To The Garage

We did our final preparations for the trip to the garage in the end of April. We attached the heater box so there wouldn't be a huge hole from the engine bay to the cabin, went through some of the vacuum hoses and checked why the speedometer didn't work. And naturally, as always when going through new systems in the car, we found more things to repair...

The vacuum hoses going to the AC control panel seemed to be in fair condition but the hose going to the actual vacuum source was cut near the firewall. I would have to attach it somewhere. I don't know the actual position where it would have been so I guess any vacuum hose from the intake manifold will do.

The speedometer proved to be more problematic. The speedo cable from the transmission seemed to be OK but things were different inside the transmission itself. The driven gear was in the transmission but the drive gear around the output shaft was missing altogether! After some reading around the net, luckily the driven gear installation didn't seem to be as difficult as I feared. We would have to remove the drive shaft, unbolt the rear section of the transmission and pull the output shaft out. Then we could install the gear. I also found an excellent picture explaining the situation.

After I received the missing parts, we fetched temporary plates for the car again and started driving to the garage. It was nerve wrecking to drive the car for the first time since it had gone through engine repair and nearly the whole electrical system had been changed. My friend drove the Corvette and I followed him in another car the 35km journey to the garage. At one point of our drive he called me and asked if something had fallen off the car. He had heard a loud bang from somewhere but everything still seemed to work. I had not seen anything so we drove on. The sound would be explained to us later...

In the end we got to the garage without other major problems. One of the rear lights wasn't working properly but other systems worked fine.

We got straight to work as we had a long list of repairs:

• Weld the driver floor
• Fix holes left in the firewall when the old floor had been screwed through it
• Change the rear body mount bushings and weld in new mounts
• Add the speedometer drive gear to the transmission
• Change the oil
• Add some washers to the rear leaf spring to rise the rear up

Dash Speakers

Before we could drive the car to the other garage, I still needed a few parts for it from the US. While waiting for them, I desided to install some speakers to the car. There should be some plastic brackets for them in the dast, but naturally they were missing. So, I had to build new ones myself.

A friend of mine works in a company that imports Kicker speakers to Finland so I had already bought some 4x6" speakers from him. They were the same size as the originals so they should fit but just needed the brackets. I desided to use fiberglass to make them as it should be a perfect material for it.

First I placed some cardboard to the speaker opening and covered it with foil. This way the fiberglass would not get stuck to the dashboard. Then I cut the fiberglass to suitable pieces and placed down three layers of it.

After the epoxy had hardened, I used a saw to cut out extra material and a file to smooth the edges. I didn't sand the whole thing smooth as it would not be left visible. I did apply some black paint just to hide the bracket a bit. In the end it worked as planned and I had some speakers in the car.

Finishing Up The Wiring

In the beginning of April 2011 I finally had all the new wiring harnesses as the one ordered from Full Throttle Corvette arrived. We got to work and I installed the redesigned headlight harness and my friend placed the dashboard harness in the car.

I had to cut some wires to correct length and solder some fusible links to them. Otherwise my job was just to attach all the connectors and use the hooks in the engine bay to route the harness. The dashboard harness seemed like a huge mess but was actually quite simple to install. Naturally the routing would need to adjusted when installing the interior but for now it went in the car without much pain.

After connecting everything up, it was time to test the system. We decided to do this carefully as every major wiring harness had been changed in the car since it last ran. And one was even completely redesigned by myself! We didn't connect the battery to the system but used a quite low power battery charger for the testing. This way if there were short circuits or some other problems, we would find them without melting the wires.

In the first test we left out all the fuses too and then connected the charger. This didn't cause any sparks or show any visible problems so next we added the fuses and tried again. Still no sparks! :) Then we went through the different systems. Lights seemed to work but there was something wrong with the front indicators. They blinked on the opposite side they should: left when turning right, right when turning left. We checked the system and found that the indicator wires were mixed at the firewall connector. They were correct according to Dr. Rebuilds diagrams but I guess the diagram had an error. We switched the wires and after this the indicators worked correctly. Note that this has been fixed in the wiring diagram in the previous post.

Testing the lights also confirmed that we finally got rid of the front brake lights! Before when pressing the brake pedal, both the front indicators lit up. Most likely this was caused by a splice added to the brake switch. Why? I have no idea! Perhaps it was some innovative safety equipment :)

As no problems were found, we removed the charger and added the battery. This way we could test higher amperage equipment. And we were really happy to find a lot of new working stuff: all lights, windshield wipers and washer, heater blower motor etc. Seems that it helps that the ground wires are not connected directly to the battery...

Then it was time to do the real test: start the engine. We turned the key and nothing happened! Luckily after a quick test we found that the starter solenoid wire was connected to the wrong terminal. We moved it to the correct place and the engine started right up and ran notably smoother than before.

Now we were almost ready to drive the car to my friends work garage and do what we originally intended half an year ago: weld the holes in the driver floor.

Redesigned Headlight Wiring Harness

As I mentioned in my last post, I redesigned the wiring in my Corvettes engine bay. Here's how I changed it and why.

Let's start with the why.

While going through the electrical problems in my car, I also learned that the wiring is far from optimal. Not nearly as bad as in the 60's but still there was a lot of room for improvement. I also wanted to add some new electrical stuff to the car and this would be difficult with the factory wiring.

I'm not an expert in car electrics but luckily I found the MAD Electrical web page. They have some great articles about electrical systems in muscle cars. After reading their texts (many times) I had had a pretty good idea what to do. The major problems were:

• Headlights
• New equipment

Headlights

Headlights of the -76 Corvette are the worst part of the electrical system. While looking through the Doc Rebuilds wiring diagram, I saw multiple problems. From the lamp itself the feed wire goes to the main connector at the back of the fuse box. From the fuse box it continues to the dimmer switch which selects high and low beams. Power to it is fed from the headlight switch which in turn has a power wire from the fuse box. Next in line is a fuse and then the main power wire from the engine bay and the battery and/or alternator.

Very simple and direct but crappy. First of all this creates a really long wire from the power source to the lamp thus causing voltage drop. This dims the lights noticeably. Secondly this means that all the current used by the lamps goes through the headlight switch causing corrosion in the connectors and might fry the switch. Third problem is the main power wire. A single 10 gauge wire feeds a lot of devices: radio, interior lights, wipers, rear lights, power windows and, of course, the headlights. That could be a lot of current through a single wire.

The simplest way to correct all these problems is to add relays for the headlights. This way a large power wire can feed the relay and the headlight switch just controls if current goes through it to the lamps. This shortens the way from the power source to the lamp, lowers the current that goes through the switch and naturally does the same for the main power wire.

Now, where to connect the feed wires for the relays? This brings us to the other major problem.

Adding New Equipment

I also wanted to add an electrical fan to my radiator. The clutch in the original fan was not working, the fan shroud was missing and the fan drained a lot of horsepower to turn. After removing it, the engine somehow seemed to run much easier.

Replacing the fan dictated that I would naturally need new wiring for it. In addition to the fan, I would also need a new temperature sensor to control it. I read a bit and decided that I would also add a relay for the fan and then control the relay with the temperature switch. If temperature got too high, the sensor would allow current to go through it which in turn would allow current to go through the relay to the fan.

To add all this new equipment, I decided that I need a central power junction from where it would be easy to distribute electricity. It would also be the place where the alternator charge and sensor wires needed to be connected. This way I would know that the junction had a stable ~14 volts. The factory wiring harness naturally also has a similar junction but it is just a splice of two wires inside the harness. It would be difficult to add any new electrical equipment to it.

That's pretty much it. With these guidelines in mind, I drew a new headlamp wiring harness diagram.

New Wiring Diagram

And there it is. Most of the wiring is the same as in the factory harness but let's go through the changes is detail.

• Junction: There is large power junction marked in the diagram. I also included an example picture how the junction could look like but almost anything will do. I bought a junction meant for car stereo systems and it works great as you can easily screw in more wires. There are two junctions in the diagram but this is just to get more room to draw the wires. If more than one are actually used, they must be connected together. Note that the engine wiring harness is now also connected directly to the junction.
• Battery: In the diagram the battery is connected directly to the junction. This is the best situation but not necessary. There is already a heavy duty cable from the battery to the starter. Factory harness is connected to the starter positive terminal and this is also what I did. I ran a new 8 gauge wire (with 12 gauge fusible link) from the starter to the junction.
• Relays: There are three relays in the new harness. For high beam lights, low beam lights and fan. Light relays are controlled by the light switch and fan relay by the temperature sensor. While building the harness, I wasn't quite sure where to place the relays. In the end I placed them far front near the left hand side marker light. After installing the harness I noticed that a better position would be in the fender near the alternator.
• Fan temperature sensor: The fan temperature sensor needs a constant power source. Connecting it directly to the red wires (ie. battery) is not a good idea because then the fan could be left running even when turning the power off from the ignition switch. Unfortunately there in no wire in the headlight harness that would be "hot" when ignition is on. Luckily the engine harness does have one nearby. The yellow wire going to the windshield washer pump will do nicely. I spliced a connector to this wire and connected it to the temperature switch. This way if the engine is running really hot, I can turn it off and the fan keeps running if necessary.
• Wiring: I tried to draw the connectors in the diagram in a similar position as they would be in the car. Naturally this is not completely possible but I think you can get a pretty good idea which connector is which from the diagram. Especially if you compare my image with the Doc Rebuild harness diagram. To build the harness, I had the original factory harness with me and I cut all my wire lengths according to it. This way I would get them correct right away. The new wires going to the junction are a bit more problematic. I left them quite long and then cut them when the harness was in the car.

And that's it. It took me a couple of nights to solder the new harness and then wrap it up in tape. Installing it to the car took a few hours and everything seemed to work correctly. Lights are now much brighter and the drain on the light switch should be much lower. All in all, I'm really happy with this new system.

Oh, and just one more precaution: if you actually build a new harness according to these instructions and your car goes up in flames or some other damage occurs, do not blame me. You do need to know something about car electrics before trying this stuff :)

Corvette Needs New Wiring

Now that the engine was finally working, we had time to concentrate on other things. The heater box and some air conditioner ducts had cracks so I took them home and my friend went through the wiring harnesses. I fixed the ducts with some fiberglass and then painted them. Perhaps they actually stay in place and won't leak any more when I get them in the car.

Meanwhile my friend made some interesting discoveries from the wiring. He was checking the AC wires when he noticed that there were sparks flying from somewhere. Quickly he found that a loose black ground wire made them when it hit the frame! WTF? He went through the wires in more detail and found that the AC ground wire was connected to the positive terminal of the starter motor. Which in turn was connected directly to the battery! This had caused a massive short circuit inside the harnesses.

After finding this he removed the AC, ignition and headlamp harnesses from the car because we could not trust them anymore. It was a miracle that the car even ran after the damage from the short circuit or that the car had not burned completely. There must have been quite a lot of smoke after this electrical genius had connected the battery...

I had to think for a while for what to do. I could order all new harnesses but they would still be as badly designed as the original and they cost quite a lot. I had been thinking about adding relays for the headlamps at some point and I also needed an electrical fan for the radiator because the original fan clutch was not working plus the fan shroud was missing. This would be a good time to add these!

In the end I redesigned the whole headlamp harness by adding a central power junction that fed two headlamp relays and a fan relay and sensor. My friend also rebuild the AC and ignition harnesses so every wire was replaced with new ones in the engine bay. This just left the dash harness. It was way too complicated to rebuild by hand so I had to buy a new one. I did some searching and found a shop called Full Throttle Corvette from eBay that had the cheapest price and would ship to Finland. After these changes every wire would be new in the car.

I'll write another post about the redesigned headlamp harness next...

New Cylinder Heads To The Rescue!

I went to spend the new years eve with my friend and we planned to get the engine running during the weekend. At midnight on friday, we first watched the fireworks, took a few beers and entered the garage. The "new" heads were already bolted on so while he started attaching the intake manifold, I took care of the oil pan. After a few hours, the engine was almost complete but still needed coolant, oil and a few hoses. Then it was time to go to sleep before the children woke up.

We continued our project on saturday and quickly completed the engine. After adding oil, we noticed that some of it had leaked on the floor. Luckily it was only caused by loose oil plug in the pan... Perhaps I should have checked it while lying under the car :)

Then it was time to start the engine. Unfortunately the battery was dead so a charging session caused a little break. After a couple of hours we tried again. The engine turned but did not start. Eventually we had to set the no. 1 piston to TDC and check the distributor. Its gear was off by one teeth... It had been off the engine too many times because we installed it according to a wrong marking.

Another try. This time the engine fired up right away! After a little distributor turning it was running great and everything seemed to be in order. If only it hadn't overheated... In a few minutes the temperature rose to the red limit and we had to stop the engine.

A quick check later we figured that there must be air in the cooling system. We started the engine again and my friend let the air out by disconnecting the heater return hose from the water pump for a second. After this the temperature dropped immediately to normal level. After doing this couple of times, the temperature settled to normal level and we let the engine idle for a few minutes. Then it was again time to take care of the children for a while and return at night to do a proper test.

We attached an electric fan to the radiator for cooling and started running the test. We ran the engine for half an hour from idle to 2000 rpm and it worked! Temperature gauge showed pretty stable 200 degrees fahrenheit (about 93 degrees celsius) and gone was the overheating problem! As happy men, we went to sleep.

On sunday we ran the engine again and took the car for a short test drive. There was a lot of snow on the road so you couldn't really touch the gas pedal but at least the engine was working and you could drive the car. Well, actually, we were really lucky that the whole car didn't burn as we later found out but for now we were really happy to finally see some progress in the project.

Engine Dilemma

After finding bolts from the heads, we had a small break thinking about our options. I would at least need new heads but we weren't sure if they were the only problem. New Edelbrock E-Street heads could be had for about 850€ but I didn't want to buy anything that expensive before knowing that the block is fine. If it wasn't, I would have to buy a new engine. Luckily a user from Finnshark told me that he had old but functional stock heads that I could borrow. This sealed the deal. We would test the old engine one more time with borrowed heads and see what would happen.

It took me some time to get the heads and take them to my friend so he also decided to have a look in the oil pan. It was leaking a bit anyway so this was a good time to change the gasget.

There was nothing alarming in the pan. Some dirt but not much. Block was also very clean and even seemed to have four bolt mains. Crank had two stamps: 3932442 and B237. So it was a basic 350 crank made in 23. of February 1977. There was still hope for this block.

Finally in the beginning of December I got the heads to my friend. He had to clean them a bit first but we talked that we could put the engine back together after christmas. I didn't have anything useful to do at home so I took the oil pan for painting. After stripping all the old paint and cleaning the dirt, I applied some POR-15 Chevy Orange to it.

Not like new but much better than before.

Then, at new years eve, it was time to put the engine back together one more time and see if it would finally work.