Starfox07

Well I've got the throttle setup working, although it's not perfect yet. I need to adjust a few things and it should be great.

I am finally able to use full throttle! It pulls great, especially now I've got fresh plugs in it as well. I still think it's got a bit more left in it. The racing beat carb settings are designed for use with air filters, and I have none, so I think I'm lean right now. Leaning towards trumpet socks just because they are the simplest, though I've heard not so great things about them.

dbragg

iTrader: (7)

Run an air filter. I dabbled with the idea of not doing so for a while, but after a lot of research and logical thinking, I realized it's a bad idea. The minuscule amount of power loss will be greatly returned in longevity of your engine, especially if it sucks something up.

Keep on tuning and love the top end and drive-ability of the dellorto!

Starfox07

Finally got my throttle linkage sorted. Boy does she pull hard above 6,000rpm! It's an animal!

Here are some shots I took of my 'finished' setup. I still need to figure out the mid range fuel problems.

Carb resealed and ready to be remounted...again


2x 8mm holes drilled into firewall for double throttle cable linkage:


Throttle cable sheathes fitted into firewall:


Throttle cables installed and tightened:


Setup from above:


Setup from fender level:


The throttle 'feel' is awesome with this kit, and everything is adjustable. I'm very pleased. I was concerned that the sheathes would not be long enough to loop around, but as you can see, they are just long enough. It was a bit of a hassle to drill through the firewall, but you can see there is just about a perfect spot for it just below the factory hole. I'm going to get some grommet's to fill these. I think I'm also going to try to shorten my fuel line a little bit and move the filter closer to the carb.

Starfox07

The car is still struggling in the mid range. It also doesn't like being revved in place (no load) with anything other than full throttle. To me this sounds like the emulsion tube. It's supposedly correct for the engine, and I'm just wondering if it could be fouled? I haven't taken the e-tubes out to clean them, perhaps this is what my issue is?

j9fd3s

iTrader: (3)

only way to know is to pull it and look...

Starfox07

So I was thinking my Dell was jetted correctly...but the idle isn't right.

Here is my current jetting:
Idle jet: 52 (should be 75, which is way off!)
Idle jet holder: 7850.8 (correct)
Main jet: 230 (correct)
Main jet holder: 230 (correct)
Main jet emulsion tube: 7772.8 (correct)

I'm thinking the idle jet is causing my problems.

You told me exactly that last page...I should have listened!

Starfox07

Ordered the 75 idle jets from CB performance, and because they have a minimum order amount, I also ordered an air cleaner kit from them as well. This one:



Looks nice with the finned aluminum I think.

Edit: In addition to the incorrect idle jet, one of my emulsion tubes was extremely gunked up. Some of the holes were completely blocked! Hopefully cleaning these out will result in some power gains

j_tso

iTrader: (2)

Mine ran well on 60 or 65 idle jets, it was a similar wrap around set up with 48 DCO on a 6 port 13B.

However, every engine is different.

Starfox07

If the 75's don't work, I may try the 65's. 52 is way to small though.

Starfox07

So I put in the .75 idle jets and it seems to be running very rich. It sounds like a bridgeport at idle, and that's with the idle mixture screws turned all the way in, which is as lean as you can go on the idle mixture, right? I think I'll run the .65 jets as suggested above.

j_tso

iTrader: (2)

yep, that would be too rich.

However, it should die with the idle screws turned all the way in. Did you set the "idle speed" screw, the one that moves the butterflies, to very lightly touch the throttle lever stop?

Starfox07

No, I screwed that all the way in. Ha. I should probably fix that.

Starfox07

Welp, here is the finished product with the new air cleaner on it. I didn't notice any drop in power, so I'm happy.









Now I just have to swap the idle jets, and it should run perfect.

Starfox07

Ok so my .65 idle jets arrived and I put them in, and it seemed to have absolutely zero effect on the way the car is behaving. It's still idling like a bridgeport and only seems to run well at wide open throttle. If I slowly bring the RPM's up to about 4,000, with no load, it runs very unsteady, like a brap brap idle, except at 4,000rpm. I thought maybe my fuel pressure was unsteady, but I looked, and it's a rock solid 2.5psi or so, whatever the load or rpm.

Any ideas? I feel like it runs fine when the main circuit comes online, and it seems to handle abrupt throttle changes well, so I think main jet, e-tube, and holder are fine, as well as the accelerator pump jet and that adjustment. The idle circuit should be correct for a stock motor. It's almost like I have a vacuum leak, but I'm pulling perfect vacuum at idle.

To recap:
Originally had .52 idle jets. Car ran terribly at low RPM
Switched to .75 idle jets. Car ran better at low RPM, but idled like a bridgeport, even with the idle mixture screws as lean as they could get
Switched to .65 idle jets. No change.


I do have some .62 idle jets I could try, but I think the problem is elsewhere. Any ideas?

Could an incorrect float level cause this problem? I set the float level not long ago, but I have moved the carb quite a lot and I suppose the setting could have been messed up. There is some smoke, but not an usually large amount considering I'm premixing.

rwatson5651

iTrader: (5)

I think the fuel level could cause this issue, causing it to idle pig rich. Leaky needles could also do the same thing.

Starfox07

Would this also cause it to run poorly at any RPM under low-load? For example, I can bring the revs up to 5,000rpm, slowly, in neutral or under low load in gear, and it runs horribly. If I put my foot in it, it runs great!

I think it's time to pull the carb again :/

rwatson5651

iTrader: (5)

I think it might, when you put your foot in it the fuel level would drop, so I would check the float levels and needle valve.

j_tso

iTrader: (2)

You don't need to remove the carb to check/set the float level, just remove the top cover.

Take off the air filter and turn on the fuel pump. Do you see fuel dripping down the venturis? If so, the needle isn't shutting off the fuel supply. I've had a stuck needle make the car run poorly, but it usually just dies after trying to idle for a minute.

Starfox07

It will die if the throttle plate isn't opened slightly. This might be culprit!

Starfox07

So I took the carb apart and there is this kind of powdery yellow goo all over the inside of the carb? What on earth is it? I couldn't tell if the needle was being blocked, but I cleaned it all out anyways. Will report in a little while how it's running.

Starfox07

Update: After cleaning up and reassembling the carb, I started it up again. Seems to idle and respond to throttle slightly better, but I'm still having the same issue. The float level was right on the money. Both the idle and main jets are clean. Ugh, what could this issue be?! From other sources, my issue would appear to be an incorrect emulsion tube, but it's correct from every source, so I feel that isn't the issue.

I'm beginning to wonder if it is ignition related and not fuel related. I noticed that when I started the engine from cold, then immediately brought the RPM's up to 2,000 or so, it seemed pretty steady. As the engine started to warm up the skip-firing started. Coils? Ignitors? Any thoughts?

wankel=awesome

it sounds rich. A carbed engine that runs well when cold, and then like crap warmed up is typically a "choke" problem when talking about other carbs. You have no choke, so it seems to me it actually is just getting too much fuel all time. Like a choke effect, except your rich condition comes from something else.

Starfox07

Maybe I should try lowering my fuel pressure a little bit?

Edit: Lowered it to 2psi. No change.

Maybe something is broken?

One thing I did notice is that both emulsion tubes have been stamped twice, almost like they were rebuilt/redrilled and stamped again. Does anyone have the specs on what the hole sizes in a 7772.8 E-tube are supposed to be?

wankel=awesome

I recall you having issues with your fuel pump and reg, what did you do to solve it? Also can you take a picture of your fuel lines coming out of the firewall? Something doest seem right...

The "pulsing" your pump was doing was its internal bypass, which should only happen when pressure is high. Whats brand/spec fuel pump are you running?

My smallish jegster 95 gph pump bypasses internally when pressure reaches 6.5 psi, which is too high for your carb. Any pump hitting that mark indicates higher than normal pressure in line, which could be an issue with your return line, as is standard with return regulators.

I had a similar issue with one of my test cars. No matter what I did, with a 130 gph pump, the return line (stock) wasnt big enough, which caused the pressure in line to be all messed up, and pressurize the return line to ridiculous levels.

Changing to a lower pressure pump, and lower GPH solved the problem. Im trying to find what pump you used in your thread right now..

wankel=awesome

I think you used the gslse stock pump after reading this a little better. Something is really wrong in your fuel system for that pump to pulse that way...

My previous statement about the pumps "internal bypass" is no longer good information for you, seeing as im not even sure if a GSLSE pump has an internal bypass. I automatically assumed you were running a holley or carter pump..