Ford Muscle Forums : Ford Muscle Cars Tech Forum - Reply to Topic
Thread: Holley Carb Tuning with AEM A/F gauge Reply to Thread
Title:
Message:
Trackback:
Send Trackbacks to (Separate multiple URLs with spaces) :

Register Now



In order to be able to post messages on the Ford Muscle Forums : Ford Muscle Cars Tech Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in










  Additional Options
Miscellaneous Options

  Topic Review (Newest First)
04-29-2019 08:55 AM
65merccyclone
Re: Holley Carb Tuning with AEM A/F gauge

Quote:
Originally Posted by Rusty_S85 View Post
Nice im looking at their 306 short block for my build but I got some people telling me the engines aren't blue printed nor are they tested like they proclaim. But for me its the only one I was able to find that was reasonably priced with a decent warranty.

So far, I have found their customer support to be very good. Responsive, knowledgeable and willing to help. Since I bought my car with this engine installed, I didn't have the option to look at other suppliers. This engine was over $5K. I can't comment on what you have heard from others regarding testing etc. I hope you get the right engine, no matter what vendor you choose.
04-29-2019 08:51 AM
65merccyclone
Re: Holley Carb Tuning with AEM A/F gauge

Quote:
Originally Posted by DeepRoots View Post
Price point does matter, and I think in a large sense it is a selling point for fuel injection :P (we sell crappy carburetors, so you might as well buy our crappy fuel injection as it is marginally better).



The $299 special carbs that have come through here have been horrible in regards to quality control. Missdrilled holes, etc I've actually stopped accepting that work except for rare cases where I just like the person or I find their project interesting.

I regularly take a customers core of varying value and charge them $400 to completely restore, replate, blue print and test it.
I've never heard a negative comment regarding price, so obviously there are many who view the service as valuable. This wasn't meant to be a ego stroke or an advertisement, more that many people understand how critical these things are and are willing to pay for them.


Even with the care I try to attend to these carburetors, fuel pressure and ignition timing are still out of my control and I would wager are 99% of the issues that crop up, I've published guides for people, but it seems I have to reiterate the same things.


Drew

It sounds like you are providing value to the customer, which is always good. I didn't think I had a bad carb. I thought I had a tuning problem all along. Things changed after I couldn't adjust it using the AEM gauge. The kicker was the fast idle screw preventing the proper adjustment of the transfer slot. Keep up the good work.
04-28-2019 05:12 PM
Rusty_S85
Re: Holley Carb Tuning with AEM A/F gauge

Quote:
Originally Posted by DeepRoots View Post
Price point does matter, and I think in a large sense it is a selling point for fuel injection :P (we sell crappy carburetors, so you might as well buy our crappy fuel injection as it is marginally better).



The $299 special carbs that have come through here have been horrible in regards to quality control. Missdrilled holes, etc I've actually stopped accepting that work except for rare cases where I just like the person or I find their project interesting.

I regularly take a customers core of varying value and charge them $400 to completely restore, replate, blue print and test it.
I've never heard a negative comment regarding price, so obviously there are many who view the service as valuable. This wasn't meant to be a ego stroke or an advertisement, more that many people understand how critical these things are and are willing to pay for them.


Even with the care I try to attend to these carburetors, fuel pressure and ignition timing are still out of my control and I would wager are 99% of the issues that crop up, I've published guides for people, but it seems I have to reiterate the same things.


Drew
At work we've ran a regulator and dropped pressure down to 3.5-4.5 psi when the customer brings a vehicle in complaining about hot restarts on their carbed engines. seems reducing the pressure in these cases prevents the hot restart issue. I personally never had the issue on my carbs with hot restarts but there are people out there that do and the dropping of fuel pressure works.
04-28-2019 05:07 PM
Rusty_S85
Re: Holley Carb Tuning with AEM A/F gauge

Quote:
Originally Posted by 65merccyclone View Post
Yes. The car came with a BP 306 installed in it. Documentation says it makes 390 hp.
Nice im looking at their 306 short block for my build but I got some people telling me the engines aren't blue printed nor are they tested like they proclaim. But for me its the only one I was able to find that was reasonably priced with a decent warranty.
04-28-2019 05:00 PM
DeepRoots
Re: Holley Carb Tuning with AEM A/F gauge

Price point does matter, and I think in a large sense it is a selling point for fuel injection :P (we sell crappy carburetors, so you might as well buy our crappy fuel injection as it is marginally better).



The $299 special carbs that have come through here have been horrible in regards to quality control. Missdrilled holes, etc I've actually stopped accepting that work except for rare cases where I just like the person or I find their project interesting.

I regularly take a customers core of varying value and charge them $400 to completely restore, replate, blue print and test it.
I've never heard a negative comment regarding price, so obviously there are many who view the service as valuable. This wasn't meant to be a ego stroke or an advertisement, more that many people understand how critical these things are and are willing to pay for them.


Even with the care I try to attend to these carburetors, fuel pressure and ignition timing are still out of my control and I would wager are 99% of the issues that crop up, I've published guides for people, but it seems I have to reiterate the same things.


Drew
04-28-2019 04:40 PM
65merccyclone
Re: Holley Carb Tuning with AEM A/F gauge

Quote:
Originally Posted by DeepRoots View Post
Float level is often ignored but it's fairly critical.
To throw a wrench in the works, often with a mechanical pump what is good at idle might be a problem at WOT or cruise, etc.
I'm a fan of regulating at a low pressure for this reason. Another bonus to low pressure is you can have the float itself set high as it will not take a ton of bouyancy to seal the needle, this allows for more float drop at WOT. Seems counter intuitive, but running lower pressure can actually provide more fuel availability simply due to this....

With 550hp I don't seem to ever be lacking fuel at 4.5psi. Makes float settings more consistent and blowing past a needle less of an issue.


That said, Holley part quality is hit or miss these days. I can't trust anything, new out of the box no matter the brand. I have found a ton of needle/seats that were weak brand new.
This is why despite the trouble it is to do it, every carb I ship out gets tested here. Far easier to catch an issue in my shop than it is when it's 1,000 miles away on a customer's car.


Drew

that's interesting. I put a pressure gauge on my car but could only measure the output in the garage. It was a consistent 6 lbs.

Even carbs are part of the competitive retail market where price is king. There will always be pressure to meet a price point, meaning quality will suffer in some areas. I'd be interested to see what they use as an acceptable number of defective returns.

Now, you planted the seed to put a regulator on it to see how it runs at 4.5 psi. I agree with the float bowl comments.

It sounds like you have a good plan to ensure quality products are delivered to the customer. Good job on that. thanks for the information.
04-28-2019 03:19 PM
DeepRoots
Re: Holley Carb Tuning with AEM A/F gauge

Float level is often ignored but it's fairly critical.
To throw a wrench in the works, often with a mechanical pump what is good at idle might be a problem at WOT or cruise, etc.
I'm a fan of regulating at a low pressure for this reason. Another bonus to low pressure is you can have the float itself set high as it will not take a ton of bouyancy to seal the needle, this allows for more float drop at WOT. Seems counter intuitive, but running lower pressure can actually provide more fuel availability simply due to this....

With 550hp I don't seem to ever be lacking fuel at 4.5psi. Makes float settings more consistent and blowing past a needle less of an issue.


That said, Holley part quality is hit or miss these days. I can't trust anything, new out of the box no matter the brand. I have found a ton of needle/seats that were weak brand new.
This is why despite the trouble it is to do it, every carb I ship out gets tested here. Far easier to catch an issue in my shop than it is when it's 1,000 miles away on a customer's car.


Drew
04-28-2019 11:58 AM
65merccyclone
Re: Holley Carb Tuning with AEM A/F gauge

Quote:
Originally Posted by Rusty_S85 View Post
Not to get off topic but you mentioned Blueprint Engines, is that the engine you are running?

Yes. The car came with a BP 306 installed in it. Documentation says it makes 390 hp.
04-28-2019 10:32 AM
Rusty_S85
Re: Holley Carb Tuning with AEM A/F gauge

Quote:
Originally Posted by 65merccyclone View Post
I thought I would post an update. Blueprint Engines sent me a replacement carb. I got it on Tuesday, transferred my stuff from the old carb to it (secondary spring kit, blue accelerator cam and demon 66 jets). I looked at the carb before installing it and found the transfer slot was adjusted properly.

I started the engine and the high idle was way too high (2600 rpms) so I turned it down and changed the setting for the choke from the 8 slot to the 3 slot. (it's warm here so I don't need that much choke) I set the idle screws to 1/2 turn where it registered A/F of 14.3 - 14.7 at idle. This was a little too low so I opened them up 1/16. A/F at idle is 13.2 - 13.7 but at cruise it's 14.7 - 15. Vacuum went from 13.5 to 15. The accelerator pump spring is at 5/8 and moves when the throttle is cracked.Throttle response is crisp, the engine is running better than it has since I've owned it.

I don't know what is wrong with the carb I got with the car when I bought it but this one is much better.
Not to get off topic but you mentioned Blueprint Engines, is that the engine you are running?
04-25-2019 09:40 AM
65merccyclone
Re: Holley Carb Tuning with AEM A/F gauge

Quote:
Originally Posted by extech View Post
bet float level was off

It could be the floats. I had the car at a local hot rod shop last October. One of the things they did was set the float levels, along with tuning the carb.
04-24-2019 06:43 PM
extech
Re: Holley Carb Tuning with AEM A/F gauge

bet float level was off
04-24-2019 02:33 PM
65merccyclone
Re: Holley Carb Tuning with AEM A/F gauge

I thought I would post an update. Blueprint Engines sent me a replacement carb. I got it on Tuesday, transferred my stuff from the old carb to it (secondary spring kit, blue accelerator cam and demon 66 jets). I looked at the carb before installing it and found the transfer slot was adjusted properly.

I started the engine and the high idle was way too high (2600 rpms) so I turned it down and changed the setting for the choke from the 8 slot to the 3 slot. (it's warm here so I don't need that much choke) I set the idle screws to 1/2 turn where it registered A/F of 14.3 - 14.7 at idle. This was a little too low so I opened them up 1/16. A/F at idle is 13.2 - 13.7 but at cruise it's 14.7 - 15. Vacuum went from 13.5 to 15. The accelerator pump spring is at 5/8 and moves when the throttle is cracked.Throttle response is crisp, the engine is running better than it has since I've owned it.

I don't know what is wrong with the carb I got with the car when I bought it but this one is much better.
04-18-2019 08:32 PM
65merccyclone
Re: Holley Carb Tuning with AEM A/F gauge

Quote:
Originally Posted by DeepRoots View Post
All I work with are older 4160/4150 Holleys. Adjustments in my case are via set screws that I drill to different sizes.


Anyway, your accelerator pump setting is incorrect.
Here is thing I wrote last time:


https://www.fordmuscleforums.com/fal...ator-pump.html

I have heard that installing set screws and drilling them out is a good technique. I'm not quite that advanced yet.

You are correct regarding the accelerator pump spring. I couldn't really make a good measurement with the carb on the car but it seems to be less than 5/8 in length. I put the feeler gauge on it at the idle point not wide open throttle. I'll be pulling the carb off again so I'll check it on the bench.

Good write up on that other thread. Thanks for the comments.
04-18-2019 11:44 AM
DeepRoots
Re: Holley Carb Tuning with AEM A/F gauge

All I work with are older 4160/4150 Holleys. Adjustments in my case are via set screws that I drill to different sizes.


Anyway, your accelerator pump setting is incorrect.
Here is thing I wrote last time:


https://www.fordmuscleforums.com/fal...ator-pump.html
04-17-2019 05:38 PM
65merccyclone
Re: Holley Carb Tuning with AEM A/F gauge

Quote:
Originally Posted by DeepRoots View Post
A few thoughts:


-Wideband A/F meters are awesome. That said, don't get hung up on a "correct number" there isn't one. Some engines want to idle at 12.5, some want to idle at 14, whatever, just figure out what the engine wants and use the O2 as a reference point for that particular situation.
For instance, finding your cruise "lean limit" would be by jetting down until you encounter a slight surge at cruise. At that point you jet up until the surge is gone. Again, this leanest cruise may be at 14:1, it may be at 16.... there are more factors than I care to list, but the main ones have to do with camshaft duration, and ignition timing at that point. This will effect your overall WOT fuel flow obviously, and the appropriate thing to do is enlarge the PVCR to bring your total fuel back into the range you require.



-I was gonna say the choke screw was probably holding open the throttle, but you already figured that out. Happens all the time and is annoying.

Opening the secondary DOES add air, but if you hit the secondary transfer slot it will add a ton of fuel. The secondaries always bleed some fuel via the .024 hole below the secondary slot. 99% of the "overly rich" idle issues I encounter have to do with transfer slot settings. This is even more critical on multicarb setups.
I like to change out the Holley flat head secondary adjuster for a 10-32, 1/2inch long set screw. This makes minor changes with an allen wrench very easy.


You need to take this effort one step at a time. Order of operation is generally:
-timing curve
-idle settings
-cruise settings
-WOT settings
-Secondary WOT tuning

-fix whatever stumble via accelerator pump settings. Adjusting the idle speed even a small amount can create a stumble just by loosing preload on the pump, etc. This is why I put this last, hate to fix an issue and have to revisit it.


Good luck


Drew
I came close to just keeping it the way it was when it was getting 13.2 at idle and the cruise ratios were in the mid 14s. I read David Vizard's book and he mentions getting incredible fuel economy along with good power numbers so I decided to continue tinkering. I think my problem might be the carb itself. It's a 4160 and does not have the tuning options that other holley carbs offer. I might need to determine if buying a better carb is the right decision. At $4.00 + per gallon, increasing the fuel economy by 50% should make the change worth the financial cost.

The engine ran worse with the 65 main jets in it so I put those back in today. The little bit of hesitation is gone. The transition slots are not as open as they were before because I don't have the choke screw engaged as much. I thought I would try tuning it with the least amount of transition slot possible. (it's currently at square plus 1 turn of the curb idle screw so it's probably closed less than it was before) The odd thing is, it's running a little richer throughout the rpm range, more in the 'best power' range of 13-13.9 and 11-12.5 during acceleration.

I didn't know what the size or thread pitch of the secondary adjustment screw so I bought several sizes and all were wrong. I found a small bolt in my spares box that was the right thread size, pitch and length so I installed that.

I think the accelerator pump is set right. At the current idle speed, the lever can be rocked a little bit and has a .015 gap. It moves as soon as the throttle is moved.

The advice you have given is sound advice. Thank you
This thread has more than 15 replies. Click here to review the whole thread.

Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On

 
For the best viewing experience please update your browser to Google Chrome