Re-jetting (or not) the DFEV

[wetminkey]

I have also found that vendors, and folks in general, seem to be less tolerant than they used to be,...and less helpful. Rudeness,...product of the times, I think. This is a pretty civil forum,...my favorite!
My car has an electric fuel pump. Worked perfectly before the DFEV. I reset floats to proper settings, but I will double check again before I close it up. I've seen settings and the two ways that the float is checked and set, but I was wondering what you guys understand the DFEV setting to be? I've also seen what might be conflicting information,...
What do you understand the DFEV float settings to be, and what method do you use to check them? Thanks!
The DFEV A/F screw should be 2 turns out, no more,...which means that my idle must be leaner than it should be (since I have to richen the mix to make it run smoothly). Just an observation, since I do not feel like the A/F mixture is proper at this setting,...engine running poorly, may have been too warm, etc,...A/F can't really be set well that way.
More when I can,...

[SteinOnkel]

Hmmm...I don't have any experience with the DFEV. So I can't help you with the float settings.

However from many years of tinkering with different carbs, I've always found that the higher the load/rpm, the better they run. Unless something is grossly out of whack.

Last year we had the case were a set of IDFs from Redline Weber (kings of rudeness and not helpful at all) the venturis on one carburetor were literally installed upside down. That engine also refused to rev passed 3-4k. So instead of fuel spraying into the throat, it just kind of dribbled out the top. Took us the better part of two weekends to figure this out. The other carburettor was full of fuel residue and needed to be ultrasonic cleaned. $1200 for the set, thank you very much...

Is your secondary throttle blade opening?

You really need to check the absolute basics with new webers. Made in Spain, China, makes no difference, they have zero quality control and seem to pull random people off the street to assemble these things.

[wetminkey]

I checked my float settings again, and they are right on, according to this link to Pierce Manifold's site:
https://www.piercemanifolds.com/category_s/317.htm
35 mm and 51 mm,...I even made a guide. Redline Weber's DFEV instructions say to "set it at 18 mm from the edge of the float",...but do not state what edge, where, and how to check that. Pretty stupid, huh?
I'll have a new distributor tomorrow, so I'd like to run the car again and see what happens,...the existing one has a lot of slop in the advance mechanism, and is 40 years old, besides!
I checked my old 2l core-block, and I see where the timing pointer is supposed to be. And that ten degrees is about an inch from TDC on this pulley,...so my car's timing is too advanced.
I'll make some changes tomorrow and consult my Weber-wizard friend, too. I also want to check out more at the link I provided above,...
Later.

[SteinOnkel]

Relevant:

http://www.fiatspider.com/f15/viewtopic.php?f=5&t=38062

Best upgrade I've done to the car so far. When it's at operating temperature, you can't even hear the starter crank because it fires up so fast.

[focodave]

Todd,

I hate to ask questions that take you backward, but I just feel compelled to ask --- Is there possibly a vacuum leak somewhere?
The fact that you have to turn the idle mixture screw out 3 turns, and the fact that he car does not do well at higher RPM/load, just makes me want to ask that question.
I am just finding it hard to believe that the jetting that was in the carb would make the car run so poorly.
Don't get me wrong -- the jets need to be sized properly for your engine and the jets that are in there now are probably not ideal and should definitely be changed, but I just cannot believe that would add up to the symptoms your engine exhibits.

Just my 2 cents...

Dave

[focodave]

Oh, and guys -- I am 57 years old -- old enough to be completely appalled by the rudeness exhibited by a majority of people these days, and especially the atrocious behavior on internet forums.
I agree that this forum is one of the more civil ones on the web -- probably because most of us on this forum are old farts like myself who just don't want to deal with rude a%#holes.
I've met some very respectful young folks (few and far between), but the rudeness seems to have no age limits these days.
Incredible...

[geospider]

Todd,
You're still at it. It's like we are back at our Vac advance days: remember.

I used that Pierce manifolds guide as well and it worked for me.
your jet sizes are the same that I have. And from my research on this site, seems to be the "norm" for the set ups we have.
With timing that advanced, I would think your idle would be high. ?

Also, my mixture screw is about 1 1/2 to 2 turns. I was running lean and it's idle was stumbling. opened it up a bit more and Now idles great, but high. Timing is right on and my idle speed screw is backed off as much as possible: how about that.
It does revs quickly and smooth.

I would work on it with the jetting you have and then dial it in from there if needed. But, you do live a lot higher than me; Elevation 705.
good luck

Geo

[manoa matt]

Your new distributor parts, did the lack of RPM above 2500-3000K start after that rebuild? Assuming you have a 79 electronic distributor, what does your rotor look like? Is there a resistor in line between the carbon button contact and the end? Or is it a single brass piece un-interrupted by a small puddle of epoxy?

The early block mount distributors use a rotor that looks almost like the later electronic distributors. The early rotor will work and the engine will run. However, the underside has plastic castings that will interfere with the advance weights preventing them from their full travel limiting the engine's RPM range.

[wetminkey]

New distributor came today from Vick's.
When I inspected my present advance mechanism, I found that the replacement advance springs allow free-travel before they act,...in other words SLOP! Rather than 'fart' around with the 40 year old distributor, I'm simply replacing it.
New distributor has a nice tight advance system, and that could explain a lot, if that's the problem source! We'll see.
DFEV is back in. No sense in changing anything inside of it, until I've eliminated all of the other possibilities. Doesn't seem like too many folks have found it necessary to re-jet their Webers! But now I've confirmed what's in this DFEV. And now all of you know,...and also know that you can probably trust the information presented at:
https://www.carbparts.eu/jetting_table
Just knowing that could save someone from questioning what is inside their (unaltered) Weber carb! ALL of the jets are listed for each Weber carb.
I'll start the car and run it for a bit, then I'll yank the old distributor and install the new one. I can just about guarantee that it will make SOME difference! I hope it makes a HUGE difference, and proves to be the problem source, like focodave anticipated,...
Sorry, outta-state, visiting friends have slowing my progress,...along with the usual chores, of course.
Thanks for everybody's interest, input, and motivation!
Todd.

[wetminkey]

Idles a bit smoother, but no real change.
Engine will just barely rev beyond 2000 rpm, and then seriously bogs, with proper ignition timing (per my TDC marks and guessing ~12 - 14 degrees advance) and carb settings at the proper 1.5 turns out on speed, and one turn richer (3 turns out) than it should be for A/F.
I seriously doubt that the DFEV is responsible for this engine running this crappy,...I STILL doubt my timing belt timing at the crankshaft! I'm going to do another compression check and pull the cam box covers, so that I can see what is going on, when.
Guess I'll get a good pic of my old block's timing marks and see if I can measure that out on this engine's lower cover. I'm gonna guess that the crank needs to be advanced one cog. Anyone have any idea of how an engine acts when the valves are behind the crank by a couple of degrees? I'm suspecting that I simply set the timing belt back at the same spot that I had it before,...
Man! I can build V8s in my sleep, but the lack of timing marks on this 2 liter DOHC engine is just KILLING ME!

[18Fiatsandcounting]

Sorry to hear about all the difficulties... I can't remember if you checked this, but the first thing that I would verify is that your ignition timing is indeed advancing when you rev the engine. Somewhere between 10 and 15 degrees BTDC may be OK for idle, but it should start advancing soon after you get above idle and then max out around 35-40 degrees at 3000-4000 rpm. I realize that you can't rev this high, but you can verify that your ignition advance is getting to around 25-30 degrees at 2500 rpm or so. Since there are no timing marks that go this high, you either have to eyeball it, or use one of those timing lights that allows you to delay the firing of the timing light, so you just adjust the timing light until you are back at 0 degrees TDC and then read off what you dialed in on your timing light. That then is your advance at that rpm.

Another thought: Sometimes it's assumed that when putting in a new carburetor that bigger main fuel jets are better. Depending on the size of your engine, it will pull in 1.4, 1.6, 1.8 or 2.0 liters of air no matter what carb you have installed. Consider the engine to be just a large vacuum pump. Your challenge is to find the right main fuel jet size that gives the right amount of fuel depending on how much air the engine is pulling in for a given rpm, and keeping this A/F ratio at 13 or so.

After you get the A/F ratio roughly correct across the rpm range, then you can fine tune for altitude, peak power, richer or leaner at high rpms, etc. using the air corrector and emulsion tubes. But again, get the main fuel jets in the ballpark before messing with air corrector jets or emulsion tubes.

Hope this is of some help.
-Bryan

[geospider]

Todd,
Mine had a similar problem initially. But, it was a float adjustment issue and I know you already did that. I believe our set-ups; down to the jets is the same.

question fro Bryan, even if the timing didn 't advance properly, wouldn't it still rev past what he has, but just not really have any power. I accident;y was driving around with the vac advance disconnected and it was not that noticeable. I know the mech part is more significant.

Geo

[focodave]

The vacuum advance is used only at idle, to advance the spark so as to keep emissions (and things like over-run backfire) to a minimum.

The mechanical advance is what gives you the "all-in" total advance number at higher RPM. The vacuum advance has nothing to do with the "all-in" number. Your initial BTDC advance does add up to what the total "all-in" number will be when the advance weights do their thing at higher-than-idle RPM.

[focodave]

Todd,

If you truly found TDC with the old pencil-in-hole trick, then you lined up all the cam timing marks properly, there is no reason that the cam timing should be off by any degree.

The only thing that would cause error there is if you were not at true TDC with the pencil, when you thought you were.

Dave

[focodave]

Todd,

A couple more things that come to mind:
Did you have your pencil in hole # 4 ? -- or hole # 1? -- compression stroke
Stupid question, but do you have the plug wires in the correct order? --- might want to check that as even the best of us often get them mixed up!

Dave