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'72 K5 - Where do I go from here?

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So I get a good coolant temp from my edelbrock intake for my after market efi from that location.

My stock gauge uses the head though. Is that not an option? Not saying it's better, just how mine was setup by the p.o.
 
I found the o'ring I am holding in the picture below around the transmission dipstick (obviously I left it there a year and a half ago for a reason). So I start seeing where it fits - place I have it in picture is the only place I have found. Anyone know if that is the correct place? It's a 'square' o'ring (if that makes sense....)

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When I placed the carb on the intake manifold last night I discovered that I cannot use the vacuum port behind the carb (Edelbrock Performer 2104) because the carb hits (would have to put on a 2" spacer plate for it to clear, not doing that). Anyway, that got me trying to figure out what exactly my 'vacuum needs' are so that I can determine whether or not this is a serious problem. One of the things I wanted to see if I needed was a PCV. I came across this write-up and wanted to share:

For those who wonder if they SHOULD RUN or NOT RUN a PCV, consider the following:

Old road draft tube setups run on older cars could hardly be said to produce negative crankcase pressure. They are merely bleeding off crankcase pressure like ordinary breathers until you get up enough road speed to produce any delta P at all, and even then it can't be called much suction, more like fresh air being gently drawn in, at best. And high performance Japanese motorcycles that make way more hp per cubic inch than most of our stuff ever will, and that turn more rpm than most of our stuff ever will, for decades used only a single vent tube to simply prevent crankcase pressure from building up. They had no intake vent at all, they just simply couldn't build up any crankcase pressure. There was no ventilation flowing THROUGH the crankcase at all. Though they've changed now in more recent years due to emissions requirements. A PCV system does nothing to really help an engine per se, it really only helps overall emissions, which is why it was originally designed. Without it, blow-by would simply be released into the atmosphere, which has been a big no-no for decades, for cars, and more recently for motorcycles. A lawnmower is another simple example of not having a PCV, the same thing as the older motorcycles just venting to atmosphere. A PCV is also not the main mechanism to get rid of moisture, though air flow can help that somewhat. The main mechanism for removing moisture from inside the engine is hot oil above 212* boiling off the water. That's why numerous short cold running trips are harder on an engine than highway driving, because the short trips don't get the oilup to temp for long enough to boil off the water.

Race engine builders use crankcase vacuum pumps in order to use low tension rings for less drag and that vacuum pump helps those rings stay in contact with the cyl walls to retain cylinder pressure, plus the vacuum reduces windage issues, thus making more hp. They do not use it for crankcase ventilation, they use it for crankcase vacuum - big difference. There can be NO crankcase ventilation flow if a vacuum pump is to work. There can't be any CRANKCASE INTAKE VENT on those setups, because they have to create a suction of around 10 to 15" of vacuum, and there could be no suction if there is an intake vent. If there was an intake vent, they would not be able to create any vacuum at all. Here is a statement from a vacuum system supplier:

"Vacuum leaks in the crankcase, valve covers, distributor base, timing chain cover, oil dipstick, etc. reduce the amount of vacuum you will generate. You can easily check your engineby pressurizing it with air, be careful though, you don't need much to find leaks and you could damage gaskets and seals."

Here they are splitting hairs to prevent any vacuum leaks that would affect how well the vacuum system can work, so its easy to see that an open breather that would allow actual ventilation air flow, would render the vacuum system useless. This is a positive "vacuum" system but NOT a "ventilation" system at all. It's the same sort of thing with a header extraction system, only it is much weaker than a vacuum pump, and this one really only works at higher rpm. It also cannot have any crankcase intake vent or it else it couldn't work either.

Positive crankcase ventilation is not imperative to ring sealing and power production. Rings seal because of combustion pressure getting behind them and forcing them out against the cylinder walls. That's why ring side clearance is important, so that the pressure can get behind the rings to push them out. Race motor pistons often have a series of holes drilled in their tops just behind the rings, precisely for the purpose of getting max pressure behind the rings for optimum sealing.

Most hardcore hotrods and many sportsman race cars just use two breathers to vent the crankcase, and they have run just fine for many many years this way. Those engine's don't typically smoke or use oil either, if they are in reasonable condition. And two ordinary breathers will increase performance somewhat by elimination of the engine sucking spent blowby exhaust gases back into the combustion chamber, that a PCV would provide. A totally fresh mixture makes more hp, so not having a PCV does solve the problem of a PCV diluting the incoming charge. And you don't have to be Warren Johnson to appreciate this, because most hotrodders want to get all they can out of their engines. For anything less than truly hardcore race cars that run vacuum pumps, you also don't need to have a slightly lower pressure on the bottom side of the pistons as provided by a PCV system, to try to help high rpm power. The pressure difference between the very few inches of vacuum from a PCV and atmospheric pressure, is negligible to say the least, when compared to the enormous pressure above the piston. Consider a stout big block hotrod's combustion pressure which would typically be somewhere around 1,200 psi, and that is what pushes the rings out against the cylinder wall as well as pushing the piston down. So, a few inches of vacuum beneath pistons would do nothing compared to that. Not only that, but any teeny tiny gains you might theoretically make when the piston goes down with the aid of a little vacuum, you'd lose when the piston goes back up against that same vacuum. You always have pistons going up, while others are going down, for no net gain with regard to that idea.

So if people do want to run a PCV system, there is nothing wrong with doing that, other than you will lose a bit of performance. Remember, a PCV valve is at its most open position with low vacuum on it, so even with only a little bit of vacuum at WOT (which is an absolute necessity if you are to have any carb signal), you will still be sucking in spent blowby gases and reducing performance somewhat. And for those who don't want to run a PCV system, in order to gain a little extra performance and to simplify things under the hood, there is absolutely nothing wrong with doing that either, other than causing a bit more pollution. And running or not running a PCV system also has nothing to do with engine wear, oil change intervals or sludge build-up. Sludge build-up is a result of infrequent oil changes and/or engines running too cold, thus not boiling off the condensation. So, pick your poison, either ventilation system will get the job done. They are just two different ways of doing things. One makes a little more hp and one is more socially responsible.

Personally, I do not run PCV's in my Hotrods, never have. This stuff is not rocket science……………….
 
Small diversion this weekend - picked up a running 1951 Farmall. Runs great, everything works. Hell, I did some grading with it today, I freakin love this thing!

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Finally got a little time to work on the Blazer today. Been working (pay the bills work) far too much lately, with many weekends/travel mixed in. Figured out where all the wires go, and how the damn alternator mounts. Need to call Vintage Air this week to clear up exactly which unit I need (dryer?), and then I will order one. Someday......it shall run again!

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Dirsuper said:
Factory markings?

View attachment 251847
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Looks like it. I believe all the ones I saw on mine were in white grease pencil like that. I hate that I lost mine that were on the firewall when I sanded it down. If the part is original on the Blazer it almost has to be...only other folks that grease pencil stuff are salvage yards...and the ones I have seen are usually yellow.

Wish I knew a little more about the Chevy factory markings...that guy on Graveyard Cars does a good job with Dodge factory markings...but I've never seen or read anything on Chevy markings.
 
Alignment issues or am I good? Power steering to crankshaft and alternator to crankshaft/water pump are my concerns.......

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Far more than a smidge. Is it ok to use a spacer between the two pieces of the crankshaft pulley? I put one in there and got it lined up, but want to make sure I'm not gonna have it come flying apart......
 
Dirsuper said:
Far more than a smidge. Is it ok to use a spacer between the two pieces of the crankshaft pulley? I put one in there and got it lined up, but want to make sure I'm not gonna have it come flying apart......
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I wouldn't space the crank pulley, but I know they make spacers for the waterpump pulley. Not sure about the others. Longer belts can tolerate a bit more misalignment, but I'd keep everything aligned as close as possible.
 
Late start today after last night's festivities, but I think it's the wrong pulley on the power steering pump. I found the old pump and pulley (pulley is bent, I bent it trying to remove it) and it is a single groove, not the double groove I ordered for this one. Does anyone know the part number for the correct power steering pump pulley? Every bracket except the Vintage Air is stock, so I see no reason it should not all line up properly with the correct pulley.
 
In case anyone else is ever dealing with this issue, it is 3993325DJ. I found a thread on 67-72 talking about it (and took a wire brush to my old one). Apparently the 4X4s have a different pulley than the 4X2s. I found/ordered one off Ebay.
 
Too me, it looks like the p/s belt is too far out. What about putting the belt on the inner pulley groove on the pump? Hard to tell if that would fix it or be just as bad.
 
nvrenuf said:
Too me, it looks like the p/s belt is too far out. What about putting the belt on the inner pulley groove on the pump? Hard to tell if that would fix it or be just as bad.
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When I had v belts, that's how mine was setup. I remember cause it was a pain to change the belt since it was under the other one.
 
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