[brownnote]

Ok, so I added a Zeitronix wideband recently, and was looking at the afr today... and I am generally happy with what I see, but I need some advice on my rich wot afr. I am running pretty much 11.8:1 at wot, on my 327 w/ 1850-3 holley (66primarey, 134-9 secondary plate).

Now, if I only want to lean out the wot portion (kind of fixed everything else already), then how would I do this? Is there something I can do to modify the secondary metering plate, add wire somewhere etc.... or do I need to get a secondary jet conversion kit and run smaller than equivalent secondary jets? I have looked at a ton of threads, and I don't know if I should mess with the secondary plate (change to jets etc) or if I can modify the PVCR's smaller etc?

Any help would be greatly appreciated.

All in all the car drives great, but can always be better!

[Steptoe]

Now, if I only want to lean out the wot portion

Why do you want to melt your pistons? burm you valves?

(kind of fixed everything else already),

Since you have fixed everything and WOT is rich everything is fixed.

then how would I do this?

I dont think you want to know..but basically screw everything else up to make it lean at WOT so you can melt your pistons.

OR put it another way...Bloody good on you..never done it before? Time for a few beers m8

[SIDEWAYS]

Assnine response above.

Anyway, yes 11.8 is rich up top. You'll want to get it around 12.5-13.0:1. Much easier with actual jets, or PCVRs. If your happy with part throttle, reduce the PCVR's, as reducing jets will lean out part throttle also.

But, I sorta question that fat WOT reading. Have you done anything else to the carb? I think your better off at the strip and jet for MPH...these AFR meters, even the best ones, can be off a bit.

[brownnote]

Originally Posted by Steptoe

Why do you want to melt your pistons? burm you valves?

Since you have fixed everything and WOT is rich everything is fixed.

I dont think you want to know..but basically screw everything else up to make it lean at WOT so you can melt your pistons.

OR put it another way...Bloody good on you..never done it before? Time for a few beers m8

seriously? I'm just coming in here to get answers to my questions man, no need to take out anything on me.

And no, I have not melted a piston... have you? If so, maybe you are doing something wrong?

Anyways, I would have expected more out of someone like you than get a response like that.... Oh well, to each their own.

Originally Posted by SIDEWAYS

Assnine response above.

Anyway, yes 11.8 is rich up top. You'll want to get it around 12.5-13.0:1. Much easier with actual jets, or PCVRs. If your happy with part throttle, reduce the PCVR's, as reducing jets will lean out part throttle also.

But, I sorta question that fat WOT reading. Have you done anything else to the carb? I think your better off at the strip and jet for MPH...these AFR meters, even the best ones, can be off a bit.

Thanks, that is kind of what I was thinking with respect to the secondary adjustment.

And yes, I have had very very good results with the wideband, especially the Zeitronix brand. Yes, all widebands are not created equal, and some are known to be sketchy at best, but I trust this one, and have used it on other applications in the past with great success.

The thing is that I do not have the option of going to a strip to double check this. I might hit a dyno just to make a couple pulls to verify everything... but again I trust the meter. It is very nice to be able to see what is going on realtime, instead of reading plugs or spending the day at the track (not that I don't enjoy that though!).

[SIDEWAYS]

I also had excellent luck with my LM-1, and actually backed it up at the strip. I guess I'm suprised that your carb is that fat at WOT. Seems like I always have to get them a bit fatter up top. Did you increase jet size for part throttle?

Oddly, my 850DP was only giving me 14:1 WOT. I had to increase jetting by 6 sizes to get the WOT around 12.5-13:1. I didnt believe the readings, so I put the carb back to stock, and lost 3mph at the strip! Upped the jetting, and the mph came back. Now, you could imagine what 6 more jet sizes did to my part throttle cruise AFR right? I ended up just putting the stock jetting in and opening the PVCR's up till the AFR fell back to where I wanted. You will likely need to tap and install set screws in the metering blocks to reduce the IFR's. Really only have to do the primary PVCR's, as the rear block you can just jet up since cruise isnt really affected here.

[brownnote]

well, wouldn't I have to drill and tap the pcvr's only for wot? I have a metering plate in the secondary, so I think I might just get a secondary metering block conversion kit so I have more options.

Would closing the pcvrs a tad be the same as going smaller on the secondary side? I guess the pcvrs could affect a broader range though if I am not mistaken.

Yep, I think having the carb w/ the wideband is the best of both worlds. I mean, why not take advantage of the technology! It was kind of nice to hook it up finally and see in 1/2 hour of driving that my power valve is not sized right, I was too lean at idle and cruise, and rich at wot.... that would have cost me about the same on someone's dyno, and now I have the thing to monitor and do my own tuning. I only wish all the bleeds were adjustable out of the box, but nothing some blanks, a tap and drill bits can't fix. I just might leave that fine tuning for when I get more time.

The only thing is that I feel it would be better to pick up another unit to monitor both banks at the same time.... the fast one can do this, but I can get two lightly used Zeitronix units for less than a FAST one and there is a lot of functionality there. I am just going a little rich everywhere to be on the safe side, tune it, then swap banks when I get another bung welded in and verify the other bank isn't too lean. A lot of my friends use the lm-1 or the zeitronix units. The only thing is that some of these only go to 10:1 on the rich side, whereas mine goes to 9.5, which was nice when I had my alcohol injection on my other project, and my target afr was richer than what it would have been with straight gasoline due to the different stoich amounts of the ethanol based alcohol vs. gasoline.

[SIDEWAYS]

Originally Posted by brownnote

well, wouldn't I have to drill and tap the pcvr's only for wot? I have a metering plate in the secondary, so I think I might just get a secondary metering block conversion kit so I have more options.

Yes, PCVR's are for WOT only - actually, whenever the PV is engaged (or disengaged) the PVCR's contribute. Not sure how the metering plates are constructed, but since your tuning, go ahead and get the block - much easier.

Would closing the pcvrs a tad be the same as going smaller on the secondary side? I guess the pcvrs could affect a broader range though if I am not mistaken.

Closing the PCVR's on both blocks is like reducing the overall jetting - front and back.

IMO, you want to keep the factory "balance" between the front and back of a carb. I see too many people just jetting the rears up for best performance. I dont think this is a good idea, so I I like to move everything evenly. This includes jets and PCVR's. You dont want to get a lean/rich corner on the motor, so keep what the factory did. Unless, you have specialzed equip (EGT probes on each header tube).


Yep, I think having the carb w/ the wideband is the best of both worlds. I mean, why not take advantage of the technology! It was kind of nice to hook it up finally and see in 1/2 hour of driving that my power valve is not sized right, I was too lean at idle and cruise, and rich at wot.... that would have cost me about the same on someone's dyno, and now I have the thing to monitor and do my own tuning. I only wish all the bleeds were adjustable out of the box, but nothing some blanks, a tap and drill bits can't fix. I just might leave that fine tuning for when I get more time.

The only thing is that I feel it would be better to pick up another unit to monitor both banks at the same time.... the fast one can do this, but I can get two lightly used Zeitronix units for less than a FAST one and there is a lot of functionality there. I am just going a little rich everywhere to be on the safe side, tune it, then swap banks when I get another bung welded in and verify the other bank isn't too lean. A lot of my friends use the lm-1 or the zeitronix units. The only thing is that some of these only go to 10:1 on the rich side, whereas mine goes to 9.5, which was nice when I had my alcohol injection on my other project, and my target afr was richer than what it would have been with straight gasoline due to the different stoich amounts of the ethanol based alcohol vs. gasoline.

My responses are in the above fields^

Although both banks would be nice to read, I dont think its really necessary. You'll be close enough with the 1 sensor. Typically, a single plane intake will give better mixture distribution than a dual plane. Some factory motors has staggered jetting to compensate for this. I learned from a reknowned engined builder though that a 1" spacer or more will correct this distribution issue.

[brownnote]

hmmm, looks like I might be hitting the speed shop tomorrow

and I can't do a spacer due to a non-cowl hood and no more room... I have about 1/2" spacer (heat dissipator plates... gasket, metal, gasket, metal etc).

[Steptoe]

seriously? I'm just coming in here to get answers to my questions man, no need to take out anything on me.
And no, I have not melted a piston... have you? If so, maybe you are doing something wrong?
Anyways, I would have expected more out of someone like you than get a response like that.... Oh well, to each their own.

lighten up m8....cant believe someone read my post and not realise its a little tonge in cheek. And lets face it hell some dort of response like that would be expected of me lol
Bet you didnt even read the last line before going off 1/2 cocked

OR put it another way...Bloody good on you..never done it before? Time for a few beers m8

Sideways

Anyway, yes 11.8 is rich up top. You'll want to get it around 12.5-13.0:1

like u say m8 one doesnt know how well zroed the gauge is or how well positioned in the exhaust the sesor is....same reason I let that part go...far better to be a little on the rich side than have small ball of melted piston sticking to the plugs
And no I have never melted a piston or blown an engine...as close as I have come to it was running a cam lobe yrs back and cracking a lifter...why ..well that why like others here, I know what the bloody hell Im doing....and if you dont like a bit of humour thrown in ...thats your problem, I really dont care either way m8.

Even so, if my engine, no would not lean the WOT out anymore, unless you have it up on a dyno, that you know has just been recaliberated...(most are not) and the guy dyno guy is a top notch guy paid 10 times more than the ave shop dyno tech... a couple pionts in A/F can be put down to atmosheric pressure...got a bit of rain heading your way? low presures, or nice fine day, sun out, warmer ambiant temps.... All stuff that gets calibrated into a dyno...thats why they do it.

[brownnote]

Damn, just did a lengthy reply and forgot to send....anyways.

Steptoe, if you were just joking, I totally missed it... guess it didn't translate?? ha ha ha

Anyways, those are valid points about the wideband, but I am fine with it, and if I blow it up, then well, I guess I will just upgrade or pick up another 327 and be where I started. My 327 probably needs a rebuild anyways.

I just basically am trying to see what will fix just wot, be it needing to go a tad richer, leaner or w/e. I would rather run it on the safe side too, but would feel better with 12.3-12.5:1.

The nice thing about having a wideband display/gauge in my car is that I can monitor all the time, and if I need to change something I'll know.

[BlackoutSteve]

I have just breezed through this thread so forgive if I'm talking about what's already been said.

If you have a good midrange A/F but you top end is rich, you need to open up your high-speed air bleeds. Get a book on Holleys and read up! The Holley you have won't have replaceable ones unless you go to a HP or Ultra HP Holley that come with them as standard.. You can drill & tap for using interchangeable bleeds if you wish, but have it done properly so everything is nice & square and neat. Not the sort of thing you want to do with a hand held drill or if you're unsure..
Holley's tech line will tell you the sizes.. I think 10-32 from memory. Better check, could be 10-24.

Anyway, what you want to do is why they have interchangeable air bleeds on performance carbs..

[Steptoe]

Damn, just did a lengthy reply and forgot to send....anyways.

Damn ..yeah and always happens when is a long post to...bloody murphy lol

Steptoe, if you were just joking, I totally missed it... guess it didn't translate?? ha ha ha

IF? nah put it down to a American accent m8 ....we dont have one lol
....ever had a rattle between the top of the window and hood?
or a water leak in the boot?
Or a rust repair behing the wheel well in the gaurd.
And does your car have a hand brake?
Ever got disorinated watching the dizzy?
A gudgen given way?

Its all in the American accent ...you guys dont talk proper lol

[brownnote]

riiiiight, ha haha!

Anyways, I am going to mess with my secondaries hopefully today... just to see if I can cure a tad lean spot and have them open sooner.... went to the speed shop and they were out of the power valve that I needed and didn't have the secondary metering block conversion kit either! They had EVERYTHING else, but oh well... gotta wait for some parts. Maybe I can fix it without the secondary plate, we'll see. Time for some experimenting!

[mahunt]

Two great countries separated by a common language.

[brownnote]

Ok, well got a chance to run the car again. I put a new secondary diaphragm in there because the old one was a little scuzzy, and put the quick change spring top in there. Saw a screw that was bottoming out on the secondary cap, cut it and seals properly too. I went down one spring (plain to purple basically) just because I wanted to see if I had the secondaries opening all the way.

Well, It seems that they might not have been opening all the way? The car now runs wot at 12.3-12.5.... which I think is just fine, so I am happy with that. This is same time of day, same temp etc (about 100 out ha ha). All I need to do now is put the 8.5 power valve in there to have the enrichment come in a little sooner, and I will leave it alone. I might go to the next spring on the secondaries just to make sure I have it right, but the car runs fairly strong right now, with no flat spots.

So, for now...

Idle = ~13.2-13.5 (might mess with that a touch)
Low throttle cruise = ~13.3-13.4
Med. throttle med load = 13.5 -13.9... adding the 8.5 from 6.5/should fix the leaner area because it happens right there (~8.5") on the vacuum side.
Wot = 12.2-12.5 all the way up from 2500-5500/~6000 rpms.

It was way richer before... I have the idle mix screws out a smidge more than 1-1/4... started with them at 1-3/4... so that made a decent difference.

Now I just need more power ha ha ha... the 327 is fun though.