As mentioned before the vac tank is in the right front wing, the valve is connected directly to it, they are both behind a shield.

Below is a shot of the area which shows the servo cover on the left, and the tank behind the shield to the right.

 

Thanks Jon.
Looks nice and clean. Mine seems to have had undercoating.
I’ve not been back to the car since I last posted due to a number of other demands, but I will. I’ll have to back for trouble shooting steps, and the Servo diagram description was great.
I may start by bypassing the tank as mentioned in an earlier post to eliminate that possibility, and then move on to opening up the air valve diaphragm unit to see if something is keeping it stuck open while simply idling.

 

Mine has been stripped back to bare metal, so the picture is how it is now, not the mess of undercoating etc that was all over it when I got the car !

Let us know how you get on.

 

You can find the carb manual here, SU in chapter 17 if that helps

Resources

 

Gentlemen!!!

I’m back and just picked up the car from winter storage and detailing. Long cold winter here this year.

After getting her going thanks to wonderful help from you, you may recall I was talking about her being gutless on the acceleration, and that it reeks of strong gas. What I also noticed since, when I went to drive it to the storage facility last fall, is the tank was needing to be filled, after only 100 miles on the tank. So my question is, have you got a sequence of steps for which carb adjustments to make, and in which order, to tune the air fuel mixture properly? The guzzling and chugging may be related, and hopefully, a simple solution.

Thanks kindly in advance for your yime,
Jerry.

 

Remove the tops of the float bowls and make sure that the float valves are indeed closing off.
Inspect the floats themselves to make sure there are no holes in them.

After sitting all winter long, change you points and condenser too, assuming that you have points.
It depends how it was stored, if the garage is heated, then your points may be fine.

Don't touch the mixture at this point, until you find the source of the excessive fuel use.
Carb adjustments rarely need tuning, they don't suddenly go out of tune.

Also check the oil level in the dampening tubes as well, the oil has a tendency to leak out sitting all winter long.
Low oil in the damper tubes can also be a source of excessive fuel consumption.

 

Attached section for the carbs from the service manual, give that a read and then ask any further questions you have.

 

Skimmed through the thread again, I wonder if the OP rebuilt the brake servo ???

 

JeffR1: thanks again for joining in with some help.... Yes.. the Brake servo was a suspicion due to odd engine revving with the vac hose removed. This thread was quite a progressive discussion with TilleyJon and yourself in the fall, and you guys walked me through some troubleshooting, to where I finally (and miraculously) changed the points, condenser, and ignition coil, and she fired up again... but there was an obvious power drop in Acceleration, which is where we got into Vac Servo discussions. But I did not do ant work on the brake servo, because it had to store it for winter. On your other questions, stored warm, and the floats and oil are all fine. That’s not to say there isn’t a carb issue, but she burned a full tank pretty much in 100 miles, and that’s mostly from before the points repair job, but the richness is very evident.

I’m open to any tests to confirm fuel / air mixtures as I don’t want to ruin it. It ran fine from a power and ride perspective for the 200 miles I’ve put on it since buying it last summer. But always smelled rich, and that’s a lot of fuel probably two to three times my re than it should burn.

TilleyJon: thanks for the link on carb adjustment.

Any thoughts on possible mechanical tests before I start regretting adjustments?

 

Firstly, get the engine warmed up and possibly take it for a bit of a run for ten mins, then take out the spark plugs and see what colour / state they are in.

If the mixture is rich, the plugs will be black, but a correct mixture would leave them greyish.

If they are black, check :-
The choke to make sure it is off
Air cleaner
Timing (assuming that the points are good and set correctly as you have changed them.)
Valve Clearance

If all the above are good then look at adjusting the carbs.

You can read these for more info too. (Please confirm you have the 240 fitted with HS6 carbs)

Tuning - General - SU Carburetters

Tuning - Multi - SU Carburetters

 

Thanks Jon. I will start going through these points as suggested. I’ll provide an update as I go along. Plugs were brand new and adjusted in the fall. Part of trying to see things through for causes. Old ones were black then. Be interesting to see what they’re like with less than 20 miles on them.

 

Hi Jon... Pic of one plug (just randomly pulled one), after maybe 25 miles.
Choke was off and funtions well (full range of reaction when I move it and I can see the linkage all the way)
Air filter fine... runs this way even with it off.
Timing??? You may recall from prior posts in the fall that the timing mark was way off under the strobe, but my manual said to use a different cyclinder than you for the 240. Also, I have played with timing on cars in my earlier years by rotating the Dist Cap, and found it idles only right in one spot, and doesn't take much to be off... That's the enigma... This baby idles okay without any sputtering (but the gas is strong in smell), and she becomes gutless when trying to accelerate, which h wasnt an issue back in June when I bought her.
Should I okay with the Dist Cap, or is there another check to do next based on fuel consumption?
I'd say it's black...

 

Timing doesn't make the spark plugs black and sooty like that.
If you're certain the choke is off, then your carbs are running way too rich.
Could also be leaky float valves and or the floats themselves are not shutting the valves off.

 

Jeff, my list of checks is everything that should be done prior to carb adjustment, timing being one of those checks, retarded timing can actually present with carbon fouled plugs due to the late combustion not burning the fuel fully, and the exhaust would also smell rich, but that tends to take a little longer to manifest itself.


gbourck has checked the floats and said they were all ok in earlier post, but not as yet checked the needle valves, that would be my next step as the first step to tuning the carbs.


gbourck, just before you check the needle valves, pull all the plugs and make sure they are all black, if 3 (back or front) are black and the other 3 (front or back) are good then it will be only one carb causing the problem (the one where the plugs are black) if it is only one or two then come back for further advice.
If it is only 3 plugs, then the corresponding float valve would be the first place I would look. Let us know what you find.

 

Will do and thanks. Will look to check them by the weekend.

 

All six plugs are black, which seems odd. Again, maybe 25 miles on them.
Question, which oil should I have in the carb dampener... I think I used a thicker oil when originally checking the carbs last fall and spilled them out... and would that be a possible cause even to such richness?

 

5/20 oil or thinner

 

It's not odd if the carbs are both set too rich. it probably rules out float needles, it would be odd to get both valves letting some fuel through but not enough to come out the overflows.


First take off both dashpots and clear out the oil with some rag, make sure you keep the piston with their respective dashpot, check that the needles are both correctly positioned, if they have been put in too far into the piston they will give a rich mixture as they will be too high in the bridge.


If that is ok, replace the dashpots, refill with oil as Jose has said, and tune the carbs as per SU manual.

 

It would be great to have a couple of photos of the needle position in the piston and one of the jet in relation to the jet bridge on both carbs.

 

Forgot to say, thicker oil will more likely make the mixture leaner on acceleration as the needle will not rise as quickly, if the carbs are generally rich, this may in fact have helped the situation on acceleration, but thick oil is not a solution to rich mixture setting though, so it would need changing and the carbs setting.


As Jeff said, a couple of pics of the needle setting in the piston and the jet in the bridge would be good, there are 2 different needle shapes, which sit differently in the piston, and the chamfered type are easier to set wrong.