'72 SU Float Level

[landmizzle]

Hi all,

I'm still dealing with a high rpm issue, but I'll leave that to another thread.

What I would like to know is the float level for 1972 carbs; I hear that they are not the same front and rear. I believe the typical level ('70 and '71) is 23 mm measured from the bottom of the lid to the fuel level with the floats in the fuel bowl.

Measuring from bottom of lid to fuel level (using clear plastic hose from fuel drain and aligning it up against side of bowl.) I can get a level of 1 inch (25.4 mm) pretty easily for both carbs. Is this close enough?

I'm getting pretty good with the whole procedure, but it's still fairly time consuming. Unfortunately, so far, all my attempts to reduce the fuel level a few millimeters results in the level going too high and gas overflowing. If an inch is good enough, I would rather move onto other issues to trouble-shot my high rpm hesitation issue. It feels like I'm chasing a phantom goose trying to get get that last 2 mm precision. Is the fuel level that finicky?

[Bruce Palmer]

We've spoken

[zdogg]

Give Bruce a call and get the Just SU video from z therapy it make things so much easier.......I know first hand

[nasdstynguyen]

flip the float over and do a 1/8 gap. go rich on your A/F mix then then crank it back to lean it out

[emptech]

Don't have an answer but am working on the same thing. I have Bruce's dvd, but there seems to be a flaw

in using a gage like he does. I machined a gage, my bowls over-flowed. I ended up machining a barb fitting

that goes in the drain hole (like Bruce sells) and used a plastic tube. I've found it is a "cut and try" process,

when I had the level right, the gap between the rim of the lid and top of the float wasn't anything near the

.55". I just bent things to make the 23mm of fuel level to come out right. Took several times.

I also found that often the float would hang up on the sides of the bowl. I took the over-flow barb off and

inserted a small piece of wire to make sure the float was free and not catching. I couldn't figure why my bending

of the tab wasn't changing the level, the float was sticking on something. Now I keep the four screws loose,

wiggle the lid until I know it is free then tighten the screws.

Finished one carb tonight, will finish the second one tomorrow. I bought new bowl valves from Bruce, but they aren't

the ones like in the video with the balls. I have to wonder if that's why my measurement of the bowl height is different,

did he change valves?

Incidentally, I'm using Tygon F4040 fuel line, gasoline proof. Clear and very flexible.

Jim

[Bruce Palmer]

The flaw is that the video Scott did way back when, used the Grose Jets which are no longer available. The needles and seats need the lid to be held with the float hanging down. blow lightly into the fuel inlet tube while moving the float toward the lid. When the needle closes you can feel it and that is where you meaure from the bottom of the flloat bown lid to the float. I've been bugging Steve and Pam to re-do that section of the video for years with out success.

Inverting like the video shows, automatically will over power the little spring in the needles and seat giving an incorrect float level setting.... Any one waqnt to chat about any of this, I'm just a phone call away.....

[emptech]

That's funny Bruce, that's exactly what I ended up doing, the bowl lid in the normal position,

while I blew into the inlet, I slowly raised the float. I held a metric machinist's scale next to

the float, when the flow stopped, I read the number. I can't 100% agree with your number

of .55" (about 14mm), I'm getting closer to 18mm, but I'm confirming my final measurement

with a site glass (tube). I think your .55" is accurate, IF the same Grose jet had been used,

but that's not the case now.

Most important, we are all on the same page.

Jim

[Bruce Palmer]

I think the measurements to the top of the float or the top of the fuel should all be equated to where one's happiness setting on the fuel nozzles are. When all is said and done and the nozzles are where ya like 'em, the fuel level as viewed down in the nozzle should be about a sixteenth of an inch below the top of the nozzle. Puddling up on top of the nozzle things'll be fat and contrary to that if the fuel level is too far down the nozzle things'll be lean. That is what all the jumping around is about.... where the fuel level is in relation to the top of the brass fuel nozzle.....

Just putting this out there as crib notes for any and all looking over our shoulders.....

[Gary in NJ]

I've been bugging Steve and Pam to re-do that section of the video for years with out success.

Just a suggestion but when and if you do re-shoot that section, I would post a clip here on this website. Many of us on this site have purchased the DVD and it would be helpful to have the correct footage.

[Jeff G 78]

I bought the VHS tape back in the 90's when Scott ran the business and it's barely viewable anymore even though I've only watched it a few times. With enough tries, I can usually get the tracking in line so I have some sort of picture and sound.

[Lone_Star]

Hate to dig up an old thread (but the last post is only 6 weeks ago), but I am still looking for a clear answer. Is the 23mm down from the lid the starting measurement for ALL the round-tops? I have a '72 set with the different length float hangers and want to be sure I get the correct starting point. The car is running now, but I am going back and fine tuning the carbs.

I have a second issue that I have not been able to find any info on; when the car has been driven then parked for 15-30 minutes, when trying to re-start, I have to give it some throttle to get it to fire. I have double checked to be sure the choke is not causing the problem. I am thinking it is a heat-soak issue, but not sure how to resolve it. I do have the heat shield in place, and am running headers, so wondering if the heat shield needs to be changed/enlarged to better protect the float bowls. Any thoughts?

Thanks!

Bryan

[Bruce Palmer]

Headers, in Texas, in the summer...... Sounds like triple dipping to me. When you think you are facing that situation try pulling the choke on just a tick and see what that does. Not too much but just a bit to see if richening things up just to get started will help.