Fixing The Exhaust Pipe

I noticed my passenger side exhaust pipe was blowing quite badly. First meter of it was poorly made from flexible tube and the welds were terrible. Luckily the rest of the pipe was better so only the front part had to be changed.

At first I thought that I'd make the pipe myself but after crawling under the car for a while, I decided that it would be too difficult and dangerous without a lift. I called a few garages but most were on holiday. Finally I found JM Autohuolto from Järvenpää that could fix the it.

I drove the Corvette there in the morning and picked it up later. The new pipe had been build and welded together. I took a short test drive and the car sounded much better again. The nasty burble was gone as the exhaust was again flowing where it was supposed to.

Adding Stripes

I wanted to give a bit of new look for my car so I ordered some matte black 3M 1080 masking wrap from Automatrix. I decided to start small and just add some highlights for the hood bump. I began by taping some paper on the hood and marking the outline on it. After cutting it out, I used it as a template for cutting the tape.

I also painted the hood grille black so it matches the stripes.

I'm not absolutely sure if the car look better or worse with the stripes. I'll have to let the new look sink in a few days :) Luckily it is easy to peel the tapes off without damage. The 3M tape was really simple to use so changing the look is no problem.

Cabin Heat Problems

I took a longer drive with the Corvette and noticed that adding Stinger Roadkill to the cabin did not solve the heat issues in the car. It just took a bit longer for the cabin to become a sauna. So more needed to be done. I spent some time googling and many others have the same issues with C3 Corvettes. I found three different issues that I addressed:

1. Heater core isolation
2. Hood weatherstrip
3. AC and heater box sealing

Heater Core Isolation

The biggest issue was the heater core. I found that the heater feed hose should have a vacuum operated valve that cuts the water circulation when the AC temperature setting is in cold. The valve was missing so it meant that the heater was always working at full power! No wonder the cabin temperature rose...

Seems that many people have problems with the vacuum valve and have replaced it with a manual valve. As I only drive during summer, the heater is not really needed so I decided to do the same. And I can get a manual valve from the local hardware store as opposed to ordering from US. To completely isolate the heater core, I added valves to both hoses. Otherwise heat can creep up through the drain hose on long drives.

I found some nice, small ball valves, cut the hoses and installed them. It will be easy to replace them later if I decide to install an original vacuum valve. When doing this, just note that the feed hose (from the intake manifold) needs 1/2 inch nipples and the drain hose 3/4 inch.

While doing this investigation, I also realised that I need to find the vacuum hose that should feed the valve. And I found it sticking out from the firewall under other hoses and wires. It had been cut so it was causing a vacuum leak! No wonder the other vacuum operated valves in the dash did not work correctly.

Hood Weatherstrip

Another common reason for cabin heat is a perished hood weatherstrip. Mine was missing completely. I've had one for years but had not installed it yet... This allows engine heat to enter the cowl area where the fresh air intake is. This could be fixed with a little drop of glue so I got that sorted in a few minutes.

AC And Heater Box Sealing

While working under the hood, I noticed that a lot of air was flowing out of the heater/AC box. Sealing was mostly gone so nearly all of the fresh air from the blower escaped through the seams to the engine bay. I did not have the sealing kit available so I stuffed some foam in the gaps.

Results

I've taken some shorter drives with the car after these changes. Cabin temperature has dropped to much more tolerable level. It's still pretty warm but nowhere near the oven heat it was before. I also noticed that the car is much quieter now with the hood weatherstrip in place. I guess a lot of air was flowing through the gap as it was causing wind noise.

Unfortunately sealing the heater box did not fix the poor air flow in the car. Even with the blower at full power, there's hardly any air coming out of the vents. I'll need to investigate that a bit more.

Sony DSX-A50BT

I finally got fed up with the radio in my car. The USB connector did not work as the whole device shut down when I connected the memory stick. I even bought a memory card but that slot did not work either. I was worried that the problem was caused by the wiring in the car but as the radio was working normally, it did not seem likely.

The space in the car is very limited so I spent some time earlier trying to find a shallow head unit. The only one available (that I could find from Finland) was the Sony DSX-A50BT. I ordered one from Verkkokauppa.com, and it arrived in a day.

Installing the radio took about 5 minutes as everything plugged straight in. I tested the USB and Bluetooth playback and it worked perfectly. I was a bit worried that the unit did not have iPod controls but Bluetooth support could be used just as easily. Sound quality was also much better now!

On The Road Again

I took my Corvette for inspection last week. It did not pass because one of the rear brake hoses was leaking. Luckily it was only because the connecting nut had loosened when I fixed the parking brake during winter. I tightened the nut and the car passed the inspection today!

On the drive home I also tested the car on the freeway. I drove about 110kph for a few kilometers and there was no overheating problem anymore. Seems that it was caused by the wrong ignition timing.

New Tail Lights

I happened to find some pretty nice tail lights on sale in Finnshark. Mine are in horrible condition so I decided to buy them. I took a short drive today to get the lights and besides a few scratches, they were great. I also made a few other nice purchases but more about those later :) Changing the lights only took a few minutes but it really made a huge difference to the rear appearance.

Out with the old...

...and in with the new!

I've also been busy with the parts I ordered from Big City Corvette. I've installed the new side tail lights, rear window trim and driver side ducts. Installing the passenger side duct seems to require removal of some interior panels so I have not bothered yet...

Picture screaming "wash me!"

Setting Ignition Timing

Finding Top Dead Center

The ignition timing in my car has thus far been set to "seems to run" standard by ear. I've come to the conclusion that perhaps I should actually measure it before next summer. But, as always, there's a catch. The problem is the top dead center mark in the damper. I don't really trust that it is correct and even if it is, the water pump prevents seeing it at TDC.

Luckily I found an easy way to find the TDC without taking the heads off. I ordered a piston stop tool by Comp Cams from Amazon. It is quite easy to build a similar tool from an old spark plug but it is cheap so I decided to order one. Package arrived in about a week so I got to work.

To use the tool, I first needed a marker to the engine to use as reference. The power steering pump bracket was at a convenient place close to the damper so I decided to use it. I loosened one of its bolts, bended a small wire and placed it under the bolt.

Next I replaced the number one spark plug with the piston stop and very carefully turned the engine to clockwise direction by hand until the piston contacted with the tool. I added a small drop of paint to the damper where the marker was pointing. Next I turned the engine to counterclockwise until contact happened again and another small drop of paint was added. The top dead center is in the middle of the points. For me they were about 1,5 cm away from each other so I painted a longer line between the points. I bended the wire a bit so it was pointing at the line.

Finally I returned the plug to the first cylinder and removed all other tools from the engine bay so it was safe to start up.

Setting Ignition Timing

Another tool that I needed was the timing lamp. I went to Motonet where they had three different models:

• A really basic model that had no settings at all. It would just flash the light when the spark plug fired.
• Second, a bit more expensive one where you could set the wanted advance between 0 and 60 degrees.
• Third one was way more expensive but it had a lot of features: adjustable advance, a tachometer, volmeter and who knows what else.

To use the cheapest one, I would need to have the degrees marked to the damper itself. I could buy a ready made sticker or just count and draw them myself (damper diameter 8 inches * PI / 360 = 1,77mm per degree) but save some hassle, I bought the lamp with the adjustable advance. With that, I could just turn the knob until TDC marking aligned with the pointer and then read the advance from the lamp.

I began by measuring the initial timing. I removed and plugged the distributor vacuum hose and started the car. Without the vacuum advance the engine was idling (according its own tach) at only 400rpm so I tuned the carb a bit until it rose to 500rpm. When the engine had warmed up, I checked the timing and got about 38 degrees! Phew, that's what the total timing should be, not idle!

I turned the engine off to call a few friends and surf the web a bit. I thought I had done something wrong with my markings or something. After some investigation I came to the conclusion that it is possible for the engine to run with that much timing so it was time to correct it. I loosened the distributor, marked its initial position and started the car again.

I let the car settle to normal idle, measured the timing and got the same 38 degrees. I turned the distributor to clockwise until the advance showed 8 degrees. I was surprised that I only needed to turn it a few centimeters to get it correct. Engine also sounded better now.

Finally I also measured the total timing. I reconnected the distributor vacuum hose and asked my wife to help. She worked the gas pedal and kept the engine at 2000 rpm for me. There the advance was 30 degrees. What I read from the web, that should be OK.

Perhaps this was the reason why my engine started to get hot at high rpm on the highway? We'll see when driving season starts soon!