Excessive fuel consumption...5L RV8 Race Engine on Carbs

[pk500]

I got a mallery set up on a road car and it aint making fuel consumption worse ! fuel econimy and 5l v8 dont go together

NTEL said:

Gents, I have a 5L Rover V8 race engine (Eales) using quad 48 dellorto carbs. After every race it seems to be using more and more fuel and is starting to sound a bit "fluffy" when going back on the loud pedal. Timing, plug gaps, tappets are all spot on but it does run cool (probably due to it running rich)

Could it be possible that the ethanol in Tesco 99 / Shell / BP fuel I am using is rotting the, already rather large, main jets and making them even bigger?

Or do you have any other ideas? Ignition system is Mallory / MSD

[anonymous-user]

Hi Ho, Hi Ho, it's off to the rolling road you go.......... ;-)

[stevieturbo]

NTEL said:

Chaps, is there any evidence that modern fuels rot old skool jets?

If there is, I think it would be up there with evidence of aliens etc.

[NTEL]

OK, thanks for the input. I think we will leave it there. Max and Stevie, have you ever seen a Carb? I'll speak with people who know what they are talking about................Good god...there are some friggin' knobs on this forum!!!!!!!! bye bye

Edited by NTEL on Thursday 25th July 23:37

Edited by NTEL on Thursday 25th July 23:40

[paolow]

[stevieturbo]

NTEL said:

OK, thanks for the input. I think we will leave it there. Max and Stevie, have you ever seen a Carb? I'll speak with people who know what they are talking about................Good god...there are some friggin' knobs on this forum!!!!!!!! bye bye

Edited by NTEL on Thursday 25th July 23:37

Edited by NTEL on Thursday 25th July 23:40

Of course I have, Ive seen hundreds. They are usually brass, and not a chance in hell will a minute percentage of ethanol do them any harm.

Unless they have been flowing fuel for centuries/millenia and eroded away like water did to the grand canyon

[anonymous-user]

It always amazes me how many people have "race" cars / engine, and can't seem to just spend about £50 getting them checked/setup on some rollers.................... ;-)

[jwoffshore]

Neither ethanol nor methanol will go for brass in the short/medium term. The main issue long term is that these liquids are hygroscopic and absorb water, causing corrosion. Also, certain O-ring materials are not compatible.

You have FOUR carbs, each with it's own fuel supply via a float chamber. A fault with any one carb could be giving you the problem. My main experience is on bikes. If only one carb of the four goes bad, it will run like a bag of nails.

[Chromed]

"Rotting the jets, making them larger" , classic . Some people should stand well away from spanners.

[Number 7]

Back in the eighties when I had bikes, a least one road going Yam I owned had non-metallic mains - possibly nylon. Fine with petrol and oil, but not sure how such stuff might react to modern fuel additives, or even if car type carbs would use any material like this.

[HustleRussell]

Float level adjustment?

[eliot]

NTEL said:

Max and Stevie, have you ever seen a Carb? I'll speak with people who know what they are talking about

I think you will find that they have seen a carb. Question is - have you? Brass isn't going to be eroded by anything other than a drill bit.

[Steve_D]

I think some on here are being a little harsh on the OP when the press is alive with reports of ethanol eating various car components.
Telegraph report

Whilst most of this may just be press hype I for one would like to see reports of a counter argument.

Would those who would flame the OP like to provide the evidence?

Steve

[eliot]

Get a wideband fitted and at least determine the current rod/jet combo and go down a couple of stages if its really rich.

[blitzracing]

Who needs widebands?- just look at the colours of the plugs across all 8 cyclinders and ss if some are more sooty than others. At least that will pin down an issue with one carb bank. Lambda sensors are of limited use when the exhaust gas's get mixed between cyclinders in the down tubes, you would need to be very acurate to see rich pulses on the probe outputs and ties it up with a particular cylinder. I like colour tunes for this sort of issue- just buy 8 of them and you can simply look across the colour of burn across all the pots at the same time.

[Mr2Mike]

Steve_D said:

Whilst most of this may just be press hype I for one would like to see reports of a counter argument.

Would those who would flame the OP like to provide the evidence?

Steve

There are still a huge number of carburetored vehicles on the road and used in competition. If ethanol dissolved brass jets at the rate the OP is suggesting there would be considerable evidence of it by now.

[v8 racing]

out of interest what is the fuel economy of this engine?

[357RS]

When I did off road racing I had a self built 4.0 litre Rover V8 using modified twin SUs.

Everyone who tried was very surprised at how it would rev instantly in response to throttle input.

That did approx 4 mpg - is yours worse?