Holley/Demon Carb stumble
- Thread starter Cudafever
- Start date
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Ugh.
Tell us that's just a qualifying hole and the restriction is at the bottom.
It looks like it slotted and unscrews. yes?
Got two choices in that case. Buy the smaller ones or make out of set screws.
And we see the e-holes aren't threaded either.
If you have soft lead, you can gently plug the bottom or middle ones.
Or you can tap them and do the set screw thing.
FIXED
Those blocks look like the've lowered the air well. I've seen that but havent dealt with them myself.
Compare that with the ones this guy bought
Need Quick Fuel carb tuning assistance
or this 3310-2
Fuel level is roughly at the same hight as the upper emulsion bleed (e-hole).
Lowere-hole is above PVCRs.
That's why plugging the bottom e-hole on those deep well blocks may be a starting point.
Compare that with the ones this guy bought
Need Quick Fuel carb tuning assistance
or this 3310-2
Fuel level is roughly at the same hight as the upper emulsion bleed (e-hole).
Lowere-hole is above PVCRs.
That's why plugging the bottom e-hole on those deep well blocks may be a starting point.
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I'm just saying if the IFR is .054 all the way through, and it seems like it is, then unscrew it and put an .033 something like that in there.
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And lead is just a quick and dirty way to get two e-holes in the .027 range without tapping and drilling.
For four corner idle, and the transfer slots are about the same lengths, I would think square is a good starting point.
The good 3310 blocks you have are .033 or .035 right?
And I thought this starting point was for a carb with similar throttles and venturis.
.031, .033, .035 are all pretty typical IFR.
.053 is way out of line IMO
yellow rose
Overnight Sensation
That is a MASSIVE IFR.
I agree that .033 is a good starting point and a .070-.072 IAB.
Damn. That .054 IFR puts a ton of fuel in at idle.
I agree that .033 is a good starting point and a .070-.072 IAB.
Damn. That .054 IFR puts a ton of fuel in at idle.
PRH
Well-Known Member
The Demon catalog shows the IFR for a downleg booster 850 Mighty Demon is supposed to be .038”.
Emulsion holes- bottom .033”, other two 031”.
Siphon break .028”
PVCR .059”
IAB .070
HSAB .031
Stock jetting 85/93
I don’t feel it’s likely the best carb for CF’s combo, but the one I had and was using for a dyno mule....... I only did a tweak to the air bleeds and jets.
It was actually one of the better running Demon carbs I’d used.
However, I was using it for higher HP builds mostly.
Emulsion holes- bottom .033”, other two 031”.
Siphon break .028”
PVCR .059”
IAB .070
HSAB .031
Stock jetting 85/93
I don’t feel it’s likely the best carb for CF’s combo, but the one I had and was using for a dyno mule....... I only did a tweak to the air bleeds and jets.
It was actually one of the better running Demon carbs I’d used.
However, I was using it for higher HP builds mostly.
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well took your advice and jetted it back up so it only 2 jet sizes below what came with the main body
put it all back together with the new base plate and jet extensions.
Turned mixture screws out 1-1/2 on all for corners. it was late but had to hear it run. started right up, but by the time i got the float level set. it was loading up bad. Rev it up enough to clean it up and shut it off. A little late for raw/ open exhaust!!!
Got to work tomorrow so will have to fiddle with it when i get home.
put it all back together with the new base plate and jet extensions.
Turned mixture screws out 1-1/2 on all for corners. it was late but had to hear it run. started right up, but by the time i got the float level set. it was loading up bad. Rev it up enough to clean it up and shut it off. A little late for raw/ open exhaust!!!
Got to work tomorrow so will have to fiddle with it when i get home.
PRH
Well-Known Member
That Brawler 850 is starting to look better and betterIf i did Give up and just buy a Brawler it would probably be the 750 race carb.(yes i have probably spent enough to buy one.) But in the end, will probably do as you said and have 2 carbs for he price of 3!!!!
But i'm not giving up yet.
Just got home.
Time to see if it make my eyes water at idle and if i can tune it out.
But i'm not giving up yet.
Just got home.
Time to see if it make my eyes water at idle and if i can tune it out.
PRH
Well-Known Member
What are you working with right now?
new body, new baseplate, Demon blocks?
Looking at your “build sheet”, it would appear much of what you’ve listed for orifice sizing on the Demon blocks doesn’t agree with the specs in the catalog.
After thinking about your rich idle situation....... and the fact that you can get a .054” drill bit pretty far into the IFR....... if just doesn’t seem to want to come around....... I’d replace those with “fresh” IFR’s that were the desired size all the way through.
The length of the restriction is a factor(at least it is with jets).
new body, new baseplate, Demon blocks?
Looking at your “build sheet”, it would appear much of what you’ve listed for orifice sizing on the Demon blocks doesn’t agree with the specs in the catalog.
After thinking about your rich idle situation....... and the fact that you can get a .054” drill bit pretty far into the IFR....... if just doesn’t seem to want to come around....... I’d replace those with “fresh” IFR’s that were the desired size all the way through.
The length of the restriction is a factor(at least it is with jets).
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I'm just mad as @#$%@#$^^@ at myself!
Get home from work, wife has honey does, final get back to my car. Go to shut my hood and my new Super Sucker spacer is just a little bit higher than the spacer I was using before and the air cleaner/carb stud was hitting my hood. pull it off and get my hacksaw out and proceed to shorten it. well won't go threw all the details of my stupidity!!!!! but the last push of the hacksaw was threw my KNUCKLE!!!!!!
Just missed my tendent(thank heavens!) and 7 stitches later, as well as a tetanus shot.
I'm back home.
Get home from work, wife has honey does, final get back to my car. Go to shut my hood and my new Super Sucker spacer is just a little bit higher than the spacer I was using before and the air cleaner/carb stud was hitting my hood. pull it off and get my hacksaw out and proceed to shorten it. well won't go threw all the details of my stupidity!!!!! but the last push of the hacksaw was threw my KNUCKLE!!!!!!
Just missed my tendent(thank heavens!) and 7 stitches later, as well as a tetanus shot.
I'm back home.
PRH
Well-Known Member
Yikes!!!
That’s gonna leave a mark.
That’s gonna leave a mark.
yellow rose
Overnight Sensation
I'm just mad as @#$%@#$^^@ at myself!
Get home from work, wife has honey does, final get back to my car. Go to shut my hood and my new Super Sucker spacer is just a little bit higher than the spacer I was using before and the air cleaner/carb stud was hitting my hood. pull it off and get my hacksaw out and proceed to shorten it. well won't go threw all the details of my stupidity!!!!! but the last push of the hacksaw was threw my KNUCKLE!!!!!!
Just missed my tendent(thank heavens!) and 7 stitches later, as well as a tetanus shot.
I'm back home.
Damn. This carb work is giving you a beat down!!!
OK now that i have vented.
Yes proform base,main and Demon metering blocks
I'm not going to condemn the metering block or that it has been modified.......I need to re check it all the next time it's apart. Pulled out all my pin vic drill bits and for an example i said that the emulsion hole were 29 and 25s.......I have a 22 31 and a 33 so don't know where that came from except poor judgment on my part.
Will be more diligent with the next measuring.
After thinking about your rich idle situation....... and the fact that you can get a .054” drill bit pretty far into the IFR....... if just doesn’t seem to want to come around....... I’d replace those with “fresh” IFR’s that were the desired size all the way through.
The length of the restriction is a factor(at least it is with jets).
After i turn in the idle mixture screws in about half of a turn(around 3/4 to 1 turn out) it idle just fine and there is no super strong exhaust smell at idle, like there was last night.
so i think i'm ok with with that....for now.
I wasn't able to drive it today but the stumble is still there. whack the throttle in neutral, primaries only no problem. To the floor and stumble. when completely heat soaked stumble goes away. In gear, in 3d gear stomp and stumble.
I'm really beginning to think the stumble is a RICH stumble, not Lean stumble. when i whack it to the floor, in gear, if i don't hold some throttle after the full throttle stomp it will die. Then i have to hold the throttle part of the way open to restart.
Yes proform base,main and Demon metering blocks
I'm not going to condemn the metering block or that it has been modified.......I need to re check it all the next time it's apart. Pulled out all my pin vic drill bits and for an example i said that the emulsion hole were 29 and 25s.......I have a 22 31 and a 33 so don't know where that came from except poor judgment on my part.
Will be more diligent with the next measuring.
After thinking about your rich idle situation....... and the fact that you can get a .054” drill bit pretty far into the IFR....... if just doesn’t seem to want to come around....... I’d replace those with “fresh” IFR’s that were the desired size all the way through.
The length of the restriction is a factor(at least it is with jets).
After i turn in the idle mixture screws in about half of a turn(around 3/4 to 1 turn out) it idle just fine and there is no super strong exhaust smell at idle, like there was last night.
so i think i'm ok with with that....for now.
I wasn't able to drive it today but the stumble is still there. whack the throttle in neutral, primaries only no problem. To the floor and stumble. when completely heat soaked stumble goes away. In gear, in 3d gear stomp and stumble.
I'm really beginning to think the stumble is a RICH stumble, not Lean stumble. when i whack it to the floor, in gear, if i don't hold some throttle after the full throttle stomp it will die. Then i have to hold the throttle part of the way open to restart.
PRH
Well-Known Member
Just keep in mind the basic premise of the discharge nozzle sizing is the duration of the pump shot, not the volume.
Smaller nozzle = longer shot
Bigger nozzle = shorter shot
The length of pump stroke determines the volume, via the pump cam lift.
Smaller nozzle = longer shot
Bigger nozzle = shorter shot
The length of pump stroke determines the volume, via the pump cam lift.
I have played all around with nozzle sizes cam sizes. It just don't seem to be the problem.(really hasn't change a thing. 50cc squirter i have not tried yet....but if it's over rich at the hit, should be more so with a 50cc)
I really and truly think it has to do with the timing of the rear transfer slot and the ventures. but have now way of proving...let alone fix it.
Maybe i loosen the squirter arm on the primary side, (less shot), rev past that point and whack the throttle......see what happens. do the same with the secondary pump arm. With the squirter timing late on the secondary side.....It will bog less if it's were the problem is.?1...!1?
Or maybe lower the float level on the secondary........will cause the booster to come in later........right........or would it make it start sooner.
Sorry just grasping at straw.
I really and truly think it has to do with the timing of the rear transfer slot and the ventures. but have now way of proving...let alone fix it.
Maybe i loosen the squirter arm on the primary side, (less shot), rev past that point and whack the throttle......see what happens. do the same with the secondary pump arm. With the squirter timing late on the secondary side.....It will bog less if it's were the problem is.?1...!1?
Or maybe lower the float level on the secondary........will cause the booster to come in later........right........or would it make it start sooner.
Sorry just grasping at straw.
The only time i have not been dealing with this stumble was when i was having the lean pop problem.
Maybe i should point the Gopro at the secondary venturi and see what the fuel pattern look like.....
can't do this while i'm driving, but in neutral.
Maybe i should point the Gopro at the secondary venturi and see what the fuel pattern look like.....
can't do this while i'm driving, but in neutral.
I thought that i had posted this video but i guess not.
this is not from today but is exactly what it is doing today!!!!!
Ok not EXACTLY.....It is idling after the hit.
Today it will die coming back to idle.
That is My Demon before the main body change.
if you watch it to the end there is some slo mo of it.
this is not from today but is exactly what it is doing today!!!!!
Ok not EXACTLY.....It is idling after the hit.
Today it will die coming back to idle.
That is My Demon before the main body change.
if you watch it to the end there is some slo mo of it.
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