined: 22 Apr 2004 Posts: 1247 540238.26 points

The gen 4 BB goes through the side of the oil pan quite a bit below the pan rail, and the tube is one piece, but goes way into the pan, like 5 inches or something like that, also the tube on a BB actually touches the oil, and almost totally conceals the stick. There is no way the crank could eat it.

af2 · Posted: Mon Dec 01, 2014 8:20 pm Post subject:

osmiumfoot · Member Joined: 11 Jun 2002 Posts: 299 2387.84 points

I've used the exhaust evac system from Mr. Gasket for years and had oil control issues at high rpm through a 2.5" exhaust with Hooker Maxi-flow mufflers. My buddy hooked up a water manometer to a nearly identical setup and actually saw a crankcase pressure increase above 5k. This last season at the track I disconnected the extractor hoses from collectors and capped the connection, leaving the ends of the hoses open and positioned next to the collectors much like the old breather downtubes on the first small blocks in the 50's, and found this works much better. I no longer am puffing smoke on the big end and no longer have oil on the intake manifold. Of course, if this is a track car and you are running an open exhaust then the extractor system may work well for you.

Knarley Darley · Member Joined: 22 Apr 2004 Posts: 1247 540238.26 points

Exhaust evacuators dont work with mufflers, and need to be near the exit of the collector. If you have pressure above 5000 rpm, or any rpm then the mufflers are slowing you down. It would be interesting to make passes with, and then without the mufflers, and see if it runs quicker, and faster. Another thing I have seen done is remove the dip stick, and run a piece of hose from the top of the dip stick tube to a hose barb installed on the valve cover.

osmiumfoot · Member Joined: 11 Jun 2002 Posts: 299 2387.84 points

I have run the car both ways and am about a tenth and a half quicker without the exhaust. I drive the car to and from the track (well, to the track always and most of the time from) and it becomes an adventure in tinnitus if the exhaust is open. On Fridays I race in a street legal class that requires a muffled exhaust, but on Saturdays I run Pro where exhaust is optional. For the last couple of seasons I have become too lazy (old and fat?) to bother with dropping the pipes. Maybe Santa will leave some electric cutouts in my stocking.

aharris05 · Posted: Mon Apr 27, 2015 10:42 am Post subject: Big improvement

I wanted to follow up on all this advice last fall. I seem to have the crankcase venting cured. Here is what I did, based on all your advice:
Installed dipstick extension tube and a new dipstick.
Got the high flow PCV for 1970 LT1, Fram FV178, in right hand valve cover, connected to manifold vac at back of carb.
Made a baffle and placed over the PCV hole.
Added a nice open element breather filter on the other valve cover.
Added a 3 inch tall, 14" round, washable air cleaner.

Knarley Darley · Member Joined: 22 Apr 2004 Posts: 1247 540238.26 points

So have you had a chance to test it? Sounds like you made some nice upgrades.

aharris05 · Posted: Mon May 04, 2015 1:01 pm Post subject:

Well I did get to run it a couple weeks ago, and it seems to have the crankcase pressure issue corrected, but I tried a different carb, and lost time at the tree. So you might see my latest post looking for input on how to get it all tuned to work together.