Cough Cough Choke...

...Hold my heart and stumble back.  Shed a tear as what was once in my wallet is no longer.  You don't want to know what these aftermarket Viper engine and transmission mounts cost.  Needless to say, the Viper Tax is significant.  On the plus side, I should never need to replace them again.

This is important.

AK 47s are known for their reliability.  There are videos of guys on Youtube literally filling their guns with all kinds of stuff and still having them function.  Some examples HERE, HERE, HERE, and HERE.  As previously mentioned, the reason for this is loose tolerances.  Everything has enough clearance in it that it takes a whole lot to make it jam.  In fact, even jam won't make it jam. 

There is only one place on the entire gun that actually needs to be precise, and that's the headspace.  In simple terms, headspace is the amount of room the cartridge has to move fore and aft in the chamber.  If your headspace is too tight, the bolt won't lock closed, causing it to blow up when fired.  If the headspace is too loose, the shell case ruptures, causing it to blow up when fired.  So, it's either right, or it blows up.  On the AK pattern rifles, the difference between "right" and "blows up" is six thousandths of an inch(.006").  That's two sheets of notebook paper thick.

Headspace on most rifles is set by how far the barrel is installed into the receiver.  Many barrels are screwed in, but the AK barrels are pressed in.  A rubber mallet won't work well because the barrel depth is so critical.  A press works best, but I don't have one.  So, I made another special tool.  The main piece is a chunk of grade 8 all thread.  Grade 8 is necessary because the standard hardware store stuff isn't strong enough and will snap.  The barrel end uses some copper washers to keep from marring the barrel, with some regular washers and a nut after that.  The receiver end uses the bolt carrier to press against with an 1/4"  steel plate behind it to keep it from getting marred up.  It works pretty well, just tighten the nuts, and the barrel presses in.  It's a slow process of tighten, check, repeat.  Real actual headspace gauges are available, but are expensive.  Instead, I used a bullet as my "Go" gauge, and the same bullet with .006" worth of aluminum tape on the back as my "No-Go" gauge.  When it's set right, the bolt will close and lock on the Go gauge, and won't close on the No-Go gauge.

No clever title...

While I was working in the engine compartment, I took care of a minor, yet annoying thing on the Viper, he throttle cable. There is a stud sticking out of the intake that a cable holder snaps onto. On my car, the plastic snaps are worn out, so the cable doesn't stay attached to the stud. It doesn't affect functionality, but it looks bad under the hood.

It's a pretty simple fix.  I just wrapped the stud with a few winds of plumber's tape.  This makes the diameter a bit bigger so the snaps fit tighter.  Any tape would work, I went with the plumbers tape because it conforms to the threads better so the snap gets a better "bite."  It's good and snug now, and the white tape doesn't show.

You've got to plug the holes with something

I was getting some occasional misfiring in the Viper I decided that I should probably change the spark plugs as a first step.  Here's how the job started:


Me: "I need some spark plugs"
Guy at the counter "Ok what have you got?"
Me "Champion part number RC12LYC"
Guy "OK, I've got lots of those in stock, how many do you need?"
"10"
"Oh. Well, I've got nine of them."

For how big the engine is and how small the car is, getting to the spark plugs is pretty easy.  On the pass. side, I highly recommend removing HVAC plenum.  It's only four screws and really open up that side of the engine.  After pulling a plug, I'm pretty sure that the plugs in it were the originals.  47,000 miles is well past their service life.  The electrodes were very well worn.  Here's the old next to the new:

Since we're dealing with aluminum heads, the new spark plug threads got some anti-seize on them, and the boots greased with Dielectric grease.  Speaking of boots, since they'd been on the plug so long, some of them were pretty stuck to the spark plugs.  In pulling one of them off, I managed to break one of the plug wire separators.

They're made from a fairly brittle plastic, and 17 years living above exhaust manifolds didn't help the situation any.  Fortunately, this type of plastic super glues very well.  I know it's a cheap part to replace, but a fixed free one is still cheaper.  I can always replace it later if it breaks again.

That's hot.

I don't have any pictures of how to place them, but with the trunnion installed, I could locate and weld in the bolt guide rails.  They just get spot welded into the receiver.  Here you can see the left side rail.  It's also got the shell ejector on it.

Before we continue assembling the receiver, it first needs to be heat treated.  There are three areas on an AK receiver that need to be hardened.  They are the holes where the trigger and hammer axis pins go, and the ejector tip that kicks out the spent shell.  The AK-Builder receiver flat is made from 4130 chromoly steel, and is oil hardenable.  That means, you heat it up, dunk it in oil, and it comes out hardened.  Me being me, I always have a variety of flammable gasses and used oil laying around.  Propane doesn't quite burn hot enough to get 4130 over it's critical temperature, so MAPP gas needs to be used.  First step, heat the area we want hardened.  The holes are spaced far enough apart that they need to be done one at a time.

Once it's as hot as it's going to get, it gets dunked in the oil:

I didn't really think this one through.  Since I don't drink coffee, I don't have coffee cans laying about, so I used a plastic bucket.  It works fine, except that I forgot that it melts.  The ring right at the top of the oil started melting away...oops...

Hardening this way actually makes the metal too hard, and it becomes brittle.  It needs to be tempered.  So into the oven it goes at 500° for 45 minutes.  This will draw the hardness back to a more reasonable level so it's hard without being brittle.  Here's how it looks now.  Much less pretty than before, but since it'll be painted anyway, the discoloration doesn't matter.

Front trunnion

Because the receiver on an AK is just sheet metal, it needs some other bits attached to it to actually be functional.  One of the most important is the front trunnion.  It's the piece that holds the barrel.  Like all the other pieces, it gets riveted in.  We can't just slid it in and rivet it though, there are no holes in the receiver for the rivets, and because the trunnion slides into the receiver, you can't see the holes to mark them.  Now, I could measure, mark, drill undersize, and file the holes to an exact fit, but even typing that sounds like a lot of work.  There's a much simpler way.  Enter the Post-It note.  You can see here the three holes we need to transfer, with the Post-It note attached to the top of the trunnion:

With the Post-It flipped down, a pencil is used to find the holes the same way we all did to make textures in grade school:

Then the trunnion gets slid into the receiver.  You'll notice that I've got the magazine in place too.  That's because the trunnion locates off the magazine, and the magazine locates off the trigger guard, and that's why the trigger guard was our first step. 

The Post-It note is now outside the receiver, while the trunnion is inside, and we know exactly where to center punch the rivet holes. 

With the holes located and drilled, we have to install the rivets.  It's once again time for a special tool.  We'll call this one the Harbor Freight Bolt Cutter Rivet Smasher Tool™.  It's one of those tools who's name describes everything about it.  It's a Harbor Freight 24" bolt cutter with rivet smashing jaws.  Most people modify the stock jaws.  I didn't want to because the bolt cutters cost me a whopping $14 and I might actually want to cut bolts with them some day.  So, I made my own jaws from some 3/8" steel plate.  The skinny side has a flat face for smashing the rivet, the round side has a 5/16" dimple to support the rivet head:

With everything ready to go, I painted the inside surfaces with Duracoat so that there wouldn't be any bare metal in where moisture might get and I couldn't clean.

Here's the HFBCRST™ in action.  It works pretty slick, and smashes the rivets right over.

Here's what we end up with.  The rivets are smooshed flat on the inside, and the heads are still nice and rounded on the outside.  Even though the receiver is already classified as a firearm, it still is no where near being operable, but we're one step closer.

Plate

WI requires all cars and trucks to have a front license plate.  Usually, I don't mind, and I've always run them.  I've also always had a front bumper that made mounting easy and unobtrusive.  That's not the case with the Viper.  Front plates on these things stick out like a sore thumb, and generally look terrible.  There's also the matter of drilling holes into a $1000 bumper for a bracket.  No-drill removable brackets are available, but again, the car looks stupid with a plate hanging off the front.  I opted to put mine on the dashboard.  After putting it on the dash, I needed something to make sure that the plate stands up in the window and doesn't slide around.  Tape would work, but look tacky.  So, I came up with another solution.  I went down to the hardware store, and found some suction cups that fit into the bolt holes.  They work like a charm, keep the plate in place, and are almost invisible.  It's technically still not legal, but is one of those things where you generally only get called on it if you're doing something else stupid or are a jerk to the guy who pulls you over.

En Garde!

AKs are best known throughout the world for their incredible reliability.  That reliability is due in large part to the loose tolerances they are built with.  Everything in the mechanism fits loose enough that they can be packed full of sand and mud and still work.  Given that though, there are some places where tight tolerances must be maintained, and they are primarily in the parts that make up the complete receiver.  Everything in our receiver is located off the magazine, and the magazine locates off the trigger guard.  That means that installing the trigger guard is our first step, and everything else will locate off it.  Because AKs are sheet metal, they were originally riveted together.  The internet rages with "rivet VS screw" debates, and both work equally well.  I think the rivets look better.  Plus, I get to make more special tools for them, and that's half the fun.

To rivet the trigger guard on and make sure it's square, I needed another a jig.  The jig holds the trigger guard and all five of the necessary rivets.  Like the bending jig, they are available, but too expensive for a single use.  Mine is an aluminum base with a steel top plate.  Here you can see the jig with the dimples for the rivet heads:

Here's how the trigger guard and rivets sit in the jig:

After getting everything aligned and clamped down, I used a punch to smash over the rivets on the inside of the receiver:

With all five of the rivets smashed, we're done with the second step in our AK build and we have something that is starting to look like a gun.

Get Bent

With all "Parts Kit" guns, the receiver is destroyed or missing entirely.  As shown in my first AK post, with AK variants it's the latter.  To lower the cost and speed up production, the Soviets switched from a milled steel to a stamped sheet metal receiver when they switched from the original design of the AK47s to the AKMs in the mid 50's.  This makes AKM receivers fairly easy to make with some skills and the proper tools.  There is a thing in the AK world known as a Receiver Flat.  It's basically a flat piece of sheet metal with some holes stamped in it.  The BATF has determined that a flat is not a firearm and because of this, they can be sold to anyone without having to go through a licensed firearms dealer.  Here's what the AK receiver looks like(not my pic):

To build an AK receiver, we'll need some special tools.  The very first step is to get the thing bent.  A regular brake won't work because the bends are deep and at 90°.  To make sure everything stays straight and square, a special bending jig is required.  Like everything else, jigs are available online, but are far too expensive for a one time use.  So, I made my own using some 1/4" angle iron, some 3/8" plate, and a hunk of aluminum.  After making a jig to make the jig, here's what I ended up with:

There's not much to it, but the spacing needs to be fairly exact.  The receiver flat gets bolted between the "T" steel and the aluminum block.  I don't have any pictures of the actual thing, so just pretend that this cardboard is our flat:

Then you put the jig in a press, and press the thing down.  The aluminum block acts as a guide to make sure it gets pressed straight.

When it's removed from the jig, you're left with a bent AK receiver(again, not my pic):

Congratulations, you've just turned a piece of sheet metal into a firerarm.  The instant it's bent, even though it's no where near being complete and shootable, it's now a firearm in the eyes of the BATF.  With the flat bent, the rest of the parts can be mocked up and test fit:

Just a pic

I was digging through some old folders, and came across this one.  Every now and then, I can take a good picture...

I need to vent a little

I made another small but incredibly important addition to the Viper.  For whatever reason, the power steering caps on the Vipers have a tendency to work loose.  When that happens, you get power steering fluid splashing onto your nice and hot exhaust.  The end result is often calling your insurance guy and finding a new car.  There is a very simple fix for the problem.  All you have to do is add a vent line to the cap.  The vent prevents the cap from turning so it can't fall off.  Like many of the things I've made, there is a commercially available vent kit, but we all know how cheap I am.  I took a chunk of 3/8 steel line and some hose that I had laying around and made up a line.

It has some twists and turns to clear everything on it's way down to below the frame rail.  It's pretty long, and there isn't really anything to attach it to under the car.  Since it has to move with the engine, it couldn't be attached to the frame.  This left me with a very long and unsupported tube hanging off a plastic cap.  With all that weight dangling there, I didn't really like how it was mounted and was concerned about it vibrating and damaging the cap.  After sitting on it for a few days, it occurred to me that it's a vent, not a drain tube.  It's only real purpose is to keep the cap tight so it doesn't need to be anywhere near as long as I had it.  So, I made another one.

This one extends just past the PS pump and is much more manageable.  It's not the prettiest, but once installed, it blends in with the rest of the engine compartment.  I may switch to some better looking line in the future, but for now, this was a no cost mod and I can quit worrying about the car bursting into flames from a faulty cap.