'87 turbo II

iTrader: (1)

Today my friend(Crit on here) and I rebuilt my Dellorto carburetor with a service kit from Eurocarb's website. After we got it back together after carefully rebuilding it making sure not to break anything, the car wouldn't start and the fuel pump wouldn't shut off. We took off the top cover off to see the empty float bowls. We cycled the floats up and down a bit, then re-assembled the top cover. I turned the ignition to on and let the floats fill (it worked the time) then started her up. Now when we took the carb apart, we discovered the idle mixture screws were pretty much garbage and the fact the car was working properly before the rebuild was kind of a miracle cause the needle on one of them was broken off. So in order to not worry about it, we set the idle to about 1600 to bypass the idle circuit until new screws arrive in a few weeks from Eurocarb. The car will now start, idle(at 1600-2000RPM) and die after 5 to 15 seconds, usually backfiring REALLY bad before shutting off. It wont start again until the carb is re-primed. It almost seems like the carb fills with fuel, then uses it up while running, and needs time to refill. Does anybody have an idea what the problem might be? I tried not to overtighten anything like the jets and such so if one of them is slightly loose could it cause the problem?

Short version, rebuilt carb, it won't stay running, and runs like crap when it is running.

I need a list of possible problems and solutions by Sunday as Billy (from ReSpeed), Crit, and I are going to look at it again and try to get her running again.

t_g_farrell

iTrader: (1)

I have a DHLA on my stock port 12A and you should be able to get it running smoothly.

You didn't say in your post what you did do with the bad idle mixture screws; are they still in there or out or screwed all the way in or what? Also what was actually wrong with them besides the one being broken? I had a bent needle on mine one time but it still ran ok. Didn't find it till I was fine tuning the carb and noticed one barrel ran richer/leaner than the other. Its real important that the screws have the small seat and the spring on them. Also the red plastic caps that go over them are just as important, they keep dirt out of the screws.

One thing to note is you don't stop needing those idle screws unless your butterfly is completely past the progression holes and you develped enough venturi flow to render the idle mixture inconsqential. Often times even cruising at 2 or 3k your still mostly running off the mixture set by those idle mixture screws.

That said, it doesn't sound like thats your immediate problem. It sounds like you have low pressure or poor flow on the fuel inlet. These carbs only need about 2.5 to 3 psi of fuel pressure but need 60 gph flow at WOT to be most affective. Since it will start and run for 15 to 30 seconds and then die it sounds like the bowls are filling up slowly (or not at all) for some reason. I would first check your fuel pressure and then unhook the fuel hose to the carb and run it into a fairly large container with 1 gallon markings on it and see how fast it reaches a gallon of fuel. Then you can determine if the flow is close to what you'll eventually need.

What size needle and seat did the rebuild kit supply? You might want to try using the old one just to see if it makes a difference. They may have given you one thats too small or something.

'87 turbo II

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One mixture screw has the needle completely broken off at the base so that it is flat, this screw is fully seated in its housing. The other is fine but set to 1.5 turns away from full seat, it has not been tuned for a good idle like it was set to presumably (car must have idled on one rotor before. The old needle seat for the fuel cut was tossed I think, I am not sure as the car and parts are stranded at Crit's house until he gets back in town Sunday. The new one probably can be turned in a bit more though, as the brand new crush washer seemed pretty thick, it might not hurt it to try and muscle it down more, the rebuild kit came with 2 of them anyway (in case I mess up the brass) so I could try that. I will also check the fuel pressure,but I doubt it is the problem as the car ran before the carb rebuild. I will go look at the size of the float needle and seat when I get to Crit's house again. Thanks for the help.

pinoyremix

hope you get it running..its a great carb...

'87 turbo II

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We'll get it running somehow, It was performing wonderfully a few hours before the rebuild, just leaking fuel like mad from the lowermost gasket on the accelerator pump. Leak is fixed now though haha.

DriveFast7

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cut the tip off the other idle mixture screw so you're working with both the same dimensions.

did you guys reset the float level, that could be it.

and, take the lid off, hold it over a drain pan and turn on fuel pump. cycle the floats up and down to see fuel exiting the needle and seat. ensure it flows fuel when floats all the way down, and it stops when the tip of the float is 14mm away from the lid gasket.

'87 turbo II

iTrader: (1)

I'm scared to mess up my one good mixture screw until I have 2 brand new ones to play with, but I did check the cover with the pump on, it does flow with the floats down, but I didn't check the clearance when up (more important really haha) also we didn't reset the float level but Crit said it shouldn't have to be done if it worked before, he was my expert of the day haha. But thanks for the suggestions, so far I've got a good little list of "to dos" on Sunday when I get back to the car.

-Check fuel flow with floats down and note the shutoff distance
-reset float levels
-tinker with idle mixture screws (the good and bad one I guess) cutting the good screw is a last resort
-test fuel pump flow w/ bucket and sharpie

It also might be worth noting that the little tiny basket filter that attaches to the needle seat was overlooked and forgotten upon re-instillation due to the kit not having a new one. The one near the banjo bolt is there, but the other one is left out, is that going to be a problem maybe? We still have the old filter, should we remove the floats and install it this time? (I want to avoid removing the floats if I can as removing the pin from that housing is a very difficult and unnerving process. The top cover looks like an expensive or hard to find piece.

pinoyremix

they run great...plus you get a choke..although i have yet to take advantage of that...broke my choke cable..but...for me i found that the stock pump started to give out on me..used a gslse pump, lines and fuel tank..and mallory fpr..and now it runs great..

'87 turbo II

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Haha I am aware of how it's supposed to run, and I am familiar with using the choke. I keep saying I had the carb on the car before the rebuild, it was just leaking fuel from a hack-job previous owner's rebuild. Now I fixed the leak but I must have done something wrong because since the rebuild the car won't start and stay running.

DriveFast7

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It'll never run right with one tip missing from one idle mixture screw. That rotor will run extremely rich. Before installing the new idle miixture screws, blast the passage out with carb cleaner and put a liberal amount of anti-seize compound on the new threads. That'll keep them from rusting or galling.

'87 turbo II

iTrader: (1)

It ran nearly perfect, just didn't idle until warm, probably fault of the screw (might've idled on one rotor even). If I got it so smooth before, I'm excited to think it could run BETTER than before, but the needle was missing entirely from the carburetor and must have been before the disassembly because it didn't come out with the screw, nor was it still inside the passageway.

Blasted it with carb cleaner, simple green, a detailing brush, thin wire, and finally compressed air and the passages are treated with antisieze even on the bad screws right now. I'm trying to do this thing right. Thanks though, it's good advice. All the passageways and jets and such are all cleaned really well. Little parts in a dump tank, big parts getting the degreaser, simple green, brush,wire, air combo.

'87 turbo II

iTrader: (1)

Got the 7 running again! It idles like it's ported (not a good thing) and at anyhting under 2500 RPM it drives like crap. These problems will be fixed with the new mixture screws. The good news is that 2500-3000 RPM and up it drives smoother than ever before.

t_g_farrell

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Sounds good. You'll need those needles if you try to cruise as well. I assume your just blipping the throttle in neutral right now.

Crit

iTrader: (6)

No, we ran his throttle stop screw all the way down and got it idling around 1100 revs on the idle and progression circuits. Once he gets his idle screws he'll be fine.

For what it's worth, I talked to a guy at Deal's Gap about Dellorto problems, AND had a buddy that was having idle issues with his Dellorto. It's just been raining carbs all weekend.