original Miller head

[pat in Santa Cruz]

DSCN0192 by tiopato2000, on Flickr


I'm assembling a B engine with an original Miller head. I'll post some pics later of the poor thing before we got it to rebuild.

Someone in the past plugged the 2 vents in the aluminum valve cover. I assume this was because it probably blew oil all over the top. But I've always been a proponent of better crankcase ventilation. These engine must breathe.

My question is, does anyone with experience on these have any idea if plugging the vents is something that evolved into being "normal" or not? I'm inclined to re open them, but hope some other's experience might be available.

TIA

Pat

[sturgis 39]

That is a nice looking engine.

[BILL WILLIAMSON]

Pat,
Have you considered a very simple P.C.V. system? Mine on Minerva, my '30 coupe worked very well, kept the oil much cleaner and that dude leaked NO OIL! If I can help, just holler. Bill W.

[BRENT in 10-uh-C]

Pat I doubt that it "blew oil all over" as it was probably more of a vapor issue. I am curious to know if someone has modified the rocker shaft for pressure or if they are still lubed via an oil can? If they are lubed via an oil can (between races or street jaunts) then there probably wasn't much being spewed out. If someone has pressurized the shaft, then it is possible they had too much oil pressure where it was making a mess. I see the oil line behind the #2 exhaust pipe, but I cannot tell where it is going. (I also see the uncapped oil fitting in the side plate from the pressure rail.)

One area that does create a little concern for me is the amount of copper lines that you are using in both oil and fuel transfer. As you probably know, copper has a nasty habit of fracturing when subjected to vibrations, --which your engine will undoubtedbly create just by design, ...and by the use of Float-a-motor mounts.

[pat in Santa Cruz]

yes Brent, it has pressurized rockers. The other fitting is for a pressure gauge. Sharp eyes.

I am also aware of the copper tubing issue. The customer has not gotten back to us regarding replacing those, but thanks anyway for the concern as well as relating your experience with oil vapors. On my 27 Buick, which has vents on the cover, there is a baffle under the vent. I was thinking of fabricating one for this one. It seems to me that having vents in the cover would help pull the oil vapors up over the rockers and valves, which would be a good thing. The last head obviously suffered from too little oil.

I also hate float o motors. I have made B mounts from A mounts before. Its not difficult and it adds a lot of rigidity to the frame. Again, the customer needs to make the decision.. Perhaps when I show him how far his frame has already sagged he'll want to remedy that. It was jury rigged with a sawed off V8 mount as a shim under the FOM. Whomever restored this car was a good painter and a very lousy mechanic. Unfortunately I see way too much of that. You are obviously an exception to that rule.

[pat in Santa Cruz]

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Originally Posted by BILL WILLIAMSON

Pat,
Have you considered a very simple P.C.V. system? Mine on Minerva, my '30 coupe worked very well, kept the oil much cleaner and that dude leaked NO OIL! If I can help, just holler. Bill W.

I did think about that. Do you know the part number off hand for what PCV valve you used on Minerva?

[Dana Barlow]

A 5.0 v8 ford pvc is just a small "L" looking deal and would work well.
The new hiams look out of place to me.

[MikeK]

Originally Posted by Dana Barlow

A 5.0 v8 ford pvc is just a small "L" looking deal and would work well.

I don't think so. Everyone assumes all pcv valves are the same inside, differing only in mounting, material, and other physical appearance properties.

Actually there are three parameters in a PCV system. The first two, flow rate to the intake manifold and vacuum opening set-point are designed into the valve itself. That 5.0 V8 valve would likely flow far too much and open at too low of a set-point causing poor starting and running at slow and medium throttle. Also, placing a PCV valve in a different orientation (up/down/sideways) than original design will render it inoperable.

The third variable is the flow rate of the air intake, or 'breather' you are using to supply fresh air to the crankcase. The PCV SYSTEM is an application specific, engineered balancing act between drivability and benefits. Change a cam, change compression, change anything and the Detroit engineers tweaked the calibration. That’s why there are 100 different PCV valves, not one universal replacement with 100 adapters.

A starting point to 'guess' at what existing valves may have a semi-close set of specs would involve comparing the linear total of piston ring length and the peak horsepower. In an A the ring length totals 4 x 3.875 x pi = 48.7" Find a PCV app for an engine within 15% of that ring length and near equal to your peak HP and go from there. You will probably have to stuff one or more copper pot scrubbers in the oil filler tube to give some air intake resistance (third parameter). Without it idle may be rough.

[Jim Brierley]

Don't plug the vents, as you say, they are there for a reason. I too am not a lover of float-o-motors. a PCV system is a good idea, it can help reduce leaks.

[BILL WILLIAMSON]

Originally Posted by pat in Santa Cruz

I did think about that. Do you know the part number off hand for what PCV valve you used on Minerva?

Pat,
As best I remember it was a 1/4" N.P.T. valve for an early S.B.C. Originally screwed in the side of their oil filler pipe. I drilled & tapped it into the upper rear corner of the side cover. I bent the oil cap tabs in so the cap would be sealed, brazed a nipple on top of cap & ran a hose to existing nipple under my K&N air filter. (I was running a Weber carb & manifold) Bill W.

[BILL WILLIAMSON]

Originally Posted by pat in Santa Cruz

yes Brent, it has pressurized rockers. The other fitting is for a pressure gauge. Sharp eyes.

I am also aware of the copper tubing issue. The customer has not gotten back to us regarding replacing those, but thanks anyway for the concern as well as relating your experience with oil vapors. On my 27 Buick, which has vents on the cover, there is a baffle under the vent. I was thinking of fabricating one for this one. It seems to me that having vents in the cover would help pull the oil vapors up over the rockers and valves, which would be a good thing. The last head obviously suffered from too little oil.

I also hate float o motors. I have made B mounts from A mounts before. Its not difficult and it adds a lot of rigidity to the frame. Again, the customer needs to make the decision.. Perhaps when I show him how far his frame has already sagged he'll want to remedy that. It was jury rigged with a sawed off V8 mount as a shim under the FOM. Whomever restored this car was a good painter and a very lousy mechanic. Unfortunately I see way too much of that. You are obviously an exception to that rule.

Pat,
RE: oil vapors, I read that on the Novi-V8 with it's humongeous centrifugal supercharger turning a kazillion R.P.M's, it would literally rip out the bushings when fed by engine oil pressure. They plugged the oil supply & relied on crankcase "oil smoke" to lube the bushings, & IT WORKED!! Bill W.