SU Sightglasses available (see fuel bowl levels)

[Captain_Zeros]

This reminds me, anybody hear of or try this method? Technical Information Page ..... Carburation

By measuring fuel at the jet nozzle, that should rule out any error produced by carb rotation.

TIP: We did some measuring with a straightedge and found that on my 4-screw SUs a 23mm fuel level in the float bowl corresponds to exactly 1 centimeter (10 millimeters) below the fuel nozzle "ledge" in the carb. But how do you see to measure fuel 1 centimeter down inside the fuel nozzle? See below.

Remove the dome and main piston from each carb so you can look down the tip of both fuel nozzles.

Screw each mixture nut exactly 10 turns down from fully up. Each full turn drops the nozzle tip 1 mm, so 10 turns puts the tip of the fuel nozzle 10 mm (1cm) down....which happens to be the 23mm float bowl level.

Then look down the tip of each fuel nozzle and adjust each float to set the gas level at the fuel nozzle tip.

We ended up taking 9 turns down and set the fuel at the meniscus of the tip. Then when I went to 10 turns the fuel was exactly at the tip. A bit of a juggling act but after a few minutes you will get the hang of it. When you get them to match it's a great feeling.

Edited June 5, 2013 by Captain_Zeros

[Stanley]

Some good points. I looked at the acceleration slosh thing, seemed to me the effects Blue describes happen regardless of long/short ears. BTW I copied the result wrong - a=1.1 mm and 2a=2.2 mm. Not that you can adjust the floats to tenths of a mm unless you're Supermechanic.

Is it true that 4-screws have equal length ears on the float lids? The 72 FSM didn't mention a change. One more thing, is that 23mm carved in stone? If I was racing up Pikes Peak I might want to raise that rear float a little, same thing for long WOT runs with a 3.1 stroker with SU's for example. Haven't seen any information about modding float settings, maybe anybody doing it would keep it a secret depending on class rules. It's hard to get the level much higher without gas running out the vent, though.

[Jeff G 78]

This reminds me, anybody hear of or try this method? Technical Information Page ..... Carburation

By measuring fuel at the jet nozzle, that should rule out any error produced by carb rotation.

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I have read that, but I haven't tried it yet. I am about to adjust the float heights within the next week or two, so I will try all methods and report back.

My biggest problem is that I can never keep track of how many turns I've made. I painted a dot on the adjuster so I can tell, but once I put my hand down on under the carb, I can no longer see anything. I have to turn a little and then look and repeat. I thought about drilling a hole in the adjuster and tying a ribbon to it so I can do it all by feel. Does anybody else struggle with this. or is it just me?

[Stanley]

Back to Jarvo2's original topic, $15 sounds OK. It's easy enough to make a sightglass but that would same the time of scrounging up the parts. IMO observing the level in the nozzles is still the most accurate method, but unless you can get it set right in one or two tries it's way too much work.

For 3-screws though, I'd rather have it hooked up at the drain. Then you can fill the bowl just starting the engine (if you do one bowl at a time). Also you can leave it hooked up a run the car with it, like Grant does with his track car in the ZTherapy video. I bought the ZT sightglass, but would rather have something else to leave installed full time.

Seems like it would be real handy to have one permanently installed - you could check it any time you have the engine running with the hood up. Might be able to see low level from a sticky float valve, low FP or whatever, also see a too high condition before it starts leaking. One more diagnostic tool.

Somebody should snap up that eBay one, if it's the real deal - too bad it's not a pair. Please post photos if anyone installs any of the sights from those links.

[zKars]

Jeff: Do you have the early knurled knob style or the flat plate scalloped edge style adjuster?

The knurled knob has a little ball bearing embedded on the side that you can feel, and the scalloped one has a screw head on the underside that I use as a finger feeling reference. Turn them all the way in, note the rotation position of the ball/screw head relative to an imaginary clock face from the top, then spin away. As you turn past that starting position your brain will register that "aha! I've been here before" feeling.

[Jeff G 78]

Jim, mine are round and smooth. There are no knurls or scallops. I removed the detent limiter thingy a long time ago. They *might* have one or more threaded holes in the faces, but there are no fasteners in the holes. The knobs are impossible to adjust by feel alone.

[Darrel]

This is a great thread. It saved me from trying to find fittings for the drain plug. I wouldn't want "permanent" site glass because once you set the floats they should be good as long as the needles are in good shape and the float isn't hanging up on anything inside or have a hole in it. My main problem was not being able to use the adjustment knob and have any changes at all unless they were screwed way rich.

Now I can play with them and make sure I am completely in tune without guessing.

In the future I can use my site glass to double check float level or to see if I can get it closer, but if it's within 1mm I am good with it. The next step now is to adjust the knobs so the fluid level is the same at the nozzle of each carb regardless of the float settings. The float level gets the mixture knobs reasonably close to each other to be able to tune them better.

I watched the ZT vid again yesterday. For the 4 crew he used washers to get the mixture nuts at the same starting point so when the knob is all the way up, it would stop at the same place on each carb, like he said, make two carbs as one.

Now i wish ZT could redo the video and break it down in sections. Float adjustment, needles, etc. Maybe the dvd has that, but the old vhs doesn't. Kind of tough when it's 5 hrs long. I did copy it to dvd, maybe I can use my movie maker and break it down myself. I will have to play with that as well, anyone got any popcorn?

[Jeff G 78]

My VHS tape is in rough shape. I got it right when it first came out and after about 2 times through, it started having tracking issues and is really hard to watch. Is the DVD the same material from Scott, or did Steve remake it?

[zKars]

Jeff, is what you are turning a flat plate or a round cylinder that is about 3/8" high? Sounds like the flat plate. There is supposed to be two parts/layers that are held together with a screw, guess you've lost that. There is a slot/hole to put a bolt/nut back on there so you have a reference

Other than that, bubble gum, dab of JB weld, something anything that you can feel. Put a scratch/nick in it. paperclip, small cable tie, Ya! cable tie!, either style of adjustment knob, gives you a small permanent bump you can feel.

Edited June 5, 2013 by zKars

[Jeff G 78]

Jim, it's a round, smooth disc about the size of a Loonie (did you like my Canadian reference?) and ~4mm thick.

I remember removing the locking plate, but otherwise I don't know what was there. If there is a threaded hole, I will put a bolt in it as the reference point. If not, I'll add some sort of tactile feature. Right now, it sucks to adjust.

[Darrel]

My VHS tape is in rough shape. I got it right when it first came out and after about 2 times through, it started having tracking issues and is really hard to watch. Is the DVD the same material from Scott, or did Steve remake it?

I had a friend transfer my vhs copy to dvd, so it's the same quality as what the vhs tape was. I don't think ZT remade any portion, but I do believe they transferred it to dvd. I couldn't tell you for sure though.

[Captain_Zeros]

I bought the DVD at Canby a few years back and it's a solid 4 hours of Scott transferred off VHS. I ripped it to my computer's hard drive so I can skip around more easily.

On another note, anybody know the thread pitch of the drain plug offhand? A semi-permanent sightglass doesn't sound too hard to get together with all that's available from places like McMaster, but only if I know what I'm looking for.