bloody carby Q's again

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i know this has been talked about alot lately, and thiss question might end up with alot of repeated answers, if so im sorry!
basically i think its time to spend even more money on my XF and i figure the next step is a nice big carby..... and i guess the manifold has to come with it too right?? now basically what do u recomend? ive heard is it a 465 or 500 holley?? suggestions are great ;) and what manifold?...... but my main question is:
with a new manifold and carby will it still sit in the same place as the stock one?? eg will the aircleaner sit in the exact same place?

cheers fellas!
-matt-
 
Hard to say I dont know what condition your engines in. My TE 77 Cortina 250 engine was in such bad condition that it would go much slower once you pushed your foot down past half way and this was with the small stock one barrel carb.
Putting on a bigger carb may not do much at all. If everything is ok I think a 465 would be OK even on a stocker. Ive heard it will give some improvement.
Theirs plenty of posts on this sort of thing. I dont know where your air cleaner will end up.
 
thanx for the reply,

my enigine was completly rebuilt about 6months ago, pretty close to stock, except its got a crow cam(14770), molly retainers, heavy duty double valve springs.... and all that other usual fruit that comes with it....so its in good condition... BW auto and 3.23:1 diff..

-matt-
 
I looked at your specs and If it were me (I know people will disagree) I would put a Holley 600 4 barrel double pumber on it with those specs. If you want too play it a bit safer go for a 465 4bbl.
 
As long as it isn't far too big, and if it can be lean off throttle and rich enough for good power, who cares?

I've refined my carby selection process a little. Go for a 465 Holley vac sec. It's set up for a 175 hp engine as it comes from Holley. The new 470 Avenger or 525 Barry Grant Demon is also a good prospect. These carbs need to be jetted to suit you car.

If it's all out performance, then 600 vac sec or even that double pumper 600 or 650 is a good plug. These are easier to tune. The heavier your car is, the less it likes a big carb.

The A7M rule is, take the 1.5"Hg cfm rating, and divide by 2. That gives you:-

232 hp from a 465 cfm,(290 hp possible if all is optimised. Seldom occurs)
235 hp from a 470 cfm,(294 hp possible if all is optimised. Seldom occurs)
263 hp from a 525 cfm,(328 hp possible if all is optimised. Seldom occurs)
300 hp from a 600 cfm,(375 hp possible if all is optimised. Seldom occurs)
325 hp from a 650 cfm.(406 hp possible if all is optimised. Seldom occurs)

Race cars, like the Commodre Challange, and some oval trackers can make a 465 hit well over 280 hp for each of those cfms, but it takes perfect manifolding, cam and compression to make it work. I've posted some carby info giving maximum power equal to cfm divided by 1.6, but you sledom get that on a streeter.Some thing like a 500 cfm 2-bbl is just a 354 cfm carb, and its hard to get over 177hp from one of these on a streeter.

More info for nutters:-
What you do is take the realistic peak rpm level, not rpm at maximum power, multiply it by the cubes, and then divide by 3456. Then multiply it by 0.85. You'll be looking at 5500*254 divided by 3456. This is 404 cfm. Times 0.85, that's 344 cfm.

1. The best streetable power comes when the carby cfm is 1.4 times the calculated cfm maximum power
Click to expand...
.Answer is 481 cfm. So a 465, 470 or 525 4-bbl will do just fine.

2.For best ecconomy/performance compromise, the factor is 1.2
Click to expand...
. This is approx 412 cfm @ 1.5"Hg, or use a 390 cfm 4-bbl.

3.For best ecconomy, with reasonable power, the factor is 0.9
Click to expand...
. This is 310 cfm @ 1.5"Hg, or a 435 cfm 2-bbl.
 
matt a 465 might be a bit big for it unless its had a lot odf work done, i have a mate witha fairly worked 25gutless and the 465 feeds it too much adni ghave a mate in perth with a 4.9 falcon who reckons the same, adn he said if i can get a smaller 4 barrel around the 400 or so use that not a 465 on a 250.
 
I've refined my carby selection process a little. Go for a 465 Holley vac sec
Click to expand...

now just to be a dumbass, i always here it mentioned but until now have not really needed to kno what it meant...... you say 465 holley VAC SEC what u mean by vac sec?

also what about manifold?? that needs to be changed right?? and all my emission gear goes, correct?

thanx again!!!!!
-matt-[/quote]
 
Vaccuum secondaries. Part number #1848-1. The back 2-barrels of the 4- barrel carb are opened by vaccum, only when needed. Set up right, they are very economical and have excellent performance. 245 Km/h 253 Commodores use them, without the kickdown cable. The rear jets are not cheaply replaceable, but they are good carbs if you get the right one. The 465 mechanical secondaries and 450 machanical secondaries carbs also exist. If it doesn't work right, you dont have the #1848-1.


A cammed 250 behaves much the same way as a 265 Hemi 4-bbl. It will most likely need bigger jets than the stock 57's at the front, and 34-3 metering block at the back. The guy sorting the carb should be able to make it work fine.
 
Execute.
You say the 465 is set up for 175 hp from the factory I believe from earlier posts it can be made OK for 280 hp (I think matts should be a lot more than 175 hp). I wonder, what HP is a 600 bbl set up for from the factory when it can be made OK for 370 hp.
A 465 seems alot more sensible but what about Gravelrashes (Gregs) 600 dp on a 250 2V. If it works???
And and "XT falcon"posted he has a 600 vac sec on his crossflow and alledges it makes 130kw to rear at around 5000 rpm (on Dyno). This sounds about right and should be very similar to Matts.
 
Hi,

I am using a Holley 600 vac secondaries on my 250 Xflow and find it works great. I am using the same 770 cam, 60" oversize acl flat top pistons, shaved, ported and polished alloy head, YT Rollor rockers and a balanced bottom end.

I would go with the 465 for a good medium between ecconomy and performance. You will need either a redline 4 barrel manifold or a ultraflow with a adaptor plate.

The position of the mainifold is the same just watch for bonnet clearence if you are using a big carb spacer or a high aircleaner.

Heres a link to some pics of a ultraflow manifold fitted
1.jpg

6.jpg

7.jpg


Cheers

Simon
 
Thanks for the pictures. That Ultraflow manifold looks like one "fine" piece of hardware.
How did you adapt that 600 to fit on it I thought from previous posts that they only made a two barrel manifold. Is there an aftermarket adapter plate or did you do some fabricating to make it yourself?
 
hi,

thats not my motor i sort of borrowed the pics pics, i think it is www.hoon.tk if you wanna check out the site its pretty cool. the chaps name is deon i think. He said he purchased the manifold like ( with the adaptor plate) that lucky bugger.

I am using a redline 4 barrel manifold ultraflo mainfolds are out of my price range at the moment.

Cheers

Simon
 
I have it on good authority (the above picture is not a four barrel manifold) that Utraflow only make a two barrel manifold.
Adapting four barrel carbs to 2V 2 barrel and to 2 barrel crossflow manifolds might OK with a bit of skill and planning but Ideally it would be better to get a manifold designed especially for this purpose. There are a lot of factors to include and I would hope that a Redline four barrel would incorporrate all of this into its overall design. I am almost certain that a Redline four barrel manifold would be far superior for a four barrel carb than the set up in the above which was "specifically" designed for a 2 barrel.
Still the Ultraflow for its intended purpose (a 2 bbl) looks superb.

Matt!
Ive seen Redline four barrel manifolds in Parts Peddler magazine secondhand. Its something you could save a few dollars on.
 
tim ,
i am always keen on saving money!! haha what sorta price should i look to pay?? how much do the roughly go for?? what about the carby?? secondhand still fine to use???

and sory but, all emission gear goes right??

-matt-
 
Hard to say but I generally tend to look for something around half of the New price maybe a bit more if its good. Im not sure what they are new you could check with Redline (maybe $300).
Not really the sort of thing that wears out so if its second hand shouldnt matter at all so long as it hasnt been modified or damaged.
 
hi,

your right tim that is a two barrel manifold with a adaptor. I think i posted some reply's i got from ultraflow a while back regarding there manifolds.

Matt, for a new Redline 4 barrel manifold i think your looking at about $230. For a 465 fully rebuilt carby your looking at about $280 from a carby shop.

As tim said parts pedler or the trading posts are a good start to find what you want.

Cheers

Simon
 
Hi all ,Does anyone know what sort of cost the ultraflow 2 barrell manifolds are going for and is there anyone in sydney who sells them .

cheer dave
 
Heres a email they sent me after i enquiring.


Simon
I'm sorry we do not manufacture a manifold to suit a 4 barrel carby for an Alloy 250 X-Flow. We only make one for the 2 barrel Holley. The reason we don't make a 4 barrel manifold is due to the fact that it is very difficult, if not impossible to get good fuel distribution with a 4 barrel carby on an inline six cylinder engine. Also a 500cfm 2 barrel Holley will supply all the air that a 250 X-Flow needs. We have customers that are claiming to get 325+ HP using one of our 2 barrel manifolds and a 500cfm Holley.
The cost of the 250 X-Flow "Limited Sprint" manifold is $440.00 plus freight. The best method for sending the manifold to you is COD Australia Post which should cost approx. $15.
If you would like to phone me, you can contact me on 07 3800 9188.

Regards

Bruce
 
What is the difference between the redline and the ultraflow manifold besides the price

Joip
 
hey xecute

http://www.holleycarbs.com.au/carb_info.html

when i put in the very basic details at this holley site it recomends a carb with a cfm of less than 300..... youve recomended a 465? am i missing something here or is there just more to this that i dont know.... and also whats the difference to a 450 holley?? theres one on ebay for $60

-matt-
 
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