Black soot in my exhaust Options

[terrymason]

I fired up my 914, and let it idle in the drive way for a while, and noticed that small dots of black stuff (looks like oil splatter) seem to come out and stain the concrete. These aren't liquid at all, but are a black powdery soot.

Is it normal to have these black soot marks? Do you think this is because my car has sat for some time?

[Eric_Shea]

Rich (IMG:style_emoticons/default/wink.gif)

[terrymason]

Coming right after I put on dual carbs.....

I think you're right. Anyone know a good method to set the mixture? I'll have to re-read my dellorto superperformance book tonight.

[So.Cal.914]

That was an important part of the puzzle the fact that you just put on carbs.

Rich, rich, rich.

[Eric_Shea]

Aren't you the Terry Mason I've been trying to get in touch with? (IMG:style_emoticons/default/biggrin.gif)

I believe I goofed up and found a check of yours and we didn't send you some brake clips. Should I tear that check up? Do you need clips?

There should be two screws at the base as most of these Dellorto and Zeinith carbs are kinda Weber clones.

The smaller screw sets the balance between throats. Close them all down and read the one with the most airflow. Open the others up to match.

The larger screw is the enrichment screw. There are various ways to set these but, you should try to find an EGA. Otherwise, you can set by ear and idle. I don't have a 911 manual around me here but they give a decent method for tunning Webers etc...

E.

[PinetreePorsche]

yeah, rich--do Dellortos have a cold-start enrichment (my Webers don't--what a pain in this weather--re-started 7 times before my artful flutter could keep it going)? If so, may not have come off to hot run position. We'll be watching with interest--"aw, shit, a grand into some new carbs, and I got this!"

[terrymason]

Eric - don't worry about the check, I found some other brake clips that worked.



I thought the carb install went way to easily! I guess that's because I didnt' mess with the mixture at all (IMG:style_emoticons/default/unsure.gif) . The thing runs great now (compared with the single weber I had before).

[Eric_Shea]

OK... I'm going to tear it up. I'll PM you the check number so you can void it out. Sorry about that. I had the clips sitting there waiting for the check and a shipping address... finally found the check burried in a "stack".

Sounds like you've got a good foundation on the carbs. Get a UniSyn gauge and start the fun. You may simply want to experiment by turning in the enrichment screws 1/4 each (if it's running great now). If you begin to get some lean "pop" you've gone too far (IMG:style_emoticons/default/wink.gif)

[So.Cal.914]

You can get them pretty even by pitch. I have used a piece of tubeing, put it

in your ear and the other end in the carb (one barrel at a time). Listen to the

pitch and match the others to it. But a syncgauge is by far the best.

[terrymason]

I sat down with my Superperformance book, and looked at the section for setting the mixture, and it really didn't tell me much. I think that I'm missing a few of the underlying ideas. Are these two statements accurate?

1 The goal of setting the mixture is to get the engine as lean as possible without having any detonation

2 Detonation can destroy an engine pretty quickly.

[Coy]

Not to high jack this thread... but...

When I cold start my dual webber it generally takes a couple times to get her started and running smooth. I can generally find a little soot on the gagarge floor right after it starts, but none after it warms up. I just figured, that possibly due to my poor starting talent, a little soot is to be expected on an overnight cold engine. Am I way off?

[ahdoman]

You can get them pretty even by pitch. I have used a piece of tubeing, put it

in your ear and the other end in the carb (one barrel at a time). Listen to the

pitch and match the others to it. But a syncgauge is by far the best.

I supplement my setting the way Paul does BUT PLEASE BE CAREFUL! IF THE CARB POPS (BACKFIRES) IT WILL DAMAGE YOUR HEARING! Please don't stick the tube into your ear.

[terrymason]

Well, It's been a while, and I've finally gotten to work on my carbs. I've installed a new wideband 02 sensor, and have set the dwell and timing for my engine. Now I'm trying to dial in the mixture for my engine.

My wideband o2 meter starts off at 20 for about 10 seconds when I start the engine, then as the engine warms up, it settles down to a reading of 12. As I goose the engine, the readings go up to 15 or so, and fluctuate alittle, but eventually come back to 12 at idle


Per my dell book, I started the mixture screws at 3 1/2 turns out. I kept turning them in until I was only 1 turn out. My o2 sensor read 13, but the car ran worse, popping and backfiring whenever I hit the gas.

So now I'm sitting at 2 1/2 turns out, with a air fuel ratio of 12.2 or so. At this point, should I pull my idle jets (I currently have 60s on my 1.8L) and replace them with some #52 or #46 that I got off ebay?

[orange914]

Is it normal to have these black soot marks?

hear about the islamic terorist asigned to blow up the bus?... burnt his lips on the exhaust (IMG:style_emoticons/default/av-943.gif)

[SGB]

60s are pretty big. I would definately try something smaller. With my 40IDF webers on a 2.0, I run 50 idles and 125 mains, with each air bypass screw (do dells have these?) out 1.5 turns and each mixture volume screw starting at 3.5 also, but dailed back to about 2.5 before there is popping somewhere. I set all the mixture screws to whatever the biggest setting is so all cylinders are drawing the same amount. Make sure the linkage is square with the carb lever so both sides advance at the same rate.

[r_towle]

look up the dellorto guy on Ebay. He is from Italy.
He knows these carbs really well, and he probably can tell you the right jets for the motor.
Once you find his ad on ebay, click on the "about me" thing in the top right.
He has a very nice web site with all the different applications of these carbs.

Sounds like you need to rejet it.

Rich

[r_towle]

http://cgi3.ebay.com/ws/eBayISAPI.dll?View...userid=alfa1750

I found him, and you need smaller jets for sure.

Rich

[Gint]

Wow. We have the same color 914, we both just swapped out a single progressive for dual carbs...

(IMG:style_emoticons/default/agree.gif) with just about everything said here. Including alfa1750 on ebay. I just got a set of Weber jets in from Italy.

[terrymason]

Thanks guys. These carbs actually came from Alfa1750.

I also got some new jets from him a couple of weeks ago, so I'll try putting those in this weekend and reporting back.

[lotus_65]

You can get them pretty even by pitch. I have used a piece of tubeing, put it

in your ear and the other end in the carb (one barrel at a time). Listen to the

pitch and match the others to it. But a syncgauge is by far the best.

I supplement my setting the way Paul does BUT PLEASE BE CAREFUL! IF THE CARB POPS (BACKFIRES) IT WILL DAMAGE YOUR HEARING! Please don't stick the tube into your ear.

Just revving the motor makes you deaf!

I crammed the tuft of cotton off a Q-tip into my length of hose and it works great!