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carb adjustment


HxC240z

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okay I have 2 questions what is the corect level of oil in the dampers on the roundtop carbs because the haynes manual tells you to fill the dampers to the correct level with SAE 20 engine oil, BUT IT NEVER TELLS YOU WHAT THE CORRECT LEVEL IS!!! Also how do you adjust the carbs if the car isnt running (is it just guess and check??) because the Haynes manual tells you to adjust the carbs after the engine obtains normal operatring temperature but my car doesnt run and I think I need to adjust to get it to run, ( is cold enginge adjustment covered in the Z therapy video??) thanks, Ill be back monday.

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There are two grooves on the damper rod to indicate the high and low level. It's just like a conventional dip stick.

As for adjusting the carbs much has been written about this already, including the fact that many people decide to adjust the carbs when the problem lies elsewhere thus making things worse.

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Search here and Google. There is loads of info out there.

Your basic starting point is to screw the mixture adjustment nuts on the base of the carb all the way in and then back them out 3 full turns (1080deg). Start the car. From there you screw them each in 1/2 a turn until the car dies. This all assumes that everything else is 100%, plugs, wires, valve adjustment, etc.

Good luck. Do yourself a favor and do some more research on the net.

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Your basic starting point is to screw the mixture adjustment nuts on the base of the carb all the way in and then back them out 3 full turns (1080deg).
NO! Everyone just passes by the REAL first step. Verify and set the float level in each float bowl! If the float level is wrong, any other "starting point" is worthless. ALWAYS set the float level first!
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If you end up w/ too much oil, all you have to do is raise the piston to the top w/ your finger and the excess will drain off into the engine w/ no harm done.

Once you do what Arne and Enigma said and you get the car started is when you start changing the idle screws along w/ a flowmeter to get the carbs adjusted just right.

That is the basics, but there is a lot more detail on the website or on the Ztherapy video.

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The only source of 20w oil that I have found , without buying it by the small bottle form mail order , is a Cycle shop. They have 20w Fork oil that is used for the forks on a motorcycle. I have tried several weights and for my Z far and away the 20w is the best . But do a search . There are many posts on step by step on how to adjust the SUs. Gary:)

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There are two grooves on the damper rod to indicate the high and low level. It's just like a conventional dip stick....

Note here: I have the [very] early SU's with the metal top damper rods and they do not have any of the oil level "grooves" on them. Go figure!

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thanks for all the suggestions, Ill check the float levels today, I read my manual and I think I figured out how to do it. Will they not work at all if the wrong oil is put in, these are from ebay and Im not sure what oil is in them so I might open em up clean em out and refill with 20w.

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Marvel Mystery Oil.

marvel oil is about 8w ATF is 5w both cause lean condition at first throttle opening and a stumble . 20w will allow the richer mixture to the engine just like a accelerator pump in a carburetor like on a V-8 . As to the amount of oil needed, they take about 4cc each . If over filled the excess will just be burned off by the engine , no worries . If you cannot get 20w go with some 10w30 . that will get you by nicely . Better to be thicker than thinner so the dampener can do it's job as intended . If you were running on a track and keeping the engine up in the high revs , you could eliminate the oil completely because you would be at WOT most of the time anyway . Its for normal street driving that this makes a difference . I have , over the years , heard of members trying everything from brake fluid to water looking for the '' golden bullet of power and performance ''. The makers of these carbs call for 20w for a reason. 33+ years later the debate still goes on. LOL Gary ( Gazza ) for you bloks in Auzzy land . LOL

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I've got 10W-30 in mine, but only because I haven't made it out to the motorcycle shop to get 20 wt. I can confirm that ATF doesn't work all that well, as I tried that before changing to the 10W-30.

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I know I've posted this before and someone else mentioned it above:

http://www.wd40.com/Brands/3in1_product_info.html

You'll notice that the blue and white can is SAE 20, only costs a couple of dollars at any hardware store, and is the perfect size and has the perfect nozzle for squirting in a few cc's.

Hey! Thanks for the tip Mike.

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Just wondering...

If 10W-30 will work, would something like 5W-30 or 5W-20 be better? I notice that a most new cars in the U.S. require one of those oil weights anymore, so both are widely available.

By the way Mike thanks for the blue can of 3 in one . I have never see that stuff in any store. I have a qt of fork oil and that will last me the rest of my life .LOL but I would use it if I didn't . To answer the question of 5w-30 or 20 . I wouldn't put it in my engine. And remember these engines are a design that dates back to the '50s When Mercedes was building it as there 4 banger. True today's new iron use lighter oils but my engine is a 30 year old design , I run 10w30 . and no lighter. The dampener is dependent on the weight or thickness of the oil to slow down the rise of the vacuum piston. With light fluid being lighter than 20w oil the piston snaps up and allows too much air to flow as soon as the butterfly is opened. There is not a proper amount of fuel in this air and thus a lean condition. This is for only a split second but it causes the stumble like a ignition that is weak. Then the engine takes off when it recovers and as long as the RPMs are up there is no problem . But when at idle and the throttle is opened this is where the dampener must do it's function. This is the best I can do to explain this , I hope it makes since to others . If not , take my word for it. Gaza AKA Gary LOL

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hey I opened up the float and adjusted it like suggested and it needed it too, but I had a bigger problem just for kicks I decided to check the jet that the float controlls and it was completly plugged with this stupid rubber sealing wrap that was on the threads of the fitting that came with the carbs. I cleaned it out and now it should work. The gasket that was on the float cover to the float chamber was dissintegrated and advanced dosent carry em, does any one know what theyre made of so I can make my own??

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The float cover gasket is not important. If the needle valve gets stuck the bowl will fill up and the fuel will leak out. With a gasket in place it will go through the hose to the air cleaner where it will puddle up and leak out.

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Just changed from MMO to "3 in 1". :eek:

No longer is there fluttering in the carbs on acceleration! :sick:

Much better throttle response!! My accelerator pedal actually gives positive feedback for the first time!

YMMV, but it did wonders for this 73 with round tops! LOL

Kudos to Gary (beandip) for the best explanation for using a specific weight of oil that I've ever seen.

20 wt. carb oil might be even better, but I think "3 in 1" gets it pretty close and is available just about everywhere.

Again thanks for this thread!

Another small but significant mystery solved for me. :stupid:

Jim D.

"Zup" :bunny:

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Got it running but I still have some fine tuning to do, does anyone know where to find a uni-sun or any other flowmeter because I called advanced auto parts, napa, and atuo zone advanced had something for 50$ but I though that was too much, I also tried summit but they put me on hold forever ( I hate summit with a passion!) If it helps I live in kent,OH. Also in my driveway I noticed that the clutch grinds when its put in reverse only when at an angle(on a hill) any one know what would cause that???

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