Learning Holley Tuning 101

[STINEY]

So my buddy Brian with the Camaro calls up and we start discussing why the changes he made to his ride resulted in actually going slower.

Lots of advice from lots of people, and he is trying to sort out the conflicting and varied opinions. Change jets, add timing, read plugs, etc, with no specifics other than "that worked for me" kind of stuff.

He knows I like to science stuff out, and make changes methodically and slowly. And I do a lot of tuning on Weber 40-44-48 IDA carbs, with fairly good results.

I readily admit I know next to nothing about Holleys, other than basic carb theory that crosses over.

And I mention something along the lines of "why don't you weld a bung in your exhaust so we can stick my LC-1 on and see what is REALLY going on?"

I don't trust reading plugs (other than with a Loupe to check for detonation) especially with todays gas. Just too vague.

So he drops by with said bung installed, I shove the sandrail to the storage bay of the barn, load up the CJ7 drivetrain on the trailer, and we go to work.



Install went well on the LC-1. Had to do the free-air sensor calibration twice as that big weather-pack style connection was not plugged in all the way due to a bent connector, but otherwise things were good.

And showed a reading of 10-11 throughout the whole range, idle all the way to WOT under load. Way way rich.........and this was with plugs that showed lean. Yeah, I really don't do the "read plugs" thing.

His carb was pretty cool to start learning on. Neat stuff.



Called Milner351 for a point in the right direction and a kick in the pants......John steered us towards the idle screws on the metering blocks.

Just like he said, they were out way too far. Running them to 3/4 turn out got us in the 13-14 range from idle to mid-range, WOT is still doing something wacky, but the WOT mixture seems rich at first then gets better to end up at 11-12.

Going to change the power valve to a 3.5 next, and see what that change does.

Thanks for the pointers John!

[oletrux4evr]

Holley recommends using vacuum to determine the best idle mixtures, among other things....

www.holleytv.com is your friend. I've learned a bunch there.

https://www.holley.com/blog/carburet..._and_tuning/1/

I don't know why everything is underlined.....it won't stop doing it even when I de-select it.......sorry.

[squirrel]

Step 1: pick the right carb for the application.
Step 2: leave the jetting stock or return it to stock if it's a used carb.
Step 3: remove the AFR gauge.
Step 4: if it drives good and does not foul the plugs, leave it alone

[anotheridiot]

I think my problem has always been adjusting the idle speed screw first and never getting that back to where it belongs.

[BlueCuda340]

There is some very good carb threads over on Yellowbullet in the tech section(which doesn't have as much yellowbullet going on). I found a lot of the guys said to not use anything but a 6.5 pv for a variety of reasons.

I have had very good luck with my holley 830, the car has been [email protected] with a 360@3500lbs and has knocked out as good as high 14s for mpg on drag week. Most of the stuff I learned I got from Yellowbullet. I learned enough to know I don't like it, I have drill bits that look like hair and other small pieces I don't want to mess with. My EFI conversion is coming along nicely

[dieselgeek]

Step 1: pick the right carb for the application.
Step 2: leave the jetting stock or return it to stock if it's a used carb.
Step 3: remove the AFR gauge.
Step 4: if it drives good and does not foul the plugs, leave it alone

You forgot a major rule: "Just because that worked once for you, doesn't mean it works that way for everyone else"


I've loaned out my O2 sensor to probably 50 carb guys. Literally every single one of them thinking their carb was "close, out of the box" and they were idling/running around in the 10s AFR. The increased wear to ring seal alone is enough to fund the purchase of a wideband. And at that AFR, the engine "feels just fine."

[BigAL]

You forgot a major rule: "Just because that worked once for you, doesn't mean it works that way for everyone else"


I've loaned out my O2 sensor to probably 50 carb guys. Literally every single one of them thinking their carb was "close, out of the box" and they were idling/running around in the 10s AFR. The increased wear to ring seal alone is enough to fund the purchase of a wideband. And at that AFR, the engine "feels just fine."

I have to agree with you Scott, tuning without an AFR meter is just stabbing in the dark. On my 355 with an 830cfm Holley we had to go from the stock 82 jets to 88's front and rear to get the AFR's in check.

[Polyhead]

I have to agree with you Scott, tuning without an AFR meter is just stabbing in the dark. On my 355 with an 830cfm Holley we had to go from the stock 82 jets to 88's front and rear to get the AFR's in check.

it's not that bad really. One thing you should always do. So the thing is running fairly well, but you arn't sure if the plugs are clean due to a high heat range, or mixture, there is an easy way to check that out. Put some larger jets in, if the plugs come back clean still, you know you're way way way to hot on the plug. Then you have my method, which is jsut take the exaughst loose, the drive the thing around on open headers and see how it smells. If it smells rich but the plugs are comming out clean, time for some colder plugs. If it smells ok, plugs are dirty, warmer plugs. Heh, option 3 I suppose is lean the ####er out till it has holes in the pistons and then you know for sure you're lean!