Need Ideas for a Chevy 235 PCV and brake booster to coexist
Truck Geniuses, I have a challenge I'm trying to resolve without making it look like crap or buy too many expensive brass fittings.
I have a 3/8" steel line headed to the intake manifold to tap into the vacuum port that is commonly plugged. I also have a vacuum hose coming from the brake booster that needs vacuum from that same location. I have the ability to add an inverted flare fitting to the steel line. I'd really prefer not to drill another hole in the manifold....what approach would yall take to cleanly integrate both of these hoses into this one port? The intake manifold vacuum port is 3/8" NPT. Any ideas? So far I thought of an 3/8 NPT male to 3/8 npt female tee, then add a 3/8 NPT to 3/8 hose barb on one side, and a 3/8 NPT to 3/8 OD inverted flare adapter to the other... and thats a whole lotta fittings and crap. |
Re: Need Ideas for a Chevy 235 PCV and brake booster to coexist
Could you use a fitting with multiple ports? GM often resolved these issues with specially made fittings. There are many versions.
https://www.google.com/search?q=gm+v...w=1024&bih=622 https://www.corvettecentral.com/prod...03318.main.jpg |
Re: Need Ideas for a Chevy 235 PCV and brake booster to coexist
you can't run the PCV hose off the vacuum outlet in the Intake manifold behind the carb. It feeds off the back cyls. & will cause a bad miss at idle & low speeds & cause a rough idle. The power brake unit only draws vacuum on desceleration so it won't cause this unless the booster dia. is leaking. There usually is an outlet at the bbase of the carb for the PCV system.
George |
Re: Need Ideas for a Chevy 235 PCV and brake booster to coexist
I can't comment on what Wrenchbender says, but I have mine set up exactly how you are describing, I used this fitting... https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
with 3/8" line threaded into each side, then ran the hard lines to the PVC and booster. So far I've only yard driven the truck but it seems to work fine. You will need a 1/4" to 3/8" reducer/adapter bushing to fit into your manifold. |
Re: Need Ideas for a Chevy 235 PCV and brake booster to coexist
What Zenwren suggested should work.
I'd suggest putting a check valve in the line to the booster and you may end up needing a vacuum booster tank for the brakes They are sold by Summit, Jegs and other speed outfits for cammed up cars with vacuum boosters on the brakes to store up vacuum. That would let you have reserve vacuum for the brakes. Example https://www.summitracing.com/parts/s...+5ba29eacb7da9 I think some of the big luxury sedans in the 70s and maybe 80's with all the miles of vacuum hose and vacuum controlled stuff had reserve tanks but have no idea and those barges are few and far between in wrecking yards now. |
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George |
Re: Need Ideas for a Chevy 235 PCV and brake booster to coexist
This is my crusty 292. 500 bucks worth of polished aluminum in boxes and it is still grimy.
https://hosting.photobucket.com/imag...720&fit=bounds PVC line runs from back of valve cover to the intake. Red arrow. The plug on the outside of the intake would be for the brake booster. I see no reason to not run them of one Tee though . A breather with an actual filter in it will work fine at the filler hole of the cover. The line to the air cleaner on top of the carb just insures clean air going into the engine from the factory stand point. |
Re: Need Ideas for a Chevy 235 PCV and brake booster to coexist
Dave don’t forget to install a vapor separator in the booster line high on the firewall.
If you don’t in time the oil/fuel vapors we do a number on the p/b booster diaphragm and you’ll have to replace it . |
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Another option might be to use a spacer under the carburetor and add as many fittings as necessary. A phenolic spacer would insulate the carb slightly and could help prevent or reduce unwanted fuel vaporization. Today's fuel definitely does not perform like gasoline in the '40s and '50s. |
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Ford did that for years on their V8 engines using an aluminum plate with passages for what ever setup they were needing vacuum for. |
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Most of the thermac systems try to maintain a minimum of 90 degrees for emissions. But getting warm air into the crankcase sooner helps get the engine to temp quicker and helps keep water and blowby from condensing on the engine walls. And most folks are installing the PCV to "clean up" the inside of the engine, so why not go the extra step? It isn't going to make an engine run a million miles. IMO it's more like taking time to make sure the electrical connections are all clean if you're already replacing wires. |
Re: Need Ideas for a Chevy 235 PCV and brake booster to coexist
I’m a bunch confused here.
Thermac controls inlet air temperature into the intake and cylinders. Not into the crankcase. |
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It's up to the builder of course and ultimately it likely makes only a small difference. My '36 Plymouth hasn't gotten a PCV even though Mopar offered a "Vacuumatic Crankcase Ventilator" modification for those engines. I keep thinking about it and it's likely I'm going to do it eventually. The garbage the builds up in that block is incredible, even running detergent oils. For closed type PCV look at the bottom half of this drawing... https://i.pinimg.com/originals/f1/69...a5b5d4c510.gif |
Re: Need Ideas for a Chevy 235 PCV and brake booster to coexist
I see what you’re getting at but likely that warm air won’t make any difference in the crankcase temperature. Minuscule amount of warmish air mixing with a huge volume of air in the crankcase likely doesn’t amount to much.
Likely better heating for the crankcase could be had from an oil pan heater or water jacket block heater which helps on initial start up and run. |
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I just wanted point out something that most folks don't think about... |
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Here is a link to the PCV conversion I'm doing that replaces the road draft tube. |
Re: Need Ideas for a Chevy 235 PCV and brake booster to coexist
Well I had the bright idea of contacting the guy who created this how-to and he affirmed what ZenWren said, that compiling together the brass fittings is the most straightforward option, so I'll likely take that approach and I'll post photos on this thread when I'm done for search purposes.
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Re: Need Ideas for a Chevy 235 PCV and brake booster to coexist
This is a good way to eliminate the road draft tube.
http://devestechnet.com/Home/PCVInstall Many good tech articles and options for the Chevy and GMC sixes. |
Re: Need Ideas for a Chevy 235 PCV and brake booster to coexist
Now that my brain kicked into gear, I have changed a couple of stock valve cover 235's to PCV by cutting off the road draft tube an inch or so from the tube it runs off and putting a rubber plug for a PCV valve in the cut off end and sticking the PCV valve in it.
I think that we did it on one we built in the school shop that one of my students who did a lot of work on it now owns. |
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Re: Need Ideas for a Chevy 235 PCV and brake booster to coexist
Now you're talking..... That generally follows the Deve's approach.
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