Holley/Demon Carb stumble

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It will be here Wednesday.
It comes with main jets....Do you think i should start with them? Even though i Race at 6600 feet?
skrews Wrote.
Yes, and drop down if needed. The carb I have with that main body was spot on with the supplied jets.

I should have just left them stock main jets that was supplied with the main body!:BangHead:
For those that don't want to listen to all my mumbo jumbo, I have to clarify a few things before you watch the the videos.
First,.. first video, is as set up last night(carbs).
2nt video is after i upped the jets. Then i video the launch from the rear, and then from the front.
sorry you will have to wait for the next post to view the videos as there still up loading as i'm typing.

Ok so the first launch it bogged Hard! I'm blaming it on a cold eng as the temp needle has just started to move off of cold. And it never stumbled again all day.

My 2nt launch felt great!!! but, just seemed lazy after that. going down the track BUT NO popping banging backfiring, whatever you want to call it. So that was a plus and i knew the spare 600 was going to stay wrap up in it towel!

So after loading the video up on my laptop, i decided to jet it up 2 more steps AKA the stock jet the proform came with.
felt much better but no Change in et or mph. However the first runs were at 8920 foot adj altitude. after my jetting up, the altitude when up to 9532. My last run of the day it was at 10,269 feet:eek: My mile per hour was down 1 to 1 and a half mile per hour all day long.85.2-86.1 The last race, were the air stayed the same at 7960 feet my mph was 97.xx all day long. it was in the 60 degrees all day and today it got up to 97 degrees were my camper was parked.

I have a stall light that has been set at 2200 for years. today i turned it down to 1600 and that is what it was at when i put the GoPro back under the car.
That part of the video, i did a normal and a slo mo of the launch. from the driver seat it felt like it scratched off of the launch. but i don't see any in the video.
What makes me feel good is that the bite on the track was **** by this time and a scratch was all i got!!!!!!

And those that don't read down to here.......I will know:D yes that is Header Wrap dangling and dropping behind me.
One of the things on my list that i didn't have time to fix. Didn't realise that it had unraveled that much until i watched the video:rofl: A WOOPS!

And last, Sorry about the Ricer Footage:D
 
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So the object of tuning the MAB is to equalize air fuel ratio throughout the full rpm range, of full throttle...? But don't you want it to get slightly richer as you head to the top of your rpm? in other words say when you first start pulling at full throttle your o2 reads say 12.0 at the top of the rpm range shouldn't it be say, mid 11 or am i thinking backwards.

My car was down 1.5 mph, and a tenth and a half (0.16) My 60 foot was right in line(1.7XX)
I'm giving the air a lot of credit for the loss of ET and MPH. but i don't think thats all of it. I think it needs more tuning, but not smart enough to now which way to go.

I know my idle circuit is **** and need some help, but until i get some long extensions on my collector my o2 meter is worthless.
I pulled a spark plug out today and took a couple of pictures of it. these are old spark plugs.....at least a year or so old spark plugs and the plug was removed this morning before i started it, and pull it off the trailer. The one picture show the base ring as shiny or wet/oil. It is not, it is vary dry.

Tell me what you think.
 
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fuel ring

fuel ring.PNG
 
Yes running a power valve, like i said theses plugs are well over a year old(Probably longer) and not a clean cut plug.
I know my idle and "tip in" is way rich.....ah well i really think so.
I finally got my o2 meter reading and it was showing 12.0 to 11 air fuel ratio threw all three gears.........

I will be buying some new plugs for the next race and a couple of spares to boot, for testing. hope to have the idle circuit/ tip in sorted out by then.
The problem with reading a spark plug after a full hit. Is that i have a reverse manual shift valve body so i have to slow down a lot before i can get it into neutral and kill it. still have the factory slap stick, that is worthless because of the reverse valve body.
I'm guessing the oil deposit was from all the lean banging (Lifting oil of the ring..?
Like i said the plugs are old and the idle circuit could be what is being seen on the plug.
Normally the ceramic is bone white. it looked different so i posted up a couple pics However i usually put a fresh plug in before i check the burn. This time i did just because i haven't pull plug for a long while.
 
Cudafever said:
Yes running a power valve, like i said theses plugs are well over a year old(Probably longer) and not a clean cut plug.
I know my idle and "tip in" is way rich.....ah well i really think so.
I finally got my o2 meter reading and it was showing 12.0 to 11 air fuel ratio threw all three gears.........

I will be buying some new plugs for the next race and a couple of spares to boot, for testing. hope to have the idle circuit/ tip in sorted out by then.
The problem with reading a spark plug after a full hit. Is that i have a reverse manual shift valve body so i have to slow down a lot before i can get it into neutral and kill it. still have the factory slap stick, that is worthless because of the reverse valve body.
I'm guessing the oil deposit was from all the lean banging (Lifting oil of the ring..?
Like i said the plugs are old and the idle circuit could be what is being seen on the plug.
Normally the ceramic is bone white. it looked different so i posted up a couple pics However i usually put a fresh plug in before i check the burn. This time i did just because i haven't pull plug for a long while.
Click to expand...


My friend, you are SO FAR OFF you need to stop trying to pick the fly poop out of the pepper.

You ain't nowhere close to needing an O2 sensor as it's just screwing you up. And you damn sure don't need to clean cut for a plug read yet. You ain't close.

I'm not trying to hurt your feelings. I'm just telling you from decades of doing this stop looking at O2 numbers and learn to look at the plugs until you are much closer. You don't need new plugs to see how far off you are.

Get your new plugs in there. Make a pass and pull a plug when you get back. I don't like saying it this way, but a very smart tuner told me years ago (when I was too young to drive but was working on 2 strokes) don't trick **** yourself. You just don't have the experience to know when the O2 is telling you the truth or bullshitting you. Learn to read plugs. It's not that hard.

I'd start by pulling 4 sizes of main jet out of the primary and 2 out of the secondary side. Open up the idle air bleed .004 or close down the idle feed restriction .004 but take some fuel out (or add some air) of the idle side. You'll probably need Tslot restrictors. Probably need to be around .072-.078 for those. You can see where to tap the main body for those and use some 8/32 brass set screws to change the hole size. You need to do the primary and secondary side on those.

Then start making runs. When you get the idle side clean you can just drive back to the pits and read the main jet tune up until you get much closer. You don't need a new plug for every run either until you are way closer. One run on gasoline will show up. Don't look at anything other than the fuel ring in the bottom of the plug for WOT. When you get close, you can start taking the shell off the plug to measure the fuel ring.

Then, you can start clean cutting and doing a plug read. At that point you can use the O2 sensor again, but never tune to a number. Tune for MPH and then use that as your number. Not every engine will like the same A/F ratio, plus the fuel makes a difference as well.

You've got a long way to go. Don't let the fence leaners tell you you need to clean cut plug read as far off as you are.
 
Not trying to argue with you but when i put the ProForm main body on. When 4 size down on the front and rear main jet for the elevation i live in.
"This is what happened.

"Its together and i took it for a stomp. that's when the o2 gauge took a crap.
It didn't stumble and it didn't hook but then it started lean popping after the 1-2 shift. idled it back and check the float bowls and haven't started it sence."

OK so i richened it up 2 jet size but couldn't test in until i got to the track. It launched good but seem lazy and popped just as i lifted. it also seamed lazy up top.

So pulled the bowls and jetted back up 2 more jet sizes(what came in the ProForm kit.
took it for another stomp and it didn't pop and it didn't seam lazy on top.

Now you say the plug looks pig rich, and i agree, but if i go back down on jet it's going to pop.
I have went 4 (33 to 29)and then another 2 (29 to 27) smaller on the MAB.

When it was popping and banging in 2nt gear the AFR read14 at full throttle after jetting up 4 sizes total it didn't pop and bang and the o2 said 12 to 11s

I was racing at 10,000 foot elevation on Saturday, could have had something to do with it.

Ok now that i have said all of that i don't understand all of this.VVVVVVVVVVVVVVVVVVVV

You'll probably need Tslot restrictors. Probably need to be around .072-.078 for those. You can see where to tap the main body for those and use some 8/32 brass set screws to change the hole size. You need to do the primary and secondary side on those.

If i start throwing a hole bunch of changes at i will be so far down the hole i may never get back out of. It running decent now i don't want to ruin a working carb with stuff i don't understand.
Is this to improve the idle circuit or the Mains???????????????
 
Every time you go smaller on the MAB you make the booster come on later. So you effectively make the transition take longer, as in transition from the T slots to the booster.

You are trying to correct a very small top end rich condition by squeezing the MAB down and you ain't there yet. That's what I'm saying to you. You ain't that close.

I forget what you have for emulsion but post that up if you know what it is. You probably have too much and that will cause fuel to slug in the main well. It's kinda like when you turn on a hose for the first time and it pushes out some air and then water and it spits and sputters until you get solid water. That's what happens when you get too much emulsion. I can't remember what blocks you have.

Again, you are way out over the skis trying to pinch off the MAB and following the O2 sensor. I believe the plug long before a sensor and that thing is rich.
 
Cudafever said:
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So after loading the video up on my laptop, i decided to jet it up 2 more steps AKA the stock jet the proform came with.
felt much better but no Change in et or mph. However the first runs were at 8920 foot adj altitude. after my jetting up, the altitude when up to 9532. My last run of the day it was at 10,269 feet My mile per hour was down 1 to 1 and a half mile per hour all day long.85.2-86.1 The last race, were the air stayed the same at 7960 feet my mph was 97.xx all day long. it was in the 60 degrees all day and today it got up to 97 degrees were my camper was parked.
Click to expand...

You're saying the MPH this weekend was 85-86 in 10,269 DA but it was 97 MPH in 7960 DA the previous race. I don't think it should have a swing that wide for 2000 feet of air change. If you meant 87 MPH thats totally in line with the DA change. You should try that other carb just to see where it stands.
 
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I had the day off and wasn't on call, so i slipped out to the track and did some testing. no timing equipment up at the track. just the track surface to make some stomps on. If i just need one i will sneak out the back road. but i wanted to string a bunch of them together.

This is the the same plug i posted above. pulled it off the trailer and let it idle, nothing else until it was up to 180 degrees(were my cooling fan turns on. shut it down to Pull this old plug out for a new one
OLD Plug idle.PNG
OLD Plug idle-.PNG

With the new plug install, i made a stomp down the track and clean killed as best i could. pulled plug out.
new plug 1st hit.PNG
new plug 1st hit-.PNG

drove back to the pits and pulled the plug again
Idle cruise from top of track to the pits.PNG
new plug 1st hit-.PNG

2nt and 3d stomp when i pulled the plug i cut the picture. didn't figure this out until i got home.
The last one is hot lapping! I did 3 runs back to back and then clean kill it at the top end to take these pictures
3 run hot lapping.PNG
3 run hot lapping.-.PNG


That's as accurate as i can get Sorry some are blurry............what do you think of the fuel/jetting.....timing....heat wrange........ i want to hear all the appinions even if they differ one from another.

Idle cruise from top of track to the pits.-.PNG
Disregard this one.
 
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Cudafever said:
I had the day off and wasn't on call, so i slipped out to the track and did some testing. no timing equipment up at the track. just the track surface to make some stomps on. If i just need one i will sneak out the back road. but i wanted to string a bunch of them together.

This is the the same plug i posted above. pulled it off the trailer and let it idle, nothing else until it was up to 180 degrees(were my cooling fan turns on. shut it down to Pull this old plug out for a new one
View attachment 1715367898 View attachment 1715367899
With the new plug install, i made a stomp down the track and clean killed as best i could. pulled plug out.
View attachment 1715367900 View attachment 1715367901
drove back to the pits and pulled the plug again
View attachment 1715367902 View attachment 1715367901
2nt and 3d stomp when i pulled the plug i cut the picture. didn't figure this out until i got home.
The last one is hot lapping! I did 3 runs back to back and then clean kill it at the top end to take these pictures
View attachment 1715367904 View attachment 1715367905

That's as accurate as i can get Sorry some are blurry............what do you think of the fuel/jetting.....timing....heat wrange........ i want to hear all the appinions even if they differ one from another.

View attachment 1715367903
Click to expand...


What brand plug is that. It makes a difference in how it reads.

If that is an NGK and its changing color 4-5 threads down that plug is 2 ranges too hot.

Also, remind me what fuel. If it's pump gas, the timing is too slow, probably because the plug is too hot. It's hard to see in those pictures. Cut a shell off of the plug you think is the best so we can see the fuel ring and better see all the porcelain.

Edit: either not enough timing or you have a bunch of initial and too much total. Damn I just don't see enough in those pictures. Old eyes suck.
 
12.8 compression Sunoco 110 leaded racing fuel
NGK BCP6ES or stock # 4930
 
yellow rose said:
What brand plug is that. It makes a difference in how it reads.

If that is an NGK and its changing color 4-5 threads down that plug is 2 ranges too hot.

Also, remind me what fuel. If it's pump gas, the timing is too slow, probably because the plug is too hot. It's hard to see in those pictures. Cut a shell off of the plug you think is the best so we can see the fuel ring and better see all the porcelain.

Edit: either not enough timing or you have a bunch of initial and too much total. Damn I just don't see enough in those pictures. Old eyes suck.
Click to expand...

That first plug has been in for a while and has been threw 3 different carb.
All the rest are a fresh plug from today.
 
Cudafever said:
12.8 compression Sunoco 110 leaded racing fuel
NGK BCP6ES or stock # 4930
Click to expand...


Ok, that's equal to a 9 in a Champion. That is a street plug.

At that CR and that gasoline, your plug should be a racing plug and not a street plug. In a Champion that would be a C63YC. I don't know NGK numbers but the equivalent to that in an NGK is ok.

You have to start with the correct heat range plug. That is way too hot. Fix that first. And then start over. It's no wonder pulling fuel out of it pissed it off so bad. You are using fuel to cool the plug.
 
God knows I hate NGK plugs. Near as I can tell, if I was going to use an NGK plug I'd use the R5672-8 plug to start and tune from there.
 
yellow rose said:
Ok, that's equal to a 9 in a Champion. That is a street plug.

At that CR and that gasoline, your plug should be a racing plug and not a street plug. In a Champion that would be a C63YC. I don't know NGK numbers but the equivalent to that in an NGK is ok.

You have to start with the correct heat range plug. That is way too hot. Fix that first. And then start over. It's no wonder pulling fuel out of it pissed it off so bad. You are using fuel to cool the plug.
Click to expand...
Well that make cents! i thought i was colder than stock........shows how much i know.:BangHead:
The cross reference chart i found says my plug crosses over to a RN11YC

Haven't found the cross from your suggested C63YC...............
 
Cudafever said:
Well that make cents! i thought i was colder than stock........shows how much i know.:BangHead:
The cross reference chart i found says my plug crosses over to a RN11YC

Haven't found the cross from your suggested C63YC...............
Click to expand...


That's why I don't like cross reference charts because there is too much fudge room. I always consult my trusty Champion catalog. I really need to get an NGK and Autolite catalog so I can reference them.

You could really be at an 11 heat range in a Champion plug. The cross reference I used said 9 but your plug looks plenty hot.
 
I found a sight that shows the heat ranges and YR is right it show a number 7 is normal and 9 is cold/High performance.........mine is a 6:wtf::BangHead:
Thanks for the link.
I haven't use cham for a long time and really liked the NGK's
I just order 10 new plugs......hope i can cancel that order tomorrow
 
I agree 100% with skrews. Before you buy any more plugs call NGK and let them pick the plug. I'm only about 78% comfortable picking an NGK plug. I'd bet my house and the wife on my Champion pick. But if you want to use NGK's I have zero issues with it. They are a bit harder for me to read.


And FWIW...I wouldn't bet everything on my Champion plug pick. I'd wager my wife. But not the house. I can replace the old ball and chain pretty easy. The house not so much.
 
I’d look into a chassis dyno in your area........ tune for power....... bring the old main body with you, and some notes on how to put that carb back how it was when the car went the quickest/fastest.
In fact, that’s probably the place to start.

I’ve tested a number of home brewed carbs on the dyno over the years....... some have been so far off(both from a power and/or fuel curve standpoint) that no amount of jetting or air bleed changes were going to fix it.
They needed more reworking than that.

The best luck I had with building a carb from readily available parts was the original Proform HP 750 body, using stock Holley 4779 metering blocks and a plain Jane 4779 type baseplate.
I built a few of those, and they required minimal tuning to get dialed in.

I built a similar carb with a Holley HP body, QFT billet metering blocks and baseplate.
I haven’t had a suitable candidate on the dyno I could use to dial it in....... so at this point, it’s still an unknown.

When we were selling BG stuff, and the Demon carbs........ I found the calibration of those things to be properly set up for.......almost nothing.
The Speed Demons in particular always seemed to have idle, driveability, and wot fuel curve issues.
Often all three!!
It got to where if I was going to be using a new one on the dyno for a build we did, I’d just modify them for adjustable air bleeds before ever being run.
By that time we had a better handle on what changes to make to the baseline calibration so they’d be closer to “right” from the start.
Some of those things as they came ootb were particularly bad.......they’d hardly even run.
Wouldn’t idle, super lean at wot, headers start glowing right away at part throttle, etc.

But......they looked good.

Eventually, it just got to the point where they were just more trouble than they were worth........ and we stopped selling them.
 
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