I just bought a new flame trap assembly from IPD. It is the first one I've seen with a removable flame suppresser. When I looked down into the molded casing, I was supprised to see that the diameter of the outflow tube after the supresser is reduced considerably by an intentional restriction.

Given that my brick has well over 200K on it and blowby is a natural consequence of wear, would it make sense to ream out the restriction in order to increase the crankcase ventilation flow rate?

Is this restriction designed to provide some sort of venturi effect?

I recently blew a crank seal during a 500 mi trip that saw some milage whiz by at 90+. (cafine induced throttle management...she hummed like a sewing machine). I'd like to avoid that job again although I'm getting good at it.

Thanks guys

/// The orifice is normally in the hose barb at the intake manifold. Is this the port you are discussing? Other than removing the orifice from the vicinity of the manifold to limit carbon build up, or providing a new one with this replacement part I don't know why this orifice is there.

I thought all flame traps were removable from the housing, I have never heard of non-removable ones before. Granted some may be difficult to remove due to age, gunk etc but they are supposed to be removable.

Not sure which you mean by the outflow tube, but I don't remember there being a restriction anywhere, just that the vacuum feed is a small diameter. The vacuum is regulated by the metering orifice (the brass fitting that screws into the manifold) os enlarging the hole in the flame trap housing will not make much difference. Reaming out the metering orifice in the manifold is going to introduce more unmetered 'air' thus leaning out the mixture slightly, not something to be recommended.

If you blew the crank seal I would guess that other parts of the PCV are still blocked eg metering orifice, hoses or oil trap. Do you pass the jiggle test?

If the blowby is enough to overwhelm a functioning PCV system then I would guess that the engine would not be running very well and burning a lot of oil. It should always be easier for blowby to escape via oil trap, flame trap and hose to intake than to blow out a seal so check the rest of your PCV system.

Mabey I was getting too descriptive.

The orifice I was referring to is actually in the replacement flame trap I bought from IPD. Normally the flame trap is a one piece unit but the one I got has a removable flame suppresser. ( the connical portion with all of the holes in it).

Without the suppresser installed, I can look down into the casing of the flame trap. The diameter is reduced from about 3/4 inch, the diameter of the connector to the oil trap, to about 1/4 inch. I thought that was wierd. Why would they restrict flow?

I'm going to try reaming it out just for the hell of it. The part is cheap anyway. I will be doing more high speed cruising and I want to keep pressure as low as possible in the crankcase to prevent future oil leaks.

Thanks for your help.

I still don't get it. All flame traps that I know about are removable from their housings. The flame trap itself (white plastic full of holes or spiral wound brass) is wider than the hoses in or out, this is because it needs to compensate for the restriction it causes. If you are saying there is a further restriction in the housing to below the diameter of the hoses then I do not think that it will make much difference either way.

You need to check you are getting vacuum from the manifold and that the oil trap is not clogged, this should be enough to stop pressure building in the crankcase.

if you find you have a problem with oil leaking while you are on your long drive do as i had to once and that is to pop the oil dipstick out about an inch or so to relieve the pressure,oil leak stopped and ran great.

then the oil would spew out of the dipstick hole and gets all over the wiring hardness and brake master cylinder. Took me 1/2 day to clean the whole thing.

Sure sign your PCV system is clogged somewhere.