Using script valve covers in NOM's...
Thread Starter
Administrator
Joined: Jul 2000
Posts: 53,996
Likes: 6,213
From: About 1100 miles from where I call home.
Using script valve covers in NOM's...
I'm sure this has been discussed before. I have a '58 with a '69 350, and I, like many people would like to use the Corvette "script" aluminum valve covers seen on so many 58-67 Corvettes.
The '69 valve covers came with breathers and an oil fill cap. Adding a replacement aluminum intake (Edlebrock) with an early style oil filler tube usually addresses oil filling problems and makes the look right. However, the issue is adding the valve covers without the breather(s). Concerns about the engine breathing/running properly, oil blow-by in the engine compartment, etc remain.
These 2 cars on ebay appear to have this set-up without cutting into the covers for breathers. Any thoughts on this? Is there a problem/solution I'm missing?
-------
http://cgi.ebay.com/ebaymotors/ws/eB...ayphotohosting
AND this car:
http://cgi.ebay.com/ebaymotors/ws/eB...557755670&rd=1
The '69 valve covers came with breathers and an oil fill cap. Adding a replacement aluminum intake (Edlebrock) with an early style oil filler tube usually addresses oil filling problems and makes the look right. However, the issue is adding the valve covers without the breather(s). Concerns about the engine breathing/running properly, oil blow-by in the engine compartment, etc remain.
These 2 cars on ebay appear to have this set-up without cutting into the covers for breathers. Any thoughts on this? Is there a problem/solution I'm missing?
-------
http://cgi.ebay.com/ebaymotors/ws/eB...ayphotohosting
AND this car:
http://cgi.ebay.com/ebaymotors/ws/eB...557755670&rd=1
Melting Slicks
Joined: Dec 2002
Posts: 2,257
Likes: 6
From: Mission Viejo California
You can use the oil fill tube that is threaded for a PVC valve and run it like that. The PVC valve screws into the side of the tube and the rubber hose goes to the carb. I think the 1966 and 1967 327s were made this way.
This way you get a low-cost simple solution and you're not venting the blow-by to the atmosphere.
Will this picture work?
This way you get a low-cost simple solution and you're not venting the blow-by to the atmosphere.
Will this picture work?
Last edited by Seaside63; Jun 22, 2005 at 10:06 PM.
Safety Car
Joined: Feb 2003
Posts: 4,068
Likes: 27
From: St. Joseph Mo
That solves the 'out' problem, but what about the 'in'. You will have to have a breather to let fresh air in, either in a valve cover or in the back of the block. The later 350 block lacks the vent can in the lifter valley.
Use the later covers for cross engine ventilation.
Use the later covers for cross engine ventilation.
Melting Slicks
Joined: Mar 2004
Posts: 2,965
Likes: 419
From: Melbourne FL
I don't think that quite solves the problem. The engine needs a filtered air intake somewhere. For his 350, that was on the valve cover. For the period engines with the script covers, they had a crankcase vent on the back of the block drawing air from a port on the air cleaner.
Thread Starter
Administrator
Joined: Jul 2000
Posts: 53,996
Likes: 6,213
From: About 1100 miles from where I call home.
Any guesses what the 2 cars on ebay are doing? I asked one of them and he just said his car ran fine.
Thanks for the suggestions, I'm starting to think I may have to add breather(s) to inconspicuous places on the covers, probably at the backside (closest to the firewall).
Thanks for the suggestions, I'm starting to think I may have to add breather(s) to inconspicuous places on the covers, probably at the backside (closest to the firewall).
Le Mans Master
Joined: Sep 2003
Posts: 8,934
Likes: 657
From: Norwalk ohio
2019 Corvette of the Year Winner
St. Jude Donor '15
I am planning on doing nothing at this point....my engine builder and I talked about doing something, but came to the conclusion that unless I was going to run the heck out of it, that for normal driving and some kick in the butt driving every now and then that the vents would not be needed.....he did see someone at a car show recently that solved the problem by taking a cover and machining out the script and then rewelding the left over end pieces together.
Then they closed the bottom to make a box out of it. Added a filler neck to it and ran some very SS small hoses to the back sides of the covers where a fitting had been welded in. They used this set up for filling as well as breathing. The covers and the box had been chromed. He said it had been tastefully done.
I plan on leaving it like it is.....no vents....let me know what you find out.....by the way, my 350 was out of a mid 70's Camaro...took it out and it was really tired....redid the entire motor....and it ended up as a 383 stroker......
Then they closed the bottom to make a box out of it. Added a filler neck to it and ran some very SS small hoses to the back sides of the covers where a fitting had been welded in. They used this set up for filling as well as breathing. The covers and the box had been chromed. He said it had been tastefully done.
I plan on leaving it like it is.....no vents....let me know what you find out.....by the way, my 350 was out of a mid 70's Camaro...took it out and it was really tired....redid the entire motor....and it ended up as a 383 stroker......
Le Mans Master
Joined: Sep 2003
Posts: 8,934
Likes: 657
From: Norwalk ohio
2019 Corvette of the Year Winner
St. Jude Donor '15
by the way....look at the '63...you can see that they used the covers with the casting flaw in it.....I found a real nice set with out the flaw...you have to look, but they are out there.....I am thinking of polishing my covers....thought about chrome...but I think the expense is too much for me....
Intermediate
Joined: Aug 2003
Posts: 30
Likes: 0
From: Rogers AR
This is how I fixed my valve covers
I don't know how to attach the photo to show how I fixed my crankcase venting, but I can tell you for a fact without the ventilation,oil will go everywhere on the underside of the car.
What I did was drill a one inch hole in the side of the left valve cover that faces the back of the carb, got a rubber grommet from O'Reilly's and put a PCV valve in and it is barely visible when the air cleaner is on and it works. NOM so why split hairs now?
Done this way it isn't really too obvious but if you want the solid valve covers this is the easy way to fix it.
If you email me at jacob.adcock@potlatchcorp.com, I can email you the picture of how it looks.
What I did was drill a one inch hole in the side of the left valve cover that faces the back of the carb, got a rubber grommet from O'Reilly's and put a PCV valve in and it is barely visible when the air cleaner is on and it works. NOM so why split hairs now?
Done this way it isn't really too obvious but if you want the solid valve covers this is the easy way to fix it.
If you email me at jacob.adcock@potlatchcorp.com, I can email you the picture of how it looks.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Every 2027 Corvette Engine Explained
Joe Kucinski
Designer Imagines A Corvette That Looks More Like a Corvette Than the Corvette
Verdad Gallardo
10 Ugly Corvettes That We Still Kinda Love
Joe Kucinski
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Advanced
Joined: Oct 2000
Posts: 54
Likes: 0
From: Winfield, West Virginia, USA
Forget the Intake
My '67 had the same setup (1969 350ci) when I bought it 21 years ago. Some Einstein had drilled a hole in left hand script valve cover and put a cheapo PCV. I bought a replacement script valve cover, put on the original PCV setup and let her go. I've driven it now for 21 plus years without a problem. I agree with your mechanic. Don't worry about the intake unless you're planning to raw dog it all the time.
Team Owner
Joined: Oct 2000
Posts: 38,897
Likes: 1,926
From: Washington Michigan
Originally Posted by Vettebuyer5863
These 2 cars on ebay appear to have this set-up without cutting into the covers for breathers. Any thoughts on this? Is there a problem/solution I'm missing?
-------
http://cgi.ebay.com/ebaymotors/ws/eB...ayphotohosting
AND this car:
http://cgi.ebay.com/ebaymotors/ws/eB...557755670&rd=1
-------
http://cgi.ebay.com/ebaymotors/ws/eB...ayphotohosting
AND this car:
http://cgi.ebay.com/ebaymotors/ws/eB...557755670&rd=1
The second one (the SWC) doesn't even have pressure relief - it has a sealed cap on the oil fill tube, and no other openings at all, and will have gasket and seal oil leaks as a result.
Here are two solutions for proper PCV systems on late blocks without the rear vent hole - either one will work fine, as both have an "intake" side for incoming outside air and an "exhaust" side with a PCV valve to the carb base.
This one uses the stock PCV valve and hose from the oil fill tube with a sealed cap to the carb, and an "intake" hose from the air cleaner to a hole on the inboard side of the valve cover:
This one uses a vented cap on the oil fill tube as the "intake" point, and has a PCV valve installed in a hole drilled in the intake with an oil baffle underneath it and a hose to the carb:
One gear at a time
Joined: Aug 2003
Posts: 5,244
Likes: 24
CI 8-9-10 Veteran
St. Jude Donor '07-'08-'09
JohnZ, I recently picked-up a cap that is supposed to go in the rear road draft tube vent hole (at the back of the block). The "cap" has a threaded hole in it that looks like it can take a PCV valve. Assuming the fitting takes a PCV valve, and a breather was run on the fill tube, would that provide adequate ventillation? Would the oil separator/canister under the intake still be needed? This would be for a 59 283. Thank you, Wes
Melting Slicks
Joined: Dec 2002
Posts: 2,257
Likes: 6
From: Mission Viejo California
My '63 has only Positive Crankcase Ventilation (first year of any pollution controls). There is no provision for negative pressure ventilation.
I am inclined to believe that there should be very little negative crankcase pressure (vacuum) due mostly to the presence of blow-by, where cylinder gasses are forced past the piston and rings into the crankcase.
It's hard to imagine a situation where gasses are sucked UP into the combustion chamber from the crankcase below. Any vacuum during an intake stroke would have to be more than offset by a power stroke elsewhere.
I also enjoy the second solution John showed with the PVC valve tapped into the valley cover of the manifold. Simple, sweet and innocuous.
I am inclined to believe that there should be very little negative crankcase pressure (vacuum) due mostly to the presence of blow-by, where cylinder gasses are forced past the piston and rings into the crankcase.
It's hard to imagine a situation where gasses are sucked UP into the combustion chamber from the crankcase below. Any vacuum during an intake stroke would have to be more than offset by a power stroke elsewhere.
I also enjoy the second solution John showed with the PVC valve tapped into the valley cover of the manifold. Simple, sweet and innocuous.
Melting Slicks
Joined: Dec 2002
Posts: 2,257
Likes: 6
From: Mission Viejo California
Originally Posted by Seaside63
My '63 has only Positive Crankcase Ventilation (first year of any pollution controls). There is no provision for negative pressure ventilation.
I guess that's what I get for trying to be an analytical smart-a@@
Thread Starter
Administrator
Joined: Jul 2000
Posts: 53,996
Likes: 6,213
From: About 1100 miles from where I call home.
Great help everyone. Thank you.
I believe I'll buy an Edlebrock #2101, open up the front boss and add the '58 style oil fill tube, along with the correct vented cap. I'll add the hole in the intake behind the carb and hose it to the carb. That should look nice and clean, and very stock-ish.
I also had some help from Rick who I found in the archives; he sent some nice pics of a drilled manifold with a welded baffle underneath. Great stuff.
See ya at Bloomington.
I believe I'll buy an Edlebrock #2101, open up the front boss and add the '58 style oil fill tube, along with the correct vented cap. I'll add the hole in the intake behind the carb and hose it to the carb. That should look nice and clean, and very stock-ish.
I also had some help from Rick who I found in the archives; he sent some nice pics of a drilled manifold with a welded baffle underneath. Great stuff.
See ya at Bloomington.
Team Owner
Joined: Oct 2000
Posts: 38,897
Likes: 1,926
From: Washington Michigan
Originally Posted by wesmigletz
JohnZ, I recently picked-up a cap that is supposed to go in the rear road draft tube vent hole (at the back of the block). The "cap" has a threaded hole in it that looks like it can take a PCV valve. Assuming the fitting takes a PCV valve, and a breather was run on the fill tube, would that provide adequate ventillation? Would the oil separator/canister under the intake still be needed? This would be for a 59 283. Thank you, Wes
