Starfox07

I have a fuel filter before the regulator, it's in the hard lines. No way I'd put a low pressure filter in a high pressure line!

The screw was out for that picture, but it's in now. I'm able to run 2.5psi or even lower without issue now, although sometimes it will still start surging for no reason. Still trying to figure that one out.

Starfox07

Sad as it is, I was just today able to take the carb off the car and disassemble it.

The floats float and do not leak. So they are fine.

I'm not certain about the needle valve. I'm not sure how it's supposed to look when functioning properly. Anyone have some good pictures? It seems to be moving ok doesn't look gunked up or anything, but I can't really tell if it's seating properly.

duffman692002

iTrader: (5)

Just because the floats float doesn't mean thu are set correctly. The way I test the needle valve is to turn the pump on w the bowl off and with the floats hanging down it should spray fuel. Gently Pick up on the floats to to close the needle valve. If the flow stops then it's fine. Since you've got it this far apart already just hit he needle and seat with a few jets or carb cleaner, that should clear up any trash that may be hiding there.

Starfox07

Alright well that's done then.

If the floats (floating) and the jet is functioning fine, I don't understand what my issue could be.

I need a carb expert to help me.

edit: Just checked the float level. At droop its 22mm and when the needle is seated it is 8mm, measured with vernier calipers. That seems way off, right?

duffman692002

iTrader: (5)

Dunno on webber but on a Holley there is a sight plug/glass and the fuel level is set at halfway on the sight glass. Google or YouTube may be able to tell ya the correct setting.

Starfox07

RB says 15mm, so yeah, way off. I've set it correctly now, I'm hoping that will fix the issue.

I noticed that the gasket for the top cover was missing a piece around the perimeter, which I'm thinking might have been allowing a vacuum leak. What do you guys think?

edit: Here are some pictures. One is showing the top cover gasket and the piece missing (very bottom, the part that goes around the float 'hanger.'



It's obviously not good that the gasket isn't intact, but what issues could it cause?



The second picture is showing how I'm measuring the float level, does it look correct? The needle is fully seated. You can't see the caliper readout, but it says 0.60in, which is almost exactly 15mm

duffman692002

iTrader: (5)

Ah, was Googling some info and it seems that 15-28mm is the accepted range, couldnt find anything rotary specific but then again i didn't think to check RBs site lol.

Starfox07

Do I have this right?

Float level set too low (small value, like 8mm) it would cause fuel starvation
Float level set too high (large value, like 30mm) it would cause excess fuel in the bowls

j_tso

iTrader: (2)

You don't want vacuum leaks after the throttle butterflies. The top of the jets are at regular atmospheric pressure, so any openings aren't a big deal.
A missing part of the gasket could cause fuel to leak out. For Webers there's a rubber top cover gasket, see if there's one for Dellortos, it'll last way longer than the paper ones.
That looks right, I prefer having the float hinge at the top, so it swings easier, but as long as the needle spring isn't totally compressed it's fine.

j_tso

iTrader: (2)

Other way around:
float is too high = it's closer to the top, which would make the fuel level in the bowls too high.

There are two measurements: float level and float drop
float level (15mm) is when you measure with the needle closed, float drop (28mm) is the floats hanging down. You want the floats to not move out of this range.

Starfox07

So mine were at 8mm and 22mm, respectively. I'm guessing this would cause the bowls to have too much fuel.

What is the result of this in regards to how the engine runs?

j_tso

iTrader: (2)

Short answer: it'll bugger up your air/fuel ratio.

Here's a diagram of a Weber DCOE (DHLA is very similar):


About half of the emulsion tube + main jet assembly sits in fuel. If the fuel level is too high, the holes in the e-tube won't mix the air+fuel the right way. And as you can see from the pic, the outlet for the main jets isn't that high up, so raw fuel can fall into the venturis if the floats are too high or not closing.

Starfox07

I really need to get an A/F gauge. My initial idea was that the car was running too lean, not too rich. Could too much fuel in the bowls cause it to run lean somehow? Either way, I've ordered a rebuild kit, and I'm going to take her down and put her back together. It's not nearly as daunting as I thought it would be.

j_tso

iTrader: (2)

I'm not seeing how it can be too lean with too much fuel in the float bowls.
See how it runs after the floats are set correctly and the new gaskets installed.

Starfox07

I think the only explanation is vacuum leaks. I will look into it.

Starfox07

Ok. Was able to work on the car today. I rebuilt the carb and set the floats correctly. Surprise surprise, the car is now idling very well @1,000rpm and pretty steady. Steadier than the EFI was actually.

I decided to take the car on a drive and this was the result:

Low RPM, low to medium load: Very good response and no hesitation nor bogging

Anything above 1/4 throttle: Terrible bogging, no power, will not rev over 4,000rpm backfiring, etc.

At idle, the car is pulling around 17psi of vacuum.

When I shut the engine off, there is about a 3 second pause, and then it backfires.

I took off the accelerator pump on the bottom of the carb to change it's gasket, and I think I may have changed it's adjustment, but I'm not certain.

I'm also having an issue where the battery is not charging. I have everything hooked up, and it just slowly drains while the car is running. I'm not sure if this is related, but all of the idiot lights remain on after the car starts. They turn off after a few minutes of driving...which seems strange to me.

KansasCityREPU

iTrader: (9)

Do you have the 5th and 6th ports working?

Starfox07

Lets ignore the 6 port system. They are completely removed. It's nothing to do with them.

Starfox07

Too late to edit previous post.

I really think my problem has something to do with the alternator/battery. When the car is running it goes down below 8 volts and starts running poorly. This makes sense, right? I figure with the battery so low and the alternator not charging it, the spark is going to be much weaker.

j_tso

iTrader: (2)

Getting the electrics sorted is a good start.

What jets are you running? A midrange bog can occur because of a too rich or too lean main jet.

When I used a 48 DCO and now on a 48 IDA I've had to use jets that were a bit leaner than what Racing Beat recommends.

Alex84GSL

Timing? Timing has been the hidden culprit for me, when my header heat wrap was smoking and the rb header glowed red!
I'm running an edelbrock though. Good luck, that is a VERY sexy carb.

Starfox07

The carb is jetted correctly for a stock 13b according to racing beat.

Main Emulsion Tube #7772.8
Main Fuel Jet #230
Main Air Jet #230
Idle Holder/Emulsion Tube #7850.8
Idle Jet #75
Accelerator Pump Jet #80
Needle and Seat #300

The timing is unchanged from stock, I haven't touched it since removing the EFI components. I did disconnect the vacuum advance, as per RB instructions.

The smoke coming off of the header wrap must have just been the chemicals that had soaked into it from cleaning the engine. It no longer smokes and the coolant temp is spot on. So it's in the ballpark for mixture, but there is some issue still. I feel it is either the accelerator pump (I can not get it to match RB's 13/32" specification without making the engine run at 3,000rpm at idle!) or something to do with the electrics, or possibly both. Since the stumbling occurs with both abrupt throttle changes and gradual ones, I am thinking it is less likely to be the A-pump.

Can someone point me to a troubleshooting on why an alternator won't turn on? I disconnected a lot of the main harness (obviously) but I believe the alternator is hooked up correctly. I don't get why it won't turn on when the engine is running.

Again, it is running very well at idle and low load, low rpm conditions, but stumbles, hesitates, and makes no power everywhere else. I think I am going to buy a wideband 02 + a/f gauge to make tuning a little easier.

Starfox07

So I took a new video today illustrating how the car is running.

Basically, anything other than careful progression of the throttle causes stumbling. I can get it up to higher RPM if I am very delicate with the throttle, but anything other than that causes it to bog, backfire, hesitate, and even die a few times.


This is leading me to believe the accelerator pump is set incorrectly. Probably too rich by the sound of things. Does anyone have pictures of how they set their accelerator pump arm? I tried adjusting it to the spec that RB suggests, but it doesn't seem to make any sense. With their setting, it actually holds the throttle open and essentially won't let the engine run under 3,000rpm.

Starfox07

With the car off, I decided to see if I could hear the pump jets working. From what I understand, they are supposed to squirt fuel immediately when the throttle is pushed, but with mine, it needs about a 1/4 turn of the throttle before I hear fuel squirting. So I'm guessing the car is running way too lean under throttle changes. Also, I can hear a ton of air being sucked in while this is happening, without any combustion. So I think I know what the problem is, I'm just not sure how to fix it...:/

Siraniko

iTrader: (13)

84-85 has a fuel pump relay, you can say it will only work with the engine cranking . on Pre-84, fuel pump works with key on ON position