RobBrown
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| posted on 16/9/06 at 04:35 PM |
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Pinto ports not sucking (Drawing Fuel)
I managed to get hold of Carbtune II Kit, to help me synchronise the twin 40's on the pinto, to help try and smooth out the roughness.
Whilst doing this I discovered that the 2nd chamber from the front wasn't showing a reading on the tube. It would appear that this chamber
isn't drawing the fuel in and unlike the back 2 chambers when I cover the trumpet with my hand nothing happened.
I suspected timing so played around with it for a bit, but it made no difference.
I also notice that there is a puddle of fuel in the carb on the 2nd port, unlike the others where they are relatively dry.
Any ideas?
This is a new set up so now have a good selection of chokes and jets. Is there a setting I have missed?
Thanks in advance!
Rob
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DIY Si
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| posted on 16/9/06 at 05:13 PM |
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What does the carbtune kit show? air flow rates/prssure drop? If so, are you saying that port 2 is drawing no air? or that the carb is flooding down
port 2?
“Let your plans be dark and as impenetratable as night, and when you move, fall like a thunderbolt.”
Sun Tzu, The Art of War
My new blog: http://spritecave.blogspot.co.uk/
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RobBrown
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| posted on 16/9/06 at 05:19 PM |
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Both.
The Carbtune kit (link)shows the air pulled through each port, which allows you to sync both carbs so they are the
same. Essentially making sure the butterflys are open the same amount.
There is no draw on the 2nd port and there is a fuel puddle.
This could be 2 different problems, but it seems a coincidence that it is on the same port
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DIY Si
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| posted on 16/9/06 at 05:22 PM |
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So ports 1, 3 +4 show roughly the same, with port 2 at zero? This indicates that for some reason there's probably a blockage somewhere. Does
that butterfly open at all? Is there any chance the valve could be sticking? or a gasket blocking the port/leaking massively?
“Let your plans be dark and as impenetratable as night, and when you move, fall like a thunderbolt.”
Sun Tzu, The Art of War
My new blog: http://spritecave.blogspot.co.uk/
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rusty nuts
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| posted on 16/9/06 at 05:31 PM |
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First thing to check would be compressions followed by valve clearances . If it was caused by timing all four cylinders would be affected. Check H.T.
leads , distributor cap , rotor and spark plugs then test for inlet manifold leaks .
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RobBrown
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| posted on 16/9/06 at 05:32 PM |
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Great Call...
1, 3 and 4 are all OK, showing the same air flow.
The butterfly definitly moves.
There could be a leak between the manifold and the carb on this port. The rubber spacer is slightly off centre (I had the carbs off the manifold
earlier in the week).
I'll have a closer look this evening, and retry running the engine tomorrow.
Cheers
Rob
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smac
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| posted on 16/9/06 at 06:37 PM |
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I had exactly the same symptoms and it was low compression on the duff cylinder caused by valve clearance out of spec. Adjusted clearance and problem
solved.
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RobBrown
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| posted on 16/9/06 at 07:21 PM |
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Bottom 2 nuts loose on front carb, but will also look at valve clearance's this evening and retry running the engine tomorrow.
Thanks guys
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jollygreengiant
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| posted on 17/9/06 at 11:31 AM |
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Sounds like a compression problem to me, either inlet valve not opening at all, or, a major problem with the gasket, or a major problem with the gas
tight seal of the spark plug. My favourite would be a problem with the opening (at all ) of the inlet valve, As the others would all give some sort of
air flow (however small) through the carb and if the carb wasn't seated properly then it would normally affect both barrels of the same carb.
Hope you get it sorted.
Beware of the Goldfish in the tulip mines. The ONLY defence against them is smoking peanut butter sandwiches.
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roadboy
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| posted on 17/9/06 at 01:29 PM |
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Take off rocker cover & check inlet valve is opening, could be broken rocker or loose adjuster.
HTH
Ian
Jude Performance Services
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