C1: Crate engine or rebuild?

[Robert I.]

Re: C1: Crate engine or rebuild?

Well, this is 2014 and I've just bought the 290/350 crate engine. I'm going to install it with the metal valve covers and PCV valve and solve the problem of running the original valve covers later.

Somewhere in the back of my mind I remember somebody addressing the PCV problem. There was a photo of some copper plumbing in the middle of the V. But I can't find that anywhere.

[Joe R.]

Re: C1: Crate engine or rebuild?

Bob,

I believe Tom Parsons provided some photos like that.

Joe

[Joe R.]

Re: C1: Crate engine or rebuild?

Well, this is 2014 and I've just bought the 290/350 crate engine. I'm going to install it with the metal valve covers and PCV valve and solve the problem of running the original valve covers later.

Somewhere in the back of my mind I remember somebody addressing the PCV problem. There was a photo of some copper plumbing in the middle of the V. But I can't find that anywhere.

Hi Bob:

I'm glad to hear how you eventually decided to proceed. This is a difficult choice and there is probably no "right" answer. I considered the same issue for some time and eventually decided to use an original 327 block to build a 383 (subject of an upcoming Restorer article). However, before I went that way I spent some time thinking about how to modify a 383 crate engine to duplicate the function of the original crankcase vent that the 327 had on the back of the block.

What is needed is a vent connection into the lifter valley. However, this connection must have an adequate oil baffle to prevent splashed oil from coming out with the crankcase gases. I recommend that you carefully study how GM did this using a rather large cylindrical baffle inside the lifter valley. We know that oil baffle works, so that is a good reference point.

Some people gain access to the lifter valley by boring a hole through the intake manifold in an area where the hole would not penetrate an intake runner. It would be a shame to do that to an original Corvette intake. There are several vintage aftermarket intakes that look very similar to the Corvette intake, so you could modify one of them instead. This approach still requires an appropriate oil baffle.

Another approach is to cut a hole in the back end of a valve cover to make it less conspicuous than a hole in the top surface. Again, this would best be done with a repro valve cover rather than an original. The design of the oil baffle would be challenging because you have to avoid hitting a rocker arm, but I suspect something adequate could be constructed. Perhaps an aluminum baffle could be TIG welded directly into the end of the valve cover.

A third approach that I recall Joe Lucia suggesting some time back is to bore a hole through the thin "China wall" at the back of the block to gain access to to the lifter valley. Since your crate motor will arrive without an intake anyway, you have easy access for this operation. The challenge would be coming up with an arrangement that provides an adequate oil baffle and an adequate seal at the China wall.

I think these are the three main options you have for maintaining the appearance of the original valve covers. Let us know what you end up doing, and include some photos (or maybe a short Restorer article). This problem of crankcase venting with a crate motor is one that many members have run into.


Joe Randolph

[Robert I.]

Re: C1: Crate engine or rebuild?

What is needed is a vent connection into the lifter valley. However, this connection must have an adequate oil baffle to prevent splashed oil from coming out with the crankcase gases. I recommend that you carefully study how GM did this using a rather large cylindrical baffle inside the lifter valley. We know that oil baffle works, so that is a good reference point.

So that's what's sitting in the valley on the old block!

I found this possible solution:

http://www.jalopyjournal.com/forum/t...covers.731232/

[Joe R.]

Re: C1: Crate engine or rebuild?

What is needed is a vent connection into the lifter valley. However, this connection must have an adequate oil baffle to prevent splashed oil from coming out with the crankcase gases. I recommend that you carefully study how GM did this using a rather large cylindrical baffle inside the lifter valley. We know that oil baffle works, so that is a good reference point.

So that's what's sitting in the valley on the old block!

I found this possible solution:

http://www.jalopyjournal.com/forum/t...covers.731232/

Hi Bob:

That's a great thread. As usual, some of the comments and suggestions are good while others are off-base. If you read the discussion carefully you will get a handle on the issue and some good ideas to consider.

As I recall, you have a 62 (?). I'm not sure whether the 62 Corvette used a simple draft tube or a PCV system. If you are trying to duplicate a PCV system, the important thing is to remember that the PCV system must have a filtered fresh air intake *and* a path to vacuum side of the intake.

GM used a few different locations for these two connections over the years. On my 67, the fresh air inake comes from the inside of the carb's air cleaner. Filtered intake air flows into lifter valley through the connection at the back of the block. The PCV valve is mounted in the oil fill tube at the front of the intake, drawing air out of the fill tube into the carb.

As you can see in the thread that you referenced, the key challenge is creating an adequate oil baffle so that oil does not get pulled into the PCV valve. That's why I suggested studying the baffle that GM used in 1962 as an example of something that is known to work.


Joe Randolph

[Joe C.]

Re: C1: Crate engine or rebuild?

What is needed is a vent connection into the lifter valley. However, this connection must have an adequate oil baffle to prevent splashed oil from coming out with the crankcase gases. I recommend that you carefully study how GM did this using a rather large cylindrical baffle inside the lifter valley. We know that oil baffle works, so that is a good reference point.

So that's what's sitting in the valley on the old block!

I found this possible solution:

http://www.jalopyjournal.com/forum/t...covers.731232/

You need a source of clean air entering the crankcase at the same rate as that being suctioned out. The Jalopy Journal solution doesn't seem to have a fresh air return, unless that system is using a vented breather cap. If not, then the crankcase will be under vacuum and pull oil into the chambers through the valve stems.

[Robert I.]

Re: C1: Crate engine or rebuild?

You need a source of clean air entering the crankcase at the same rate as that being suctioned out. The Jalopy Journal solution doesn't seem to have a fresh air return, unless that system is using a vented breather cap. If not, then the crankcase will be under vacuum and pull oil into the chambers through the valve stems.

From a thread on Corvette Forum: "5. Chevy offered a PCV system as an option for 1962. I'd build to that, rather than the road breather tube. The PCV system parts are readily available from the usual Corvette parts suppliers. Cheaper than the road draft breather tube too. The PCV system will keep your car's engine compartment and underside cleaner, to say nothing about improving air quality. "

I looked up in the Corvette Black Book and indeed there was a PCV system offered in 62 as a $5.40 option. But NONE were installed.

In a previous lifetime, I had a 350 hp, 65. Being a California car, this must have had a PCV system, but I don't remember it. It had the aluminum valve covers and there were no holes in them.

I found a photo of a Chevelle that had a rubber hose coming off the side of the oil filler tube. This must have been for the PCV system.

So there must be a way to rig up a PCV system without cutting holes in the valve covers.

[Dennis C.]

Re: C1: Crate engine or rebuild?

PCV systems were offered and installed for model year 1962. They were required for all vehicles shipped to California.

Dennis

[Mike T.]

Re: C1: Crate engine or rebuild?

The actual PCV setup using a spring loaded valve didn't begin, as I remember it, until the 66 model year. The system in place for 65 Corvettes was a simple carburetor fitting that had a metered orifice to allow a small amount of crankcase vapors to be drawn into the base of the carb and into the combustion chambers. If you are dead set on having the early script valve covers that had no openings, you'll have to get creative and either create an opening in the rear wall of the block or somewhere on the intake manifold but then you run into a problem having to fabricate that oil baffle to prevent excess oily vapors being sucked up into your intake. I still like the LT1 valve covers that showed up around 1969, you still get the finned look but one side will have the cap for adding oil and the other side will have the smaller grommet for the PCV valve.

[Robert I.]

Re: C1: Crate engine or rebuild?

"PCV systems were offered and installed for model year 1962. They were required for all vehicles shipped to California.

Dennis"

My car was picked up in St. Louis and then driven to California. Perhaps that's why it didn't have it.

[Gene M.]

Re: C1: Crate engine or rebuild?

When the hood is closed and you are riding down the highway nobody will be looking at the engine bay. The 62 will be noticed as a 62 and heads will be turning. What ever you put under the hood since the original engine the car was born with is gone will put the car in the "resto mod" classification. Even a restamped 870 correct dated casting is form of "illusion" of being original and/or real. But it's not and never will be. It is NOT the same as replacing seat covers or repainting. The numbers were only original to one car and one car only. A resto mod car is fun to drive and can be made to out perform the original. It sounds like you are adding ponies and will enjoy the new creation under the hood that you are building. It is your car so enjoy it as you like.

[Joe L.]

Re: C1: Crate engine or rebuild?

The actual PCV setup using a spring loaded valve didn't begin, as I remember it, until the 66 model year. The system in place for 65 Corvettes was a simple carburetor fitting that had a metered orifice to allow a small amount of crankcase vapors to be drawn into the base of the carb and into the combustion chambers. If you are dead set on having the early script valve covers that had no openings, you'll have to get creative and either create an opening in the rear wall of the block or somewhere on the intake manifold but then you run into a problem having to fabricate that oil baffle to prevent excess oily vapors being sucked up into your intake. I still like the LT1 valve covers that showed up around 1969, you still get the finned look but one side will have the cap for adding oil and the other side will have the smaller grommet for the PCV valve.

Mike------


The 1962 PCV system for Corvettes did use a traditional-style PCV valve. It is a VERY difficult part to find. However, other similar valves can be obtained rather easily and I believe these will function just fine.

[Mike T.]

Re: C1: Crate engine or rebuild?

Joe - I didn't know that. If the finned valve covers were intact, where was the valve located?

[Joe R.]

Re: C1: Crate engine or rebuild?

From a thread on Corvette Forum: "5. Chevy offered a PCV system as an option for 1962. I'd build to that, rather than the road breather tube. The PCV system parts are readily available from the usual Corvette parts suppliers. Cheaper than the road draft breather tube too. The PCV system will keep your car's engine compartment and underside cleaner, to say nothing about improving air quality. "

I looked up in the Corvette Black Book and indeed there was a PCV system offered in 62 as a $5.40 option. But NONE were installed.

In a previous lifetime, I had a 350 hp, 65. Being a California car, this must have had a PCV system, but I don't remember it. It had the aluminum valve covers and there were no holes in them.

I found a photo of a Chevelle that had a rubber hose coming off the side of the oil filler tube. This must have been for the PCV system.

So there must be a way to rig up a PCV system without cutting holes in the valve covers.

Hi Bob:

Any PCV system installed before 1968 had the available crankcase vent at the back of the block. This is how GM could avoid holes in the valve covers on pre-1968 small blocks.

The PCV system needs an intake port for fresh air and an exit port for crankcase gasses to go into the carb base. If you have an oil fill tube on the intake manifold, that provides a location for one of the ports, but on small blocks with no holes in the valve covers, GM used the port at the back of the block as the second port.

The problem that you have is that your crate motor lacks the vent at the back of the block. So, if you want to use valve covers with no holes, you have to somehow create the second port.

My impression is that the simplest and most common method is to drill a hole in the intake manifold in the area between the carb and the distributor. This provides direct access to the lifter valley. You still need to fabricate an oil baffle on the underside of the intake, but that can be done in several ways. The overall solution is very neat and clean, and the only visual evidence top side is a hose and PCV valve going from the carb to the hole in the intake. This is completely hidden by the air cleaner.

While this is the simplest and cleanest method, it requires drilling a hole through the intake manifold. Most of us here on the TDB would cringe at doing that to an original intake, but the counter argument is that hole is small and it could be filled in the future if someone wanted to restore the manifold to its original appearance.

Another alternative is to use an aftermarket intake that resembles the original. Such an intake would need to have the front oil fill tube. There are several vintage aftermarket manifolds that have the required features, and these can be found at swap meets or on ebay. In addition, I *think* Edelbrock sells a manifold today that has the boss for the oil tube hole. BTW, if you start searching for such a manifold, note that the oil tube pointed in different directions for different years of the C2.

Another poster noted that the 1968 Z28 valve covers have a family resemblence to the C2 Corvette covers, but have the required holes. I ran these valve covers on a previous build, and I think they are quite handsome. So, this is another option to consider.


Joe Randolph

[Tom P.]

Re: C1: Crate engine or rebuild?

Here is an example of what Joe is referring to about a hole in the rear of an intake manifold for a PCV valve plumbing.






Also, I have a SB400 in my 56 with FI. I put a hole through the rear of the block, going into the lifter valley and installed plumbing for a PCV valve. The end setup is essentially the same as a 63 FI engine (except the PCV valve is on the opposite side).






Here is another method of plumbing for a PCV setup with FI, including the needed baffle on the underside of the base plate.