No Pressure

It was with a certain sense of confidence that I went out to run errands with the ‘Bird last week. With the new spacer under the carb, I figured I was good for any distance and all the stops I wanted. Unfortunately, my confidence was misplaced. After the third stop on a 15 mile round trip, the engine died in traffic, just as it had in the past. I was able to re-start it and by holding it to a higher idle, find my way back home.

The question is, now what?

I put my fuel pressure gauge back on and took a couple of readings. At idle, with the car cold, I had a good flow of fuel: 4 pounds with the regulator in place, and a little over 5 with the regulator removed. (I took the regulator off, suspecting it to be part of the problem. It wasn’t, but the car is running fine without it, despite the issues I had before.) After a few miles and the engine warmed up, the pressure always dropped to zero (or close–the engine was still running).

After a lengthy discussion on the VTCI forum, suspicion has come to rest on the fuel pump, a restriction somewhere in the line or potentially a bad gas cap. The gas cap is an easy check; something I can do next time I run out with the car. Nonetheless, like the starting and charging system–which had to be replace in total–it looks like the road to reliability is all new parts from the tank to the carb.

Soaked

I am learning quite a bit about heat soak, in which the carburetor soaks up heat from the motor, vaporizing the fuel, turning a strong running motor into a sputtering embarrassment. On my ‘Bird there is a water jacket plate under the carb to help cool it. Turning off a warm engine (to go shopping, for instance) or sitting at idle (at, say, a series of long stoplights) stops or slows the flow of coolant and allows the carb to absorb enough heat to boil the gas.

Edelbrock Heat Insulator
Head insulator and gaskets. To the right is a new throttle spring bracket–still waiting for installation.

Not everyone seems to have this issue. Perhaps it is less of a problem for stock setups, and my Edelbrock is just more susceptible. Ethanol blend fuels are said to vaporize at lower temperatures then the gasolines of the past–it’s possible that the blends in my area are higher than average and also contribute to the problem.

I tried a Holley insulating plate a few weeks back. The insulation worked well, but the carburetor made obnoxious noises. I took that plate out and returned to just the stock water jacket.

Last week I was caught doing a series of errands in heavy rush hour traffic. After a few stops and long waits in traffic, the engine started to stumble and idle roughly. With my destination in sight, just across the intersection, I waited three agonizing minutes at a light while the idle got slower and slower. When it turned green, I feathered the throttle and just made it to the parking lot.

Washer Motor
The washer motor, before installing. Two of the three original installation holes are visible on the inner fender.

Well, that was enough. More research turned up a few Edelbrock insulation products that looked like a better match then the Holley. I found two kinds, wood fiber and phenolic. I couldn’t find anything to say the one type is more effective than the other, so I ordered a half-inch thick wood fiber insulator bored with four holes to match up to the carb correctly. (This thickness leaves about an inch of clearance between the top of my air cleaner and the hood.)

I placed an order with JEGS.com and the new part arrived Friday, just in time to install Saturday morning. Putting it in was simple. (Getting really good at the carb R & R now.)

Saturday afternoon I ran a series of errands in the madness of weekend traffic. We even took in a movie. Hot starts were effortless. No evidence of vapor lock in traffic. It’s hard to say “problem solved” after only a day–but greatly improved certainly.

Washer Motor
Washer motor installed. Now what?

While I was out in the garage, I sorted though some of the spare parts, trying to free up some space, and came across the washer motor. I think it was removed to make way for a high-performance ignition system (which I removed some time ago). I reinstalled it in what appears to be the original location. If anyone knows how the fluid lines are supposed to run, I would love to hear.

Today, though, I plan to be underneath, changing the oil and lubing the front end.

Throttle Stopper

When I purchased the T-Bird–wow, almost a year ago now–the double-jointed throttle linkage was flopping around under the hood and the gas pedal didn’t connect properly with the linkage under the dash. I cobbled together a fix and left the matter for another day.

Today, in fact.

Missing from the linkage equation was a throttle stop plate, which attaches to the upper bellhousing bolt. It doesn’t connect to the linkage, just gives it something to bang up against. (Why it was designed this way, I don’t know; it seems overly complex to me.) I got a replacement from Thunderbird Headquarters after confirming with the helpful folks on the VCTI forum that I was on the right track.The Throttle Stop

Turns out, this is a lesson in the dangers of non-stock modifications. The top bellhousing bolt came off easily, even with the linkage in place, but I couldn’t get the stop plate to fit at all. The transmission on my car is not original, and while it belongs in the same family as the one that should be there, it’s a poor fit. Like everything else that bolts to the tranny, the stop plate needed to be modified. I removed a substantial bit of metal to clear the bellhousing and install the plate. Modified Throttle Stop

I installed and removed both the plate and the linkage assembly a few times before getting the fit right. It’s a long stretch down there behind the motor. Even with long arms, it was a tiring reach.5/8th Wrench on the bellhousing bolt

 

The finished assembly.Thorttle Stop, Installed

Once correctly in, there was the matter of a connection to the carburetor. It’s a straight rod from the end of the linkage to the throttle actuator, but it has to be the right length. Too short and the gas pedal doesn’t properly connect. Too long and you can’t open the throttle all the way.

I “fabricated” a new connector rod from straight aluminum rod; basically cutting it to length and notching it where the set screws attach to provide a little extra security to those connections.Throttle Connection

The throttle response on my test drive was vastly improved. I was just going to go around the block, but I realized immediately that before, even with the gas pedal all the way down, I was at half-throttle at best.

To the expressway!

Wow. This car is fast. Much faster than I thought. Next stop, though, the gas station.