SU HS2 Carburetor

A few weeks ago I removed the carburetor from the Morris to rebuild it. Progress has been slow, mostly because I had no idea what I was doing so I didn't want to get in a hurry and mess anything up.

I have been doing a lot of reading and it is starting to pay off. I am beginning to understand how it all works, including why the gas vaporizes in a carburetor. After reading many many different sets of instructions on how to adjust it, and they seem to differ wildly, I hope to get it all figured out soon.

Last night, I successfully got the jet centered. It took several attempts, but once I got it right, it was dead on. Tonight I installed the carburetor back on the manifold. (I haven't hooked the throttle or choke cables yet.) After getting it mounted, I gave it a shot of starter fluid and attempted to turn the motor over. Unfortunately the battery was dead so after hooking up the charger I hit the starter switch again. It cranked up (and ran very smoothly) until all the starter fluid burned off. Two more attempts at cranking it before the bowl finally filled with fuel and the car started running off gasoline. I was fairly impressed with my efforts at this point because it was probably running smoother than I have ever heard it.

Tomorrow I plan to get back out to the garage and adjust the fuel mixture, idle, and fast idle. Hopefully it will all come together without much trouble.

(Dirty carburetor, before cleaning.)

Did you know that the reason fuel atomizes in a carburetor, is that when air passes through a venturi, the air speed increases thus causing the atmospheric pressure to decrease. (This decrease relative to atmospheric pressure is a slight vacuum.) The decrease in air pressure lowers the boiling point of the gasoline. The lower boiling power causes the gas to vaporize. Any extra fuel that does not vaporize at this point, will vapor due to the heat as it flows through the intake manifold.

My daughter would say this was "very interesting." This of course would mean she was not really listening.

SU HS2 Carburetor Rebuild

The SU HS2 carburetor off the Morris Minor has been on hold for a couple of weeks. I had two problems that needed to be solved (without causing any permanent damage).

1) The brass jet was stuck in the jet pilot. This was keeping the jet from moving when the choke handle was pulled. I believe the strongest adhesive in the world is probably varnish made from dried gasoline. After soaking the pieces in carb cleaner for two weeks, they were still stuck. The solution to this problem turned out to be taking a propane torch to the brass for about 10 seconds and then dropping it in a bucket of water. Presto! The parts had separated.

2) The threads for the jet locking nut on the carburetor body had been cross-threaded at some point in the past. This made it impossible to put the nut back on correctly.

It was suggested to me that I could remove the first row of threads using a roto-tool. It would probably work but I was not certain I would improve the situation.

I checked the net for a tap and die set so I could clean up the threads. The problem here is that the nut has 3/8 Whitworth threads. (Three-eights of what? Not metric, not SAE. Whitworth!) I found a set online, but wasn't sure I wanted to throw $40 at the problem. I would if that turned out to be the only viable option, but I continued to search for other options.

I ended up borrowing a 3/8 Whitworth wrench from Lott. Using the wrench I was able to non-forcefully coerce the nut back across the threads. After a few twists back and forth, the threads were clean enough to hand tighten the nut.

The two problems are now behind me. Maybe I will finally get the carburetor put back together in the near future.

Roger Update

This week a couple of boxes were delivered. One contained a new gas tank for the Morris Minor. The tank was purchased on Ebay. Another box contained a new fuel pump which I purchased from Amazon (lowest price), and the final box contained spark plugs, distributor cap, rotor cap, points, condenser, coil, and plug wires which I purchased from the web site of one of our local parts house chains. I am still expecting a final box containing a new stainless steel gas cap.

Some of the parts go on the car, some will be used to repay the nice guy who loaned me some parts at the recent car show. Hopefully I will get around to delivering/installing all these one evening this week.

Roger's Day Out

Today we took the Morris to a Euro-Brit car show. Lots of Triumphs, MGs, Austin Healeys and Volkswagens. Quite a few Range Rovers, Minis and Porsches. On Ferrari, one Lotus, and one Morris.

The trip, fewer than 10 miles, to the show was uneventful. That is until I stopped for parking directions. At that point Roger refused to start. That has not happened before (when I had gas in the tank – I have already run out twice because the fuel gauge doesn’t work). Fortunately the car is British so no one was surprised when it wouldn’t start.

I popped the bonnet and a bunch of guys leaned in under the hood. These guys were great. And knowledgeable. And prepared. After checking to make sure there was fuel, they checked for spark. The spark was weak. Eventually they had replaced the distributor cap, the rotor cap, and the spark plugs. And Roger was alive again. The amazing part was that they had all these parts with them. And more.

I got the name of the guy that supplied all the parts so I could replace them. I also learned a lot through the process. Basically the car didn’t want to start because the spark was weak – it basically needed a tune up. The weak spark alone was not the problem. The plugs were also really dirty. The plugs were dirty because the car was running rich. And the car was running rich because the electric fuel pump was the wrong part.

Normally these cars have mechanical fuel pumps but they often get replaced with electronic equivalents. The problem was that this one pushes about 5-7 pounds of pressure where the carburetor only needs about 2 pounds. The increased gas pressure basically forces gas through the carb which is what has been causing the car to run rich. This all made complete sense, after it was explained.

The car has been running rich. I had been studying how to tune the carb in order to correct the problem. Using the instructions from my manual, I had tuned the carb down as lean as possible. I was baffled as to why it was running so rich. Now we know. We also know I need to replace the fuel pump. (One of the guys even offered to loan me one.)

I also found out that as the distributor wears out the car loses power at medium to high RPMs. I would say that based on this knowledge I would say my distributor was well worn. The car definitely felt peppier after the meta-tune-up.

And finally I received lots of good advice I plan to follow:

0. Replace the fuel pump. Soon.

1. Finish the tuneup. Replace the plug wires, the condenser, the coil, etc.

2. Carry some spare parts in the boot. Extra plugs, distributor cap, rotor cap. The parts are cheap and don’t take up much space.

3. Buy some extra tools and leave them in the boot as well. With a Harbor Freight nearby, I think I can accomplish this for about $20.

One of guys in my neighborhood invited me to this car show. I already knew about it and planned to attend. I had talked with him about my carburetor already. He was at the show and had brought me a copy of a tuneup guide for my carburetor. (Did I mention these guys were all really helpful.) Ernie is a very interesting and knowledgeable guy. He is also a Fiat guy. I believe he has 4 Fiats, maybe 5, 3 are convertibles. At least one is a parts car. He also has a couple of 1967 Datsun 1600s which are also convertibles and which I think are pretty awesome cars – I mentioned one in a post several years ago when I first saw one in a salvage yard. Most of his cars are still in the project stage and I suspect he is actually working on all of them. (And he is an accomplished brew master.)

Last night the local Euro-Brit car club went on a drive. I had wanted to attend but I was pretty sure Roger wasn’t up to it. It is a good thing I didn’t attempt the drive. Hopefully we will be up to it next year.

Overall, I had a very enjoyable day, even with the breakdown. The kids went with me and I think they had a pretty good time as well.

The Morris Minor 1000

Hello Roger

Thursday night while browsing Craig's List, I came across an interesting ad: For Sale: 1967 Morris Minor, yada yada yada.



(To get a good idea how big this car is notice the Volkswagen Beetle in the adjacent spot.)

Thirty-six hours later it was parked in my driveway. When I saw the ad, I knew it would go quickly. I called the owner. He said two others had already made arrangements to come see the car. I made my appointment for earlier in the day!

This car is roughly the same size as a VW Beetle. The interior is spacious but sparse. The exterior styling is reminiscent of cars 20 years older that it. It has a very small engine (1 liter) and a fairly large trunk boot. The paint looks good in the pictures and from about 20' - closer than that you can tell it needs some attention.

It quit once on the trip home. The previous owner said the gas tank was full. The gauge showed the tank was full. Fewer than 15 miles later I was out of gas. The gauge still showed the tank was full - it was not. In what seemed like a fortuitous event, the car ran out of gas right in front of a gas station. Unfortunately it was an unattended commercial refueling station. None of my cards worked there. My neighbor Brian who was still following me at this point, went and bought a gas can and brought me back some gas. At this point I headed straight for the station and filled up the tank and the empty gas can, just in case.

Did I say it quit once? It also developed a vacuum leak on the way home. This is kind of the opposite of quitting. The leak caused the engine to idle high. Nothing that couldn't be dealt with if I ever made it back home. Because it was idling high, I turned the motor off each time I had to stop for a light. (This reminded me of my hyper-mile-ing experiments the summer of 2008.)

Each time I stopped, there were one or more people there to ask me about the car. Two British car guys stopped to chat, they both wished me luck which I understand one needs when they have a car from the UK. Lots of people waving also. I think this car was getting more attention than the 1925 Chevy truck did. Amazing.

It has a few problems, but nothing we can't live without. I hope to get it running a little smoother soon. It won't be too soon though, my calendar is booked pretty solid for the next couple weeks.

Several folks have asked me what I am going to do with this car. The short answer is nothing. I don't plan on restoring it - basically I just want to keep it running and go get a milk shake from time to time.

Oh, yeah, we have decided to call it Roger, a name that stuck very quickly.