a bunch, basically step one is to make sure all the mechanical parts of the carb work like they should, IE the accel pump needs to be not intermittently stick like mine...

second you need to change jets. the jetting chart is a good place to START, but its not where you're going to end up. the exhaust, intake, air filter, altitude, engine health, ignition, fuel pressure, and the fuels ethanol content, all are different car to car, and this means that one jetting chart cannot work for every car.

when i tuned my car it took a while to throw away the jetting chart and just listen to the engine.

give the engine what it wants, right now you're giving it what you think it wants

 

^^^

Ive had 3 engines all made the same model year whose jets in the same carb varied up to 9 jet sizes...

 

Tell me if you guys think this could help my diagnosis.

I have a pair of .52 idle jets, which are very very lean, but I could potentially put those in, then richen the fuel mixture something like 6 turns out. If it runs better, wouldn't that tell me that the idle jets are the problem, I could more closely choose idle jets?

 

Tried that. It was still too rich. It's almost as if the idle jets aren't doing anything. It doesn't change anything from one to another. I guess I'll check the choke next.

 

if its not the choke, then you need to make sure its actually idling on the idle circuit. the webers have an idle hole, and either 2 or 3 transition holes, and just because the rotary wants more air than the equivalent piston engine, usually we open the throttle so we're actually idling on the transition circuit, and in this case the idle mixture screws don't work much because you're not using them....

the IDA is a little bit of a bummer because it doesn't have an idle air screw, like the DCOE does

not sure about the dell, if you have an idle air screw you need more air, and less (or proper) throttle plate opening.

 

I Still think that carb is overloaded with fuel.

 

I cannot figure out how to get the venturis out. I took off the retaining nut for that set screw on the side of the body, but now I don't know what the hell to do. There isn't a single detailed instruction in that piece of **** dellorto book about how to actually remove the venturi, it just tells you to remove it.

 

An update as to what I find with the same problem, Checked compression and found it a little low but even as you would expect from a run hard engine. then Took the carb apart; no problems found, float was a mm hi and drop was a lot, put both at spec, back on car and got 60 idles to kinda work at 2,5 turns but had to leave a little of the progression port open to hold idle. put o2 sensor bung in pipe and took it on road with a lm-1 portable broad band. mostly in 11s and 12s except pulling a light grade it would sometimes get into the 14s was fairly smooth with light to moderate load, but when romped on promptly went into low 10s and even lower and missed nasty with out any power. Will have to agree with the one who said it is fat rich, makes sense and should perhaps go up a size on idles whit a smaller main and get the progression port closed. With a weber dcoe48 and a 42 venturi this just is not going to be a good street set up. have an assortment of mains coming and will do more later in week. Will to thank everyone for the good advice and the original one asking for the timely question. Broadbands are not just for injection. wish we had them back in the 50s

 

I have kind of the reverse. I guess I'm just really picky because most people would probably be happy. The car behaves really well under load. Driving around at normal speeds it doesn't buck or backfire or jump or anything, and it runs very well under heavy throttle. It's just this idle and zero load condition that I can't wrap my head around.

I had a theory about maybe pulling the ignition leads on each rotor and see if it runs differently depending on which rotor is receiving spark. But I flooded it before the test could be done. :/

 

Why not buy a wideband? it'll make youe tuning heaps easier.

 

I'm going to see if I can borrow one.

 

Dude there's AEM ones for 150-200 plus shipping..I saw one for 180 free shipping.

 

Link?

 

http://item.mobileweb.ebay.ca/viewit...d=360538007974

That one is 170, 11 for shipping

http://item.mobileweb.ebay.ca/viewit...d=230831716837

there ya go

 

$166.00 on Amazon, free 2 day shipping for prime.

 

So now the car won't start at all. I thought maybe it was flooded so I took out the leading plugs and cranked it for about 30 seconds then put the plugs back in, but it's still not starting. Even with starting fluid shot straight down the chokes, it won't start. I haven't changed anything on the carb since it last ran somewhat decently. Any ideas?

Any experienced Dellorto people out there want to rebuild my DHLA for me? Name your price. Otherwise I'm probably going to sell it and get a Holley or Weber IDA.

 

Bit of an update. De-flooded it again gave it another go. After quite a long time, I managed to get it started, but it's now consistently running on 1 rotor. What on earth is going on here?

I feel like the rear rotor just isn't working. I took the idle jet out completely from the rear and it didn't have much of an effect, only difference was that it made a bigger bang from the tailpipe when the rotor did fire, which was once every few seconds.

Are there ignition issues that could cause one rotor to fire and not the other?

Edit: Doesn't make since for it to be an ignition issue. I'm going to pull the carb this weekend and thoroughly and comprehensively clean everything. What is a good 'bath' for carb parts? Carb cleaner evaporates too quickly. Maybe just soak everything in ATF? lol

 

This engine ran well before the swap, right?

 

Eh, it ran ok. It never idled correctly. Way too low always, and then a loping idle when I held it at 1k. Here is a video of what it used to idle like with the EFI stuff.


I just assumed it was one of the myriad of vacuum system's that wasn't working properly. One of the reasons I decided to do the swap actually.

Perhaps it is an ignition problem afterall?

 

Once that happened to me on my Dellorto, and after trying for hours, replacing the spark plugs fixed it. Went from running on 1 rotor to both. I think maybe one cracked? I don't know. The plugs all looked dry and clean after I cleaned them, but replacing them made it fire right up like nothing was ever wrong. Even just old parts bin plugs worked.

 

Have you done a compression test? That video shows what seems to be another pig rich engine. The GSL-SE's idle was adjustable by a device next to the AFM. Did you ever try this?

Too bad youre so far away, I have about 5 complete SE injection sys that were in good tune when I pulled them, and a couple with bad bits of squirrel modified harness... Ive been playing with the SE system on my personal car, and It ran like that with when I first installed it, but went away after the first drive. Ill never really know why..

 

I haven't done a compression test, but I heard strong pulses when the plugs were out and I was deflooding it. They all sounded uniform. Also, the engine makes good power at high RPM.

I had tried to fix the idle on the EFI system with resetting the TPS and adjusting the idle air screw, but nothing seemed to help. If it was a bad coil or bad ignitors would, or could it cause these symptoms? I think a bad [leading] ignitor would just cause it to not run at all. The plugs are actually new, so I doubt that's the issue.

 

Do you guys think it would be worth it to switch to this intake manifold?


86-91 Rx7 Wrap Over Intake Manifold & Weber 45...

I don't have functioning six ports anyways, and I've heard this manifold flows a lot better than the rb upper/stock lower combo. Also, it would simplify the engine bay without all those vacuum ports and injector holes to plug up. I would probably wrap the lower portion in gold reflective tape to keep the exhaust heat off, kind of like what evo guys do with their intake tubes.

 

Finally got some time to take the carb out and apart. Only took about an hour, maybe two. Not bad.

Anyhow, the main choke is 39mm and the booster Venturi is 8011.1 so those should be fine.

I found a few potential problems. Number one is that the carb is just filthy. Absolutely disgusting. Grime and grit everywhere. Secondly, one of the bolts attaching the carb to the manifold was barely finger tight. Potential vacuum leak. It was the lower bolt which i couldn't spray to test.

I'm going to prepare a bath for all of the pieces and the body tomorrow. Any tips for what to soak it in?

 

One solution to a rich idle and cruise (i.e. just maintaining speed) is to drill a small hole in each throttle plate near the top. This will provide more air when the throttle is pretty much closed and allow you to not try to compensate by turning the throttle skrew causing you to open the progression holes.