Fuel System Help Needed

[theorangeperil]

Need some thoughts from you guys.
I have an expert working on my car, a great, and well known guy but I'm not sure about some of his thoughts so I need some other opinions.

Cars a modded 2.4 on carbs running about 190+hp (rolling road), so quite highly tuned. I run a facet competition red-top below the fuel tank, because I've been told these pumps are better at pushing than pulling fuel. Right? My man has suggested it should be in the engine bay?

Next the car was running a Malpassi Filter King regulator, in the engine bay, setting the fuel pressure at 3psi. My car is a 69 so has no return fuel line to the tank. My man has disconnected this, suggesting it will be causing a problem, but my understanding is that the Facet will be running at between 6-8psi? What psi should the webers run at? If we regulate it will it damage the facet?

The exhaust pops like mad, always has, but now more than before, my man suggests this is my Bursch silencer, not having a chamber like the factory exhaust, therefore allowing unburnt fuel from the valve 'overlap' to explode in the hot pipework? Thoughts?

Another well known 'expert' a couple of years ago changed my non-vacuum advance distributor to a vacuum advance distributor, despite the fact we are not using the vacuum advance. I have just read somewhere the vacuum advance should be fixed solid with a self tapping screw if used with an EMS system. Is this right?

Despite having the car rolling roaded the week before, my man has now disconnected my Omex 3D ems and tweeked it using a Gunsons colour tune. An alleged race car expert at the weekend told me this is pony, and the only way to tune a car is on a rolling road with a 'wide angle' something or other.

I have to say the car is running a lot better than it was '7 months!?!' ago when I first took it in to him (he's not a fast worker). And he assures me he has got to the bottom of the problems I was suffering. But the pub chat with the alleged race car expert at the weekend has got me worrying a little...

I know often everyone's an expert, but I thought the ddk was the best place for some impartial advice!

[impmad2000]

Cars a modded 2.4 on carbs running about 190+hp (rolling road), so quite highly tuned. I run a facet competition red-top below the fuel tank, because I've been told these pumps are better at pushing than pulling fuel. Right? My man has suggested it should be in the engine bay?

- Some cars run two pumps, a pre pump at the tank and a high pressure pump in the engine bay, but this is usually EFI systems.

Next the car was running a Malpassi Filter King regulator, in the engine bay, setting the fuel pressure at 3psi. My car is a 69 so has no return fuel line to the tank. My man has disconnected this, suggesting it will be causing a problem, but my understanding is that the Facet will be running at between 6-8psi? What psi should the webers run at? If we regulate it will it damage the facet?

- so if the fuel return is blanked off, where does the excess pressure get bled off to ? 3 - 4 PSI for carbs I believe. The limitation is the needle valve in the carbs. If this starts to leak, you'll over fuel the carbs and possible leaks etc... If the needle valves seem to be holding, great, but they may start to fail. High pressure fuel leaks can be very scary ! What are the needle valves rated at ?

The exhaust pops like mad, always has, but now more than before, my man suggests this is my Bursch silencer, not having a chamber like the factory exhaust, therefore allowing unburnt fuel from the valve 'overlap' to explode in the hot pipework? Thoughts?

- Exhaust pops can be caused by air leaking into the exhaust, or by excessively weak mixture - -just some more ideas...

Another well known 'expert' a couple of years ago changed my non-vacuum advance distributor to a vacuum advance distributor, despite the fact we are not using the vacuum advance. I have just read somewhere the vacuum advance should be fixed solid with a self tapping screw if used with an EMS system. Is this right?

- The ems will expect the mechanical aspects of the ignition to remain constant. Fixing the vaccuum will remove any variance in ignition timing caused by the mechanism moving around. Sounds like a good idea to me.

Despite having the car rolling roaded the week before, my man has now disconnected my Omex 3D ems and tweeked it using a Gunsons colour tune. An alleged race car expert at the weekend told me this is pony, and the only way to tune a car is on a rolling road with a 'wide angle' something or other.

- "Wide band" rather than "wide angle" I think... This will check the fuel mixture with a wide band lambda senosr over a wide range of engine speeds and loads. It is up to the rolling road operator to use his skill to set the optimum setting over the range. It does not mean that he actually managed to achieve this ! Perhaps your man with vast experience and knowledge preferred the result achieved with a colour tune ! Who knows, go with the one that you trust. More technology doesn't necessarily mean better.

I have to say the car is running a lot better than it was '7 months!?!' ago when I first took it in to him (he's not a fast worker). And he assures me he has got to the bottom of the problems I was suffering. But the pub chat with the alleged race car expert at the weekend has got me worrying a little...

- there are a lot of pub experts out there, Myself included. If it goes better, then it must be better mustn't it ?

I know often everyone's an expert, but I thought the ddk was the best place for some impartial advice!

I offer my thought as simply that. Im definately NOT an expert. Please disregard as much of the above as you like


Cheers
Tim

[theorangeperil]

Cheers Tim, as you said: if it goes better, it must be better!

Any one else?

[speedysimon]

Hi - I have just fitted webers, with a red top as well, but mounted inside the 'boot' on the bulkhead by the fuel tank - mainly as i just did'nt want it exposed underneath. The pressure regulator is in the rear set to 3 psi by the inline guage and my return is disconnected. I have the biggest fuel filter i could buy just before the pressure regulator.

Couple of points: I have to be a bit careful not to run the pump without starting the engine .... I would also say the only way to achieve optimum performance is on a rolling road with someone with a proven ability and never forget, as previously posted, the numbers you get are all relative and not a definitative BHP etc - which i did'nt realise at first!

But what has amazed me most is the increase in torque, which is now a straight line up to 6500, i can pull 30 to 110 in 4th very, very quickly - I am running straight thru's with Super Traps with 12 plates on each, and they do bang on over run - all in all removing the CIS was the best thing I have ever done!

[theorangeperil]

Talked to my man again tonight and went over my concerns. He said that although he has used many rolling roads over the years he has never witnessed anyone being able to set up each sparkplug/cylinder to run at optimum burn. He feels that combined with the rolling road he is able to tweek with the colour tune in a way that is impossible by any other means.

He also feels that it is unlikely that the facet will be running at the full 6-8psi due to manufacturing tolerances and the pressure loss between the pump and the engine.

As far as the EMS goes, he questions how effective high tech sits with an older engine design, although he doesn't discount using it in the future...

Speedy Simon: what happens in the fuel line at the point where the pump is attempting to pump say 6-8psi anf the regulator is allowing 3psi?

As you say headline bhp figure mean nothing, its the torque and driveability that make the difference. That's where the E cams really come in to their own.

Glad to hear you're pleased with the carbs, most people seem to harp on about the benefits of fuel injection.

[speedysimon]

''Speedy Simon: what happens in the fuel line at the point where the pump is attempting to pump say 6-8psi anf the regulator is allowing 3psi? ''

The fuel line goes straight into the regulator which has two outlets, one goes to carb the other goes to the guage which then goes into the other carb.
As for optimum burn, my rolling road man simply uses a gas analyser, which was a little awkard with two outlets, but he was happy at the end of the runs.
Certainly, everyone I have spoken to says the biggest problem is over fueling, so the lower the pressure (within reason) the better. On the works cars I understand they have a pump at the front mounted on top of the bulkhead, which is set up for each bank of carbs.
The other problem i had was, originally i disconnected the heater feeds and this caused pinking because the exhuast valves were getting too hot.