Holley Air Bleed Modification.

[BlackoutSteve]

Re: Holley Air Bleed Modification.

The only listed Holley main body is the 134-300 which is a 750 cfm.

I haven't enquired to see if the 1000cfm HP annular bodies are available as a spare part because I don't think the costs will be at all worth it compared to the $30 I've already spent on the 4.1mm drill and 10/32 intermediate and bottoming thread taps.
$30 and it will be air-bleed ready. ;)

Simply buying the required air bleeds is a lot cheaper than buying the gear to drill my own. Who knows, I might lash out and get the full Holley kit.

[urwurznitmahre]

Re: Holley Air Bleed Modification.

I buy brass set screws 50 or 100 at a time from www.mcmaster.com. They are much cheaper than air bleeds and you are not stuck with the 10-32 size. On most Holley main bodies that I have done the high speed bleed usually goes to 8-32 and the low speed bleed goes to 10-32. The IFR goes to 6-32 and PVCR I like to take out to 10-32.

The mod is very easy. I use a drill one index size smaller than the casting and drill down into the pressed in brass bleed. About halfway through the brass insert usually grabs, spins, then pulls out leaving the hole "as cast."

After removing the factory brass bleed I use the appropriate size tap and slowly cut about 4 or 5 full threads down into the hole. The taper on the end of the tap will leave partial threads that the set screw will bottom out into and seal. Don't go too deep or the set screw will screw all the way in.

After you have the set screws fitting its easy to swap air bleeds -- you just drill your own brass set screws with your indexed drill set and you're golden.

if you make your own .
how hard you think it be to make them like a needle and seat..
for total adjustablity without having to carry a bunch of bleads to a tuning dyno or track..
the needle would just need a lock nut like the float ..so it not move once set..
input???is this possable.. i'd think with a cnc machine it be a piece of cake to make a ton of them..

[BlackoutSteve]

Re: Holley Air Bleed Modification.

Much easier to swap the bleeds than the effort required to make them adjustable IMO.

[urwurznitmahre]

Re: Holley Air Bleed Modification.

Much easier to swap the bleeds than the effort required to make them adjustable IMO.

maybe so.. but it be one part to stock instead of what 12 different part #
less chance of dropping one into the carb.. brass isn't magnetic.
steve if an adjustable bleed was avilable,stocked beside the bags of 12 different sizes, of bleeds..
would you by the set of 4 adjustable ones.. or 6 bags of 10, sized bleeds..

it was just an idea, the seems marketable, and cost no more to make on a cnc machine as the standard ones ..

[Eric68]

Re: Holley Air Bleed Modification.

urwurznitmahre,

That could be done and is a neat idea. The problem is that every Tom, Dick, and Harry would start messing with their air bleeds and cause themselves all kinds of problems ;)

You would also have to find a way to consistently set them to the flow rate you want and have a way to keep them from moving once set. Air bleeds are very sensitive -- especially the high speed bleeds. A thousandth or two change in orifice diameter can make a noticeable difference in carb behavior.

milner351,

My setup is really as simple as dirt. I have a cheapo $50 Harbor Freight drill press. The teeth in the chuck do not have all the fancy machine work that a high end (or even decent US made low end LOL) press does -- since the teeth in the chuck aren't rounded much the chuck will grab bits down to .025". I'd be embarrassed posting a picture of my "high tech" HF drill press. LOL

To hold the set screws I just use a flat piece of steel with threaded holes that are not tapped all the way through. That way I can screw in a batch of 4 set screws at a time and have at it.

[mrmustangman357]

Re: Holley Air Bleed Modification.

you sure your idle circuit is not coming off too early? or is this WOT testing?

PVCRs may need to be looked at. you'd have to look at AFR on the dyno to notice it

[Scott Liggett]

Re: Holley Air Bleed Modification.

Steve, I went back and reread this thread because I'm thinking of opening up my 850's air bleeds for the idle circuit. I remembered that I got spare screw in air bleeds from Quik Fuel for my Proform carb. I got 8 of them and they are just pilot drilled very small and you work your way up from your current air bleed size. They were cheap and sent in a envelope so no expensive shipping.

Now, if I just could remember which bleeds are for the idle circuit.

[BlackoutSteve]

Re: Holley Air Bleed Modification.

Page 8, fig 10. ;)

http://www.holley.com/data/Products/Technical/199R10016-2.pdf

Opening your air bleeds is leaning.. Are you running rich?

[Scott Liggett]

Re: Holley Air Bleed Modification.

Page 8, fig 10. ;)

http://www.holley.com/data/Products/Technical/199R10016-2.pdf

Opening your air bleeds is leaning.. Are you running rich?

The 850's idle circuit is rich on my engine. Yes, I want to lean it out. The four idle screws are out 1 turn, but the car will make your eyes water if stand around it idling too long. Turning in the screws in any farther makes the car not want to idle at all.

[joe_rocket45]

Re: Holley Air Bleed Modification.

my hillbilly method is to just solder up the jets if too big and redrill to the proper size, if too small I just drill.
solder, it's cheap and easy.

[BlackoutSteve]

Re: Holley Air Bleed Modification.

Page 8, fig 10. ;)

http://www.holley.com/data/Products/Technical/199R10016-2.pdf

Opening your air bleeds is leaning.. Are you running rich?

The 850's idle circuit is rich on my engine. Yes, I want to lean it out. The four idle screws are out 1 turn, but the car will make your eyes water if stand around it idling too long. Turning in the screws in any farther makes the car not want to idle at all.

Before you touch the air bleeds (which really shouldn't need adjustment), check your ingition has reasonable static advance (at least 12-14?), your idle speed adjustment has a little throttle blade tip-in, and your idle screws should be around 1.5 turns.
Try fitting a vacuum gauge and adjust to get the higest reading possible.
If your cam is anything 1/2 decent, give it 16? initial. My cam is ~260? @ 0.050" and I have 20? initial. Starts well, idle no choke and good vacuum at idle considering the duration.

[Scott Liggett]

Re: Holley Air Bleed Modification.

The car has 16-18 degrees right now. Timing tape came off, so I'm not exactly positive. Cam has 236/242. I'll check the idle speed adjustment to see if the blades are open a bit. I have the dash vacuum gauge. I also have a gauge I made from a vacuum pump. The car idles right about 14-15 inches at 900 rpm.

I did this on the Proform 750, but had screw in studs on that carb. Westech's guys say I was really close when I had the car on the chassis dyno.

[JeffMcKC]

Re: Holley Air Bleed Modification.

Page 8, fig 10. ;)

http://www.holley.com/data/Products/Technical/199R10016-2.pdf

Opening your air bleeds is leaning.. Are you running rich?

The 850's idle circuit is rich on my engine. Yes, I want to lean it out. The four idle screws are out 1 turn, but the car will make your eyes water if stand around it idling too long. Turning in the screws in any farther makes the car not want to idle at all.

OK this will sound dumb at first, but stop and think, do not confuse unburned fuel, with being to rich.

[BlackoutSteve]

Re: Holley Air Bleed Modification.

Good point.. How's your ignition Scott?

I remember switching from a mallory twin point to an MSD electronic with a 6AL and the difference was huge. With the same timing and no other changes, my idle speed was up by almost 300rpm purely from the lack of misfire.
Gone was the fumey idle too.

[JeffMcKC]

Re: Holley Air Bleed Modification.

To cold of plug, not enough timing.........