Ford Muscle Cars Tech Forum banner
1 - 5 of 5 Posts

·
Registered
Joined
·
2 Posts
Discussion Starter · #1 ·
I'm starting a street/strip 69 Torino project. I've had the car for awhile but i'm just getting around to messing with it. I noticed yesterday while doing some carb adjustments that air is being sucked in the oil dipstick tub. I'm new to BBF's and i'm not sure if this is normal or not. Everything checks normal. Here's some history if it could help in the solving of this problem if it is one. It's a 1970 429 with dove-c heads and the previous owner had it bored .030 over and the intake side of the heads ported. It has a torker 460 intake, holley 4160 750cfm carb and it still has the factory exhaust manifolds on it cause the guy said he couldn't find any headers he could afford that would fit. It has an aftermarket cam in but I don't the specs cause the guy lost them but he said it's a pretty high duration cam. I would like to finish building this motor one day in the near future and I need to know if the above mentioned problem is serious or not. Thanks
 

·
Registered
Joined
·
557 Posts
If the engine is equipped with a PCV valve, and its in good sealing condition, then its normal....the suction in the dipstick tube is because the PCV is hooked into the intake manifold or the carburetor.
But this would typically rule out a long duration cam, because vacuum at idle would be a lot less than a mild cam! So if it has a lot of vacuum going into the dipstick tube, then its probably not a very big cam...but if its vacuum is only slight, then the cam may be big after all.
One way of finding out your cam specs is to use a degree wheel to determine what its duration figures are.
 

·
Registered
Joined
·
398 Posts
If your PCV valve is stuck wide open, you'll get full manifold vacuum to the crankcase and it'll cause the problem you describe.

Pull the PCV hose out of the valve cover and see if the engine dies or if the idle changes. If so, you might want to invest in a $2 new PCV valve.

Greg
 

·
Registered
Joined
·
3,700 Posts
http://www.hastingsfilter.com/engineering/tsb_94-2r.html

This site describes (Positive Crankcase Ventilation) ...

As said ... if the rings are sealing real well ... and the intake is sucking air from the Crankcase, the crank case has to take air in somewhere, by design that would be through a breather or a vent to the air cleaner assembly ... but trust me on this one ... air will enter from where ever it can


What you have going on is not a problem at all ... unless of course (as Greg said) the PCV is stuck "open"


_________________

Larry Madsen
Las Vegas Nevada



<font size=-1>[ This Message was edited by: MonsterMach on 5/2/02 11:21pm ]</font>

<font size=-1>[ This Message was edited by: MonsterMach on 5/2/02 11:22pm ]</font>
 

·
Registered
Joined
·
35 Posts
If you don't already have one you may want to put a vented breather on the other valve cover where you fill it with oil. They are made with a filter in them so you won't be pulling dirt in your engine from somewhere else.
 
1 - 5 of 5 Posts
Top