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Discussion Starter · #1 ·
I was looking at some post from the past had an idea. Maybe we should make a thread with jet sizes and motor combo. Could be used as a quick reffrence of some sort, or even some starter jets used to begin fine tuning.

(example)
Motor Combo:
Jet Sizes:
Misc. stuff like how it ran before and after.

It's just a thought that might save some people time :rolleyes:
 

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101st Airborne 1/327 Inf
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Carb/Jets Engine Type Reference Guide

I think this would be a great reference tool for the users of this site. The questions of what jets to install or use had been asked so many times. But don't forget to indicate the carb type too. Great suggestion Betta Carotene!! :)
 

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boomerang opeler
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Betta Carotene said:
I was looking at some post from the past had an idea. Maybe we should make a thread with jet sizes and motor combo. Could be used as a quick reffrence of some sort, or even some starter jets used to begin fine tuning.

(example)
Motor Combo:
Jet Sizes:
Misc. stuff like how it ran before and after.

It's just a thought that might save some people time :rolleyes:
well i must agree it would be easyer for folks
when are you going to troll through all the archives to compile it :D :D
 

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It's a good idea, and years ago I had my own database, but be warned it needs to be very precisely documented. At a minimum, you need the following info:

>engine size including overbore
>compression ratio
>head type and valve sizes
>if porting work has been done
>cam specs, especially lobe separation angle
>if cam has been advanced or retarded (very important!)
>ignition timing specs, including modified curves
>intake type, porting work done?
>carburetor type, (venturi size and air horn length if side drafts)
>manifold or header type, diameter, length
>exhaust pipe diameter, even muffler brand/type
>altitude the car is normally run at
>if your local fuel is oxygenated or not, and has methanol in it

If any one of these factors is different, it will alter the tuning outcome and can change the jetting. You can see why there is no 'easy' jetting guidelines to be followed.

Bob
 

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The problem you would get into is all the variables like altitude, electronic ignition, cams, compression, motor new or tired. Then of course the driving style of the owner, weekend warrior or daily driver.
 

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101st Airborne 1/327 Inf
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1,322 Posts
I would yield to the fact that most of you guys are much deeper in the Opel and Weber than I, but isn't there a base or ground zero we can advise from for the carb type with jets for the base engine. Tweaking can be done by the individual. The problem for us Opel owners is the Weber may not be set up with our modified engines (ported intake) and such in mind???
 

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boomerang opeler
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MICAH1 said:
I would yield to the fact that most of you guys are much deeper in the Opel and Weber than I, but isn't there a base or ground zero we can advise from for the carb type with jets for the base engine. Tweaking can be done by the individual. The problem for us Opel owners is the Weber may not be set up with our modified engines (ported intake) and such in mind???
there is no base line because of so many things in the states not only the gas that seems to differ from state to state but things like altitude (bring them all over here we only drive between sea level and 1600 feet or so )
there is only 1 way to jet a car right (any car) it has to be done on a rolling road, so there is no base line, as bob says every time you change 1 bit in the system it changes settings through the rest of it and the cost of an hour or so on a rolling road that knows webers will do it the quickest and right for any hight or state of tuning
there are a boat load of threads about how folks have had success with this set up or that but they relate to the engine they are on
the hard part in the states is to find a tuning house that knows the weber and has a stock of jets and tubes for them
 

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Discussion Starter · #8 ·
Does anyone want to start? Maybe we could kick it off with a stock hi/low comp weber jetting.
 

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Discussion Starter · #9 ·
I got these from an old jetting thread. Hope you dont mind dean

Jets:primary (32): Main 135; Air 165; Idle 50
Secondary (36): Main 140; Air 160; Idle 55

Engine: stock hi comp 1.9, weber 32/36, ported intake, sprint and 2" exhaust
 

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Discussion Starter · #10 ·
is there any way to measure jets? Cant think of any way to do it.
 

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boomerang opeler
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size is stamped on jets normally , i would not use anything to stick in a jet hole to gauge it as any thing soft enough to not damage the jets would run the risk of snapping off in the jet
 

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How about stock engines

Don't forget that many people (probably most) have completely stock engines with just the carb. changed to a Weber. Isn't that the place to start this?

Most of the variables in the first list would be stock and therefore an unchanged baseline. It's important to start from an unchanged baseline like this because A) it applies to most people's cars and B) It doesn't make things unnecessarily and deceptively complex by starting with variables.

This would be one setup, the primary one and the jetting could be A) that which works and, B) that which tweaks the performance a bit for a stock 1.9 Liter engine.

Starting with variables is a problem because, as has been stated, changing one thing can affect and alter several other things. This leads only to confusion.

I see that Micah1 stated this first in fewer words. He's right. It's a good and primary point.
 

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1970-GT
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OK, I read all the posts! Now I know enough to be dangerous:confused:
I pulled my 38 DGES apart and have (185 air jets), ( 142 fuel jets) and (F50 Emulsion tubes).
I'm going to order a rebuild kit and a few jets and F66 Emulsion tubes.
Before I waste too much $ and time, what direction I should go?
I live at sea level.
2000cc motor, 9:1 compression, big valve head, solid lifter sport cam, Intake modified, MSD with Pertronics, Distributor 8 degree at idle 35 degree max advance, header & 2" exhaust. This is kind of the "normal Bob" mild modifications alot of Opel's have!
Would appreciate any advice.
Thanks Lyle
 

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Tru-Craft said:
I pulled my 38 DGES apart and have (185 air jets), ( 142 fuel jets) and (F50 Emulsion tubes).
I'm going to order a rebuild kit and a few jets and F66 Emulsion tubes.
Before I waste too much $ and time, what direction I should go?
I live at sea level.
How do the plugs look like right now with the 142 mains? At least with this knowledge you can get a range of jets in the correct direction.
 

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1970-GT
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Bob, I bought the 38 carb used and it has not been on the car!
Maybe this info will let you make a good guess on jets!
The 38 DGES has 142/185 = 77%.
My 32-36 has these jets:
Primary 140/160 = 88%
Secondary 140/170 = 82%
The 32-36 carb on my GT now runs slightly rich, but pulls strong and no bogging.
Should I use this percentage 82-88 as a jet size starting point? Does it matter if I use a smaller main jet or larger air jet?

You also recommended the F66 tubes, smaller inlet needle, moving the fuel inlet to the other side, carb spacer....anything else?
Want to bolt on something close and tune from there!
Thanks Lyle
 

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Tru-Craft said:
The 32-36 carb on my GT now runs slightly rich, but pulls strong and no bogging.
Should I use this percentage 82-88 as a jet size starting point? Does it matter if I use a smaller main jet or larger air jet?
Percentage doesn't really apply since the 38's throttle plate-to-venturi ratio is different than a 32/36's. So no fair comparing the two directly! Best bet is to bolt it on and try it 'as is' for starters. There are too many variables to consider trying to 'prejet'. Make sure the ignition timing is 'correct' otherwise you'll end up starting over with the jetting. My best guess is you'll end up somewhere between 140-155 on the mains.
You also recommended the F66 tubes, smaller inlet needle, moving the fuel inlet to the other side, carb spacer....anything else?
Want to bolt on something close and tune from there!
Thanks Lyle
Definitely swap the emulsion tubes, they really help the idle-to-main transitiion. The needle is not as critical, but I'd suggest the fuel inlet swap if only to reduce the chances of fuel boiling (it gets close to the thermostat housing and exhaust heat otherwise).
 

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1970-GT
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Yep, I tend to look at things as linear, your right too many variables with air flow! I will rebuild it with the F66 tubes and try it!
I want to do a few acceleration runs with the 32-36 carb for a base line. Then the 38DGAS when tuned properly. Just for the heck of it!
I was thinking of doing a 2nd-3rd gear rolling test. Say 25mph to 80mph?
Everyone says the 38Dges is faster!
 

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Tru-Craft said:
I was thinking of doing a 2nd-3rd gear rolling test. Say 25mph to 80mph?
Everyone says the 38Dges is faster!
If the engine can use the added airflow, it's definitely faster. Try some 4th-gear acceleration tests, that is really where it shines. Say, 50-80 mph. This way you take the shifting variable out of the testing.

BTW, I got the 'blitz' air filter cover today. It is a thing of beauty! I am going to send you money for another one, if you are still making more. I found a perfect fitment, it fits my 3" tall sidedraft air filters like a charm. So with twin Weber 45's on the rally car engine, this will look sweet. Powdercoated yellow with the raised portion polished.

Bob
 

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1970-GT
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will do a couple 4th gear runs!
Glad you like the cover!
Your the only one that has one! Let the folks know you like it (in the cover thread), they respect your opinion!
Thanks Lyle
 
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