Friday, January 30, 2015

Better late than never

It recently occurred to me that, even though it's been done for nearly a year, I never posted pics of my finished AK.  In my last post, I had finished the assembly and test fired it.  After that, I stripped the whole thing down to refinished it.  After the all the effort with mediocre results with Tru-Oil on the Mosin, I decided to refinish the wood the modern way.  I sanded it down and sprayed it with semi-gloss polyurethane.  Not only is it much quicker and easier to use, a few shooting sessions have shown that the PU is more durable than the Tru-Oil.  It's much more scratch resistant, and just as easily repaired if it does get dinged(ie. I'm never using Tru-Oil again).  I sandblasted the metal parts and sprayed them with Duracoat in HK Black.  I also found a metal magazine at a gun show for cheap that I like better than the plastic Tapco one I was using, I'll paint it to match some day(I'm still 922r compliant with this magazine too).  Here's what I ended up with(bipod for pics only):




Monday, January 19, 2015

A big fat phony

Little known fact that most people would never guess: The oil pressure gauge in 94-96 civilian Caprices and Impala SSs is a fake.  It's nothing more than a fancy idiot light.  If there is more than 5psi of oil pressure, the needle moves up to a set point and does not change.  In all likelihood, GM did this to alleviate warranty claims.  The gauge it's self is perfectly real, but it's hooked up to a simple on-off pressure switch and fed through a resistor to make it read about 3/4.  Only the police Caprices got actual pressure senders, and gauges that move.

Because the gauge is real, and all the wiring is there, it's easy to make it work.  There are two options for actual pressure senders.  The first, and most obvious choice, is the factory police sender.  It's a direct swap for the original Impala sender, however it tends to be expensive, and is calibrated for 80 PSI.  Because it's an 80 psi sender, it will make the gauge read low.  A better choice is the Chevy pickup truck sender.  It is rated for 60 PSI so the gauge reads in a more "normal" range.  I'm using Napa # MPE OP6869SB, listed for a '90 Chevy 1500 pickup(though they used it for a wide range of years).  

The downside to the truck sender is that it uses bigger threads than the original sender, so you will need an adapter.  The adapter you need is 1/8" male pipe to 1/4" female pipe(picture shamelessly stolen from the internet):
Installation is as easy as unscrewing the original sender and screwing the new one in.  It's a tight fit since the sender is on the block behind the intake manifold, but it's reachable.  There is one other problem though, the resistor.  If we don't take the resistor out of the circuit, the gauge will read far, far to low.  Unlike the sender, the resistor takes some digging to get to.  It's wired in line with the gauge wire in the harness bundle stuffed above the glove box.  Since I had my whole dash out, it was right there, but if your dash is assembled it can be tough to reach.  In addition, GM seems to have found the stickiest tape in existence for their wiring harnesses.  Despite being nearly 20 years old, it's still as sticky and gooey as ever.  You can see where the resistor is in this pic.  It's the thing with the big red arrow pointing to it:
All you need to do is snip out the resistor, being sure to leave the tan wires connected to each other(these are the wires that go to the gauge).  Tape off the bare end of the tan wires, leave the black wire disconnected but tape it off too.  With the resistor gone, and new sender installed, the gauge actually works.  On my 166K mile car running Mobil 1 0W-40, the gauge reads around 5/8 cold, 3/8 hot.

Thursday, January 15, 2015

Filter the results

The Mighty Caprice™ always had a funny rattle coming from the front left corner that I could never track down.  Since I couldn't find it, I figured it was something loose behind the bumper since much of the original underbody filler panels were missing.  After doing some driving in the Impala, which has all it's panels in place, I was a bit annoyed to find that it had the exact same rattle.  I was working in the engine compartment one day, and unexpectedly found the source.

The stock B-body has two helmholtz resonators in the intake track.  They are there specifically to cancel intake noise at specific RPMs to help quiet down the car.  You can see them here, they are the big triangle shaped "home plate," and the rectangular "first base" in the lower right corner(pic shamelessly stolen from the internet).
Other than cancel noise, they don't help or hurt performance on an otherwise stock car.  Many, many years ago, I removed the resonators from the Caprice and built a "Home Depot" intake.  It consists of a hockey puck to plug the home plate hole, and replacing first base with PVC pipe.  While I was at it, I put on a K&N filter that I found cheap at a swap meet.  When I got the Impala, I didn't want all my hard work(Ha!) to go to waste so I swapped the intake onto it.
That's how it sat for nearly a decade on the Caprice.  With the hood closed, the filter couldn't really go anywhere, so I never really mounted it.  And that was the problem.  When I would go over bumps, the metal lip of the filter would rattle against the inner fenderwell.  Knowing where the rattle was coming from, I actually decided to do something about it.  Being cheap, I didn't want to have to buy anything.  Then I remembered that I had the factory airbox laying around taking up space.  Out came the sawzall and the grinder..
I hacked away at the airbox lid until the filter fit with the hood closed.  It's only job is to keep the filter from rattling around.  It's not the prettiest, but it works just fine.  You'll notice the AIR system inlet hose isn't really connected anymore too.  That doesn't matter at all because the AIR pump doesn't work on this car anyway.
As a side note, I see people running around with airboxes that are completely sealed from the rest of the engine compartment, many are even insulated.  The reason for this is to keep the intake air as cool as possible because colder, denser air makes more power.  The reality of the situation is this: from reading the intake air temp on a scanner while driving, if the car is moving the intake air temp is only a few degrees higher than ambient air temp.  The air is moving through the intake so fast that it doesn't have time to pick up any heat.  The temp difference is so small you won't see any HP gains, and all the airbox insulation in the world won't make any difference.



Wednesday, January 14, 2015

Same CAD time, same CAD channel

I like making stuff in Solidworks, and then machining it.  Occasionally, I even make things for other people.  Such is the case here.  I made a night light for a friend who is a bigger Batman fan than I am.  I started by drawing the pieces in Solidworks:
Then I machined them.  The bat is clear polycarbonate, the box is aluminum, and the base is an off the shelf GE 11375 automatic night light base.  The front of the bat is covered in black chrome vinyl so light doesn't show through the front, but reflects off the back. 



It's not as bright as I was hoping, but it works OK.

Tuesday, January 13, 2015

Spare some change?

Like many older B-bodys, my Impala jingled down the road.  Whenever you hit a bump, you'd hear a sound like spare change jingling in a jar.  While it's festive in the holiday season, it's embarrassing the rest of the year.  The problem is the sway bar end links.  Over time the rubber deteriorates and falls off.  When that happens, the washers on the end link bounce around causing the jingling sound.  The rubbers on my car were long gone.  Plus, the spacer was rusted to the bolt, and the spacer it's self was starting to crush on the ends from the sway bar smashing into it as the body rolled.  From the extent of the damage to the spacers, the guy must have driven it like this for the past decade.
The easiest thing to do is to just replace the whole end link.  Because the sleeve was stuck, I ended up having to sawzall through the original bolts anyway.   I replaced my end links with the Energy Suspension 9.8125G kit.

Since we're here anyway, another matter that should be addressed is the front bump stops.  The originals are just that, a hard rubber bump stop.  Not only was the original rubber pretty deteriorated, they don't really do anything to help handling.  There's a cheap upgrade here too.  GM used a special type of bump stop on their S-10 ZQ8 package.  Instead of just being a static piece of rubber, it's a urethane foam that is meant to be an active part of the suspension.  It's meant to always be in contact with the frame, and help control jounce.  It helps the car handle better for around the same cost as the original rubbers and the ZQ8 bump stops are a direct bolt on for the Impala.  GM no longer makes them, so Dorman has picked them up(any new GM parts are the same part in a GM box).  The Dorman number is 31064.  Here you can see the new ZQ8 bump stop next to the original:
With the sway bar loose, and the bump stops not doing much, the Impala floated down the road like a 70's land yacht.  I wouldn't say it handles like it's on rails, but it doesn't wallow down the road anymore.



Thursday, January 8, 2015

Chicks dig a guy with blink.

One of the fancy futuristic enhancements to the '94 B-body was it's digital dash.  No longer would we have to be slaves to a needle that told us about how fast we were going, now we would know the exact answer when the officer asks "Do you know how fast you were going?"  'Course like many "new" technologies, it's not without it's drawbacks.  In this case, the digital display starts going wonky.  Sometimes it works, sometimes it doesn't, sometimes just the odometer lights up or the speedo stays lit and odo goes out.  Any and every combination of not working can be seen, and it often blinks on and off going down the road.  For most people, the fix is relatively simple.  The digital display contacts the gauge cluster assembly through a bunch of tiny spring loaded fingers.  Over time, the fingers wear dents into the solder of the contact points on the back of the display board, and the connection becomes dodgy.  I'm not going to go through taking the thing apart, because step by step instructions can be found elsewhere on the internet.  You can see here the divots in the row of solder tabs along the bottom of the board.
The fix is pretty simple.  You just carefully touch each pad with a soldering iron, and the solder reflows into a smooth surface.  The only thing to watch out for is you don't want to accidently flow two pads together.  Here, the pads on the right side of the row have been resoldered.
With the pads resoldered, the fingers on the cluster get a gently scotch-briting to clean off any oxidation.  Sometimes it's necessary to very gently(very!) pull the fingers out a bit so they put more pressure on the contacts.  With that done and everything back together, my speedo lights up like it should.  There are some cars that this won't fix(my Caprice was one of them, I could never get it to work right), but for a majority of them, it does the trick.


I've got wood, but it's fake.

I've mentioned a few times that the Impala  came with one of those cheap woodgrain kits all over the interior.  It's basically a fake wood overlay that covers many of the plastic panels in the car.  It's supposed to make it look "classy," but is just awful.  Really awful.  On top of that, the clear was peeled off many of the panels, leaving the wood exposed.  The lower dash, window switch panels, center console, and door panel inserts were covered with it.
It's cheap, tacky looking, and just plain awful.  The worst part is that this cheap fake wood kit uses the best double sided foam tape 3M makes.  The stuff just does not come off.  Even with a heat gun and careful peeling, much of the tape stays stuck to the panel.  This is one of the main reasons I swapped the whole dash from the Caprice.  I didn't want to have to peel this stuff off the entire lower dash.
The small parts got soaked in mineral spirits overnight to soften the glue.  The big parts took lots of tedious fingernail scraping.  How anyone could think that this woodgrain looked better than the plain panels is beyond me.