NickTheFox Posted June 10, 2015 Share Posted June 10, 2015 Hey guys, I'm just after some advice. I have brought a Datsun with an a12 and twin dellortos. The current fuel setup is an electric pump mounted on the firewall with no regulator. I have had issues with fuel sometimes pouring out the opening of one carb. I was wondering if this is because of having no fuel regulator? I was thinking of replacing the fuel pump and mounting it under the car closer to the tank. Was also thinking about purchasing a low pressure fuel regulator like this. http://www.sprparts.co.nz/holley-fuel-pressure-regulator-1-4psi.html What are you guys thoughts? 1 Quote Link to comment Share on other sites More sharing options...
Unclejake Posted June 10, 2015 Share Posted June 10, 2015 Those carbs will want around 3psi (not exactly) so if there's much more than that being delivered the fuel can climb over the bowl float and spill into the carb throat. I'd suggest checking your engine oil too. It might be contaminated with fuel. You may also have a weeping float needle valve An adjustable pressure regulator is fairly cheap, as is a pressure/vacuum gauge from Repco (to test the regulator output) EDIT: Yup, the Holley one you linked to is what lots of guys use. I have used two and found them both inconsistent, but I don't know of a better one. personally - I wouldn't move the pump at the same time as fitting the regulator. One thing at a time etc. 1 Quote Link to comment Share on other sites More sharing options...
azzurro Posted June 10, 2015 Share Posted June 10, 2015 Dellortos/Webers/carbs generally need flow not pressure, >5psi is probably too high for the needle valve to control and maintain the correct level in the bowl and most books say 2.5-4psi is best. get a FP Gauge first or find out what pressure your pump is before throwing money/time at it as it could be just a worn out needle valve or poor float settings too. BTW, changing the pumps location wont alter the pressure a the carbs, so don't do that unless there is another reason (noise etc). Quote Link to comment Share on other sites More sharing options...
azzurro Posted June 10, 2015 Share Posted June 10, 2015 and what UJ said. Quote Link to comment Share on other sites More sharing options...
NickTheFox Posted June 10, 2015 Author Share Posted June 10, 2015 Thanks for the replies! Ok so I should get a fuel reg first. Does anyone else have any good suggestions for a decent low pressure one? Also most of the fuel pressure gauges I've seen go up to 100 psi. Are there any lower pressure gauges around? My reasoning for moving the fuel pump was for noise. But also because most pumps work better when pushing rather then sucking. I will get a fuel reg before doing this. Quote Link to comment Share on other sites More sharing options...
sluggy Posted June 10, 2015 Share Posted June 10, 2015 Low pressure is the answer, get a decent reg too, if its mounted under the bonnet as it heats up it will creep upwards. I ran downdraft dells at 2.5 psi max. https://www.holley.com/products/fuel_systems/fuel_pumps_regulators_and_filters/regulators/carbureted_regulators/parts/12-804 That kind of thing will do it. A return line reg is even better so you dont dead head the fuel and heat it up. Mallory make these although not cheap. Quote Link to comment Share on other sites More sharing options...
Unclejake Posted June 10, 2015 Share Posted June 10, 2015 Also most of the fuel pressure gauges I've seen go up to 100 psi. Are there any lower pressure gauges around?Repco sell a hand held one that measures vacuum and pressure in small enough increments for your use. I think they are about $55. they have a flexible hose with a tapered brass end that you can fit into your fuel line for 'bench' testing You can borrow mine if you don't want to buy one, but you'd need to meet me in the central city sometime during business hours to collect it Quote Link to comment Share on other sites More sharing options...
sluggy Posted June 10, 2015 Share Posted June 10, 2015 http://www.silvesterv8.co.nz/products.php?product=Holley-1%252d4psi-Regulator http://www.silvesterv8.co.nz/products.php?product=Holley-0%252d15psi-Liquid-Filled-Fuel-Pressure with the holley type regs you can put a block on one side of the outlet that is tapped for 1/8" npt that these gauges thread straight into. Quote Link to comment Share on other sites More sharing options...
smokin'joe Posted June 10, 2015 Share Posted June 10, 2015 i am using procomp/profuel(cfr) rotary type adjustable reg for both the DHLA40,s and now 45's on Levin as i was advised non-adjustable ones can still over fuel Quote Link to comment Share on other sites More sharing options...
BlownCorona Posted June 11, 2015 Share Posted June 11, 2015 im running the same as above ^ but am going to upgrade to a self sensing facet style pump, that shuts off when it feels the float valve shut. meant to provide best results for bike carbs, i imagine the same for you, Quote Link to comment Share on other sites More sharing options...
bigmatt4 Posted June 11, 2015 Share Posted June 11, 2015 this http://www.trademe.co.nz/motors/car-parts-accessories/performance/fuel-systems/auction-900010094.htm and this http://www.trademe.co.nz/motors/car-parts-accessories/performance/fuel-systems/auction-900458652.htm work really well together Quote Link to comment Share on other sites More sharing options...
smokin'joe Posted June 11, 2015 Share Posted June 11, 2015 im running the same as above ^ but am going to upgrade to a self sensing facet style pump, that shuts off when it feels the float valve shut. meant to provide best results for bike carbs, i imagine the same for you, originally had the low-pressure Facet pump(without reg), lent it to a mate who accidently sold it with his car and replaced with higher presure Facet pump. both self sensing, bith the higher pressure one would flood slightly and bog down too much, thus needing to regulate pressure. can't remember who's book i was reading, either Carrol Smith or corky Bell, but he claimed 0.25PSI of fuel difference can pull major gains (lap times) in certian NA applications, believe it was .5sec around certain US tracks in stock RX-7 Quote Link to comment Share on other sites More sharing options...
BlownCorona Posted June 12, 2015 Share Posted June 12, 2015 im so glad i dont care about .5 second gains haha. what a can of worms to open. Quote Link to comment Share on other sites More sharing options...
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