283 valve covers on a 350

[markeb01]

I wanted the appearance of a 283/327 Corvette engine on a 350 Chevy. I did a bunch of internet research and found no viable solution for the smog valve connection, so I came up with my own.

Following is one method to run early style sealed valve covers on a later small block - not having the road draft tube for crankcase venting. Most installations of this type I’ve seen have a hole punched in the top or side of the valve cover spoiling the cosmetic effect, or the smog hose connected to the oil fill tube just below the breather cap where it doesn’t vent the crankcase properly.

After careful analysis of the rocker arm to valve cover clearance, I was convinced a smog vent could be successfully connected to the rear of the passenger side valve cover where it would be difficult to detect. I designed the 2 piece adapter shown, and my son machined it out of aluminum. He made a few improvements from the drawings by substituting stainless flat head screws threaded into the external half of the adapter. The inside piece forms a shroud allowing oil to splash against the end wall and drain back into the head, much like a stock baffle. The external half provides the connection for the smog hose. In a conventional engine compartment the finished installation is nearly invisible. The smog hose routes behind the distributor (hiding the smog valve at the rear of the manifold) and comes up on the driver side, attaching to the rear of the carb via a fitted hard line.

Following are two pics of the finished installation.




Here are photos of the valve cover with adapter and tube attached:






This shows the connection to the rear of the carburetor. The smog valve can be seen in the upper right. It is Napa part number CRB29281.



And last, the original drawings for the adapter pieces.




After drilling holes in the rear of the valve cover, the two parts were assembled using red Loctite, cork gasket material inside, and thin composite material outside. The steel tube was a tight slip fit into the external adapter also adhered with red Loctite. There have been no oil control issues with this setup. The schematic does not indicate the curved hard tube which ultimately provided the best angle to hide the hose. If further stealth is required more effort could be put into the final shape of the external half of the adapter.

Since the Corvette covers are short, this method should also work with stock tin covers, Mickey Thompsons, or any type with a somewhat flat end wall. This arrangement may have clearance problems with roller rockers.

[Longhorn Man]

very good idea.
I would consider doing the same to the other side for a breather, and then plug the oil fill so it is a sealed cap.

[N2TRUX]

Another awesome FAQ by markeb01! I copied this to the FAQ Engine forum- LINK

[shadetree]

I had to search for this thread, to thank you for these pics, and the install info & drawings. Your engine graces my desktop as the "wallpaper". I cut my teeth on small blocks with these (old style vette finned) valve covers. I appreciate your sharing, and I am really impressed with your craftsmanship. thanks

[60ratrod]

wow thats got some injenuity behind it. i think that everyone here that's looked at this thread put their seal of approval on it.

[Winola73]

Not to take away from your ingenuity and craftsmanship because both are very impressive BUT, there is an easier way. Get an oil filler tube for a 1966-67 L-79 327/350HP. It's a chrome tube with a chrome twist in cap and it has a boss for a screw in PCV valve. It is a factory setup and unlike aftermarket versions did properly vent the crankcase. The L-79 was a high RPM Special High Performance engine used in Novas, Chevelles and Corvettes. It was even carried over as an option for a short time into '68 but rated at 325HP. All the necessary pieces are being reproduced. They pulled vacuum off a fitting in one of the rear intake runners or off the back of the carb where power brake cars picked up vacuum for the brakes. It's clean, simple and fits right in with the vintage Vette covers.

[425HP409]

This is an old thread, but I have to make one addition to it. If you are going to use the L-79 327 oil filler tube with the PCV valve screwed into it, you must have an early block (265, 283, 327, 348, 409) that has the opening behind the distributor where the the road draft tube or crankcase breather for the engine was installed for the engine. Later blocks do not have this opening as they used a valve cover for the inlet breather tube. You must have an inlet source for the engine to "Breathe" or the PCV valve will create a vacuum in the engine and cause it to "suck" oil past the rings.

[markeb01]

Another rather late follow up. The PCV equipped fill tube will indeed negate the need for my design of PCV adapter, but as noted in the previous response this won't work on a 350 block without a road draft tube opening behind the intake manifold. With the PCV on the fill tube and a breather on top, the PCV will draw fresh air from the breather cap and do nothing for ventilating the crankcase. Fresh air must flow from one end to the other (like my design), or one side to the other (valve cover breather on one, PCV on the other).

[wutnxt]

Yea I looked for a kit to do something like this and couldnt come up with one....So I have a few things I am looking at right now no solve the same problem on the same covers.... Your is mint great fab work and a very clean install .....You didn't happen to have a extra set of those made now did you ?....Lmao...I talked to my buddy who has a small C&C machine about making something similar to that but frankly your is very well done....Great job...

[bobinbc]

Dragging up an old thread here to show a different way to skin this cat lol
I had a set of those same covers that I wanted to use on a 350 block, here's what I did. Used an old Edelbrock C4B which has the provision for the oil fill tube. You can see where I drilled and tapped a hole for a threaded PCV valve, then made and attached a baffle plate on the underside. This set-up pulled fresh air in through the breather on the oil fill tube and didn't pull any oil through the PCV at all.

[Mike C]

OP's solution was really well executed. There are a bunch of variations of this on the Corvette message boards.

www.corvetteforum.com and search if you want variations.

[bobinbc]

Yes Mike C I agree his is well done. I don't want to take anything away from it but mine worked better for me. It didn't reduce my firewall clearance which was minimal. Also I had a few sets of covers, Cal Custom finned and Chevrolet script covers, that had no breather holes. This method allows me to change covers anytime without having to modify each set. Lastly, even though I don't have a milling machine or access to one for free, I was able to do this at home myself and it works perfectly. Of course, I had to plan ahead for this when building the engine, but that's ok because I knew the look I wanted before I even started to assemble the short block. Hopefully it helps someone else in a similar situation.

[mattfranklin]

A couple of pretty cool ways to do it.

[Stormin08]

Thanks OP...now i need new valve covers...i vented from the pass side and working on the driver !

NICE MOD !