3.5 v8 with su's will not run

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badlandy

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43
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Walsall West Mid's
Hi their please help, i have installed a v8 with su carbs but it takes an age to get it to start and then once it does fire it will not run, all new plugs,leads new cap and coil, i have found top dead centre but hey still no joy, the plugs on the passanger side are wet with fuel, the drivers side are black with sut, I have had it running for about 5 mins but i cant rev it up as it tries to stall. what can i try NOW

HELP:mad::confused:
 
Was the engine you fitted married to the same SUs and running previously (i.e. are they likely to be roughly tuned to that engine?)

My best guess would still be timing, but could be flooding/lack of air if you're only firing on four. That said the firing sequence isn't 'all one side, then all of the other side so it doesn't make a great deal of sense.

More details?
 
I'm better on EFI engines but maybe the following might give some inspiration.

You don't say if it is manual or automatic choke. If automatic, make sure it isn't seized, or perhaps try starting with the auto choke taken off.

Have you checked the carb diaphragms - a split/leaky diaphragm will cause problems.

Have you got any inlet leaks?

Next do a complete ignition check, are you getting a spark? did you also change the rotor arm? did you use genuine Lucas cap (and arm)?
 
badlandy said:
Hi their please help, i have installed a v8 with su carbs but it takes an age to get it to start and then once it does fire it will not run, all new plugs,leads new cap and coil, i have found top dead centre but hey still no joy, the plugs on the passanger side are wet with fuel, the drivers side are black with sut, I have had it running for about 5 mins but i cant rev it up as it tries to stall. what can i try NOW

HELP:mad::confused:
Click to expand...

I'm pretty certain that each carb supplies two ports on each bank so the fact that one side is wet and the other sooty, doesn't immediately point to a carb problem in my view. I would be leaning more towards an ignition issue. You list the new parts but you don't say if your distributor is points or electronic. If points, check gap and replace the condenser.

You say that you have found TDC. I assume that you mean that you have checked that the rotor arm is pointing at the lead for No 1 when No 1 is at TDC. Have you checked that it is TDC on the firing stroke (both valves closed). FWIW, I don't think it would fire at all if 180 degrees out but worth checking.

Good luck

Chris
 
Hi i have a Manual choke, i have had another play over the weekend and again it runs for about 15 seconds and then cuts out, I have now stipped the carbs down again and found that the needle wasnt maching so i have now replaced these, but hey still no joy appart from all the plugs being wet.
All the parts which i have fitted have been Brittpart and NGK plugs, the only thing my mate has said is the engine turns over a bit slow? any ideas?
 
take the plugs out give them a good clean and make sure your getting a good spark by syrning the engine over with a plug out. re- check ya static timing. try getting some of that easy start spray, i had the same problem i gave it a quick spray and it ran. never looked back.
 
badlandy said:
Hi i have a Manual choke, i have had another play over the weekend and again it runs for about 15 seconds and then cuts out, I have now stipped the carbs down again and found that the needle wasnt maching so i have now replaced these, but hey still no joy appart from all the plugs being wet.
All the parts which i have fitted have been Brittpart and NGK plugs, the only thing my mate has said is the engine turns over a bit slow? any ideas?
Click to expand...
See if it will run on carb cleaner or petrol sprayed into the carbs directly. If so try a tow start, could be wiring fault robbing coil of power when cranking.
Make sure jets are correct in carbs (seated propperly) needles may be too thick (economy needles - weak needles) thick needles are for high altitudes or economy engines.
The needles should be BGC or BGD or BGV depending on model. Early carbs BGC and late BGV.
Try richening them up, screw mixture screw in to richen and out to weaken, you can always screw them back if you remember how many turns, I would suggest half a turn at a time.

You could also have a problem with fuel levels in the float bowls or even sticking needle valves in the float bowls.
 
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Deffo Carbs supply 2 in 1 bank 2 in other so not carbs if only one side running, have you checked fuel ballancing pipe not caked up/drawing more on one side (look at pump fackinfacked?)

My bumol' it saying nision but what does it know...? Don't quite know why this would only effect one side though. Doube check wires!

might be worth swapping some plugs from one side t'other

Might be worth doing a compression test...
 
i have just come across some old Zenth carbs i will try these the weekend as the father in law is now trying to get me to put a 200tdi in place of the v8:eek: This cant be the answer
 
NOOOOOOOOOOOOO DONT GIVE IT UP FOR OIL BURNER!!!!!!!!!!!!!!!!!!

It will be somethin really stupid.........
 
i had a similar problem and it turned out my fuel tank was contaminated with water. I missed the signs cos it still smelt like fuel when in fact it was a mix. Tank drained, leaky cork seal renewed and its fine.
 
badlandy said:
i have just come across some old Zenth carbs i will try these the weekend as the father in law is now trying to get me to put a 200tdi in place of the v8:eek: This cant be the answer
Click to expand...

So transplanting a 200TDI is easier than getting a carb V8 running:doh: I don't think so.

In my view, don't go with the Zeniths, you are just introducing another variable into an already baffling problem.

To be honest, you have to try pretty hard for even the dodgyest SU not to work to some extent unless the jet is blocked by crud. Here is a link to how to set them up.

http://www.v8register.net/FilesV8WN/SUbookletsAUC9939AHIFtuningandservicing.pdf

I still think it would be worth disconnecting the fuel pump and give it a burst of easystart. A 3 second burst in each carb should run the engine for 15 seconds. Then try a 3 second burst in one side and try to start, then the other. This will isolate if one bank is a problem or not. If it doesn't fire on easystart, the problem isn't the carbs.

It might help with the diagnosis if you tell us a bit more about the engine. What is it in? what sort of Distributor? what sort of fuel pump? Was it running before you changed all the ignition consumables?
 
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