GTV6 3.0 litre Carburated

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konrads
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GTV6 3.0 litre Carburated

Post by konrads » Tue May 13, 2008 12:08 am

I have a problem with my Dellorto carburated 3.0 litre GTV6 on right hand corners.
It starts with a fuel smell and after a couple of laps I find evidence of fuel leaking from the left hand side on top of the cam cover.
It looks like the leak is coming from the T connector on the carbs but I only have this problem on right hand corners so far.
With the throttle fully open in a straight line there is no leaks.
Last night I checked the fuel pressure and I'm getting .5 Bar with the engine off and the fuel pump running.
Does anyone know if this is too high for carbs?

Regards

Konrad
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Dellorto Carburetors on my South African GTV 3.0 litre
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MD
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Post by MD » Tue May 13, 2008 12:34 am

As a rule carburettors do not like a lot of pressure and usually have inline regulators set for the particular type of carburettor. Suggest you do some reasearch on your carbs for prescribed pressure.

In any case, I suspect that you would have much more of an issue with the actual running of the engine with too much fuel pressure.

The fuel leak has to be other defects relating to sealing.
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Post by kevin » Tue May 13, 2008 11:40 am

Konrad, spoke to Baz, suggested we try soft almn washes which i can get from Wurth for the banjo fittings on the sides of carbs. I have also located a Alfa sei workshop manual which i will go through to get the correct pressure. (maybe baz can remember). What pressures do the chaps run on 4cyl motors, anyone, anyone.
ps remember to get earplugs and extra towels to put in the car when you drive to Phakisa race circuit on Friday(250km away )
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Post by Barry » Tue May 13, 2008 8:36 pm

K&K..(Hey Mike ?? Sharp huh? ) No more than 3 psi fuel pressure..0.5 bar is 7 psi odd...too much..
French cars are shit and shit expensive to service and bloody awful and unreliable and expensive and friends don't let friends drive french cars and you wait years for parts.
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Post by konrads » Fri May 23, 2008 12:46 am

Went to Phakisa last weekend, Good fun,

The problem was still there even though I did put new inner fire washers.
Wasn't as bad as our last practice at Midvaal but still not good.

If the pressure is too high do I need change my fuel pump or get some sort of pressure regulator?
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Post by MR2 Zig » Fri May 23, 2008 5:44 am

I'd think you would be best, easiest and cheapest with an adjustable pressure regulator. Here in the States they sell pumps for 5-7 psi to be applied to American type carbs and 1-4 psi for "foriegn" (Weber, SU, Dellorto, etc) carbs.

HTH,
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Post by Barry » Fri May 23, 2008 8:17 am

Remember that the system is a "through" flow system,much the same as std efi...The fuel recirculates all the time,pressure is controlled via the fpr...its not a dead head system..

Konrad,my offer to try my almost brand new carbs is still on the table..and I have a few sets spare.. :)
French cars are shit and shit expensive to service and bloody awful and unreliable and expensive and friends don't let friends drive french cars and you wait years for parts.
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Re: GTV6 3.0 litre Carburated

Post by kevin » Sun Apr 11, 2010 12:34 pm

Check this race prepared carbi motor. Rumour has it its way stronger than the average 24v. Will keep this build updated
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Re: GTV6 3.0 litre Carburated

Post by xrad » Sun Apr 11, 2010 4:21 pm

wow, nice pretzels!
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Re: GTV6 3.0 litre Carburated

Post by MR2 Zig » Sun Apr 11, 2010 8:37 pm

What kind of carbs are those anyway?
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Re: GTV6 3.0 litre Carburated

Post by kevin » Sun Apr 11, 2010 9:09 pm

Origional - dellorto's
konrads
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Re: GTV6 3.0 litre Carburated

Post by konrads » Mon Jun 14, 2010 1:18 am

24th April Kyalami.
Spun off during practice on a wet track slippery track.
Just before we went on one of the competitors spilled oil on the track.
Had to panel beat the wheel arch a bit.
This photo was taken during the actual race.
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kevin
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Re: GTV6 3.0 litre Carburated

Post by kevin » Fri Jun 18, 2010 12:40 pm

Konrad , you should get medal for bravery that day. Heard it was five big spins from qualifying to race two and you still made it to front of field.
Post some pics of what your catr looks like after repairs
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Re: GTV6 3.0 litre Carburated

Post by Typhoon90 » Wed Aug 04, 2010 3:55 am

I agree that 7psi or .5 bar is too high for those carbs. Most Euro and Japanese carbs are designed for 3-3.5 psi max. Even Holleys won't tolerate much more than 6 psi and they run big floats(more closing force on the float needles)
If you are running a return system and developing excess pressure in the fuel manifold, you have a restriction in your return line. If it was an unrestricted system, your fuel pressure would be pretty much zero as the fuel just pumped back to the tank, which you don't want, you need some pressure in the lines so fuel pressure can fill the float bowls.
So, there will likely be a restrictor in the return line somewhere, they're usually either a spring loaded ball or a simple orifice type. Both are easy to change or modify.
Be warned though, if you have calibrated carbs at 7psi, they will be leaner at 3.5 psi, probably by a couple of jet sizes, but it will also affect idle, transition as well. You could also have a simple blockage or kink in the return hose somewhere too.
If you only have fuel leaking in turns, this is probably too high fuel levels and you are losing fuel out of the float bowl breathers, this will also be caused by too high fuel pressure, which has the effect of raising the level of fuel in the float bowls on the carbs.

Regards, Andrew.
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Re: GTV6 3.0 litre Carburated

Post by Joemart » Mon Apr 30, 2012 10:17 pm

Some more Pics - kevin and konrad being responsible citizens by testing in neighbourhood after 9am .
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