question about restoration

[Andrew_Grannis]

Hi,
My name is Andrew. My dad and I are restoring a 1960 Austin Healey 3000 BT7 with a 1965 BJ8 engine and transmission. We have worked most of the summer getting it to run, and it does...for no more than a minute. What usually happens is the car runs smooth as long as you keep it at about 2,000 rpm but then it backfires out of the carbs and shuts off, somtimes it tries to catch itself after the backfire but eventually just stops. I was at first, told it was a sparking issue so I filed the points and put electrical contact cleaner on them to get the dust away and that didnt do a whole lot. We ordered a new condenser, put it in and tried it but that didnt help either. We checked to make sure the vacuum advance functions and it does. The only way we got the car to run longer than a minute was plug the back carb up, but once it was unplugged the car lasted for a few more seconds and backfired. We have come to the conclusion that what we need to do is simply take off the carbs, clean them out and replace all the gaskets for the intake thinking there is a vacuum leak somewhere? Any advice anyone can give me will be much appreciated. Thanks Andrew

 

[Keoke]

Hi Andrew, it sounds like the engine is running on only the front carb. I definitely would examine the piston ,needle and the float in the rear carb make sure there is adequate fuel in its fuel bowl and the bowl is free of debris in the bottom.--Fwiw---Keoke

 

[Andrew_Grannis]

For the first couple times we tried starting the car, alot of gunk ended up in the bottom of both float bowls but after running it a couple times no more gunk went into either. Gas seems to be getting into the back float also, but we havnt looked to see if the needle sit properly where it lets gas into the engine from the float bowl, maybe that is the problem. Ill look at that, Thanks Andrew

 

[Patrick67BJ8]

Try this to clean out your carbs before removing them from the engine:
As soon as you fire the engine u(before it has a chance to die), place your hand over the carb intake while giving it gas(with the throttle shaft). Do this quickly and momentarily. The fast shot of gas will sometimes unstick/ free up and/or clean out the problem parts.

I've done this many times over the years and it seems to work a lot of the times. You can also remove the chambers and piston and with the key on manually pull up on the choke linkage. You should see a good squirt of gas coming up through the center of the jet.
Patrick

 

[Cutlass]

Also, you may want to do the basic carb set-up as described in the manual. Another question I would have is whether the fuel pump is keeping up with the fuel requirements.

 

[Patrick67BJ8]

Andrew, Since you said that a lot of gunk ended up in the float bowls, you might want to blow out all the fuel lines.
Be sure to blow out the tank sump line too. Be carefull if you have a lot of gas in the tank. You could have 40 plus years of crud in your fuel lines and the sump in your tank could have a lot of sediment at the pick up tube.
Do not blow out the fuel lines while they're still attached to the pump!

 

[glemon]

Some SU carbs including those for BJ8s I believe have a small fuel filter where the line goes into the float bowl, basically a little screen sock to catch debris.

When my BN1 was awakened from its long sleep these clogged occasionally with debris from the tank. May want to check these as well as the other suggestions.

If the crud and sediment don't stop coming you may need to clean and line the gas tank or replace it, I used one of the gas tank coatings many years ago and have had no problems since, but others have not been so lucky with them.

 

[healeynut]

Andrew -

Always, always, ALWAYS follow the Bentley workshop manual for tuning the engine and tuning the carbs. All tuning should always follow the order below:

1) Set your rocker gaps first to 0.12" The Haynes workshop manual for the Healey has a nice and easy procedure for this.

2) Replace points and condensor and set your distributor contact (points) gaps per the manual.

3) Set your spark plug gaps per the manual

4) Check your idle distributor timing with a timing gun. Rough adjustment of timing at this moment with engine idling around 500 to 1000 RPM is good enough.

5) Now that all of this is set, you can now adjust and synch the carbs. The shop manual has a very good procedure for this.

6) fine tune the timing a second time

7) fine tune the carbs.

Lastly, always make sure you have oil in the SU carb dashpot pistons (20WT motorcycle fork oil). If you have no oil in here, the car will "prefire" through the carbs just like you describe.

 

[dklawson]

As mentioned, go through the basic valve adjustments and all the electrical checks and settings first. Save fuel system adjustments for last.

However, you're describing the classic symptoms of fuel starvation as was also mentioned above. Was the car parked for months (years?) at a time prior to you working on it? If so, you can expect the carb needles and jet tubes to be full of goo and varnish. Assuming you don't want to upset the existing jet settings and experiment with carb tuning (save this for much later) I have a method that may help a bit.

Paint mark the mounting ears on the carb vacuum chambers so you know the positions they were in when you removed them. Remove the screws and lift the vacuum chambers up and off. Carefully put them to the side, then remove the piston/needle from the carb. Remove any goo on the needle with carb cleaner on VERY fine ScotchBrite. Do not use coarse, you don't want to scratch anything. Spray carb cleaner down the jet tube in the carb body. Use the plastic spray tube supplied with the cleaner to swab the inside of the jet tube. DO NOT put anything sharp in the jet tube. Again, no scratches. Put the carb back together making sure you align your paint marks. Then make sure there is oil in the carb dashpots. The piston should be able to move freely in the vacuum chamber when lifted and released through the carb throat.

If that doesn't help, be sure to clean the float bowls out again and make sure that the float valves are actually opening. They can stick shut.

 

[bob hughes]

Also have a look at the output from the fuel pump, I use a 2 litre coke bottle with a line marked dead on the two litre mark - measured with wifeys measuring jug from the kitchen, remove the fuel line from the carbs and shove it into the bottle and time to fill to the mark, you will need to work out a bit of mathematics. Off hand I can not remember the rate but it is in the book and this will give two things - how dirty the tank / fuel line is and if the pump is performing properly.


Bob

 

[Healey 100]

This is all good advice but assumes that the problem is with carburation. But I would carefully check the ignition wires and make sure they are in the proper order. All this backfiring can be due to a pair of cylinders out of firing order -- a very common error when reassembling an engine. Improperly set points can also lead to lots of backfiring.

RE all the debris in the fuel lines, I suggest starting the car first using a fuel supply from a clean gas can. You can jury rig some flexible fuel line from the fuel pump to take fuel out of the can instead of your gas tank. Once you get it running OK off the can you can work on getting some filters in the line and cleaning the tank.

Good luck, break even internal combustion is just around the corner!

Bill S

 

[glemon]

Bill, I thought about plug wires too, but he describes the car as running smooth at first, probably wouldn't do that with plug wires out of order, but yes, some of the symptoms could be due to ignition issues, does the engine stop immediatly when you cover the front carb?? (indicating the back carb is doing nothing to help running) or does it keep running and if so how?

 

[Andrew_Grannis]

Thanks everybody fior you help so far. I am on vacation right now so I cannot work on the car very easily but once I get home I will start to try some of the suggestions out and see whats happens. Thanks Again,Andrew