Carburetor Central
If you have questions about the SU Carburetors, this is where you can find the answers.
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I just rebuilt my triple Mikuni PHH 44s reinstalled and set the pilot screw to it's original setting of 1.25 turns out from bottom. The butter fly valves are completely closed and it will idle around 1000 RPM(ish) then it will idle right up to 2.5 to 3K RPM after a minute or so. That's with the starters turned off. If I play with the butter fly valve opening (idle set screw) and turn in the pilot screw to about 3/4 it seems to run but its rough. I haven't balanced it out yet. I'm trying to understand what's going on so a little direction on my misunderstandings would be great. My understanding is that the pilot screw adjusts the amount of air added to the mixture. …
Last reply by madkaw, -
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The little brass screw that connects the choke bracket to the nozzle was super tight - looks like I messed the screw head slightly. Might have to replace some dome and fuel bowl lid screws too. They're all brass screws I haven't seen before: for a flat screwdriver but what looks like slot for a phillips too. Are those available? British Classic Motors sells sets of SS bowl and top screws w/ socket head, don't know if they would fit the Hitachis but can ask them. Is SS OK or should they be brass? Seems like you could wreck the threads in the carbs with SS if you're not careful. Is there a carb screw size list anywhere? The carbs are rebuilt I guess (shiny new brass stuf…
Last reply by Oiluj, -
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I normally set the needle valve closure point on carbs by blowing in the inlet and adjusting the tab so that the valve is shut at 90 degree point of swing (top of float is parallel to top of fuel bowl). The carbs I have set like this have always worked fine. However, I ran into some problems today with a set I did this fuel level technique too so I decided to check in more detail as I could not get the A/F ratio to work no matter what I did with the jet height. I decided it was best to back track and recheck every thing. I first tried adjusting the fuel level at 23mm in the bowl and also the other technique of meniscus 10 turns of the jet down the well. The carbs initial…
Last reply by Captain Obvious, -
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After a drive, checked the clear filter before the mech pump while the car was idleing - only about 1/8 or less full. Looked at it carefully and could see bubbles appearantly being drawn into the fuel pump. It's installed so it sits level, horizontally. Tried tilting the filter (due to the hoses I could only tilt it about 45 deg both ways). When I tilted it the filter started filling up. Within about 45 seconds it was filled up about 5/8 to 3/4 full and no bubbles. Put it level again. Slowly (took about 3 minutes) the level went down to almost empty. Repeated the test 3 times - same result every time. Doesn't seem to matter which end is tilted up. WTF? Have been having…
Last reply by Stanley, -
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I always used a friend's Unisyn flowgauge when balancing carbs. It worked fine at low RPMS and at high RPMS. IT DID THE JOB. I am now using an STE Synchometer with absolute measurement dial but it pegs at higher RPM's. I tried the two different rubber fitting that came with the STE tool and also tried to use the holes in these fittings as bleeders but no luck. How can this tool be used at 3000rpm?
Last reply by 240260280z, -
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1970 240z, will be dropping in a built 2.8L with Z therapy SU's, wondering if I can just use an electric fuel pump with regulator to 3lbs straight to the carbs with no return line? Thanks, Chris
Last reply by grannyknot, -
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It's 100+ deg again today, the car is running really bad at higher RPM. I didn't want to thread jack the octain thread, so here we go. I just ordered a Holley blue pump with a regulator to replace the pogo pump. This is about the last thing I haven't tried among the common remidies like insulation and heat shields. I thought about cutting the hood, but I have never seen a hood scoop that looks as good as the solid 240 unvented hood. My hood has a dent, but my body man says his father's a TV repairman and he has the ultimate set of tools and he can fix it. (thats for the old guys out there) So I figure that if I must cut the hood, now is the time as paint is coming soon. …
Last reply by 5thhorsemann, -
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I just rebuilding the carbs on my 72 z (car sat for 30 years), but now, I cant' get it to rev over 4000 RPM's. It won't free rev or while I am driving. It idles fine, but it is lacking the power it should have. I tried reseeting the float levels, made sure the lines and clear. When I try lifting the barrels, the front one almost stalls, the rear has no effect. When I place the flow meter over each carb, the fron one gives a good reading, but the back one makes the engine rev higher. This tells me that the rar carb is running lean, but I can't get it to increase the gas flow. Any advice?
Last reply by Wade Nelson, -
Has anyone thought of setting up SU's to run E85? Is it even possible? Would the nozzle be the only issue? Just curious..
Last reply by Jeff G 78, -
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I always wanted to put triple Webers with braided SS fuel lines on my late 260Z (11/74) (original owner). I have been running ’72 SU’s since the early 80’s which eliminated the dreaded vapor lock of the flat tops. Mike W’s posts provide an excellent, detailed description, problem solving and great drawings with even part numbers spelled out. His posts inspired me to do it now. Fortunately when I bought them MSA had a sale on the Webers for $1495. (Interestingly MSA’s old blue catalogue from years ago had them listed for $2000!) The Webers are 40 DCOE 151 with Main jet 130mm; Air corrector Jet 170; Emulsion tube F11; Idle jet 55 F9. The package came with Cann…
Last reply by Jeff G 78, -
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This is not about the carbs, did not know where else to post this. So my problem is that if i leave my 240z unattended for lets say 3 days, it wont start because the fuel lines are empty and fuel filter is empty. The pump will not prime the lines, i have to take a suction to one of the fuel lines for the carbs to suction the fuel through. Is the fuel supposed to empty out from the lines like that and filter? Also it seems if i drive my car everyday, and in the morning i start the car, it has trouble, because again, i think the pump isnt priming the lines and the lines are empty it seems. What do you guys think? bad pump?
Last reply by disepyon, -
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Good Morning All, Picked up another 240z which came installed with Weber DGV's. I'll be having a motor built this Fall for it, which I'll pair with a set of triples, but for now I'd like to get the car back to running as-is. The car has not run since 2000. Aside from all the 'basic' tune-up stuff already done, I'm unacquainted with the DGV's. I've done quite a bit of reading on here, but my question is a bit more basic: I didn't get a chance to look into this too much last weekend - it's tomorrow's project. When I move the throttle linkage at the firewall, the butterflies on top of the carbs don't budge. Do these require engine vacuum or something to move? The motor…
Last reply by ksbeta,
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