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|Posted - 13 Apr 2017 : 07:38:08 |
| If any of you have been following Betsy in the projects? You will probably be aware that I did a little 'head' porting. We're all back together and all is not well. Runs and sounds beautiful at tick over and free revving when stood still. However, not too good when driving. Ok (ish) if driving steady and will build up speed if you progress steadily, but put your foot down and it 'bogs' not to the point of stalling - just doesn't pull.|
Carb is a 28/36 DCD which has never previously given me any trouble. I presumed it was now incorrectly jetted. It was running 50/70 and 2 x 130 for prime and second, so I ordered a 140 and 155- better but not right. It was then I discovered the chokes were both 25's-hence the 2 x 130. Web research is pointing to 26 & 27 chokes with the 140 & 155 jets. When I gave up yesterday I had put the 130 prime & a 140 second in - a bit of trial and error, or scientific approach We're still not right!
The nearest rolling road is 50-60 mile away. I can get hold of the chokes, but don't want to just throw money away?
Could the dizzy be vacuum advancing too much, with the increased airflow? When I used to have my minis tuned they always used to come back with the advance pipes blocked off. Judging by the exhaust colour we're 'rich' rather than 'lean' which is why I'm thinking about the dizzy.
Does anyone have any thoughts/ideas on this?
|Posted - 13 Apr 2017 : 11:53:17 |
| Vacuum leaks are definitely something to consider. Could be from various spots but.... I have experienced the base of the carb warping so it is not flat and will not seal on the gasket. Get it off and put a straight edge on the base to check. Lots of folk on here have the DCD's but I have always had trouble with them so I changed to 32/36 DGV. I might still have a spare DCD in the garage.|
|Posted - 13 Apr 2017 : 13:26:27 |
| Looking at the base of my 28/36 there is quite a bit of brown staining between the carb and base plate where I presume petrol has been leaking out! |
I had the same on a Series Landy, nobody could find the cause of it not runnig right, we changed everything but tightening the nuts of the carb down onto the manifold did the trick.
|Posted - 13 Apr 2017 : 14:49:41 |
| Petrol staining is probably from changing the jets as it p$$$es out everywhere once the jet is removed.|
I've already nipped up the nuts. If it was an air leak, would it not running lean?
|Posted - 13 Apr 2017 : 18:51:40 |
| Had a short drive today and I think we're ok.|
Can't remember what I did yesterday as I've been tinkering that much recently. However, one thing I did do was check the contact gap, which was a little too close.
Hopefully job done. Will have more time tomorrow.
|Posted - 13 Apr 2017 : 21:07:31 |
| If you suspect air leaks, spray some engine start around the base of the carb/gasket. If there is no change, you don't have an issue. Opposite applies.Should be done with the engine running|
Edited by - RhysN on 14 Apr 2017 06:51:02
|Posted - 13 Apr 2017 : 22:21:19 |
| Having the points too close or too wide will give different timing to when they are correctly set. Good if you can use a strobe on it but just a very minor tweak to the timing by twisting the dizzy easily done. 1º of dizzy turn = 2º of timing. It's a sensitive adjustment so mark the original position first.|
|Posted - 14 Apr 2017 : 10:04:15 |
| I marked the dizzy timing before removing the heads, so shouldn't be too far away. Although a strobe should be something I add to a shopping list. |
Yesterday I also cleaned the foam in my air filter. There was quite a lot of crud that came out. It's a bit of a cheapy and came with the car-it really does need replacing.
Thank you for the comments.
|Posted - 14 Apr 2017 : 21:22:45 |
quote:Although this test is a good indication it's by no means more than that. I agree the opposite is true though, if the rpm increases there must be an air leak.
Originally posted by RhysN
If there is no change, you don't have an issue.
Better use Thackery washers to prevent the carb base from warping, Fast Road Cars have them.
|Posted - 17 Apr 2017 : 15:19:00 |
| I wouldn't rely on your timing still being correct. It's easy enough to set it close by static timing. Suggest trying this first.|
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