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Discussion Starter · #1 · (Edited)
I have got a misfire on my 351w motor, I have spark all round but it appears as though fuel is not getting through to cylinder number 4. I have a good spark and the engine starts fine but runs on 7 whether it is idling or when I rev it up.
I remove the plug on number 4 and it is dry and clean whilst the other plugs are a little sooty.
I have changed the leads, plugs, rotar, cap, carb and coil and no difference!
I have also done a compression test which was good and vacuum test which was good.
Anyone got any other ideas as it's driving me crazy! Cheers Tony
 

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Stab in the dark.....Is the inlet or exhaust lifter holding the valve open when it's running. This may not show up on a compression check as oil pressure maybe lower????
If it was exhaust the plug may stay dry??
 

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Discussion Starter · #3 ·
I have run the engine with the rocker cover off and it all seems ok, everything appears to be moving correctly.
 

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Discussion Starter · #7 ·
Two things I would try is to check it in the dark ( the darker the better ) to make sure the lead is not shorting out, I would also check it with one of these.

https://www.amazon.co.uk/Silverline...=1500205110&sr=8-1&keywords=spark+plug+tester
I have tried a few different leads and several plugs, the spark is good when checked with the plug out of the engine and I have a similar tester to the one you linked me too and that shows it sparking!
This is the sole reason I am really baffled.
It was running fine and was 130 miles into a 140 mile round trip when it suddenly developed the misfire . Cheers
 

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A GENTLE spray of carb cleaner around the intake manifold where it connects to the #4 cylinder part of the head. Easy check for a vacuum leak which may not always show on a vacuum test.
 

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Discussion Starter · #9 ·
A GENTLE spray of carb cleaner around the intake manifold where it connects to the #4 cylinder part of the head. Easy check for a vacuum leak which may not always show on a vacuum test.
I'll give it a try next time I'm over the the workshop .
I did fit a new intake and gasket plus new head gaskets last year so the gaskets should be good but worth a try
 

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Discussion Starter · #11 ·
Did you fix this issue?
After having another look with no luck I merely concentrated on getting my zodiac back on the road instead. But yesterday I had another look and I seem to have finally fixed it, it seems that the lever inside the distributor which operates on vacuum had seized and after freeing it off and taking the truck for a run it is perfect now!
Thanks for the advice fellas
 
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