Carb tunning question : Proform kit installed
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Carb tunning question : Proform kit installed
Just got my Proform body installed and reset the idle (Holley 3310 carb). Everything runs okay but the performance seems worse or slower in the mid-range.
Last night in the garage, I noticed 2-brass nozzles (jets ?) that came with the kit but I didn't replace the ones on the front metering block. Will my carb perform better with them in ???
Checking with you guys before tearing it down again. Also, what are those 8-rubber washers (rings) for ???
Many thanks in advance
Last night in the garage, I noticed 2-brass nozzles (jets ?) that came with the kit but I didn't replace the ones on the front metering block. Will my carb perform better with them in ???
Checking with you guys before tearing it down again. Also, what are those 8-rubber washers (rings) for ???
Many thanks in advance
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From: St Louis MO
Brett
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Thanks Brett 
Also to note, the primarys seem to be running a tad lean while the secondarys are running rich (carbon build-up on the throttle plates).
Have any tips on the Secondary metering block ?.....I installed the plate and gasket that came with it but not sure what it's for or how it works since there were no pictures with the instructions.
Also to note, the primarys seem to be running a tad lean while the secondarys are running rich (carbon build-up on the throttle plates).
Have any tips on the Secondary metering block ?.....I installed the plate and gasket that came with it but not sure what it's for or how it works since there were no pictures with the instructions.
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For anyone else looking to do this, here's a DIY site with pics (albeit Ford 
)
http://www.fordmuscle.com/archives/2005/10/CarbRebuild/
)http://www.fordmuscle.com/archives/2005/10/CarbRebuild/
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From: St Louis MO
I've really only worked with 4-corner idle double pumpers. Those 3310s are different so I can only give you general hints and nothing specific. I do know the 3310s have a secondary metering plate so there's no adjustability whatsoever on the secondary side other than float level.
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Here's a link for the upgrade > http://www.truckworld.com/How-To-Tec...y_upgrade.html
Perhaps this would allow me to lean-out my 'RICH' mixture in the Secondaries.
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Brett
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The proform bodies typically come with huge high speed bleeds. This causes the jetting to need to be way bigger. It's better (IMHO) to size the high speed bleeds pretty close to stock unless you're pulling big inches at high rpm thru the carb. Big high speed bleeds cause the main system to start late also. Typically .002 inch bigger the stock is adequate for almost every performance application.
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When you say 'speed bleeds'.....your referring to the 'air bleeds' in just above the Venturis ?
One step at a time. I'll replace the mixture screws provided in the kit. Then I plan on seeing if I can easily adapt a secondary metering block. Finally, if its the air bleeds mismatched to my engine, I'll look at downsizing.
So far you guys have been very helpful. I just don't know anyone in my area that messes with carburetors anymore. As for me, I'm still learning about Holley's since I used to deal strictly with Quadrajets and Carter AFB's in my early days.
One step at a time. I'll replace the mixture screws provided in the kit. Then I plan on seeing if I can easily adapt a secondary metering block. Finally, if its the air bleeds mismatched to my engine, I'll look at downsizing.
So far you guys have been very helpful. I just don't know anyone in my area that messes with carburetors anymore. As for me, I'm still learning about Holley's since I used to deal strictly with Quadrajets and Carter AFB's in my early days.
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Be very careful if you start messing around with the air bleeds. It's the fastest way I know of to melt a motor. The very best thing you can do is buy a Holley tuning book. It will explain how the carb operates and how the circuits interact and affect each other. It will be money well spent if you want to start modifying carbs.
If you want, I have a couple of books I can let you borrow. They really helped me understand Holleys and how to tune mine.
Another thing you might want to consider is getting an O2 sensor in your exhaust. It will allow you to get your tuning dead right. You don't even need one of the expensive wideband units, a narrow band along with a multimeter works fine for what you are trying to do.
Brett
If you want, I have a couple of books I can let you borrow. They really helped me understand Holleys and how to tune mine.
Another thing you might want to consider is getting an O2 sensor in your exhaust. It will allow you to get your tuning dead right. You don't even need one of the expensive wideband units, a narrow band along with a multimeter works fine for what you are trying to do.
Brett
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When you say 'speed bleeds'.....your referring to the 'air bleeds' in just above the Venturis ?
One step at a time. I'll replace the mixture screws provided in the kit. Then I plan on seeing if I can easily adapt a secondary metering block. Finally, if its the air bleeds mismatched to my engine, I'll look at downsizing.
So far you guys have been very helpful. I just don't know anyone in my area that messes with carburetors anymore. As for me, I'm still learning about Holley's since I used to deal strictly with Quadrajets and Carter AFB's in my early days.
One step at a time. I'll replace the mixture screws provided in the kit. Then I plan on seeing if I can easily adapt a secondary metering block. Finally, if its the air bleeds mismatched to my engine, I'll look at downsizing.
So far you guys have been very helpful. I just don't know anyone in my area that messes with carburetors anymore. As for me, I'm still learning about Holley's since I used to deal strictly with Quadrajets and Carter AFB's in my early days.
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From: St Louis MO
The high speed bleeds' function is to provide air for fuel emulsification in the main metering system. Increasing the bleed size will allow more air in the mix, leaning the air/fuel ratio. Decreasing the bleed size will decrease pressure across the main jet, allowing more fuel to be pulled from the main well. This will make the mixture richer.
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The high speed bleeds' function is to provide air for fuel emulsification in the main metering system. Increasing the bleed size will allow more air in the mix, leaning the air/fuel ratio. Decreasing the bleed size will decrease pressure across the main jet, allowing more fuel to be pulled from the main well. This will make the mixture richer.
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From: St Louis MO
Verskel - blp.com has metering blocks (even ones with adjustable emulsion bleeds) and any other carb part you may want. That's where I got the annular boosters that are in my 850 dp. Good luck on your carb adventure!
Brett
Brett
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Thanks guys.......awesome help here and I'll be re-reading your posts until I understand completely. 
Right now, I have brain overload.
Basically, my old carb was running with the choke-horn style and was a bit rich to help out the idle. I never re-adjusted the float levels after replacing the 'main body'. Anyhow, looks like I'll need to go back and re-check everything. I'll read up on the air bleeds and see what Proform provided me with.
Oh......and are the metering blocks interchangeable with Primary & Secondary ???
I have 2 Holley 3310's and I'm only using parts off of 1 of them. I'm thinking of combining parts so I can have 2 metering blocks for adjustments. Keep in mind this is a shoestring budget operation at the moment and I'm trying to be resourceful.
Right now, I have brain overload.
Basically, my old carb was running with the choke-horn style and was a bit rich to help out the idle. I never re-adjusted the float levels after replacing the 'main body'. Anyhow, looks like I'll need to go back and re-check everything. I'll read up on the air bleeds and see what Proform provided me with.
Oh......and are the metering blocks interchangeable with Primary & Secondary ???
I have 2 Holley 3310's and I'm only using parts off of 1 of them. I'm thinking of combining parts so I can have 2 metering blocks for adjustments. Keep in mind this is a shoestring budget operation at the moment and I'm trying to be resourceful.
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The front and rear metering block from a 3310 should have different size power valve restrictions (the holes behind the power valve) that's why the carbs originally had bigger jets in the rear. The standard holley carb bodies flow better in the rear versus the front. This is not true for the race style bodies (or pretty close front to rear flow anyway). So you can use front metering blocks from your 2 3310's and then square jet the carb if all the high speed bleeds are the same size. I think the proform bodies are already drilled for 4 corner idling so you can make the carb a four corner idler if you so desire (really only useful is you have a lot of cam timing).
