Holley 4150 rich at WOT, what jet sizes?
10-05-2015, 10:02 PM
#61
Update for those following the over rich condition at WOT as described in my OP. I replaced the secondary spring from natural color to the next lightest, purple, and I can tell that my secondaries are now opening more than before. The engine grunt is louder and more pronounced than before. I still have yet to get my WB02 sensor hooked up again to check the AFR. Hopefully this week sometime, it's been really busy.
10-07-2015, 12:26 PM
#62
Update. After replacement of the diaphragm and now running 69-68 jets and the yellow spring the AFR for WOT in now well above the 10-11 range.
With the secondaries not working range was 10.9-11.2 now the range is 13.1 - 13.7.
The test was using 2nd starting @ 2000 RPM - 5000 RPM
I first get a little leam then drops to ~ 11.8 for about 1/2 sec then climbs to 13.7 you can see when the secondaries open as the AFR climbs from 12.3 to 13.7 steady @ ~ 13.2 around 3000 RPM.
So it was confirmed my problem with low AFR (Rich) for WOT and changing secondary jets had no effect in AFR was due to secondaries not opening due to failed diaphragm.
With the secondaries not working range was 10.9-11.2 now the range is 13.1 - 13.7.
The test was using 2nd starting @ 2000 RPM - 5000 RPM
I first get a little leam then drops to ~ 11.8 for about 1/2 sec then climbs to 13.7 you can see when the secondaries open as the AFR climbs from 12.3 to 13.7 steady @ ~ 13.2 around 3000 RPM.
So it was confirmed my problem with low AFR (Rich) for WOT and changing secondary jets had no effect in AFR was due to secondaries not opening due to failed diaphragm.
Interesting. I went out for a ride yesterday evening before I saw this update and recorded vacuum & AFR at WOT. Here is a video:
https://vimeo.com/141678802
I checked my secondary diaphragm - it wasn't torn or anything. Made sure to install back without distortion. Maybe I should try the yellow spring?
Pop Chevy - How would you adjust the air bleeds if they are too small?
cagotzmann - Can you post that video with the GoPro?
Last edited by Jartanyon; 10-07-2015 at 12:33 PM.
10-07-2015, 11:54 PM
#63
From the video you loaded I don't think you are on WOT long enough for the AFR to average out , and I would guess at that RPM there is not enough air flow to open the secondaries very much. You would need a very light spring to get much action.
Best is to test using 2nd and 3rd through the RPM range. 1st is just to short of a run to see where things settle.
My video is RPM past 5000 running from 1st thur 4th using the yellow spring. The first part is with the torn diaphragm, the 2nd run is after the repair.
check out the holley spring specs
http://documents.holley.com/199r8219-2rev.pdf
none of the springs will open the secondaries full ~ 4300 RPM
Best is to test using 2nd and 3rd through the RPM range. 1st is just to short of a run to see where things settle.
My video is RPM past 5000 running from 1st thur 4th using the yellow spring. The first part is with the torn diaphragm, the 2nd run is after the repair.
check out the holley spring specs
http://documents.holley.com/199r8219-2rev.pdf
none of the springs will open the secondaries full ~ 4300 RPM
Last edited by cagotzmann; 10-08-2015 at 12:00 AM.
10-08-2015, 10:26 PM
#64
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Cool video. It's amazing what we can do these days with simple technology!!
JIM
JIM
10-12-2015, 10:53 PM
#65
Burning Brakes
Update for those following the over rich condition at WOT as described in my OP. I replaced the secondary spring from natural color to the next lightest, purple, and I can tell that my secondaries are now opening more than before. The engine grunt is louder and more pronounced than before. I still have yet to get my WB02 sensor hooked up again to check the AFR. Hopefully this week sometime, it's been really busy.
Matt
02-02-2016, 08:46 AM
#66
Melting Slicks
Thread Starter
Sorry for the delay in response!
My engine hesitation is cured. I performed a few different things at one time, so it is difficult to know what cured the issue. Here is what I did right before the WOT hesitation went away:
1.) Installed the correct air cleaner assembly and filter. It had a short air cleaner assembly with a short filter on it, the LT1 air cleaner assembly is much bigger and taller.
2.) Installed a Pertronix Ignitor in the distributor.
3.) Installed the purple secondary spring in the carb.
I wish I knew what change fixed the issue. Regardless, I feel as if each thing I did improved how the engine ran. The carb definitely needed to be refreshed, the ignition system was over-due for a tune up.
My wideband reading is close to stoich 14:1 +/- .5 while cruising, around 12:1 +/- .5 while accelerating and 10.5:1 +/- .5 under heavy acceleration. It no longer dips below 10:1.
Overall I am pleased with how it runs. The factory Holley is a 780cfm vs the 750cfm I have on it now, they ran rich from the get-go.
I hope this thread helps anyone who has a similar issue. Please feel free to contact me if I can offer any suggestions!
My engine hesitation is cured. I performed a few different things at one time, so it is difficult to know what cured the issue. Here is what I did right before the WOT hesitation went away:
1.) Installed the correct air cleaner assembly and filter. It had a short air cleaner assembly with a short filter on it, the LT1 air cleaner assembly is much bigger and taller.
2.) Installed a Pertronix Ignitor in the distributor.
3.) Installed the purple secondary spring in the carb.
I wish I knew what change fixed the issue. Regardless, I feel as if each thing I did improved how the engine ran. The carb definitely needed to be refreshed, the ignition system was over-due for a tune up.
My wideband reading is close to stoich 14:1 +/- .5 while cruising, around 12:1 +/- .5 while accelerating and 10.5:1 +/- .5 under heavy acceleration. It no longer dips below 10:1.
Overall I am pleased with how it runs. The factory Holley is a 780cfm vs the 750cfm I have on it now, they ran rich from the get-go.
I hope this thread helps anyone who has a similar issue. Please feel free to contact me if I can offer any suggestions!
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jim-81 (02-21-2022)
02-02-2016, 10:16 AM
#67
Safety Car
Glad you got it to run better. your WOT seams to be about what it was when you started I am curious why you did not get her into the 12.5 to 13.2 range at WOT .
02-02-2016, 12:23 PM
#68
Melting Slicks
Thread Starter
I don't believe that I can easily achieve the ideal WOT AFR without drilling/tapping the air bleeds and PVCR's. Because the jet size changes made very little impact on AFR's, and the settings and operation of the carb are correct, it is a good sign that the carb size and air bleeds are too big to achieve the optimum AFR.
The engine is running fantastic, excellent power, excellent driveability, and smooth transitions between power modes. If it ain't broke don't fix it! If I put forth any more effort it will likely be to find the correct dated 780cfm Holley and install/tune that.
02-02-2016, 01:31 PM
#69
Safety Car
As far as what the factory did that extra 30 cfm of air would lean you out more then the 750 you have now which would possibly make it 12.5 .. If your happy that matters a lot more all I was doing is pointing out what I observed by reading through your topic.
Lean is mean . Makes better economy and more power , To get it balanced is a job but it is also fun if your into tinkering ..
Lean is mean . Makes better economy and more power , To get it balanced is a job but it is also fun if your into tinkering ..
02-02-2016, 03:28 PM
#70
Team Owner
If jetting doesn't really change the secondary AFR. You have several factors other than air bleeds.
Air flow through the booster adds the fuel. Straight leg holley booster have always been the worst. I'm also for totally chokeless carbs, but anyway the problem could be that the choke flapper is impeding direct air flow to the booster.
I'd wire it vertical and retest first. Then I would look into installing annual flow boosters. Which # 4 on these charts. I have something modded to like #3 in my 830 demon
Air flow through the booster adds the fuel. Straight leg holley booster have always been the worst. I'm also for totally chokeless carbs, but anyway the problem could be that the choke flapper is impeding direct air flow to the booster.
I'd wire it vertical and retest first. Then I would look into installing annual flow boosters. Which # 4 on these charts. I have something modded to like #3 in my 830 demon
02-04-2016, 08:21 AM
#71
Melting Slicks
Thread Starter
As far as what the factory did that extra 30 cfm of air would lean you out more then the 750 you have now which would possibly make it 12.5 .. If your happy that matters a lot more all I was doing is pointing out what I observed by reading through your topic.
Lean is mean . Makes better economy and more power , To get it balanced is a job but it is also fun if your into tinkering ..
Lean is mean . Makes better economy and more power , To get it balanced is a job but it is also fun if your into tinkering ..
02-04-2016, 08:46 AM
#72
Safety Car
That is what makes forums like this cool .. We can all share what we know or think and figure crap out ..
02-04-2016, 07:13 PM
#73
Race Director
02-04-2016, 08:38 PM
#74
Safety Car
02-06-2016, 10:14 AM
#75
Melting Slicks
Member Since: May 2002
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If the rear PV's are plugged then keep dropping the jet size until you get where you want to be.
It can take up to 10 jet sizes to make a full point change in AFR
The type of booster and the size of the high speed air bleed are critical in determining the required jet size, its not a one size fits all combo situation.
Neal
Neal
It can take up to 10 jet sizes to make a full point change in AFR
The type of booster and the size of the high speed air bleed are critical in determining the required jet size, its not a one size fits all combo situation.
Neal
Neal
02-08-2016, 09:27 AM
#76
Melting Slicks
Thread Starter
If the rear PV's are plugged then keep dropping the jet size until you get where you want to be.
It can take up to 10 jet sizes to make a full point change in AFR
The type of booster and the size of the high speed air bleed are critical in determining the required jet size, its not a one size fits all combo situation.
Neal
Neal
It can take up to 10 jet sizes to make a full point change in AFR
The type of booster and the size of the high speed air bleed are critical in determining the required jet size, its not a one size fits all combo situation.
Neal
Neal
This is what I learned through this process. The air bleeds and power valve channel restrictors also play a role in how much fuel gets through the jets. It's not just the jets. Larger air bleeds = less fuel. QFT carbs (Holley clone), have interchangeable air bleeds. If I were to purchase a carb, I would highly consider a QFT so that I can really dial in the AFR's.
Last edited by n8dogg; 02-08-2016 at 11:14 AM.
02-08-2016, 11:03 AM
#77
Race Director
This is what I learned through this process. The air bleeds and power valve channel restrictors also play a role in how much fuel gets through the jets. It's not just the jets. Larger air bleeds = more fuel. QFT carbs (Holley clone), have interchangeable air bleeds. If I were to purchase a carb, I would highly consider a QFT so that I can really dial in the AFR's.Almost all the newer Holley, QF, AED, carbs have adjustable everything!
02-08-2016, 11:13 AM
#78
Melting Slicks
Thread Starter
You have it backwards. Larger air bleeds mean more air introduced into the circuit, therefore less fuel. In other words, if you enlarge the idle air bleeds, it will lean the idle. Same with the high speed.
Almost all the newer Holley, QF, AED, carbs have adjustable everything!
Almost all the newer Holley, QF, AED, carbs have adjustable everything!
02-08-2016, 01:44 PM
#79
Race Director
If you want some additional carb info, there is a lot of reading in the engine section of Speedtalk and also tech section on Yellowbullet. Search for posts by jmarkaudio and yeti.
If you want to read some interesting general threads, try the Advanced Engine Tech section on Speedtalk. There are some serious big brains in that place.
