John Bonnett
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| posted on 31/5/15 at 04:09 PM |
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A question for Weber experts
I've just got the replacement cylinder head back on my 1500 Triumph Spitfire engine and it will not run on four cylinders. Twin 40DCOEs are
fitted.
I have a feeling that the problem may be fuel related rather than electrical. With the plugs taken out and grounded each gives a good spark. When
replaced with lead to NO1 disconnected the way the engine starts is not affected, same on No2. But with 3 and then 4 disconnected, the engine
struggles to start. This makes me think that the front carb is doing little or nothing. Even a large throttle opening with the engine revving it will
not cut in on all cylinders.
I know nothing about Weber so any help would be very much appreciated. Thank you.
John
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austin man
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| posted on 31/5/15 at 04:43 PM |
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are you sure you have the leads to the correct plugs to give the correct firing order not sure on that engine whether its 1,3,4,2, have you checked
all the valve clearances etc.
You do not specify if the problem was there prior to the replacement head
Life is like a bowl of fruit, funny how all the weird looking ones are left alone
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rusty nuts
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| posted on 31/5/15 at 05:34 PM |
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As above and check the compressions , also check the distributor cap for hairline cracks , ht lead resistance etc Could be the spark breaking down
/tracking out under compression . Try spraying brake cleaner , easiistart etc down the suspect carb chokes , any increase in revs will indicate fuel
starvation . Might be worth checking the float height and needle valve operation . When the engine is running try blanking off the suspect chokes for
a few seconds with the throttle open , it sometimes help to clear blocked jets , if it works strip and clean the carb . Not very familiar with DCOE
carbs
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John Bonnett
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| posted on 31/5/15 at 06:21 PM |
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Thanks chaps. I think I've traced the problem to a blocked main jet. All appears to be well.
Thank you once again.
John
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