After all this, I've ALMOST got this 440 dialed in...need advice again!

[moparedtn]

It indicates that you have too much or too little fuel

What does?

Heat range on a spark plug has nothing to do with any of the above. It has to do with how fast heat is transferred from the plug to the head. Those RC12YC plugs are too hot for todays pump gas as far as I'm concerned.

I see. What plug do you recommend then?

 

[moparedtn]

Generally speaking a carburetor's cfm is rated for 1.5 in.Hg. vacuum at WOT. If you hook a vacuum gauge to either manifold or timed port (run a hose into passenger compartment where you can view the gauge) then what do you get? Higher vacuum indicates restriction, such as at idle when it is the highest.

Vacuum @ idle is 15-16hg.
Pretty good, I think?

Another thought - what is the difference between 5500 rpm sitting still (in neutral) compared to going through the gears?
Torque at the rear wheels is dropping as you change gears and vehicle drag is increasing as it gains speed. 4800 rpm is probably where your engine torque curve starts to level off. A trip to the dyno might prove or disprove this hypothesis.

I understand the difference between "load" and "no load" conditions.

Here, check these couple of videos I've made in the garage:



I'll be making one with it going down the road as soon as I can figure out how to mount my camera in-car. My dash cam sucks in quality, especially sound quality.

Back to the cfm's, try removing the air cleaner to see if that is acting as a restriction. Easy and free. Also, a dual plane intake can tolerate a bigger carb as it divides the carb in half, right? Maybe an open plenum spacer can help a smallish carb to feed a dual-plane intake? Just spitballing here...

As you see in the video, the air cleaner is a factory unsilenced one - with a new filter. I won't be running less than that ever, so I reckon I need to tune with it on there.
Intake (again, shown in video) is a factory dual plane with equal size primary and secondary holes that match the Edelbrock perfectly. You'll also notice I'm running a 3/4" Edelbrock phenolic spacer, used to help the linkage and such clear the heat riser in the intake.
Thanks!

 

[Homstead]

Loved the vids! That's one sweet ride!

 

[Bigal75]

A stumble at wot? Under load only? Maybe you're going lean. It's not a Cfm issue.

 

[69Runner]

Vacuum @ idle is 15-16hg.
Pretty good, I think?

Yes, but what is the reading at wide open throttle? That's where the 1.5 in.Hg comes in, not at idle.

 

[moparedtn]

Loved the vids! That's one sweet ride!

Thank you very much. It's been a long time coming. Work in progress.

 

[SlinktRR]

Try a used 800 cfm. 650 is small for a 383 at high revs, saw that on the dyno. Or just enjoy the meat of the powerband with the 650 and the responsiveness.

 

[moparedtn]

Try a used 800 cfm. 650 is small for a 383 at high revs, saw that on the dyno. Or just enjoy the meat of the powerband with the 650 and the responsiveness.

I'll grant you that - the throttle response is very smooth and linear, crisp even.
The Eddy just feels different to my right foot than any Holley I've ever had - I don't feel that very noticeable "step" when the throttle hits the secondaries.

 

[moparedtn]

A stumble at wot? Under load only? Maybe you're going lean. It's not a Cfm issue.

Thanks.
Could be? I do know when I figured out the problem with the ignition that it cleared up a TON of the splatter/bucking at high RPM the car was doing before.
This is sort of a remnant of that, just a little bit - and only once I've been beating on it all through the gears until top of 3rd.

 

[HEMI-ITIS]

We can still see a lot with a plug reading,but that must be done under a load in the top of high gear!

 

[moparedtn]

We can still see a lot with a plug reading,but that must be done under a load in the top of high gear!

As I said, coming up this weekend sir.

 

[SlinktRR]

I'll grant you that - the throttle response is very smooth and linear, crisp even.
The Eddy just feels different to my right foot than any Holley I've ever had - I don't feel that very noticeable "step" when the throttle hits the secondaries.

Yeah, the 650 AVS is designed for that. If you take the carb off and look at the bottom of it the primaries are noticeably smaller than the secondaries. Makes for better response, better gas mileage like a thermoquad. The 800 AVS has equally sized primary/secondary bores and are larger to get the 800 cfm rating. I prefer the 800 on a 383 for the wild top end. Depends on how often you are spending above 5000RPM. I shift at 6200 when having fun. If you shift at 5k then there is no reason to worry about it.

 

[moparedtn]

Yeah, the 650 AVS is designed for that. If you take the carb off and look at the bottom of it the primaries are noticeably smaller than the secondaries. Makes for better response, better gas mileage like a thermoquad. The 800 AVS has equally sized primary/secondary bores and are larger to get the 800 cfm rating. I prefer the 800 on a 383 for the wild top end. Depends on how often you are spending above 5000RPM. I shift at 6200 when having fun. If you shift at 5k then there is no reason to worry about it.

Actually, it's a "square bore" design as well - all bores are the same size.
Matches the bores in my factory intake perfectly.
The Eddy spacer I used also matches the 4 bore pattern exactly, too.
I did a lot of research into all this, trying to get it right for once.

 

[moparedtn]

Crap, being raining the last couple days, looks like tomorrow too...

Oh, I forgot to mention with all the other vehicle info!
I am NOT running the original 1/4" fuel return line to the tank. I have that plugged off and am running a vented gas cap as well.
That shouldn't matter, should it?

 

[moparedtn]

Ok gentlemen, I dug out the old Sony cam and went for a drive today.
We have video! Quality ain't great, but short of trying to hold onto a cell phone and
do this, we opted for the old Sony.
You'll hear one stumble in 2nd gear, more like a hiccup. You'll have to listen very closely to catch it, but other than that, things went pretty darn well.
First time I've stayed in it through all 4 gears, HARD.

 

[moparedtn]

Oops, that wasn't good....
Got brave and did a brief clutch drop/laying of rubber yesterday evening, which went fine and all except for immediately afterwards, when the oil pressure light came on momentarily and I heard what sounded a heavy rattling/knocking from the engine.
Just as I moved quickly to kill the ignition, the sound went away and the oil light went out and everything appeared to return to normal.
Gingerly drove it back home (less than 2 miles) and it acted like nothing had happened.
Should I be concerned?

 

[HEMI-ITIS]

Burnouts are fun!! Just have to watch the tach and not let it "WINGGGGG' above redline or keep it at the high RPM too long especially with a stock pan.AS you just found out it's easy to EMPTY the pan real fast!!

 

[moparedtn]

Burnouts are fun!! Just have to watch the tach and not let it "WINGGGGG' above redline or keep it at the high RPM too long especially with a stock pan.AS you just found out it's easy to EMPTY the pan real fast!!

Thanks for that reassurance.
Kinda what I figured, too.
Ok, HOPED. I hoped that's what happened.

Oh, by the way, the long-awaited PLUG PICS ARE HERE!
Singed fingers aside, I managed to pull three plugs right after a spirited run:

I'm actually quite pleased with these. I pulled these right after that hard run in the video I posted above.
(All 3 look pretty near identical, despite lousy photos)
In comparison to the last set I pulled out of it (see previous thread), they look soooo much better.
What do y'all think?

 

[moparedtn]

Burnouts are fun!! Just have to watch the tach and not let it "WINGGGGG' above redline or keep it at the high RPM too long especially with a stock pan.AS you just found out it's easy to EMPTY the pan real fast!!

Ok sir, you have your spark plug pics. What do you think?
Did you hear that one hiccup in 2nd in the video? Weird.

 

[HEMI-ITIS]

https://www.ngksparkplugs.com/about-ngk/spark-plug-101

http://www.dragstuff.com/techarticles/how-to-read-plugs.html

There is no change of color on the strap,you might be a tad lean which might have caused that misfire.