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 Post subject: 80586 alcohol carb
 Post Posted: Tue Jul 10, 2012 6:24 am 
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G,day all,
I am chucking a query out here for a friend of mine that has a 80586 alcohol dominator on a 445 odd cube dart blocked sbf in a falcon sedan.
he has rear mouned cell, 1/2"vent, magnafuel 500 pump and reg, hopefully he will read this and register and chime in with the finer details, hose sizes etc.
The carb has power valves front and rear, and he is currently running 192 thou jets, he has ran 200's.
He has the carb turned sideways and it 60 fts ok but he feels it doesnt pull well in the 2nd half of the track.
Fuel pressure is fairly constant and doesn't drop more than 1psi down to 6ps on the pass.
float levels have been everywhere, jet extensions are removed.
i asked him to check the size and position of the air bleeds and in the front from the centre out they go .028, .054, .028, the rear should be the same by the holley info but they are actually .028, .028, .054 from the centre out.
The carb was bought new so it has std boosters etc, etc in it.
My friend is not a mechanic so would not be comfortable modifying a carb.
Does anyone see anything obvious here or have experience with this carb?
I have had zero dominator experience!
Thanks very much!
Paul


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 Post subject: Re: 80586 alcohol carb
 Post Posted: Tue Jul 10, 2012 8:31 am 
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CLASSIC!! He's running out of fuel down track and it's likely not that he doesn't have enough fuel system. It's probably because it's very hard to get a single .150 needle seat to flow enough fuel @ 7/8psig to feed two 190s jets down track.

BLP has some larger needle seats and I'd try those before I'd go any further.

Oh, and THIS is the reason that most PPL run a belt drive pump with methanol carbs!

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 Post subject: Re: 80586 alcohol carb
 Post Posted: Tue Jul 10, 2012 10:11 am 
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According to the Holley data sheet they should be .028, .054, .028 front and back. BLP has .170 N&S's available, PM nomad here if you want a pair and anything else you need for carbs, he can save you a little.


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 Post subject: Re: 80586 alcohol carb
 Post Posted: Tue Jul 10, 2012 11:14 am 
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jmarkaudio wrote:
PM nomad here if you want a pair and anything else you need for carbs, he can save you a little.


OK so this is a 3 circuit carb then. Sorry, missed that part but the same thing applies on the .150 needle seats.

Mark, does Bruce ship to Oz? Cuz that's where this guy is. :-k

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 Post subject: Re: 80586 alcohol carb
 Post Posted: Tue Jul 10, 2012 11:16 am 
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 Post subject: Re: 80586 alcohol carb
 Post Posted: Tue Jul 10, 2012 3:04 pm 
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Hummm, isn't the IAB on the outside on a 3 circuit Dominator with the intermediate in the center? :-k If so, why would that carb have an .028 in that IAB position? :-k

I'm confused, but one thing is for sure. If this one is like that, then someone has horked with it and put them back in the wrong place! I expect that idle and T slots on one end are way out of whack also.

Having that .054 in the intermediate sure would make that part of the circuit lean, hey. #-o

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 Post subject: Re: 80586 alcohol carb
 Post Posted: Tue Jul 10, 2012 3:13 pm 
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G,day,
Thanks for the replies! i'll get him to have a look here.
Just so i'm clear Mark with the air bleeds swapped around what will that cause or what symptoms?
The funny part about it is that it has run better in the top end but has seemed to have dropped off.
we went through and had a good look at the weather over the last few months and although he has picked up in 60 ft times the mph at the deep end has dropped by at least 2.
Plugs don't look too bad.
He is in the process of putting a lambda guage into the car so that will be interesting.

So what fuel psi can you run with the 170 thou needles? i'm sure he will grab some and with power valves roughly what is the maximum jet size you can run before you max out the booster channels or what ever in a dominator that is the restriction?
I am about 7hrs awy so is a bit hard to help him.
Thanks again!
Paul


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 Post subject: Re: 80586 alcohol carb
 Post Posted: Tue Jul 10, 2012 4:03 pm 
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tuffxf wrote:
G,day,
Thanks for the replies! i'll get him to have a look here.
Just so i'm clear Mark with the air bleeds swapped around what will that cause or what symptoms?

The funny part about it is that it has run better in the top end but has seemed to have dropped off.
we went through and had a good look at the weather over the last few months and although he has picked up in 60 ft times the mph at the deep end has dropped by at least 2.
Plugs don't look too bad.
He is in the process of putting a lambda guage into the car so that will be interesting.

So what fuel psi can you run with the 170 thou needles? i'm sure he will grab some and with power valves roughly what is the maximum jet size you can run before you max out the booster channels or what ever in a dominator that is the restriction?
I am about 7hrs awy so is a bit hard to help him.
Thanks again!
Paul


Paul, I'm not Mark but I can answer some of these questions. ;-)

Those 3 circuit metering blocks most likely have the idle tubes in the mainwells and if that's the case, then that may compound the "not enough fuel" problem up top. :-k

Having the wrong air bleed in the intermediate will cause that circuit to be lean, which may not be readily apparent with the .028 in the IAB location, which would quite possibly make the T slot and idle rich and cover it up. If it's wrong in the secondary side then that makes it less likely that it would be noticed at part throttle too.

Although I've never run those .170 needle seats, I have run .150s with 8psig with no apparent problems so those .170s should stand 7psig I'm sure. Anything short of blowing the needles off the seats is good for this setup. ;-)

FYI, single needle seat methanol carb setups sold here in the "States" are usually belt drive pumps with a bypass pill like fuel injection uses so that fuel pressure is RPM dependent, ie, at idle and part throttle most see around 3psig but down track the regulator is set for between 10 and 12 psig to add enough fuel to keep the engine supplied up top. Problem with that is that once the throttle is closed and engine RPM is still up, well then you have both bowls flooded with fuel and likely a rough running engine in the shut down area. Since methanol doesn't behave the way gas does, ie, foul plugs etc then most ppl learn to put up with the shut down area flooding. Not sure if the .170 needle seats will work at a lower pressure though as they're only .020 larger than the .150s. They are cheap enough to give them a try though and I would do that before I tried anything else.

One cure for this problem is to have 2 needle seats per fuel bowl but those are expensive and one of the most popular brands, PCI Super Bowls, are no longer in production.......I THINK! I've got a set of those on an 1150 Dominator on methanol but it's a 2 circuit monster that I've modified heavily to make it supply enough fuel down track (metering block restriction problem not needle seats). But that's a story for another time after your friend gets his air bleed problems straightened out. ;-)

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 Post subject: Re: 80586 alcohol carb
 Post Posted: Tue Jul 10, 2012 4:08 pm 
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They likely have .028 IAB's in it to get enough idle and transition fuel through it. Probably not the ideal way, but Holley has not been known for it's calibrations for some time. And doubt Bruce wants to deal with overseas, I need to find out from Mike Laws who they send stuff too in Austrailia, there is a speed shop over there that is a dealer for them.

Not to muck up the thread, Mike Laws just won T/D in Norwalk this last weekend. \:D/


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 Post subject: Re: 80586 alcohol carb
 Post Posted: Tue Jul 10, 2012 10:35 pm 
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Thanks again for the replies!
When the carbs are turned sideways is there a need for different floats so that the g force of the fuel under acceleration is not holding the float up?
Cheers
Paul


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 Post subject: Re: 80586 alcohol carb
 Post Posted: Tue Jul 10, 2012 11:22 pm 
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Paul I also have a dual 750 methanol and also gas carb setup that I've run on my engine with standard Holley floats and I haven't seen anything that I would say was a problem with those. This setup was on a door car doing 1.15 short times and also on my dragster doing 1.12 short times. So go figure.

Can it be better? Dunno cuz I never tried anything different. ;-) I have however heard of a guy that run the roundy round floats on sideways mounts though. In fact, I believe one of our members does this, ie, Eric68 if memory serves.

And another FYI, I had considered turning my 1150 methanol Dominator sideways but the linkage problems and dealing with the 14 foot throttle cable kinda changed my mind. ;-)

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 Post subject: Re: 80586 alcohol carb
 Post Posted: Wed Jul 11, 2012 1:40 am 
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G,day Ken,
You are up late mate! thanks for that,
Thats good to hear, i have a apd 750 meth carb and was thinking about turning it sideways as well, don't really know why as it has no power valves anyway but the hassles with the cable and rerouting fuel lines turned me off as well!
you mentioned the pci superbowls earlier, i think they would have to be a great idea, wasn't braswell going to make some? i even have half an idea that even john kyle at apd was going to do something but i may be confused there.
If i read this whole deal right basically you should be able to jet up enough to slow the car?
Mine will do it with the belt pump.
Cheers
Paul


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 Post subject: Re: 80586 alcohol carb
 Post Posted: Wed Jul 11, 2012 3:29 am 
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Paul, you thought that last post was late? How about this one? ;-)

FYI, power valves aren't the reason I wanted to run mine sideways as I don't run power valves in any of my methanol carbs. My main reason is that I think that you get better fuel distribution front to rear. It's my opinion that with conventional carb mounting G forces cause major problems with fuel levels in the bowls and also with fuel distribution in the cross wells and banjos and the sideways mount "might" help with both.

PCI Bowls are a damn good idea and I actually have two sets of them on the two 1150 methanol carbs I have. Braswell had floats for them a few years back but the bowl itself hasn't been in production for a long time. Doug Schriefer of Braswell is a member here and there was talk a few years back about them retooling to make them again but I guess that went by the wayside. I've seen a couple of others brands out there but like the PCI version the best.

Good to hear that you're setup to run methanol the right way. Lots of ppl try to do that with an electric pump and they usually wind up either giving up or going to the belt drive. And BTW, an electric pump will work fine with either the PCI bowls or DUAL carbs as you have twice as many needle seats to produce the same power so 10 to 12 psig down track isn't needed. In fact, my first attempts at running methanol was with those dual 750s and an Aeromotive electric pump. Fuel delivery was never a problem but pump life was as I went through 3 of those pumps in 13 months so that was it for me. That was when I bought this BLP belt drive and never looked back!

Oh, and yes you are correct, ie, how do you know it's rich enough to run as fast as it can if you can't get it rich enough to slow it down??

I wish your friend luck in his endeavor but I'm not going to hold my breath while I wait for him to get it sorted out. I would be interested in seeing if those .170 needle seats will help him though. and an A/B test on that would be nice once he gets his air bleed problem sorted out. ;-)

OK, I've had my early morning snack so it's back to bed now! =; This is what happens when you take naps in the afternoon! :-

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 Post subject: Re: 80586 alcohol carb
 Post Posted: Wed Jul 11, 2012 4:00 am 
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Ken that's not late, it's early!
I'll let you know how Rick goes with it, thanks a lot for the assistance!
Cheers
Paul


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 Post subject: Re: 80586 alcohol carb
 Post Posted: Wed Jul 11, 2012 4:58 am 
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The Carb Shop also has duel needle & seat bowels but I think they were in the neighborhood of $700
bucks.. O:)

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