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Nov 18, 2015 20:24:22 GMT
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Hi
I was hoping somebody might be able to give me some advice on a problem with my triumph 3 litre engine.
The engine starts fine and runs great in the garage for about a minute.
As soon as the engine starts warming up, it starts to run ruff.
Once warmed up and with the choke in the engine starts revving on its own.
The Rev's drop until the engine almost cuts out and then it picks up and Rev's to the normal idle speed and then starts the cycle again.
It is as if I am revving the accelerator like a boy racer at the traffic lights.
It is the original engine with a weber carb conversion.
I have replaced the plugs, leads, cap, rotor arm, coil, cleaned the electronic points beam, took the rocker cover off and blown through the breather pipe.
I really don't know what else to check.
I would be extremely grateful of any advice.
Mike
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ChasR
RR Helper
motivation
Posts: 10,189
Club RR Member Number: 170
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Nov 18, 2015 23:55:02 GMT
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I would be looking out for a vacuum leak at either the carb/adaptor/manifold join (i.e the carb setup) or the gaskets from the inlet manifold to the head.
Do you have leaks at the latter at all and is there any sealer present?
There is a slim chance that it could be the throttle/throttle cable sticking. Try seeing without too much force whether the throttle returns to its stop as well as the choke. I had to put a spring onto my Holley choke cable in order to make it return to the correct position once it was not used.
Where in the country are you?
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Last Edit: Nov 18, 2015 23:57:11 GMT by ChasR
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Nov 19, 2015 11:02:49 GMT
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Hi.
Many thanks for the advice.
I will have a look for leaks at the weekend. Also check the cable.
I am in Aylesbury.
Thanks again, for advising me what to look for.
Regards Mike
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Nov 19, 2015 19:01:54 GMT
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Easiest way to look for inlet leaks is to spray eezistart, or even wd40, around the joints and listen to the engine note.
If it changes when you spray, then you found your leak!
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Koos
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Nov 19, 2015 19:28:46 GMT
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Easiest way to look for inlet leaks is to spray eezistart, or even wd40, around the joints and listen to the engine note. If it changes when you spray, then you found your leak! Now this is genius! |
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ChasR
RR Helper
motivation
Posts: 10,189
Club RR Member Number: 170
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Nov 19, 2015 21:12:59 GMT
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Carb cleaner also works. I am told that using an unlit blowtorch is meant to be better, but I am simply not brave enough! Did you buy the car with the carb conversion or have you fitted it yourself? If you are about after Xmas and don't get it sorted I may be able to lend a hand  . |
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Nov 19, 2015 21:44:58 GMT
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Easiest way to look for inlet leaks is to spray eezistart, or even wd40, around the joints and listen to the engine note. If it changes when you spray, then you found your leak! Now this is genius! really slick method of finding an air leak..will add that tip to my memory and look like a genius when i get to use it  |
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Nov 19, 2015 23:18:50 GMT
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Easiest way to look for inlet leaks is to spray eezistart, or even wd40, around the joints and listen to the engine note. If it changes when you spray, then you found your leak! Problem is if its randomly revving you won't know if its the spray causing it. |
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Easiest way to look for inlet leaks is to spray eezistart, or even wd40, around the joints and listen to the engine note. If it changes when you spray, then you found your leak! Problem is if its randomly revving you won't know if its the spray causing it. if its an air leak it will sound different to easy start |
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scimjim
Club Retro Rides Member
Posts: 1,503
Club RR Member Number: 8
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Nov 24, 2015 22:24:35 GMT
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It sounds like the anti-stall valve is doing its job. Once it warms up and comes off the choke circuit, it's too weak to run so the anti-stall circuit squirts a splash of fuel in which lifts the rpm momentarily - then repeat.
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ChasR
RR Helper
motivation
Posts: 10,189
Club RR Member Number: 170
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Nov 24, 2015 22:38:04 GMT
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AFAIK Stags never came with an anti-stall valve and neither did Weber 38DGMS carburetors.
Just had a thought. Can you take a few shots of your engine bay?
Where is the breather pipe from the cam cover plugged into? What exactly is plumbed into the Weber carb?
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Last Edit: Nov 24, 2015 22:48:32 GMT by ChasR
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Nov 26, 2015 20:07:02 GMT
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Thanks for the advice.
I have now got some carb cleaner and will test for leaks.
I can't work out how to upload images
I did the conversation myself and it was running fine to begin with.
The breather pipe runs from the rocker cover into the air filter housing.
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Nov 26, 2015 20:09:11 GMT
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Nov 26, 2015 20:10:54 GMT
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Nov 26, 2015 20:11:12 GMT
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Nov 26, 2015 21:14:32 GMT
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Nov 26, 2015 21:20:21 GMT
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scimjim
Club Retro Rides Member
Posts: 1,503
Club RR Member Number: 8
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Nov 26, 2015 23:29:23 GMT
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AFAIK Stags never came with an anti-stall valve and neither did Weber 38DGMS carburetors. later 38DGAS/DGMS definitely have anti-stall (in fact you can see it in this pic) looks like the acceleration pump but on the opposite side and has an air feed instead of a lever. |
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Last Edit: Nov 26, 2015 23:31:14 GMT by scimjim
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Hi mate,
did you get this sorted?
steve.
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Feb 10, 2016 19:34:07 GMT
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Easiest way to look for inlet leaks is to spray eezistart, or even wd40, around the joints and listen to the engine note. If it changes when you spray, then you found your leak! Now this is genius! Or if you have none, use water and if it does the reverse (ie cuts out) you have found the problem! |
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