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mcfly94

Recommend me a carb for my xflow.

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Personally Ive had great success with edelbrocks and Carters, but as far as 2 barrels go the holleys seem to be ok and really there's not much on the aftermarket in 2 barrels that are commonly available here (except maybe demons)

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It's a good idea to use a fuel shutoff tap when using bg's as they have a tendency to push fuel.past the needle and seat when sitting for periods of time (a few members of my hot rod club have had killer backfires and one even hydraulocked his Chev due to the intake being full of fuel after two weeks sitting

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Funny you mention BG's cos that what I'm gunna be using on the ute when I convert it to Methanol,BG 500cfm unit's x 3.But again there based on a holley design LOL.

 

You going to use a progressive linkage with that setup?

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Ummmm sure...foot 1/4 way is 1/4 throttle all way is full throttle...LOL There going to run IR (individual runner) style so any throttle input will be direct just like a Bud Moore set-up and or Webbers do.The thinking is that running Methanol needs extra fuel so I can jet it like a petrol carby (x3 of course) and gain the IR top end which suits my needs with the bonus of Methanol torque via burning more fuel.

 

Taken from C&S Carb's site...

 

Besides previously mentioned airflow calculations, multiplying, reading and measuring errors, four bores will not flow four times what one bore will flow when they are close together, as in a 4 barrel carburetor. The bores are actually “fighting” for the same air. Another factor is no provision is made for fuel flow. The actual air flow will be 8% to 16% less “wet” than dry flow rating. Two reasons for this are, fuel takes up space so it uses up space for air. The second reason is fuel has more mass than air so “Hollow Cone” of vaporized fuel slows down flow velocity. This can be easily observed on large wet flow benches such as the custom C&S facility (shown in photo) which will flow wet or dry. Alcohol will lose more air flow than gas simply because there is more fuel to handle.

 

Back to me...

This suggest why the current trend is to go for bigger carbs than ever before as modern carbs and tuning allows us to make more HP over a wider RPM band.Yes there are limits to the rule but the basics are the same.So while 2 barrels are measured at like 3" where as 4 barrels are done at 1.5" which is half the amount of vacumm so fitting bigger 4 barrels makes sense all of the sudden.It's not new Bud Moore was doing it 30 years ago so if we factor in RPM range and fuel used along with cam shaft engine design 3x500cfm Holleys on the ute should work if maybe a tad small TBH.

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It's a good idea to use a fuel shutoff tap when using bg's as they have a tendency to push fuel.past the needle and seat when sitting for periods of time (a few members of my hot rod club have had killer backfires and one even hydraulocked his Chev due to the intake being full of fuel after two weeks sitting

 

Thats how I killed one set of pistons in my x-flow hydraulic-ed on number 3cly and broke it from a faulty fuel pump set up.Broke the side off number 3 but people will say it was caused by timing and RPM even though it never actually started.Good old cast "race" pistons for ya...LOL

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That's not the pistons fault Rob.  You would have done the same to a forged piston, or more likely transferred the force to another area, i.e. the rod.  Yes I have a man crush on cast pistons. LOL. 

 

But back to the point of the thread, get a Holley on there Mcfly, you wont look back.  Yes Mr Ford put a whole heap of R&D into carb selection, just like they did on that beautiful cast exhaust manifold!!!  Everything factory is a compromise.  They have to design things that will work as a taxi, caravan hauler, rep car that does a million miles, and even police cars.  Then we come along and want them to be speedway, drag or fast road cars. 

 

I don't know one person that's put a Holley on their x-flow and said 'gee I wish I didn't do that'.  Cheap, easy to find and tune and they work. Makes them an easy choice for me.

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im so sick of webers at the moment. iv'e had three of them, all of them have been shit and they are bastards to tune. the local ford garage told me that they have a customer who brings his xf in every week to have the weber retuned haha. 

 

so yep im looking for a holley

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Funny you mention BG's cos that what I'm gunna be using on the ute when I convert it to Methanol,BG 500cfm unit's x 3.But again there based on a holley design LOL.

 

Make sure you follow up on this Slydog, I'd love to see this setup. Would be a sight to behold.

 

On jetting, I'd reckon bigger than stock is needed as individual runners get a "pulsed" signal only 25% of the time (one stroke out of 4) so jetting may need to be bigger than expected. Also BG carbies have easily replaceable boosters, so you could experiment with different designs to get best performance. I highly recommend annulars as I fitted them to my 600. It feels like an EFI motor to drive.

 

Mcfly on the subject of annulars, you could get a 350 modified with annulars to give better torque and efficiency. Needs smaller jets too.

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Make sure you follow up on this Slydog, I'd love to see this setup. Would be a sight to behold.

 

On jetting, I'd reckon bigger than stock is needed as individual runners get a "pulsed" signal only 25% of the time (one stroke out of 4) so jetting may need to be bigger than expected. Also BG carbies have easily replaceable boosters, so you could experiment with different designs to get best performance. I highly recommend annulars as I fitted them to my 600. It feels like an EFI motor to drive.

 

Mcfly on the subject of annulars, you could get a 350 modified with annulars to give better torque and efficiency. Needs smaller jets too.

what do the annulars do?

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what do the annulars do?

 

Annulars are a completely different design to the standard and drop-leg boosters you find in the classic old Holleys that we're familiar with.

 

The standard booster is a mini-Venturi with a discharge hole that the fuel mixture more or less spills out of whe under load. It relies on the air rushing past it to atomise the fuel coming out, and is most effective at higher flow/rpm. At lower flow rates, atomisation is pretty poor so to compensate, bigger jets/more fuel is needed. Also, the booster requires air rushing past to draw fuel out through the jet, and at low flow, the booster signal is poor. Think of it like a spray gun. At maximum trigger, the paint flows nicely, but just crack it open slightly, and paint will barely dribble out. A standard booster is like this, with only one hole to draw fuel through.

 

An annular booster is sometimes called a "banjo" type. It has a hollow tube to connect it to the carb body just like a standard one, but instead of discharging though one hole, its Venturi is hollow and has tiny holes all the way around it on the bottom that discharge fuel evenly and finely, even from low rpm/flow.

 

The venturi comes in two pieces: the banjo and the insert. The insert is available with different numbers of holes from 8 to 16, depending on application. The increased discharge area creates a stronger vacuum signal that draws fuel harder from the jet and also comes in earlier. For this reason and for the fact that atomization is better, you need to drop a few jet sizes (I've heard of up to 5).

 

They come standard in some brand new Holleys like the 570 truck avenger. They make an oversized carby "feel" smaller in operation.

 

They were originally a Ford/Autolite booster design that came in their 4100 series carbs. It wasn't until Ford stopped making these carbies that Holley took over the design and used them in their own version of the Autolite. They were also available in the Dominator range of race carbies, which needed the benefit of low-speed booster signal, being so ridiculously big.

 

Nowdays, you can get aftermarket annular boosters to fit the classic Holleys that were never originally made with them, which is what I did. You either need to get the boosters installed by a specialised Holley shop or make up a swaging tool like I did.

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Gerg  I'm real interested in this annular booster thing. I have a 650 2 barrel that has annular boosters from factory.  I like the idea of not having a booster in the way in my speedway 350 Holley.  Can you do this conversion to a 350 Holley, if so can you please post up picks of the annular boosters on your Holley.  I'm thinking no boosters in the way will increase flow through the carb which would be awesome in my application.  Always looking at ways to get around this bloody 350 Holley restriction rule. 

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Sorry Ando I should have explained them better. Annulars are actually a replacement for the standard booster and are in fact slightly more restrictive, but not by much. A 570 Truck Avenger is actually a 600 with annulars.

 

The carby you're describing has an annular body, with no boosters. I think they were popular with alcohol speedway engines, and flow decent amounts of fuel and air due to the surrounding body itself being the discharge point for the fuel into the Venturi. Quite rare and obscure these days.

 

Yes any Holley carby can be fitted with annular boosters. Your 350 is basically half of a 4-barrel, so the same mods apply. Again, annulars are more chunky so are more restrictive, therefore if you're limited to a 2-barrel, go with a 500 if annulars are what you want. I've got a post already with pics of my carby. I'll find it and link to it later.

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post-244-13709324991356_thumb.jpg

 

The Annulars are on the choke (primary) side. As you'll notice, they are much chunkier, but lack the little air hood down the middle that the standard boosters have.

 

I got them from Hume performance for around $45 delivered, that's 2 x banjos and 2 x 8-hole inserts. Alternatively, you could send your carby away and get them professionally installed.

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Thanks mate - yeah I understand what you mean now.  I have two 650 2 barrels and yes they are rare and odd looking.  We are limited to a 350 Holley in Mod prods - having said that they are a 350 only in body.  We modify them heavily with different base plates, metering blocks etc etc.  Mine is made up of 350,500 and 650 bits and was done by the late great Geoff TRUSCOTT or G.T. as he is better known.  He actually machined the hood out of the standard booster and on another G.T. carby I bought second hand recently he even extended them upwards to stop fuel 'pull over' at high rpm.

The annular boosters look very similar to mine but without all the holes.  Me thinks I will get a set and head off to the flow bench.  I don't thing they will be that much of a restriction.  thanks for the info and pictures.  always trying to build a better mouse trap....

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Well would I be good to go for a 465 with annular boosters?

And ive decided im going mild xflow so would the 465 flow enougb for 300hp dont want to have to buy two carbs, will be run off aussie 4 barrel

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If it's going to be mild and not revved over 5000rpm use a Cain or Redline but if over go the Aussiespeed.Aussiespeed kills it up top but down low the Cain and Redline give better throttle response and are easier to tune to...IMO

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Well would I be good to go for a 465 with annular boosters?

Yeah sure why not? 465 would be ample for a crossy so stepping down a fraction in flow would be no drama.

 

Aren't 465s a vac sec carby? If so, you'd be wasting your time converting the secondaries to annular, as they only come on when you're nailing it and atomization isn't a problem then. If you only put annulars in the primaries, I reckon it would drop to say 450 cfm.

 

At either flow rate, I think 300 horse is too much to ask for. 250 is more realistic with that carby. If you want 300 hp you need a 600 Holley, and pretty stout internals to handle it.

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You can get a mechinical sec 465 but I would go a 600/650 dp on a 2" open spacer.As long as you have atleast 230@50 plus duration and 550 lift with 10.5 comp it will work.

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I'd be cutting up the manifold and mounting the carby at  right angles if it was a 4 barrel. Otherwise you might encounter uneven fuel distribution, I hav no doubt the rear cylinders would run a fair bit leaner.

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for now dude just use a 465, can stuff around with the annulars if you want but its probably more money for little gain if its only going to be on there for a month or two.

 

 

i'd say this engine, 465 4 barrel, set the secondaries up properly so they open when you want, booster style well thats up to you and your wallet, annulars on the primary circuit, definatly worth it imo, but its not cheap to get done. and when you build your new donk, just buy a 600/650, the 465 won't be big enough. but you should get $250 for the 465 when you sell it, they're pretty rare and i've sold one for that price that was only a few months old.

 

wouldn't worry about it running lean on the rear cylinders, the ports are different shapes and sizes to counteract that issue, i remember reading a flow chart on the old forum with the flow rates for stock, redline, aussiespeed, and cain manifolds, and if you have fuel evaporating that majorly in the manifold its running lean on the rear and front banks, well son, i have some bad news for you.

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i spoke to engine builder today about what I wanted to do.

Mild cross flow, spin to 6500.

He said I may have trouble safely spinning the standard 250 bottom end to that, but 6000 is doable with balancing.

Straight away he said arp rod bolts.

Even he thought with 230* duration, 550 lift and 110lsa a 465 carby still may overfuel the car.

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