Are jet sizes proportional to engine size?

StarDiero75

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Howdy guys,

So with my Weber 32/36 I've noticed once the car gets to operating temp, it seems to have a lot less power than when its warming up. So my guess is that my jet sizes are a little small.

So my question here is, if i know what the jet sizes are for the 2.8 Cologne V6, can i use that to calculate what my jet sizes should be for my 200 using proportions? Or since i have a SOC L4 5200, can i use that to find proportionally what it should be?

If so, does anyone know what the Cologne V6 Holley 5200 jet sizes are?

Thanks a lot,
Ryan
 
Which do U mean - mains? idle? or air? (I think this 1 has even more - a 4th?).

"...use that to calculate..."
2.8L = 170ci.
I'd find a 3.3L as its a 20% difference, no? (or sompin closer to 200 anyway). Get some model#s offa Mike's Carbs & cross for motor w/displacement closer to whaja got. I get the Webber & Holley mixed up but they're close enuff AND on a million vehicles.

I'd ck the choke's operation rather than the more difficult re-jet 1st. (To a lesser degree but also - the linkage, probably not there as it runs right at someX, but has been named as # one or two most often on list of 'tune problems' on these carbs).

I messed w/the mains ina '82 2 dor Toy. jeep (~250ci, i6). I believe they ended up near 58 - 62 but don't recall as the 'store' I went to sold a bag w/those 5 sizes (or so) jets init & we just kept tryin among them (progressively) AND this is 50ci more'n whaja got there. Also the guy had both boars hooked together in their linkage so we would never get it a good as we wanted (we saw smoke, smelled rich). He was satisfied & that's all that matters in these cases. Not in ur or mine, so sorry 2 take ur time (less it helps some).
 
chad":12i6omj1 said:
mains? idle? or air? (I think this 1 has even more - a 4th?).

"...use that to calculate..."
2.8L = 170ci I believe (Ur cologne V6 & my bronk oe motor).
I'd find a 3.3L as its a 20% difference, no? (or sompin closer to 200 anyway). Get some model#s offa Mike's Carbs & cross for motor w/displacement closer to whaja got. I get the Webber & Holley mixed up but they're close enuff'n on a million vehicles.

I'd ck the choke's operation rather than the more difficult re-jet 1st. (To a lesser degree but also the linkage, probably not there as it runs right at someX, but has been named as one or two in list of 'tune problems').

I messed w/the mains ina '82 2 dor Toy. jeep (~250ci, i6). I believe they ended up near 58 - 62 but don't recall as the 'store' I went to sold a bag w/those 5 sizes (or so) jets init & we just kept tryin among them (progressively) AND this is 50ci more'n whaja got there. Also the guy had both boars hooked together in their linkage so we would never get it a good as we wanted (we saw smoke, smelled rich). He was satisfied & that's all that matters in these cases. Not in ur or mine, so sorry 2 take ur time (less it helps some).
The choke operates fine, and the throttle response is great. My idle couldn't be smoother. I just feel that the car has a lot more giddy up when warming up than when its warmed up. I'm taking apart my 5200 as we speak and doing calculations. I actually think i have one for the Cologne not the SOHC. I'll report back my findings

And yes, they have idle jets, main jets, and an air corrector
 
So this is what i found from doing proportions.

I have my current numbers next to the what it supposedly should be.

My air correctors are very off which would explain why the car smells rich, and would explain my not amazing gas mileage (only about 18ish with a 2.8 rear).

I couldnt make out the primary Idle jet but i think it might be 50, which puts me at a 60 jet, which is what i originally had before I upped it.

The secondary main jet is supossedly one size off of what I have.

Would you all recommend I jump up my air correctors or is all this math not correct and jet sizes are not proportional to engine size?
 

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So the answer is both yes and no, jet sizes from manufacturers are based off CFM requirements which is technically limited via engine size but you can have 2 of the same engine and the VE (volumetric efficiency) is much higher in one over the other meaning it can at any given RPM consume more CFM of air. I just had 2 brand new holley 4 barrels in my hand and decided to check the jet sizes and the 465 cfm comes with 57 jets and the 600 cfm comes with 66 jets. So when it comes to engine manufacturers it will be close to the same the jets that will come in the car will be based off what they know that engine need CFM wise in stock form to achieve the performance / fuel efficiency they want. Could it be tweaked to better fit your needs sure but they try to be at the middle ground.

When your in the ball park of what your engine wants to see fuel wise its super hard to get any sort of indication via spark plug analysis and this is where having a AFR gauge is necessary. TL;DR Choosing jet size purely off engine size with get you close but fine tuning will likely still be necessary
 
... So with my Weber 32/36 I've noticed once the car gets to operating temp, it seems to have a lot less power than when its warming up. So my guess is that my jet sizes are a little small. So my question here is, if i know what the jet sizes are for the 2.8 Cologne V6, can i use that to calculate what my jet sizes should be for my 200 using proportions? Or since i have a SOC L4 5200, can i use that to find proportionally what it should be?
... if so, does anyone know what the Cologne V6 Holley 5200 jet sizes are?
Ryan


from @ 2005:


I posted previously that I obtained a brand new - old stock 5200 spec'ed for use by a 170CID (Capri 2.8 V6). I received it today and opened it up to see what what size jets it has.

Primary / Secondary
Idle Jets - 65 / 50

Air Bleeds - 190 / 180

Mains - 171 / 477 (Yes that's right 477) I guaged the 477 to @ .071" .

The '477' jet appears to be the on the largest end of the scale available and physically is much larger than any I've seen. There is some confusion (on my part) because there was a change from 'flow rate' to diameter in mm. and can be mixed. Can anyone convert .071" to mm?.


-----------

from @2010 post:
I run the Holley / Weber version of the 32/36 progressive on a big log head through $14 - 2X1 adapter. The 5200 was offered by many manufacturers in many cars and many versions like the Weber... (@185-250CFM) , ( '63 Falcon waggin / 71-170 / T5-3.50 rear)

A clean "rebuilt" 5200 of questionable origin ran with typical off-idle bog. No difference with bigger or smaller jets. Found an Ebay carb - dirty/as used Capri 2.8 liter (170cid) spec 5200 and 170 ran great as-is dirty and all. I swapped in the jets to clean ‘bog’ carb and still ran like crap, I then put ‘bog’-carb jets in 2.8 spec 5200 and it ran with no bog at all.

(Twelve years in 2018) … Five years later 170 still runs great... Smooth consistent idle, economical (primary Bbl) light cruise performance and decent interstate ramp 2Bbl max-CFM performance.
> my 170 has stock bottom end/cam but big valve head work running @ 10:1 CR with decent mileage (on 93 octane) .. > Direct mount mod is a great performance option, but for MPG/daily driver, probably a simple 2X1 adapter is viable option .


-----------

HAVE FUN
 
powerband":91yqo7wz said:
... So with my Weber 32/36 I've noticed once the car gets to operating temp, it seems to have a lot less power than when its warming up. So my guess is that my jet sizes are a little small. So my question here is, if i know what the jet sizes are for the 2.8 Cologne V6, can i use that to calculate what my jet sizes should be for my 200 using proportions? Or since i have a SOC L4 5200, can i use that to find proportionally what it should be?
... if so, does anyone know what the Cologne V6 Holley 5200 jet sizes are?
Ryan


from @ 2005:


I posted previously that I obtained a brand new - old stock 5200 spec'ed for use by a 170CID (Capri 2.8 V6). I received it today and opened it up to see what what size jets it has.

Primary / Secondary
Idle Jets - 65 / 50

Air Bleeds - 190 / 180

Mains - 171 / 477 (Yes that's right 477) I guaged the 477 to @ .071" .

The '477' jet appears to be the on the largest end of the scale available and physically is much larger than any I've seen. There is some confusion (on my part) because there was a change from 'flow rate' to diameter in mm. and can be mixed. Can anyone convert .071" to mm?.


-----------

from @2010 post:
I run the Holley / Weber version of the 32/36 progressive on a big log head through $14 - 2X1 adapter. The 5200 was offered by many manufacturers in many cars and many versions like the Weber... (@185-250CFM) , ( '63 Falcon waggin / 71-170 / T5-3.50 rear)

A clean "rebuilt" 5200 of questionable origin ran with typical off-idle bog. No difference with bigger or smaller jets. Found an Ebay carb - dirty/as used Capri 2.8 liter (170cid) spec 5200 and 170 ran great as-is dirty and all. I swapped in the jets to clean ‘bog’ carb and still ran like crap, I then put ‘bog’-carb jets in 2.8 spec 5200 and it ran with no bog at all.

(Twelve years in 2018) … Five years later 170 still runs great... Smooth consistent idle, economical (primary Bbl) light cruise performance and decent interstate ramp 2Bbl max-CFM performance.
> my 170 has stock bottom end/cam but big valve head work running @ 10:1 CR with decent mileage (on 93 octane) .. > Direct mount mod is a great performance option, but for MPG/daily driver, probably a simple 2X1 adapter is viable option .


-----------

HAVE FUN
So you're already starting off with larger air correctors than im running, 180/160. So I'm gonna start with a 200/190 and see what it does then. That's what i was trying to figure out. Otherwise our numbers aren't that far off.

And your conversion from. 071" to mm is 1.8034

That's interesting the rebuilt 5200 was garbage while the dirty one ran great. I guess that goes to show not all carbs are created equal.

You're running much higher conpression than I so my guess is that the jet sizes will be closer. Im just trying to get into a range here, b/c those air correctors I have must make the engine run rich. A smaller air corrector= richer mix, and a larger corrector=leaner mix. So this could indeed by my gassy smell problem.
 
Just orderd the jet sizes Powerband has in his Falcon. I had to get the much larger main jets and 1 much larger air corrector.

Will post how the car feels when i get them.
 
Get your A/F ratio checked with a wideband tester. Eliminates the guesswork.
 
wsa111":2xg51kje said:
Get your A/F ratio checked with a wideband tester. Eliminates the guesswork.
I thought about getting one of these but a guy who works on nothing but old stuff told me its kind of a waste of money for what I'm trying to do. Thats why i didn't buy one when i was asking about them on here. He said checking the plugs will get me close enough for just a daily driver.
 
StarDiero75":11htxr5e said:
wsa111":11htxr5e said:
Get your A/F ratio checked with a wideband tester. Eliminates the guesswork.
I thought about getting one of these but a guy who works on nothing but old stuff told me its kind of a waste of money for what I'm trying to do. Thats why i didn't buy one when i was asking about them on here. He said checking the plugs will get me close enough for just a daily driver.
He is wrong, get the wideband.
If the A/F ratios are correct, then the spark plugs are either too hot or too cold, or spot on.
 
wsa111":32suavz7 said:
StarDiero75":32suavz7 said:
wsa111":32suavz7 said:
Get your A/F ratio checked with a wideband tester. Eliminates the guesswork.
I thought about getting one of these but a guy who works on nothing but old stuff told me its kind of a waste of money for what I'm trying to do. Thats why i didn't buy one when i was asking about them on here. He said checking the plugs will get me close enough for just a daily driver.
He is wrong, get the wideband.
If the A/F ratios are correct, then the spark plugs are either too hot or too cold, or spot on.

Bill is right, that gentleman really doesnt understand how they work cause A/F gauge will give you an actual number to test against vs the ball park estimate reading plugs will get you. Plus that is up to some mild interpretation, an AFR gauge is by far the way to correctly tune any car carbureted or fuel injected.

My guess he doesnt like any of that new fangled fuel injection either and probably thinks that they should have never put computers in cars. :roll:
 
Just orderd the jet sizes Powerband has in his Falcon. I had to get the much larger main jets and 1 much larger air corrector. Will post how the car feels when i get them.

I'm very interested in your results after installing same jets. I had just about gave up on the typical 5200 'bog' when the Cologne V6 version turned up and it's been working flawlessly over 10 years.

..


I wouldn't drive the Forced Induction 250 project out the garage without a working AFR gauge as rapid destruction can result from seeming minor mis-tuning. AFR gauges in my NA cars would be nice but are not cheap and believe they aren't quite as necessary for most builds.




Get your A/F ratio checked with a wideband tester. Eliminates the guesswork.

Is wideband AFR testing available other than with a sensor installed ? .


have fun
 
i ma going with bill on this one, get the wide band O2 sensor and use that to tune your motor. reading the plugs was fine in the old days for experienced tuners, but these days with the changes in the fuel being used, unless you know what you are doing in reading the plugs, and even experienced guys get it wrong, go with the best tools available.

i used to tune alcohol burning race engines by reading the plugs many years ago, as well as tuning gas engines reading the plugs, but that was back in the late 70s and early 80s when O2 sensors were big machines attached to oscilloscopes, as part of the exhaust gas analyzer and cost upwards of $10,000 :shock: :shock: these days O2 sensors are small hand held machines that are fairly cheap and easy to use.
 
Alright you all have convinced me I should get one. Between my dad and I we have 3 carbed cars, 65 Ranchero 200, 69 F250 390, 61 Lark 170 OHV, so this would be a good investment. Plus i have a few engines on stands i want to start running and tuning to perfection.

I would like one particularly that doesnt get installed but gets put in the tail pipe or just have a bung installed and hook up only during tuning.

I should be getting the jets on Thursday so I'll post letting you all know how it feels. I should feel a lift in my seat going from a 155 to 170 main jet primary's and 160 to 180 main jet secondary's. And larger air correctors. It'll be interesting.
 
StarDiero75":qsv4015p said:
Alright you all have convinced me I should get one. Between my dad and I we have 3 carbed cars, 65 Ranchero 200, 69 F250 390, 61 Lark 170 OHV, so this would be a good investment. Plus i have a few engines on stands i want to start running and tuning to perfection.

I would like one particularly that doesnt get installed but gets put in the tail pipe or just have a bung installed and hook up only during tuning.

I should be getting the jets on Thursday so I'll post letting you all know how it feels. I should feel a lift in my seat going from a 155 to 170 main jet primary's and 160 to 180 main jet secondary's. And larger air correctors. It'll be interesting.
You can't tune the engines on stands
First try to get a smooth idle with the idle screws close to 13-13.5.
Second you cruise @ 60 mph area & achieve an A/F reading of close to 14.7. This would be the main jet size.
Third cruise around the neighborhood 15-20 mph & shoot for an A/F 13.5-14.25 area. If too rich you need a smaller idle jet.
Fourth take it out & start from a stop all the way up to 80-100 mph if you can do it safely @ WOT & go for an A/F 12.5-13.1.
This is controlled by the jet or orifice under the power valve on a Holley or Autolite. The small end of the metering rod if it has one.
If you are doing a 4 barrel block the secondaries so they wont open & do all of the above, except WOT limit at 4000 rpms.
Then let the secondaries open & adjust the secondary jet @ WOT 80-100 mph & again go for 12.5-13.1
Even running a K & N air filter it can richen the mixture .2-.3 @ WOT.
I installed a brand new AC Delco on my engine & even at idle the A/F richened by .5
What i am saying the K & N is the only AF i know that has the least restriction.
Be advised that a lean mixture & high air temperature can promote detonation.
A rich mixture can tolerate more advance & loves cold weather.
 
wsa111":fy8vl5fv said:
StarDiero75":fy8vl5fv said:
Alright you all have convinced me I should get one. Between my dad and I we have 3 carbed cars, 65 Ranchero 200, 69 F250 390, 61 Lark 170 OHV, so this would be a good investment. Plus i have a few engines on stands i want to start running and tuning to perfection.

I would like one particularly that doesnt get installed but gets put in the tail pipe or just have a bung installed and hook up only during tuning.

I should be getting the jets on Thursday so I'll post letting you all know how it feels. I should feel a lift in my seat going from a 155 to 170 main jet primary's and 160 to 180 main jet secondary's. And larger air correctors. It'll be interesting.
You can't tune the engines on stands
First try to get a smooth idle with the idle screws close to 13-13.5.
Second you cruise @ 60 mph area & achieve an A/F reading of close to 14.7. This would be the main jet size.
Third cruise around the neighborhood 15-20 mph & shoot for an A/F 13.5-14.25 area. If too rich you need a smaller idle jet.
Fourth take it out & start from a stop all the way up to 80-100 mph if you can do it safely @ WOT & go for an A/F 12.5-13.1.
This is controlled by the jet or orifice under the power valve on a Holley or Autolite. The small end of the metering rod if it has one.
If you are doing a 4 barrel block the secondaries so they wont open & do all of the above, except WOT limit at 4000 rpms.
Then let the secondaries open & adjust the secondary jet @ WOT 80-100 mph & again go for 12.5-13.1
Even running a K & N air filter it can richen the mixture .2-.3 @ WOT.
I installed a brand new AC Delco on my engine & even at idle the A/F richened by .5
What i am saying the K & N is the only AF i know that has the least restriction.
Be advised that a lean mixture & high air temperature can promote detonation.
A rich mixture can tolerate more advance & loves cold weather.
It needs load, i didn't think of that when i said it.

Wow thats great info man. I'll make sure to do that when i can afford an A/F gauge. Thats really informational. Thanks a lot!
 
The jets came a day early, yay!! There is definitely more low end power and perty much all the flat spots are gone. No hesitation and it idles slightly smoother.

My only issue is that i still cant run 12° BTDC without pinging. I upped the timing from 10 to 12 and it still pings with larger jets. I got on a hill and floored it, my pedal also doesn't open the carb to WOT, so if it had it woulda pinged a lot more. I'll be installing a cable pedal soon. The secondary opens about half way.

My rear end is a 2.8 and with the stick thats probably too much. I'm half debating on putting a C4 that i have in it to compensate. I want a T5 but looking at the cost and what I gotta do, plus finding one near me, it all just seems too much. Would you all recommend swapping out the 3.03 to the C4? Its a V8 C4 so i need to get the torque converter, bell, 3 bolt starter, and a tranny cooler. Can i use an external one like from NAPA or do i need to get the Auto radiator?

Thanks guys,
Ryan
 
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