The V8 Owners Forum -

Could anyone tell me what pressure to set my fuel regulator at.I have a Weber 500 on a 4.6 [260bhp]Thanks,Nick.

I'm not sure about your carb but most carbs like about 5 psi.

I used to run mine at 7. Mainly because 2 regs fell to bits and the Holley Red Top poked out 7spi at the carb anyway so I did without (put a small £12 gauge there)...

The manual suggests setting your regulator at 5.5psi. What fuel pump do you have?

Kevin.

I have a facet red top pump fitted.I adjusted the regulator last night but could only get the pressure to about 3.5 psi.

I've ran a redtop into a '500 without a regulator. I did have return with a restriction in it though.

nickm wrote:I have a facet red top pump fitted.I adjusted the regulator last night but could only get the pressure to about 3.5 psi.

Well the Red Top should provide 6-8 PSI. so there would appear to be a problem, is the pump posiitioned below the level of the tank as they are not designed to suck.

Alternatively there may be some obstruction in the fuel line or filters.

Kevin.

Red top spec says 6-7psi, it does seem low still. Tried without the reg?
Presumably fuel has a line loss the same as air, in which case allowing 1psi for that, it still seems low.
Mine ran fine for donks at 7, no return, they seem much less sensitive to pressure than the Holleys.

Alley Kat wrote:Red top spec says 6-7psi, it does seem low still. Tried without the reg?
Presumably fuel has a line loss the same as air, in which case allowing 1psi for that, it still seems low.
Mine ran fine for donks at 7, no return, they seem much less sensitive to pressure than the Holleys.

Line loss only occurs if the fuel is flowing, so at standstill you should see the same pressure throughout the system.

The important thing is do you see full pressure when your carb is filling rapidly, as in full throttle running?

You can rig a temporary gauge where you can see it when driving, and watch it at full throttle, just so you know you are still getting decent fuel pressure just when you really need it.

I set my pressure up with a nice cheap gauge. It was so handy I left it there to show a low pressure problem etc, until I was told the gauges are not designed to be fitted permanently. The continual flex of the pressure tube fractures it and you get a huge fuel leak !!!!

FWIW

Dave

tetlow wrote:I set my pressure up with a nice cheap gauge. It was so handy I left it there to show a low pressure problem etc, until I was told the gauges are not designed to be fitted permanently. The continual flex of the pressure tube fractures it and you get a huge fuel leak !!!!

FWIW

Dave

Hence why I said 'temporary gauge' in my post.

There are fuel-to-oil gauges you can use in your dash, so that the fuel does not actually go into the gauge, for safety, but transfers pressure at some black magic device away under the bonnet.

I have got one of these http://cgi.ebay.co.uk/Mr-Gasket-1563-Li ... 18Q2el1247

Should look nice sitting behind the carb so I can see it through the windscreen, and I think they are permanent fixture ones.

My gauge was cheap, made no mention of having to be a temp fitting, I did wonder but left it in place anyway for the 2-3 yrs while I had it no probs, and then with new owner. Bloody regs were a pain though...