Vdub'z Dual Solex Diagnostic Thread

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vdubz
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Re: Vduz Diagnostic Thread

Post by vdubz » Thu Mar 28, 2013 1:11 pm

Just checked the valve clearances. I backed them out to zero lash and then turned them in 1 1/2 turns and on every one it was just pushing the valve and not the lifter, so i have set them all to zero lash, i will run the engine tomorrow and do another compression test and let you know how i get on. Also regarding the idle cutoff valve issue on the right carb, how can i fix this problem? could i just place a rubber washer on the cutoff valve to hold it out from the body of the carb slightly? i have tried another valve but that did not make any difference.

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Amskeptic
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Re: Vduz Diagnostic Thread

Post by Amskeptic » Thu Mar 28, 2013 4:20 pm

vdubz wrote:Just checked the valve clearances. I backed them out to zero lash and then turned them in 1 1/2 turns and on every one it was just pushing the valve and not the lifter, so i have set them all to zero lash, i will run the engine tomorrow and do another compression test and let you know how i get on. Also regarding the idle cutoff valve issue on the right carb, how can i fix this problem? could i just place a rubber washer on the cutoff valve to hold it out from the body of the carb slightly? i have tried another valve but that did not make any difference.
That the engine runs better with the cut-off unscrewed a bit does not mean that keeping the cut-off unscrewed is the repair. It is merely a canary in the coal mine of your "not happy engine". We need to get your engine pumping efficiently and running smoothly with the cut-off properly snugged up. Then perhaps, someday, we can dream can't we? someday, you will have four nicely tan plug insulators, decent fuel mileage, a good idle, and cut-offs that prevent piston damage from run-on (dieseling) when you shut off the engine on a hot day.
Colin
BobD - 78 Bus . . . 112,730 miles
Chloe - 70 bus . . . 217,593 miles
Naranja - 77 Westy . . . 142,970 miles
Pluck - 1973 Squareback . . . . . . 55,600 miles
Alexus - 91 Lexus LS400 . . . 96,675 miles

vdubz
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Re: Vduz Diagnostic Thread

Post by vdubz » Sat Mar 30, 2013 11:58 am

I have just found out what was causing the odd spark plug :cheers: while i was removing the right carburettor to swap it for another one that ive just got hold of, i looked closely at the inlet manifold and thought i could see a slight gap, so i decided to remove it and this it what i found Image :shock: somone(dumb) had put a washer underneath the manifold gasket. I'm now wondering whether i even have a problem with the cutoff valve? i will put the same carb back on tomorrow and see if i still have the stalling problem when the left carb wire is pulled, if so i'll try the spare carb and see if that works.

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Amskeptic
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Re: Vduz Diagnostic Thread

Post by Amskeptic » Sat Mar 30, 2013 8:52 pm

vdubz wrote:I'm now wondering whether i even have a problem with the cutoff valve?
Hello . . . no, nobody here thought you had a problem with the cut-off valve, more like a problem with how the engine is *pumping*.

Now this washer under the gasket deal looks like a pretty big cause, but slow down!
Is the gasket damaged? Replace it! No fooling around! Replace the other one too! It has been distorted too! It was crushed down at an angle. Methodical, my boy.
Colin
BobD - 78 Bus . . . 112,730 miles
Chloe - 70 bus . . . 217,593 miles
Naranja - 77 Westy . . . 142,970 miles
Pluck - 1973 Squareback . . . . . . 55,600 miles
Alexus - 91 Lexus LS400 . . . 96,675 miles

vdubz
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Re: Vduz Diagnostic Thread

Post by vdubz » Sun Mar 31, 2013 1:33 pm

I have ordered new gaskets for the inlets, but i tried fitting it back with the same gaskets(once i removed the washer) to see what it ran like. Straight away when i started the engine the difference was very noticeable, it now idles nicely and revs smoother. I then removed number 2 spark plug and it is definitely firing now, as its totally black and sooted up like the rest of them! So i then cleaned the spark plugs and started the engine again this time to see what happens when i pull the cut-off valve wires, what happens now when the idle is at 1000rpm and i pull left or right cut-off wires, the revs drop around 500rpm on both sides, i tried richening the mixture up but that did not decrease the rpm drop. I also noticed that when i push the throttle quickly, that theres a puff of black smoke, if i don't push the throttle quick and just rev the engine slowly then the spark plugs stay clean, so i'm thinking i have the accelerator pumps squirting to much fuel? i set them to 1.5cc of fuel per stroke(15cc for 10 pumps) as it says in the bentley, if this is not correct, then what should i set them to?

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Amskeptic
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Re: Vduz Diagnostic Thread

Post by Amskeptic » Sun Mar 31, 2013 6:47 pm

vdubz wrote:I have ordered new gaskets for the inlets, but i tried fitting it back with the same gaskets(once i removed the washer) to see what it ran like. Straight away when i started the engine the difference was very noticeable, it now idles nicely and revs smoother. I then removed number 2 spark plug and it is definitely firing now, as its totally black and sooted up like the rest of them! So i then cleaned the spark plugs and started the engine again this time to see what happens when i pull the cut-off valve wires, what happens now when the idle is at 1000rpm and i pull left or right cut-off wires, the revs drop around 500rpm on both sides, i tried richening the mixture up but that did not decrease the rpm drop. I also noticed that when i push the throttle quickly, that theres a puff of black smoke, if i don't push the throttle quick and just rev the engine slowly then the spark plugs stay clean, so i'm thinking i have the accelerator pumps squirting to much fuel? i set them to 1.5cc of fuel per stroke(15cc for 10 pumps) as it says in the bentley, if this is not correct, then what should i set them to?
Set the mixture to lean drop-off at the reference hose for the dual carbs only, and set the mixture to slight uptick with the reference hose off when the central idling circuit is plugged in.

No way no way no way do we read plugs within minutes of getting it to run. Try an hour or two on the highway shut off and coast a rest area, pull the plugs when it cools down. Sitting around a garage pulling off solenoid wires is not going to help the plugs tell you what's up.

May I recommend this engine wiring diagram for you? A lot safer on the cut-off spades.

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http://i187.photobucket.com/albums/x133 ... iringp.jpg
BobD - 78 Bus . . . 112,730 miles
Chloe - 70 bus . . . 217,593 miles
Naranja - 77 Westy . . . 142,970 miles
Pluck - 1973 Squareback . . . . . . 55,600 miles
Alexus - 91 Lexus LS400 . . . 96,675 miles

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