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cletus

Kimjon's 64 Impala discussion thread

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I couldn't find a discussion thread so here it is

 

What is the little plaque in the glovebox?

Also IMO it's always a good idea to run a PCV system, the main reason being it gets rid of stinky fumes that get in the cabin  

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The brass plate is an original feature left behind from the cars illustrious past. It was a government owned vehicle, used as a dignitarys car. 

They were manufactured in Canada, exported to New Zealand as parts, and assembled in either Thames or Wellington. Well that's what I've been told by an enthusiast.

The factory righthand drive was a huge appeal to me. Left hook is okay, but righthand drive is just so much better.

 

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My vaccum line on the carb is already in use, so I'm struggling to see an obvious place to plumb the pcv valve.

If I ran the exit line out the downdraft hole, through the catch can, the to the air filter above the carb with a pcv inline between catch can and air filter...would this do?

I'll try sketch it and add a photo to this soon.

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Does the breather on the catch can let air in or out? I've always wondered why some have breathers and others don't. In my head they shouldn't have a breather but I don't know much about much to be honest ...

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2 hours ago, Beaver said:

Does the breather on the catch can let air in or out? I've always wondered why some have breathers and others don't. In my head they shouldn't have a breather but I don't know much about much to be honest ...

Same boat as you. I have knowledge, but no understanding.

There's a couple systems. Race car = catch the oil, passively vent the gas through the breather.

Or road car; from what I know, at high rpm engines dont make inlet vaccum anymore, so in turn at high rpm the pcv valve stops working, as theres no sucky sucky...so the breather on the catch can, then takes care of this by providing an escape route for the gases to go.

At low to mid rpm range like 90% of road cars will drive in, the inlet vaccum will suck these gases through and burn them in the motor, this passage is through the pcv valve.

Pcv valves are just one way valves, so flow is restricted in one direction only, it can't go backwards like an open pipe.

But yeah, knowing how shit work versus actually having done it are two different things. I've never had to do it...so you're reading the ramblings of a moron.

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Unless the engine is a bit tired or you do a lot of high rpm stuff, IMO you probably won't need a catch can, you could simplify it a bit by blocking that hole in the back of the block, put a pcv valve in 1x rocker cover and breather in the other

Or, if you want to use the catch can, put the pcv valve in it instead of the breather otherwise there might not be enough vacuum effect to suck all the gases out properly if theres 3 breathers  

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22 minutes ago, cletus said:

Unless the engine is a bit tired or you do a lot of high rpm stuff, IMO you probably won't need a catch can, you could simplify it a bit by blocking that hole in the back of the block, put a pcv valve in 1x rocker cover and breather in the other

Or, if you want to use the catch can, put the pcv valve in it instead of the breather otherwise there might not be enough vacuum effect to suck all the gases out properly if theres 3 breathers  

Is it okay to run the exit end to the air filter above the carburetor? Or do I need to find a port below the carburetor?

My air filter has a convenient hole in the bottom lid already that I'd like to use.

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For the pcv system to work properly it has to be plumbed in to vacuum. 

See technical drawing for how factory set ups are

15788033147826220639326540142232.jpg

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The breather inlet is sometimes a gauze in the oil filler cap but from memory most us spec engines used the air filter housing to suck clean air from by the 70s

Other tips- dont run the pcv off a single runner if your manifold has a fitting in it, it will make that cylinder run lean and idle funny, and dont 't' off the vac booster hose- use a separate port  

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Thanks @cletus that's what I thought, but didn't want to be true.

I'll machine up a spacer between the carb and manifold and put a hose barb in it to provide the vaccum required.

This is an opportunity to make a plastic spacer to help with a slight fuel evaporation issue I have. So maybe kill two birds with one stone.

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Need an inline pcv and an air filter 1/2" lower to avoid potential issues with rubbing.

 

 

Resized_20200119_200350.jpeg

But this is the plan for my vaccum source for the pcv.

 

 

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Okay, after literally hours of interweb reading I'm slowly becoming more enlightened.

The penny dropped when I discovered that there are 2 ways/types of pcv valve, both ways essentially achieve the same thing.

1) a tapered shaft, which restricts flow at high vaccum and allows more air to pass at low vaccum.

2) an upper and lower seat, does same as above.

So at high rpm, low vaccum the valve flows heaps. At low rpm, high vaccum the flow is severely restricted.

2019486712_images(1).png.8b3f4bde8243b4f0a5195781c49f41fb.png

Which brings me to size? I hear it really does matter...well that's what my wife says. But how big???

If it was fuel injected the extra air fluctuations are accounted for by the maf, but for carburetor engines this isn't possible. So I'm guessing the sizing is pretty important? You wouldn't want a mini cooper pcv on a dodge hellcat for example...

So more interweb geeking out to come...

 

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