41 replies to this topic

[dklawson]

The oil that fills the dashpot is there for dampening, controlling the rate at which the piston can rise in response to engine vacuum.  Lack of oil can create driveability problems for some cars and not others.  The original SU oil from the factory would have been a straight 20W.  You will see people using everything from WD-40 to gear oil.  I would start with 20W and see if things improve.

 

There have been numerous threads about how much oil goes in the carb.  The real answer is... with the black damper cap removed, look down into the top of the carb.  You will see a steel tube in the very center.  That's where the oil goes.  Stop filling when the oil gets to about 1/4" below the top of that innermost tube.  Any more oil than that will just get sucked out and burned. 

[clayey6891]

I'm pretty sure that's what the problem is now. I will try and take a look tomorrow but not sure if I will have time as I will be out most of the day.

 

Thinking about it, I'd be surprised if it is the throttle cable sticking as I've not touched that and it was never an issue before.

 

I'll report back with my findings when I find them!

 

Thanks again for your continued support.

[cal844]

Cool cheers dk. May be a very stupid question here, should there be oil/lubricant of some sort in the carb? As I've had it open and been messing around in there should I put something back in to help the piston rise and fall freely?
 
Edit: Ok so I've done some more reading and concluded to what I initially suspected, it was a stupid question! There should be oil in the carb. This is more than likely why the throttle was sticking. So hopefully an easy fix tomorrow.

Yes, unscrew the black knob on top, pour apporox 50ml of 10w40 in there. If its too thin, try 20w50 :)

[thedjse]

Hi buddy litterally going through the same issues you are now after fiting stage one i found my throttle sitcking or taking a while to drop was the spring on the carb was very week replaced that and it was alot better.

[clayey6891]

Cheers guys. Just got back from the local establishments and can't find any 20W oil anywhere, most people haven't heard of it. So rather than wait for some to come from eBay I'm gunna go for the 10W40.

That's a good idea to look into the spring too. If the oil doesn't work I'll try that next. It's always good to hear your not the only one having troubles!!

Edited by clayey6891, 18 August 2015 - 01:40 PM.

[Keith Staley]

Halfords do their own brand of Classic Oil 20W50 but only in 5 litres though

[thedjse]

20/50w is available from most places pal, euro do it, and ebay

[clayey6891]

Ah I did see the 20w50 but thought it was supposed to be a straight weighted 20? Anyway, I've put the 10w40 in in the end as I had it in the garage. The throttle is responding better but I think I will change the spring as well, as suggested, as its still not right and is revving up on cue but revving on still

I've not had much chance for a good look at it today, but I know it's still not running right: when I first start it, it needs to rev at about 4000rpm with the choke to avoid stalling (does this seem normal or quite high?). After 10 mins it's warmed up but with choke less than 1500 it stalls, even if I give it a little throttle. Would this be down to the jet adjusting nut being set wrong?

As we've all established, I'm no expert! And don't expect to get the engine running a dream by ear but I do think I can at least get it ticking over nicely and able to run without screaming it's nuts off at the traffic lights.

Good news however, it starts first time everytime which was where this post all began!

[dklawson]

The symptoms of needing to keep the choke on and rev the engine are consistent with a vacuum leak.  I know we beat that topic to death on the first couple of pages of this thread but you still may want to give it one more review.  

 

EDIT:  I think I mentioned in a previous post that people use everything from WD-40 to gear oil in their SU carbs.  The 10W40 should be fine for starting off with.  Don't worry about finding straight 20W oil at this time.  If you do want to try straight 20W in the future, you can buy it in expensive bottles from Burlen (the current owner of SU) and/or you can look for 3-in-1 oil.  Regular 3-in-1 with the black label is straight 30W, the blue label oil is 20W.

 

Edited by dklawson, 18 August 2015 - 05:15 PM.

[clayey6891]

Yeah that makes sense. Hopefully I'll have more time tomorrow to look into it - was a rushed 15 mins today.

Thanks for the advice on the oil, I did have a good look and found some ATF which I've read is common to use but wasn't sure so decided to stick with the oil I had in the garage.

I think tomorrow I will have another look through to make sure I've hooked everything up/done everything according to this whole thread. Then I will probably head up to mini mail (not far from me luckily) and grab a new spring and see if he has some more suitable dashpot oil.

[clayey6891]

So today I managed to get the car running a lot better. I firstly went through this thread and double checked everything to make sure I'd not over looked something or undone something - which turned out to be fine.

I then looked at the level of the pistons and believe number 1 ( spark plug closest to the rad) was low so turned the engine until the piston was at its highest point. I read that this is the best starting position for the engine to fire and run smoothly.

Thirdly I sat back for a minute and had a good think about the difference between adjusting the base setting for the choke and the throttle and adjusted it accordingly.

After doing all of this the car is running much better and I even managed/braved a short drive around the block with the engine only stalling once. so I think tomorrow I will give it another little tune and hopefully that will be the end of the stalling.

I have got the inline fuel filter today in the post but am waiting until I receive some braided petrol hose to replace the hose that's there before I fit it. I've noticed there is still a small leak on entry to the fuel float chamber and believe this is because the hose is partly split. I also have coming in the post a new carb spring and the correct SU dash pot oil(ordered from minispares). Hopefully this will all come tomorrow and I can quickly bolt on all these parts in the morning.

As a side note, I've removed the butterfly valve from the air filter box and instead ran air hosing direct to the grill and I've put a breather filter on the crankcase as this was previously running a pipe to a dead end on the filter box.

Thanks to everyone for their input, I'm pretty sure I'd still have a non starter if it wasn't for you guys!

[thedjse]

Well done pal sounds a productive day, thanks for coming back to us and keeping us updated always nice to hear when things work!