Stoffregen Motorsports Posted May 18, 2017 Report Share Posted May 18, 2017 Yeah, I'm pretty sure that the Holley regulator is good for 99.99% of the guys here on Ratsun. Surging fuel pressures can affect tuning, but will an engine making 50%-60% of its power potential even notice? Doubtful. Besides, what is the range of the surge? It's still within the acceptable range of a DCOE, DGV or PHH carb. 1 Quote Link to comment
distributorguy Posted May 18, 2017 Report Share Posted May 18, 2017 On a stock truck, the Holley regulator will be a small problem compared to many other potential issues. The surge can be easily 1 1/2 psi - enough to push past a needle and seat with ease. Quote Link to comment
KoHeartsGPA Posted May 19, 2017 Report Share Posted May 19, 2017 I don't have a regulator on mine, the engine runs great and spark plugs are just right, not too dark, not too light... Quote Link to comment
Stoffregen Motorsports Posted May 19, 2017 Report Share Posted May 19, 2017 I've never had tuning issues specifically associated with the Holley regulator. Quote Link to comment
willz Posted June 14, 2017 Report Share Posted June 14, 2017 Should I be deleting the stock fuel rail that has the return? I seem to start running a lot better waaaaaaay after the engine has been warmed up. I'm thinking that the fuel might be trying to go back through the return line, which is all hooked up. I get weird random bursts of full lean up until about 15 minutes of driving. I feel like it ran better on those super hot days we had a while back. Not sure. It drives perfect on anything under 1/4 throttle during that time Quote Link to comment
Crashtd420 Posted June 14, 2017 Author Report Share Posted June 14, 2017 Didn't realize the 620s even had a return line.... remove it from the equation.. try capping it for now and see if that makes a difference. If no changw then you know it's not an issue. Quote Link to comment
Crashtd420 Posted June 14, 2017 Author Report Share Posted June 14, 2017 And willz... I bought the same wideband o2 kit and couldn't be happier. Just got mine installed,... such a good unit... and it will do data logging with a simple computer hook up.... but I was surprised it didn't read a tach signal... maybe that's where the add on modules come in... 1 Quote Link to comment
Pat murf Posted July 22, 2017 Report Share Posted July 22, 2017 I had a 750cfm Holley on a car-tec water cooled intake. I changed it out for a 600 street performer detuned to a 400 race jet. It ran amazing, it was called a Paul Newman setup, it was a Turbo car raced in FL . It was setup like his 24 hrs of lemans winning 71 240z. Quote Link to comment
Pat murf Posted July 22, 2017 Report Share Posted July 22, 2017 Always run a Mallory regulator too. Quote Link to comment
datzenmike Posted July 22, 2017 Report Share Posted July 22, 2017 You had a 750/600 Holly on an turbo L20B???? Quote Link to comment
wayno Posted July 22, 2017 Report Share Posted July 22, 2017 You had a 750/600 Holly on an turbo L20B???? I am thinking 6 cylinder since he compared it to a 71 240Z. Quote Link to comment
racerx Posted July 23, 2017 Report Share Posted July 23, 2017 Isn't a 750 or 600 a four bbl., this is what I have on my 65 289 mustang? maybe too much carb for L20, maybe a Holley 5200? Quote Link to comment
datzenmike Posted July 23, 2017 Report Share Posted July 23, 2017 This topic is about single side drafts. 2 Quote Link to comment
Stoffregen Motorsports Posted July 23, 2017 Report Share Posted July 23, 2017 Come on everybody. Take it easy on the new guy. The Paul Newman race car he is referring to is more than likely the Bob Sharp 280ZX. 2 Quote Link to comment
Doctoraudio Posted August 25, 2023 Report Share Posted August 25, 2023 (edited) Found this info. Conversion equipment jet setting Datsun B110 (A12) - single 40 DCOE 2 Choke size 27 Aux. venturi 4-5 Main jet 1-10 Emulsion tube F7 Air corrector jet 1-65 Idle jet 0-50 F9 Accel. pump jet 0-50 Accel. pump inlet valve with ex. orifice 0-50 Needle valve 2-00 Datsun B210 & F10 (A14) - single 40 DCOE 2 Choke size 33 Aux. venturi 4-5 Main jet 1-30 Emulsion tube F11 Air corrector jet 1-80 Idle jet 0-50 F8 Accel. pump jet 0-60 Accel. pump inlet valve with ex. orifice closed Needle valve 2-00 Datsun 510 (L16) - single 45 DCOE 13 Choke size 33 Aux. venturi 4-5 Main jet 1-30 Emulsion tube F16 Air corrector jet 1-90 Idle jet 0-50 F8 Accel. pump jet 0-50 Accel. pump inlet valve with ex. orifice 0-55 Needle valve 2-25 Datsun 510 (L16) - dual 45 DCOE 12 Choke size 32 Aux. venturi 4-5 Main jet 1-35 Emulsion tube F15 Air corrector jet 1-70 Idle jet 0-55 F2 Accel. pump jet 0-40 Accel. pump inlet valve with ex. orifice 0-55 Needle valve 2-00u 40 DCOE-151 redline #19550.174 baseline jetting 32 Venturis 4.5 Aux venturis 115 Main jets F11 emulsion tubes 200 Air correction jets 45F9 Idle tubes 40 Pump jet 50 Pump exh 1.75 Needle valve huicho: SINGLE 40 DCOE ON A STOCK A15 ROUND PORT COMPLETELY STOCK A15 economy version(round port head) Main Venturi 32 Aux. Venturi 4-5 Main Jet 140 Emulsion Tube F-11 Air Corrector Jet 200 Accel. Pump Jet 60 Accel.Pump Inlet Valve with Ex. Orifice closed Needle Valve 200 Idle Jet 55F9. If you do not use an air filter: * 180 on the air correctors * 130 on the main jets Edited August 25, 2023 by Doctoraudio 2 Quote Link to comment
Doctoraudio Posted August 25, 2023 Report Share Posted August 25, 2023 Process Start with venturi/choke size. For dual-carbs (one barrel per engine cylinder) 28mm is good for max power with good flexibility at 6000 RPM with a 1.2-liter engine. Larger venturis will make good power, but with less flexibility (flat spots, poor part-throttle response). See Carburetor Sizing. Next, set the float. Everything is affected by the float level, so do this first. Float Settings Early brass float: 8 to 8.5mm Late plastic float: 12.5 to 13mm In DCOE series, the main jet should start at 4 x venturi size. For example, with 30mm venturis start with 120 Main Jets. The Air Correction Jet should be 1.25 to 1.50 of the Main Jets (some say main jet + 50). For 120 main jet, start with 165 Air Jets. That much is easy (setting the air/fuel ratio which is around 13:1 for all engines). The trickier part, for which tuning to the particular engine is called for, is the transitions: When accelerating the pump jet and duration are the main factors Transition between idle circuit and cruise circuit is controlled by the Emulsion Tubes and Idle Jets. Do not attempt to fudge this by raising or lowering the float level. The Float Level should be set to the Weber specifications before any other tuning is done. Warm the engine up fully and set the Idle Speed. For a stock factory spec engine, set the idle speed to 800 RPM. The speed screw should be 1/4 to 1/2 turn in after contact with lever maximum. If it won't idle down to 800 RPM something is wrong - most likely the throttle shaft nut has been overtightened binding the throttle. But it could also be the linkage is jamming (inspect carefully). An air leak can also cause a high idle (either loose carburetor parts, a bad gasket, or a leaking/cracked hose). dcoe_a1.jpg After setting the idle speed, adjust the idle mixture screw to Lean Best Idle. If setting Lean Best Idle requires the mixture screw to be turned out 1-1/2 turns or more, the idle jet is too lean. Replace Idle Jets with half-size larger. If the mixture screw is 1/2 turn out (or less) from seated the Idle Jets are too rich. Replace Idle Jets with half-size smaller. If the Speed Screw is out more than 1/2 turn, the idle system is lean. This will cause problems with tuning the carb, so fix it now by fitting larger Idle Jets. 1 Quote Link to comment
Doctoraudio Posted August 25, 2023 Report Share Posted August 25, 2023 Is there any other info? I am running a LZ 2.2 With a 45mm single side-draft carb. Not installed yet. But in the next couple of days! 1 Quote Link to comment
Crashtd420 Posted August 25, 2023 Author Report Share Posted August 25, 2023 40 minutes ago, Doctoraudio said: Is there any other info? I am running a LZ 2.2 With a 45mm single side-draft carb. Not installed yet. But in the next couple of days! I think you got a good starting point... Only other 2 things I can think of are 1) you should also make sure the air flow between the 2 barrels are balanced... 2) if it's in the budget an air fuel gauge can be very helpful.... Quote Link to comment
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