Is my 600 Holley to small?

[Bruceynz]

I think I made a mistake in title saying to small, more like to Rich But I can't change it now.

Watch video here

At about 3000rpm my air fuel dropped to 10.6 it's way rich guess better than lean but am I loosing power? What do I need to do?

 

[jasperjacko]

yes to rich. test the afr without using the secondaries and post your results.

 

[jasperjacko]

Yes losing power.

 

[AJ/FormS]

How the heck does a 600 go rich at WOT at 3000?
With a 2200 stall that's gotta suck,lol
It may be that the secondaries are opening too late. I watched the video, and saw it go super lean first, like 17or18/1. And you can clearly hear it as the engine struggles.
Here's my 2 cents.
My guess is the secondaries are fat and they are opening too late;;;
but I agree, block the secondaries closed and tune the primaries first. You should end up with about an 8 number jet split front to rear; Something like; 68/76 ..... at 34 to 36* all-in timing no sooner than 3400; NOT 38 at 3000! jussaying, You can sneak up on the perfect power timing after , AFTER the jetting is done. 10.6 is a lotta powerloss over 12.5.
Now, before you start, put a PV in there 2 numbers smaller than what your cruise vacuum is at 2000 rpm, or 10.5 minimum. Don't think about it just do it. Instead of nailing it at 2800, roll into it while watching the AFR. Get rid of that lean Afr on the transition from transfers to mains. After it transitions nicely, then start the WOT primary-only pulls.
_____________________________
I put one of those 600s on my 367-M/T,but I found it way too small and waaay too slooow for my driving style. A 750DP solved that little problem.
So then I leaned the heck out of the 600, and with about a 2.0 final overdrive drive ratio, I got my fish up to over 30 mpgUs with it. That's what a 600 is good at.
The math says a 600 is good to 5700 on a 360 at 100%VE.
But the reality seems to be that Mopars don't seem to fit the formula all that well. Plus on the 600, the secondaries are just IMO too restrictive. And if you open them too fast, the engine hesitates,stumbles, or bogs. I like the big DP cuz when I stomp it, chit happens right away, no waiting. Not everybody is a tirespin freak like me tho.
Listen to the intake roar, and listen to the pipes.
The fat-man moan will turn into a higher-pitched wail, and the pipes will turn into screaming banshees. Watch out for the power hit beginning at about 3800. In your combo (3.23s and 904 IIRC), that would be around 36mph. If you have around 160psi cylinder pressure, it might break traction and get sideways on you.

Is that a fuel pressure gauge down there? Put your video in 50% slow mo and watch the needle. You can actually see the secondaries kick in.
Man is that engine struggling;how heavy is that car?!.
EDIT, no it seems to be a tach;

 

[Bruceynz]

AJ did you watch this video, its a complete pull to 5000rpm

 

[Bruceynz]

Just out of interest how many of you guys have actually installed an AFR gauge and checked your true tune of your carb? Be interesting to see what your results are on an engine you think is dialed in perfectly and how the carb performs over the rev range. Only place I see it happen in when they do a dyno run they monitor it.

 

[Aspen500]

I tuned my carb by the seat of the pants at first, and thought I had it pretty darn close. Then,,,,,,I installed an A/F gauge (AEM brand) and found I wasn't even close. It took a lot of trial and error to finally get the right jets in the primary and secondary, the right idle air bleed restrictors (could those things be any tinier?), power valve, along with the accel pump squirters and cam (along with converting to a 50cc pump), and can't forget the idle screw adjustment. It all was done in conjunction with getting the ignition advance curve and total where it wanted to be. It's not perfect but I got it close enough that I didn't want to mess with it anymore. Added bonus, it got rid of the eye burning exhaust in the process and went from 7 mpg to a downright miserly 10 mpg avg The gauge was worth every penny.
Being winter (at least it feels like winter, even though it's still autumn) I can't make a video. Numbers run between about 12.5 to 14.5 at cruise, depending on speed and temp. On gradual hills at 55 mph it does go a bit lean, up to the 16 range but it doesn't seem to be a problem. No surge, spark knock, or detonation. I don't recall right now what the numbers are on hard accell.

One thing to add, I am under carbed with a 750 vac sec, most likely.

 

[Bruceynz]

Hey i just clicked to something, when tuning am I looking for the mixture at cruise and idle or am I looking for it to be 12:1 under hard acceleration? (I have only been interested in acceleration but maybe I am wrong)

 

[AJ/FormS]

AJ did you watch this video, its a complete pull to 5000rpm

I did now.
Is that little gauge under your AFR a tachometer? Is it calibrated right? 5000 on it doesn't sound like 5000 to me. What's your speed at 5000? Mathematically it should be about 48 mph with 26.5s/ 83" roll-out/5% TC slip/ with your 3.21s. The engine sounds like it's just waking up.

_____________________________________
I had an AFR guage but it kept lying to me so I threw it back in the box. I tuned a tad rich by seat of the pants because I have more power than I need so not looking for the last little bit.
You have three AFR targets, WOT power(12.5), Cruise (14/15), and Part-throttle driveability (everything in between).
And like said,once your AFR s are close, you switch to timing. And repeat endlessly until you are satisfied.

I spend a lotta time sneaking up on the power timing, and the rate of advance. But again, I have a manual trans, and a gear-splitter, and more power that I need,so for me, close enough is good enough. For me 3400rpm is 25 mph, so after that, 32/34 timing with aluminum heads was lots. I can't test at WOT below 60mph anyway, cuz the tires are always spinning.

 

[Opticon77]

Just out of interest how many of you guys have actually installed an AFR gauge and checked your true tune of your carb?... Only place I see it happen in when they do a dyno run they monitor it.

My 5th had a GM TBI setup (in tank pump, hall effect distributor, etc) with a Moates prom emulator and an AFR gauge. Datalogged and tuned on a laptop. Mostly for fun. Now I have a mobile box to use while tuning old carb cars. It has sensors and gauges for vac/boost, AFR, RPM, and a knock sensor connected to some headphones. Provides realtime data to be monitored by a passenger between tweaks. Used it to tune a 392ci Poly (while the old man was teaching me how these old mechanically controlled fuel leakers function) and I'll most likely be using it on the Volare.

All that monitoring stuff is a requirement in the 80s TurboDodge community. High strung aluminum 4cyls pressurized to 400hp don't leave you much room for error.

 

[Bruceynz]

AJ
Ok engine cold 150psi and here is a photo of the plug out of number 1

 

[AJ/FormS]

What size chambers on those EQs?,........... IIRC, they are 62cc closed chambers
What elevation are you at again?................. IIRC sealevel! I think you said
Do you know what the deck clearance was or the final assembled compression ratio? ...........IIRC 8.9Scr

About that 150psi
That is about what the Wallace calculator predicts. So the calculator is fairly accurate. The problem is it also predicts your problem; a P/V of just 130.Read about P/V here;
V/P Index Calculation
.
I30 P/V is pretty soft on the bottom. About what a 5.2 Magnum makes in stock form. My 292 cam made more than that and I pulled that cam out as fast as I could, for being too soft, and it was running 11.3Scr..
Assuming the cam is installed right,Yur gonna need more compression ratio (9.5@sealevel) to boost the cylinder pressure to 160psi, and the VP into the 140s; or a higher stall to get past that soft part.
Altitude steals pressure fast; from sealevel to 3500ft is about 20 psi. If you are spending any time at altitude, you are gonna need that stroker.
EDIT: ok I see by the tach, you don't really have a soft spot, she's just all soft,lol

 

[Bruceynz]

everything above correct AJ

 

[AJ/FormS]

ouch

 

[Bruceynz]

Thats a 1mm feeler gauge

 

[Bruceynz]

T slot adjusted to 1mm, approx 40 thou

 

[AJ/FormS]

OK now don't mess with the speed screw,
adjust the idle speed with idle-timing and idle-air bypass. Adjust idle quality with the idle trimmers.

From the pic, it looks like the T-slot was at least 2 or even 3 times as high as it is supposed to be. Be sure the fast-idle cam was not engaged! They tend to do that when you flip them over.

 

[Bruceynz]

AJ your a legend! Every figure you gave me was 100% correct!

 

[Opticon77]

Judging by that V/P Index link he dropped up there I'm thinking he builds engines in spreadsheets for fun.

 

[AJ/FormS]

I know nothing about making Drag-race power.
I do know a little about how to build street power and street combos, cuz I've been doing it for nearly 5 decades, for myself, and friends, and relatives.
I just know how not to build a soft bottom end. And honestly, 50 tears ago, before 8/1 engines soft bottom ends were not a big deal; there just weren't any.. Really, it started when engine builders more or less insisted that 9.5Scr was a wall we should not attempt to get over.
In the early 2000s or so, Dcr popped up and since then builders seem to be a little more willing to break thru the barrier. But the younger generations don't seem to be as willing to embrace it; as can be seen by all the threads about big cams in low-C engines being pigs and dogs . And then we see the general loathing of LA318s,and the magnification of Magnums, when in truth,for the price of a set of pistons,the LA318 can be an excellent performer in an A-body, when properly engineered.
The biggest problems I see are 5500 rpm engines in crummy combos and applications; you know; 2.76 gears and 2200 stalls, that don't hit 6000 in first gear until 66mph, and in 8.1 engines: it's all messed up. Yet that is what we see,all too often.
My only desire is to save the young ones from making those expensive and disappointing mistakes. The Dcr calculator is just one tool, in the enthusiast's pocket, to help not build a POS street-engine.
And yes, for a streeter, Dcr ain't all that..... until you either don't have any, or you don't have the money to take advantage of it.
But then, having way too much is sure a blast.
To my way of thinking; For streeters, the VP index is an excellent barometer of what to expect when you hit the go-pedal. And to combine a high VP with the right power products,and the right TM is what makes a dynomite street car.