Roger Posted September 9, 2023 Report Share Posted September 9, 2023 2-Litre 2000 Mk I engine. Some of you might have read my ordeals with flooding carbs and now when I finally got the engine started I have another problem. The engine idle ok at 800 rpm, but will not rev properly and there is a severe lack of power. The only time I have had similar problems before was with my old beloved Volvo 240 (also with Stromberg carb) and the root cause then was a small hole in the rubber diaphragm. In that case it would also start, idle, but did not have power to accelerate since the piston would not move much in the carb. The rubber vacuum connection has a very big crack and I solved it with a bodge made of rubber tejp. Looks awful, and it probably leaks a lot. I will have to find a better solution. Could this be related to my lack of power, low revs? Thoughts? Link to comment Share on other sites More sharing options...
Pete Lewis Posted September 9, 2023 Report Share Posted September 9, 2023 no the vac unit is only an economy device to advance when cruising has absolutley no effect on power performance or acceleration it can add 4mpg to your mpg nothing else holed diaphragm or misplaced sounds likely was it ok before you had the flooding ?? Pete Link to comment Share on other sites More sharing options...
dougbgt6 Posted September 9, 2023 Report Share Posted September 9, 2023 The diaphragm has a little locating lug that fits in a slot on the carb, easy to miss and lots of problems if mislocated Doug. 1 Link to comment Share on other sites More sharing options...
Roger Posted September 9, 2023 Author Report Share Posted September 9, 2023 6 minutes ago, Pete Lewis said: was it ok before you had the flooding ? Not sure. I bought this engine for less than 100 pounds, and have not done anything else than fixed the cylinder head. I guess I should be grateful that it runs at all. Carbs are from old HC engine and has not been used on the road for about 4 years, don't remember their performance, but I think they where ok. Must check those diaphragms. I think it is the same issue as with holes in diapghragms as with those f&¤%#& rubber slivers. Even tiny ones can cause big problems. Link to comment Share on other sites More sharing options...
Roger Posted September 9, 2023 Author Report Share Posted September 9, 2023 1 minute ago, dougbgt6 said: lug that fits in a slot on the carb Lugs in corect positon, checked. Link to comment Share on other sites More sharing options...
johny Posted September 9, 2023 Report Share Posted September 9, 2023 22 minutes ago, Roger said: The rubber vacuum connection has a very big crack and I solved it with a bodge made of rubber tejp. Looks awful, and it probably leaks a lot. I will have to find a better solution. Could this be related to my lack of power, low revs? Thoughts? Although, as Pete says, the vac advance unit is an cruising economy device if your carb is sucking much air in through that connection it will upset the mixture of course... Link to comment Share on other sites More sharing options...
Roger Posted September 9, 2023 Author Report Share Posted September 9, 2023 1 hour ago, johny said: if your carb is sucking much air in through that connection it will upset the mixture That was my thinking. The crack (its big!) works as an air leak, reducing the vacuum. The vacuum is also lifting the piston in the carb (wrong word again, what is it called?). Less vacuum, piston does not go up, less power. No idea if that rambling makes any sense... Link to comment Share on other sites More sharing options...
johny Posted September 9, 2023 Report Share Posted September 9, 2023 Think the manual calls it an air valve but a lot say piston👍Anyway its not so much the piston position thats the problem with air leaks but that it puts in the correct amount of fuel for the air flow it measures and then more air is added afterwards so making the mixture going into the cylinders too weak. People adjust the jet/needle position to compensate but better just to fix the leak.... Link to comment Share on other sites More sharing options...
Iain T Posted September 9, 2023 Report Share Posted September 9, 2023 My original looking aftermarket vacuum pipe was a very loose fit at the ends so I replaced it with vacuum hose from in my case Halfords. It's a thick walled hose to stop it collapsing and about 10mm diameter. Iain Link to comment Share on other sites More sharing options...
Pete Lewis Posted September 9, 2023 Report Share Posted September 9, 2023 have a look at the size of the small port next to the throttle plates where the vacuum for this is generated its so small it wont have any real effect on mixture and it only sucks when the throttle plates are close to the port for all other throttle openings its dormant maybe a little air from the incoming manifold depression you can forget that as any power loss culprit . Pete 1 Link to comment Share on other sites More sharing options...
Roger Posted September 9, 2023 Author Report Share Posted September 9, 2023 Pinhole in the carb diaphragm is the only cause for lack of power that I can think of at the moment. Unfortunately I don't think I have any new ones in stock. The poor quality of rubber parts is a common topic on forums, and I have heard stories about receiving "elephant condoms" when ordering these parts. Any recomendation where to buy Stromberg diaphragms in order to get good ones? Thanks in advance. Link to comment Share on other sites More sharing options...
trigolf Posted September 9, 2023 Report Share Posted September 9, 2023 If it was me, I would only buy from Burlen Carbs, in Salisbury UK. 1 1 Link to comment Share on other sites More sharing options...
Pete Lewis Posted September 9, 2023 Report Share Posted September 9, 2023 i have had elephant condoms from burlen and rimmer you can often find new old stock originals on e bay for often low prices(ive not looked ) even Doug has a few spares as he bought a pack Pete 1 Link to comment Share on other sites More sharing options...
Roger Posted September 9, 2023 Author Report Share Posted September 9, 2023 I did find two diaphgrams in my boxes, must be 20 years old. Will try them. "Pulls like a train" is a common description when driving a Vitesse. Well, my pulls like my 50 cc moped at the moment. Starts ok, idles ok. Wont rev more than 2500 or 3000, and it takes forever to reach those revs. But it is not flooding (thank God). Link to comment Share on other sites More sharing options...
trigolf Posted September 9, 2023 Report Share Posted September 9, 2023 Just a thought... Had a similar fault symptoms years ago on my Vit. Turned out to be the front carb throttle spindle locking clamp was slipping with force of the return spring at higher throttle openings and not opening the butterfly fully. 1 Link to comment Share on other sites More sharing options...
Roger Posted September 9, 2023 Author Report Share Posted September 9, 2023 15 minutes ago, trigolf said: throttle spindle locking clamp Thanks! Will check this. I did check for pinholes when I assembled the carbs, so I think it could also be something else than pinholes. I did forget to tighten this clamp once, with similar result. I hope I did not do the same mistake twice... Link to comment Share on other sites More sharing options...
dougbgt6 Posted September 9, 2023 Report Share Posted September 9, 2023 There are currently half a dozen New Old Stock Stromberg diaphragm listings on Ebay. If they are NOS they should be OK, the ones I bought were. Doug 1 Link to comment Share on other sites More sharing options...
johny Posted September 9, 2023 Report Share Posted September 9, 2023 Is there still a problem with elephant condoms or has it been resolved? Link to comment Share on other sites More sharing options...
johny Posted September 9, 2023 Report Share Posted September 9, 2023 Surely the reputable places cant still be selling them... Link to comment Share on other sites More sharing options...
Roger Posted September 10, 2023 Author Report Share Posted September 10, 2023 Diaphragms now replaced with new ones. No diference, my 13/60 had MUCH more power when accelerating and going up the hills. Did another experiment. I just have the feeling that the air valves are not going up as they should, so I removed the oil from the dampers, just to see what would happen. No noticable difference there either. Spark plugs looks like its going a bit rich. Did everything according to WSM regarding the settings, but will try to make it leaner. Frustrating... Link to comment Share on other sites More sharing options...
Pete Lewis Posted September 10, 2023 Report Share Posted September 10, 2023 was she running ok before the flooding issues ???? Pete Link to comment Share on other sites More sharing options...
Roger Posted September 10, 2023 Author Report Share Posted September 10, 2023 22 minutes ago, Pete Lewis said: was she running ok before the flooding issues ? Starting and idling yes. Never tried to drive it until now. Link to comment Share on other sites More sharing options...
Roger Posted September 10, 2023 Author Report Share Posted September 10, 2023 Going back to basics whenever I can as recommended, I looked at "lack of power" in the fault finding chart in WSM. I think I can eliminate everything exept the fuel supply. As mentioned before I do not have a mechanical pump, only the Huco and the pressure regulator. Considering to increase fuel pressure in case it is fuel starvation, but increased pressure also increase the risk of flooding. I will have a fit if they flood again, then there will be men with white coats in my garage. 1 Link to comment Share on other sites More sharing options...
Pete Lewis Posted September 10, 2023 Report Share Posted September 10, 2023 can you get a compression test done but more probably a basic faul not a nasty one fault charts are just aload of made up waffle like it doesnt mention the engine was missing Pete Link to comment Share on other sites More sharing options...
Roger Posted September 10, 2023 Author Report Share Posted September 10, 2023 1 hour ago, Pete Lewis said: can you get a compression test done Compression test done, numbers ok (ish). Piston rings in cylinder 6 seems to be a bit worn, compression improves a lot with some oil in the cylinder. I just increased the fuel pressure a bit, and it seems like it added a few horsepower (or it's just my wishful thinking???). Anyway, will double check timing again, and then increase fuel pressure in small increments to avoid flooding and see if I can add a few more horses. Link to comment Share on other sites More sharing options...
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