cookietruck
Well-Known Member
buy these and ask if they can put blanks in all the emulsion holes...then drill them to yr desired size...
HOLLEY ULTRA HP Billet Metering Block, for GAS, fits QFT-BG Carburetors too | eBay
Holley/Demon Carb stumble
- Thread starter Cudafever
- Start date
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buy these and ask if they can put blanks in all the emulsion holes...then drill them to yr desired size...
HOLLEY ULTRA HP Billet Metering Block, for GAS, fits QFT-BG Carburetors too | eBay
Thats a nice plan B.
yellow rose
Overnight Sensation
What CT posted will work but you need to buy some brass and drill bits. I have no idea what is in them for emulsion. I did see those blocks have changeable power valve channel restrictors as well, which is cool.
You can really end up in the weeds if you are not careful. But if you want to learn it can be fun. And frustrating.
I found this while i was searching today.
https://documents.holley.com/techlibrary_carb_numerical_listing.pdf
https://documents.holley.com/techlibrary_carb_numerical_listing.pdf
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yellow rose
Overnight Sensation
It does have 5 holes. You can plug or open any or all of them and change the hole size just by using some brass 6/32 set screws drilled to whatever size you want.
I decided at one point I needed more emulsion so I used 4 of the 5 holes in my blocks and started with a .034 hole and went down to a .028 hole in the bottom.
I can tell you it didn't work for ****. I'm not sure how I came up with the math for that but I went back to 2 holes of .026 each. I may try one more hole in the bottom to clean up the upper end of the fuel curve but at this point I have other stuff I want to try.
mderoy340
Well-Known Member
much cheaper to get the brass set screws and drill and tap the demon blocks. Plug the bottom emulsion hole.
PRH
Well-Known Member
There’s plenty of guys who have messed with swapping parts around way more than I have........ but I’ve never really had any problems that I can remember with 3 hole emulsion.
That said, I haven’t done very much “cross breeding” of parts from one carb to another.
I also agree with modifying the Demon blocks for adjustable emulsion, which “should” make them more universal.
That said, I haven’t done very much “cross breeding” of parts from one carb to another.
I also agree with modifying the Demon blocks for adjustable emulsion, which “should” make them more universal.
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I will keep that in the back of my mind. But the main reason, i'm jumping at the chance to remove them demon metering block. Is because i had to dig half broken off thread out of the back of the main jet holes due to a mismatch. Causing the back thread to have a u shape. Causing the end tread to be a straggler. had to bend and pull on the last threads to get them out of there.
I may go back to them block at a later date, and maybe should have done that. but if i can get it to run right with the 3310 blocks, and then think i what to experiment, i have a know good block to go back to if i get spun out in the weed.
I may go back to them block at a later date, and maybe should have done that. but if i can get it to run right with the 3310 blocks, and then think i what to experiment, i have a know good block to go back to if i get spun out in the weed.
My metering blocks just showed up tonight.
hope to get off work at a decent time to clean them up and take a good look at them.
One already had jet extension in it. and the other need idle mixture screws. Will steal them from one of my other parts carbs for now.
Don't look like they have been tampered with but will know more tomorrow.
hope to get off work at a decent time to clean them up and take a good look at them.
One already had jet extension in it. and the other need idle mixture screws. Will steal them from one of my other parts carbs for now.
Don't look like they have been tampered with but will know more tomorrow.
Got home late have to be back to work early so here's some pic's and maybe i can comment on it tomorrow night
did you notice there's no kill bleed on the right one? It also does not have the hole completely drilled for the idle mixture screws????
did you notice there's no kill bleed on the right one? It also does not have the hole completely drilled for the idle mixture screws????
skrews
Well-Known Member
The block on the left is is configured correctly. The one on the right wont work, no kill bleed or idle mixture screws.
yellow rose
Overnight Sensation
I've never seen a block not have the kill bleed...unless it's off some economy carb or maybe off of the TQ replacement carb. That seems strange.
I wouldn't worry about the kill bleed.
Not always needed. Sometimes for siphon break, the angle channel was drilled horizontal. Early 3310s are like that. Maybe secondary blocks only. The number is hard to read but that might be from a -1.
On the primary block (left one), can you see the idle feed restrictions?
Not always needed. Sometimes for siphon break, the angle channel was drilled horizontal. Early 3310s are like that. Maybe secondary blocks only. The number is hard to read but that might be from a -1.
On the primary block (left one), can you see the idle feed restrictions?
PRH
Well-Known Member
Adding the mixture screws is no big deal...... I’ve done it many times when converting a 2 corner idle carb to 4 corner.
Generally a good book. Covers all the basics and then snippets of more subtle stuff. A coupe things its not clear about and the PV thing is just wrong.
I think YR covered some this.
I'll just go over everything.
#8. Top of the dogleg is opposite the main air bleed cross drilling in the main body.
Sometimes there is a hole drilled in the top of the dogleg. Originally this was done in carbs with emulsion tubes.
#22 Emulsion holes, top into the angle channel is an anti-siphon hole aka kill bleed. Call that a 2 e-hole block with kill bleed.
#24 Connecting passage to bottom of Main well.
#25 Connecting passage to bottom of Idle up well. Idle Feed restrictions are often in this passage.
Here's the bowl side with the wells and connecting passages drawn in.
Body with old gasket on it. Impressions show the Air well and Idle down well.
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Fuel level should be close to the upper e-hole.
Pressure differences will cause height of the fuel levels in the well to vary when the engine is running.
(L, P, H indicate various locations used for idle feed restrictions.)
Pressure differences will cause height of the fuel levels in the well to vary when the engine is running.
(L, P, H indicate various locations used for idle feed restrictions.)
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Skimming back, the problem you mentioned is on the 1-2 shift. I don't have the experience here to suggest one thing or another.
I noticed the 750 DP main bodies you showed are equiped with downleg boosters. I forget who, but someone mentioned these can be difficult to get started. You would think not 'cause in general they have higher signal. But at low flow they can be bitchy. I'm finding that seems to be true on the secondary side of the carb I'm working with now.
Something else you mentioned earlier. Losing track.
Get a set of micro drills (80-61) and a regualr number set.
use those as a cheap pin gages (shank side in holes).
Write or type a spreadsheet for each carb.
Something like this:
Throttle position is turns in on the screw. The amount turned in is cross referenced to amount of t-slot exposure on another part of the sheet.
I noticed the 750 DP main bodies you showed are equiped with downleg boosters. I forget who, but someone mentioned these can be difficult to get started. You would think not 'cause in general they have higher signal. But at low flow they can be bitchy. I'm finding that seems to be true on the secondary side of the carb I'm working with now.
Something else you mentioned earlier. Losing track.
Get a set of micro drills (80-61) and a regualr number set.
use those as a cheap pin gages (shank side in holes).
Write or type a spreadsheet for each carb.
Something like this:
Throttle position is turns in on the screw. The amount turned in is cross referenced to amount of t-slot exposure on another part of the sheet.
Lets ignore the effect of the idle circuit on the main.
Fuel in the air well and main well is the same as in the bowl.
Increase airflow through the booster creates a low pressure area.
The upper e-hole allows some change but also restricts flow of air and fuel.
The combination of MAB, e-hole, fuel level and booster signal may move very little to a significant amount of fuel -air mix to the booster at this stage.
The graph YR posted shows the effects of changing the air bleed and e-hole combinations.
An imprtant take away is that MAB can effect start up.
However, its main job is to controlling AFR at the highest air flows.
Therefore my approach is to adjust the MAB for flat AFR at the top end, while keeping an eye on what's going on at the lower rpms. (talking WOT conditions only).
While we're on the subject.
A hole in the angle passage can delay the start up. (hence the name kill-bleed)
But it may also speed the delivery of fuel by acting as an air jet once flow has started.
A hole in the angle passage can delay the start up. (hence the name kill-bleed)
But it may also speed the delivery of fuel by acting as an air jet once flow has started.
I'm sure i will have lots of good question on all of this, and Thank you, for taking the time to do so!
however I'm home late and have to be up early again.
will study all of this when i get a minute. thank you again
whoops i typed this and for got to send
however I'm home late and have to be up early again.
will study all of this when i get a minute. thank you again
whoops i typed this and for got to send
Ok so i think i need to update this thread so we are all on the same page.
Started with a 850 Mighty Demon carb.
Problem started out as a major bog at the starting line. which bigger squirters did not fix the problem. (Taller tires and a tighter Torque Converter is when this demon start to give me grief. Work grate up to that point)
Bought a proform main body that was smaller ventures, with hopes that it would start the booster sooner and stop the bog. this was a big improvement but caused a lean pop at mid rpm of 2ng gear. jetted up and problem when away but now thinking that it is to rich.!?
cars 60 foot was the same at 1.7XX but was a bouth a 1.5 miles per hour down in the 1/8 and 1.5 tenths slow as well. Bad air day was some of this loss.
Wanting to have a good know base for the fuel/metering, i have been trying to find a couple 3310 holley front metering blocks to try.
found one and am still on the hunt for another.
Started with a 850 Mighty Demon carb.
Problem started out as a major bog at the starting line. which bigger squirters did not fix the problem. (Taller tires and a tighter Torque Converter is when this demon start to give me grief. Work grate up to that point)
Bought a proform main body that was smaller ventures, with hopes that it would start the booster sooner and stop the bog. this was a big improvement but caused a lean pop at mid rpm of 2ng gear. jetted up and problem when away but now thinking that it is to rich.!?
cars 60 foot was the same at 1.7XX but was a bouth a 1.5 miles per hour down in the 1/8 and 1.5 tenths slow as well. Bad air day was some of this loss.
Wanting to have a good know base for the fuel/metering, i have been trying to find a couple 3310 holley front metering blocks to try.
found one and am still on the hunt for another.
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Now with all of that.
I have decided to buy a new throttle shaft or base plate(still 1.75 butterflies)
Like i have said above the primary just work!
Secondarys is were the stumble is happening. and is also were i found a couple of pieces of alu that was kinda acting like a reed valve in the fuel transfer slot of the secondarys. they look wider to me as well compared to the primary transfer slot.
Another reason i want to replace it is that this was a used carb and had holes drilled in the butteries, that are to large. I would soldier them up and re drill, but either the throttle shaft is bent or the the butterflies.
When i took the carb off this time i noticed that the butterfly/transfer slot was less than a square on the primary side and the secondary side had one blade that just showed the beginning of the transfer slot, and the other had it completely covered up.
If you want to see what came out of the secondary transfer slots go back to post 78.
I have decided to buy a new throttle shaft or base plate(still 1.75 butterflies)
Like i have said above the primary just work!
Secondarys is were the stumble is happening. and is also were i found a couple of pieces of alu that was kinda acting like a reed valve in the fuel transfer slot of the secondarys. they look wider to me as well compared to the primary transfer slot.
Another reason i want to replace it is that this was a used carb and had holes drilled in the butteries, that are to large. I would soldier them up and re drill, but either the throttle shaft is bent or the the butterflies.
When i took the carb off this time i noticed that the butterfly/transfer slot was less than a square on the primary side and the secondary side had one blade that just showed the beginning of the transfer slot, and the other had it completely covered up.
If you want to see what came out of the secondary transfer slots go back to post 78.
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