Question about carb jets

[KingFish]

I have a Escort carb, intended for the Escort 1.6l. I intend to use on a otherwise stock B3. In a Ford training book i downloaded from a member here (sorry, I cannot remember who) It list the jetting for this carb thus

idle jets pri .50 sec .60

High speed bleed pri 1.60 sec 2.20

main well tube pri x05 sec t02

Main jet pri 1.05 sec .95

My question is, what the heck does all that mean? Is this calibration too rich for the 1.3L. Can I even get jets for this turkey, and if so, where?

Thanks guys.

[drddan]

Whew! That is a BIG question! I mean all the variables involved cannot be answered in one question :eeeeeek:

I WILL try to help you out here, with what little I know

I know more than most people I talk to, but I still feel like a beginner when trying to fine tune a carb.

First= sense of the numbers:

All sizes are given in MM (millimeters)


Example

.25 is 1/4 of a mm
.50 is 1/2 of a mm
.75 is 3/4 of a mm
1.0 is a full mm (approx .040 inch)
1.50 is a mm and a half....and so forth

You will see numbers like 1.37, 1.45, ..... just different sizes of jets is all

smaller sizes = less gas or air to the carb
larger sizes = more gas or air to the carb

There are gas jets, and there are air jets - your main concern is with the gas jets, but work in conjuction with the air jets also


2nd=what they do

The different sizes determine how much gas/air is let in to a certain area of the carb...and there are differnet areas...

idle jets start the whole procedure off and control a good portion of the whole carb, even the primary and secondary.

What the process of changing jets does, is allow you to control how much GAS AND AIR each area of the carb gets. That is all!
Sounds simple, right?

In a way it is, and in a way it isnt! :p

Now that you have a basic start to what a carb does, you can read the links below

BTW...I am giving some of my secrets away here!

http://www.racetep.com/webjettune.html

http://www.piercemanifolds.com/category_s/313.htm

http://www.piercemanifolds.com/category_s/31.htm

http://www.carburetion.com/Weber/adjust.htm

I know this is all for WEBER carbs....but the princple is the same for all carbs..

..and close to the Escort carb you have

All is I can say is...good luck! LOL

You can PM me if you have a specific question, I will try to answer it.

[denguy]

The way I see it is that the ideal Air-to-Fuel ratio for a warmed up gasoline engine is about 14.7 parts air to 1 part of fuel. That is what you are varying with the jets and the choke. Altitude is a factor because the higher you go the less oxygen there is in a cup of air.

[georgeb]

You can check jetting by looking at the plugs after driving at a sustained speed for that jet.

[drddan]

The way I see it is that the ideal Air-to-Fuel ratio for a warmed up gasoline engine is about 14.7 parts air to 1 part of fuel. That is what you are varying with the jets and the choke. Altitude is a factor because the higher you go the less oxygen there is in a cup of air.

I believe the Festiva is around 13.1 and no more than 14.0 or something close to that.

Dang I just read about that and I cant remember exactly where I read that, but it was about a week ago.

I have been looking into A/F meters lately. It is the best way to tune and see what is going on with the tuning on a carb, over the entire RPM range.

A carb can run rich at a certain rpm range AND run lean at a different rpm range. The meter will tell you what jets need changed, for the different areas of the carb.

Changing jets can cure that.

[Bert]

I love Drddan's response to the question. The beauty and joy of carbs is you can change high and low speed jets to your heart's content. Sound, and ultimately power, of the engine and colour of the tailpipe and spark plugs all become visual and audible things you start dealing with in order to achieve the ideal combination and fine adjustment of jets.