Dellorto Rebuild
 

Ok Dellorto guys, I have a question. A while ago I posted a thread regarding a flooding issue I was having with my new used Dell. I got my rebuild kit today and started tearing into the carb. I found out some parts are missing....JOY! According to the diagram in the link below, part number 50, pump jet weight (my dell & weber book refers to it as a pump jet spacer rod), these parts are missing. I'm assuming this isn't a RB mod! :) Is it actually a weight, or a spacer? If it's a spacer, could someone get me some specs on this (length & diameter. I'm sure I could fabricate some new ones. Also, would these parts missing cause my engine to flood out, I'm going to replace them regardless?

!
 

heres the pic I meant to attach

I think the pump jet weight being missing IS a rb mod, because mine doesn't have them either.

Really, can anyone else confirm this?

see if this helps any ...
https://www.rx7club.com/forum/showth...light=dellorto

Alright, I put the carb back together, inspected all of the jets, and all of them were the same as what RB put in according to www.gruntled.com , except for the pump jets. These were only 60, compared to 80 that was in there Dells. Anyway, I'm wondering these smaller pump jets may be installed because of the missing pump jet weights that are missing, as some sort of compensation. I tried firing up my '83 GSL, and she started fine with a little help from the choke, about 4.5 psi according to my fuel pressure gage. When I give it some gas it definitely hesitates though. I'm thinking this may be because of the idle fuel mixture though, and not the pump jets. Rotor 13B, or anyone else for that matter with the pump jet weights missing, are you also running smaller pump jets?

I haven't checked the size of the pump jet. I can look though as i just purchased a master rebuild kit from cb performance, so i'll let you know.

I would appreciate it very much, by the way, what size needle jet and seat did they send you? They sent me a 200 (I need a 300) because I didn't specify, guess I'll just have to drill it out at work.

That's weird.... those 80 pump jets are pretty small as it is. I'm still running them, incidentally. RB actually started specifying 90's midway through production, and most people switch to those due to a smoother throttle response.

Those 60's you have sound waaaayyy too small to me. That's gotta be contributing to your hesitation. Also, have you got them lined properly? The little holes have to precisely line up with the ones on the carb body. If not, hesitation will be brutal. The way to line them up is by experimenting with different thickness washers... I had to buy some different gasket paper types and make my own, in order to get it right.

Oh, and they have to be tight! If you line them up nice but they're not tight enough, they start to leak pretty easily. I had this problem with a few of the washers I made, until I finally found some paper that was just right and allowed the screws to be tightened down properly.

Now to be honest with you, I'm not sure about this pump jet weight thing... my car is stored 6 hours away, so I can't check, and I can't remember... sorry man.

Other causes for hesitation are definitely the idle mixture, and also the accelerator pump travel. Is your idle mixture adjustment working properly; do you have the little washers, o-rings, and springs in there right? You should be able to set this without too much trouble if it's working right. The accelerator pump stuff is a little more tricky; there should be info about that on the gruntled site.

I remember at first, I had a little hesitation if I would floor the gas below 4k or so. I easily tuned it out with idle mixture and fuel pressure adjustment. After a few days of fiddling, I could floor it at 2.5k with no detectable hesitation (not that you'd want to do that lol).

It's weird with the hesitation... just when you think you have it as smooth as it could get, you fine tune things a little more, and it gets even better. It takes some work, but you should be able to get to that point as well.

I'm not too sure about the pump jets either, I'm probably going to buy some 90s anyway and see what happens.

As for the idle mixture screws, I guess I wasn't paying enough attention to the diagram, when I pulled the mixture screws, there was no springs, washers, or o-rings in there. That explains the two extra o-rings I have left over from the rebuild. That also explains why the engine doesn't really respond to me moving the idle mixture screws.

As for the pump jets, I used new o-rings and fiber washers that were supplied with the rebuild kit, so I assume that they're lined up.

Okay, maybe those washers, o-rings and springs were in with the idle mixture screws, I just neglected to see them. I found the washers and o-rings in there, just no springs when I pulled the mixture screws out. I found one of the springs on the floor of my garage where I rebuilt the carb. I ended up going to the hardware store and found another spring of similar diameter, and cut it to the same size while the springs are compressed. Put the idle mixture screw assemblies back in, and now the engine is much more responsive to the screws. Hesitation is far smaller, and is now intermitent. This may be because of the small pump jets, it may also be the small fuel inlet needle seat, which I'm going to drill out today at work, so it is 3 mm in diameter, as opposed to only 2mm.

I drove my car around the block for the first time, pulled the spark plugs out, and I can see it's running way too lean, hopefully the inlet needle seat will fix this problem.

Alright, it looks like you're making some progress here:)

Yup. that's what I was saying... if you don't have all those parts in there properly, the adjustment isn't going to work like it's supposed to, and you're gonna be running like shit.

I sure would... those 60's are way too small.

NO! (lol... sorry to be dramatic)

You can't assume they're lined up. The rebuild kit washers don't always work quite right; myself and others have *had* to make our own.

Here's what you need to do:

Take out the pump jets. Take careful note of where the little holes are on both the carb and the jet, and how it is all supposed to line up. Notice how the jet itself only fits in the carb one way, and has to be lined up right. BUT, notice how the pump jet holder (the top part which the big flathead screw top) needs to be lined up too, and this is determined by where it sits when it is tight.

So... take your screwdriver, and mark the side of the pump jet holder screwhead (I'm really good with the technical terms eh? haha) at the exact point where the hole is. Now, install it in the carb, and look at where your marking is, relative to where you know the holes are on the carb itself (just at 90*.)

I'm betting that you're gonna find out you don't have it exactly lined up.... and you're probably gonna have to make some gaskets like the rest of us. If by some miracle it's already perfect, then at least now you have peace of mind.

That sure sounds important to me; let us know if it helps your problems.

You should also have checked and adjusted the travel distance of the accelerator pump arm when you had the carb off... this can cause hesitation if it isn't just right. Details on the gruntled site I think.

Did you leave the upper/lower manifold gasket dry? That's important, because the carb needs to come off to mess with some stuff, and it's much more dificult if you can't take the top manifold with it.

Alright, I'll have to pull those pump jets out see how well they're lined up. So you basically had to make up your own fiber washers before they fit just right, huh?

As for the hesitation off the line, I think I'm also going to drill out idle jets to .82 mm like like www.gruntled.com recommends.

Looks like I probably will check the travel of the pump arm, seeing as how I have to take the carb off, anyway. As I was looking for those parts for the idle mixture screw assembly, I found another spring, The diaphram return spring....DOH!!! Looks like I forgot to put it back on. I suppose that's why it takes so long to idle back down after I hit the gas.

Fortunately, I did leave the manifold gaskets dry. I anticipated having to pull the carb on and off a few times.

By the way, thanks for the help you've been giving me Silver Rocket, I really appreciate.

Okay, I pulled the pump jets out, both of them were misaligned. After some fiddling around, I got them to line up. On one side, I could use the fiber washer they gave me, on the other side, I used one new, and one old fiber washer, and it seems to line up pretty good now. However, I couldn't tighten it down as much as I would've liked to, so I'll have to watch out for leaks, and probably make up a thick washer.

After re-aligning the pump jets there is considerably far less hesitation, I also installed the larger needle seat. The only difference I noticed from the larger needle seat is after wide open throttle up to 4k :) , the engine doesn't want to stall when I let off the throttle, which is what it used to do.

Larger idle jets are next on my to-do list. The only real hesitation I get is between 1k and 1.5k, after that she's fine. Even if I go WOT at 1.5k, (under no load) it no longer hesitates.

Ok, about the needle and seat, they (cb performance) no longer gives you a choice between the 150-300 range. All the kits come with the same needle and seat regardless of the application. Seems strange as to why they would do that unless they all come with 300's or all of them so you just choose which on you need. Sorry for taking so long, but i haven't been able to log on to the forum for a couple of days now.

Excellent!!!! My advice was actually useful:)

I'd try to stick to just one washer if possible, but it sounds like you're definitely on the right track now.

See if you can floor it in 5th gear at low rpm with no hesitation.... that's when you really have it wired:)

Will it hurt if I use the same needle jet I have now or are they prone to go out?

Silver Rocket, i think I'm ways off from being able to floor it in 5th gear, but I'm definitely making progress, and your advice sure is helping!

Rotor 13b, I guess what happens to those needles is the actual tip can have grooves worn in it, causing it not to seal properly on the neede seat. Unfortunately, you can't use the new needle on the old needle seat, because the body of the new needle is larger for some reason. what I recommend doing, is drilling out the old needle seat so there is enough clearance for the new needle to fit in it. Just be sure not to drill all the way down to the 3mm hole, where the needle seats, otherwise you may leave a burr and the needle won't seat properly.

FYI.... i just got off the phone with cb performance. they can no longer get the 300 needle and seat. i've had one backordered for a couple months now and no dice. so now where can we get 'em? btw, cb performance is always a great company to work with... friendly, helpful, timely... yada yada yada. just can't get the parts i need anymore :(

Well crap that sucks. I guess my quest isn't over yet...lol

European Motorworks is the next on the list I guess.

http://www.racecar.co.uk/dellorto/

According to www.disgruntled.com they stock every part made for the Dell, it just sucks that you have to order all the from the UK.

lol, might wanna check your link.

Alright, I think most everyone knows I meant this :)


http://www.gruntled.com/Dellorto/Parts.html

I just reused the needle and seat I got with my carb; no problems here.

Cool, I'll give it a try.