How to Rebuild SU Carburetors - 240Z Carburetor Guide Ep. 3

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Күн бұрын

Пікірлер: 24

@mileseyrally3235 4 жыл бұрын

I always remove the damper, fill to the top edge of the piston, visible if you look down into it, not half an inch from top of the chamber. I use 20/50 engine oil. After reassembly if you lift the piston manually through its full travel and there is too much oil in there it will come out through the vent. Spectacularly.

@alienpoker 4 жыл бұрын

Your method if adjusting float level is kinda ‘old skool’ - the modern needle/seats may not support the weight of the float when turned upside down. If they fall shut, the adjustment of 10mm is then incorrect. What I do is to Let the needle and seat hang as it would in the bowl, lift the float up until the valve would just shut off, and set that height -between float top and float housing cover bottom- to .55" or 14mm. You can connect a bit of fuel line to the inlet and blow into it to check when it ‘just shuts’. That’s my method, and the carbs run really well.

@bxsvx 6 жыл бұрын

Great video! Can you do a video on float adjustment? Thanks!

@jessewaite509 5 жыл бұрын

Nice video, thanks for sharing! But you're missing the hour-long cut of buffing those piston cap to a butimous sheen. FWIW, my 240z carbs used 15567 (front kit) and 15568 (rear) from Walker. What year are the linked 15566 kits for? The kits are the same except for the needle/seat assembly height, which was substantially different. So different that one of the float's adjustment tab had to be set pretty severely to make the float height spec (10.31mm for 70-71 carbs, 14.28mm for 72).

@zcarguide 4 жыл бұрын

Hey Jesse! Sorry, I originally linked only the 15566 kit but that is actually only for 1970 and 1971. As you've found, 15567 is for a front 1972 carburetor, and 15568 is for a rear 1972 carburetor. 15569 is for a 1973. I actually just started stocking and shipping these parts on my store. I will organize them by year to make things a bit less confusing.

@jessewaite509 4 жыл бұрын

@@zcarguide Awesome man, thanks for the year info! I couldn't find that anywhere. Just received the carb tuning tools, can't wait to use them! Cheers

@alienpoker 4 жыл бұрын

The only difference in the ‘72 kits is the float bowl valves are different lengths. The long one goes in the front carb. Weird they did that, but when you are accelerating... the fuel height goes lower in the front bowl vs the rear bowl. So Nissan changed the needle/seat valves in the float bowls to different heights. I know this as I have a ‘72 240Z with 3 screw dome top SUs. So IF you have different length valves in your float bowls, you’ll want to get the ‘72 kits.

@jessewaite509 4 жыл бұрын

@@alienpoker Thanks! I measured several dimensions of both float bowl covers, and they were identical all around. With the '72 15567/15568 kits I had to set the adjustment of one float severely outside what you'd assume was the normal range of the metal tabs. So... I assume these are the wrong kits. My car is a 260z with swapped round-tops, so I had to guess what year SU's. Oh well--maybe someone reading this will benefit: pop your float covers off and check the length of your float valve to id the correctish kits.

@markt4520 5 жыл бұрын

I blow out everywhere with an air hose before assembly.

@justo947 6 жыл бұрын

nice video's! are you going to do a vid on tuning them?

@zcarguide 6 жыл бұрын

Thanks Justin. The tuning video is in progress, I just need to get a few more shots of the Colortune process before I can publish it, and I have mine working so well I don't want to mess with them anymore! I'll get it uploaded soon. In the meantime, I have a text version of the tuning/adjustment procedure on my website: zcarguide.com/tuning-adjusting-datsun-240z-su-carburetors/

@justo947 6 жыл бұрын

@@zcarguide thats a really good guide to follow. the colourtune is easily the best tool for tuning carbs.

@SSGTVolken 4 жыл бұрын

That thing that unscrews from the top is a dip-stick there are 2 lines on that dipstick, use the top one. You WAY, WAY, overfilled that carb with oil. Use a 30 weight oil. The level of that oil is important, the car will run like shit if it isn't properly filled. You also have to make sure the needle does not get stuck in the fuel tube when the piston is down. The instructions literally say not to lube any part of the piston other than the bit inside the large spring. When measuring the float level (hold it upside down like the video) and lower the float, until the tab just touches the valve stem. What is not clear, do you measure from the outer sealing lip or the slightly recessed inner portion of the lid? I measured from the raised outer portion.

@zcarguide 4 жыл бұрын

Hi Jason, thanks for the input. The fill line (half inch from the top) is from the SU Carburetors Tuning, Tips and Techniques guide. That is by far the best overall resource IMO so I generally trust its instructions. I've used that on three different 240Zs now and I think it is the optimal level. The oil in that chamber is just to dampen the rise of the piston when the throttle is increased rapidly -- that's the main way to test. Measure from the recessed inner portion of the lid.

@alienpoker 4 жыл бұрын

I too would never lube the piston or the inside of the chamber. So I never clean with any lubricant substance or steel wool. You want them to slide really nicely and not gum up with trapped dirt and carbon over time. Dry is best, so that means carb cleaner only, and then wipe down clean. You can oil where the spring goes, but thats on the outside, if you see what I mean.

@alienpoker 4 жыл бұрын

@Jason Volken Agree for the most part with you... Oil depends on where you live (how hot it gets) and the altitude. I’ve had good results with 20W oil, which is Marvel Mystery Oil according to the data sheets. The damper only stops the piston from ‘fluttering’ when shifting at high revs, or slamming to the top and going too rich on hard acceleration. If you fill it too full it doesn’t work as well, but that’s way better than not having oil. It just resists the piston rising too fast, but should allow the piston to drop back rapidly. Press it up all the way & release. If it resists you going up and then falls back with a ‘clack’ when you let go, it’s fine.

@zcarguide 4 жыл бұрын

Thank you for the input guys. At some point I will set aside time to remake the video with these parts corrected but in the meantime I think it's good to have the discussion here.

@georgeramos1462 2 жыл бұрын

Right, I noticed a low and high line on the shaft of the "dip stick" just above the plunger. I was thinking to myself: "If it's not meant to be removed, why are there high/low marks?"