Should I get a spread bore carb

[Sly_drums]

Hey guys, I'd like to try something different carb-wise.

I use an old but working Holley "square bore" 600 CFM carb in my Mustang, and a Weiand single plane Xcelerator intake.

My motor is a stock 351C 2V with long tubes headers and I think I'm in the 250-260 HP range.

I like my current carb but I always kept an eye on remanufactured spread bore carbs. I like the fact it has small primaries and bigger secondaries, can be good for both performance IF YOU WANT IT and gas mileage if you drive smooth, am I totally wrong ??

I already own the Holley vacuum spring kit too, so I can swap springs to taste.

Do you think an Holley spread bore carb can be a good thing for my car ? This one looks good :

http://www.ebay.com/itm/HOLLEY-CARBURETOR-SPREADBORE-0-6210-650-CFM-4165-DOUBLE-PUMPER-PT-182-6210-/390422537059?pt=Motors_Car_Truck_Parts_Accessories&hash=item5ae6ff2363&vxp=mtr

I want to try but not sure it will fit the intake.

 

[hyena429]

Hey guys, I'd like to try something different carb-wise.

I use an old but working Holley "square bore" 600 CFM carb in my Mustang, and a Weiand single plane Xcelerator intake.

My motor is a stock 351C 2V with long tubes headers and I think I'm in the 250-260 HP range.

I like my current carb but I always kept an eye on remanufactured spread bore carbs. I like the fact it has small primaries and bigger secondaries, can be good for both performance IF YOU WANT IT and gas mileage if you drive smooth, am I totally wrong ??

I already own the Holley vacuum spring kit too, so I can swap springs to taste.

Do you think an Holley spread bore carb can be a good thing for my car ? This one looks good :

http://www.ebay.com/itm/HOLLEY-CARBURETOR-SPREADBORE-0-6210-650-CFM-4165-DOUBLE-PUMPER-PT-182-6210-/390422537059?pt=Motors_Car_Truck_Parts_Accessories&hash=item5ae6ff2363&vxp=mtr

I want to try but not sure it will fit the intake.

It should..But you mite have to get a adaptor spread bore plate...i like speadbores my self...But i would get the old stock one if it was me...lol... i like the old 4300d ..It treated me well for 15 years...but they are so spread they have a hard time fitting with out adaptor plates too.

http://www.ebay.com/itm/1967-80-YOUR-4300-D-MOTORCRAFT-CARB-RESTD-FORD-MUSTANG-/260673802793?hash=item3cb15e9229&item=260673802793&pt=Motors_Car_Truck_Parts_Accessories&vxp=mtr looks like a nice carb with out matching numbers...716cfmish i think.

 

[Jeff73Mach1]

I have not heard anything but horror stories about the Holley spreadbores. I know that the 4300D was a better carb, but it is unique in size. The Rochester Quadrajet is an awesome carb if you have it built by the right person, but very few are and most folks think they are junk. Small primaries can assist with mileage if you behave.

 

[sm3570]

Be careful with square bore-spread bore adapters. If you google it there are some (mild) horror stories regarding the performance of them. I think it has something to do with matching the size of the bores, although I could be wrong.

 

[hyena429]

I have not heard anything but horror stories about the Holley spreadbores. I know that the 4300D was a better carb, but it is unique in size. The Rochester Quadrajet is an awesome carb if you have it built by the right person, but very few are and most folks think they are junk. Small primaries can assist with mileage if you behave.

Ya..i never tried holley spreads before....but my 4300d was a great carb...And i heard alot of horror stories about quads...but i seen nothing but good out of them...All carbs will be junk if treated wrong..And some carbs got torn off cause of motor issues and blaming the carb..people messing with them that dont know what they are doing....lol..I seen holley leak..and quads after many years of use and abuse..

Right person build them and tunes them.They could last a life time..I tore mine off..Cause i thought it was getting old...and hesitating. i took the 4300D off..And i put a new performace 600cfm elder with even worst results...lol..Come to find out..I was loosing compression...Hesitation was only worse with the elder surpizingly..lol..Nothing wrong with it.....But with the huge cam im putting on..I cant run it anymore...going in a box..lol

 

[Sly_drums]

Thanks for posting !

Do you know a good place to find remanufactured spread bore carbs ? There are some on ebay that look good.

I'd love to see a video of someone driving wide open throttle using one.

I'm happy with my motor right now, I did all the basic stuff : new Weiand intake and Holley 600 carb, new NGK spark plugs, good tuning, using the right vacuum spring for my needs, etc... it drives good and I can push it to 120 MPH easy ; I have a C4 trans, 3.25 rear gear ratio and trust it runs well, anyway it can sometimes be a bit boring to drive, due to stock camshaft and automatic trans.

I thought trying a new carb may be a good idea : I heard great things about the 4300 spread bore carbs, they provide the old school muscle feeling.

My plan in the end is to buy a pair of 4V heads to replace the 2V, matched camshaft, new spread bore carb (I have a remanufactured iron 4V intake manifold in my garage that I'm not using at the moment, waiting for the new heads to come in someday). I'll need to change my headers too.

The Holley square bore carb I use at the moment is good, but maybe a spread bore can add a bit of "fun", especially using an auto trans...

 

[Jeff73Mach1]

http://www.ponycarburetors.com/default.asp?page=carburetors#autolite4300

They are not cheap, but they are said to do excellent work

 

[hyena429]

http://www.ponycarburetors.com/default.asp?page=carburetors#autolite4300

They are not cheap, but they are said to do excellent work

they went out of biz...store doesnt work


http://www.ebay.com/itm/1967-80-YOUR-4300-D-MOTORCRAFT-CARB-RESTD-FORD-MUSTANG-/260673802793?hash=item3cb15e9229&item=260673802793&pt=Motors_Car_Truck_Parts_Accessories&vxp=mtr Thats a good cheap price..Seller has ok feed back...but im not sure how good of a carb it is...It sure looks nice in the pics thou....and he putting a warranty on it..soooo i would take a crack on it at that price..buy threw paypal thou....Just in case..lol

 

[Jeff73Mach1]

You are correct, looks like the owner died last August and the IRS came in at some point.

 

[Don65Stang]

Try contacting Kurt who was a Pony Carbs employee before they moved out west.

http://mysite.verizon.net/vze2gsgu/index.html

 

[Jeff73Mach1]

Don65stang is the man!

If that doesn't pan out try Australia as Clevelands were big over there and 4300 carbs may be more plentiful.

 

[Sly_drums]

Thanks ! I'm going to check them. Can't decide between Holley or Motorcraft yet.

As I said, I plan to buy 4V heads soon and a new cam.

I already own a factory matching intake to replace the Weiand Xcelerator, do you think an Holley or Motorcraft spread bore carb can mount on it ? Here is a pic :

 

[hyena429]

I would get the 4300D to go with that intake....I wouldnt mess around...Make sure its a 4300D too...Not the square bore regular 4300....I tried to mess around sticking a 600cfm 1405 elder on my stock intake....I got the plate and everything..And still would have to puddy to make it work....And you could tell the carb was waaaay too small...and the rear spread bore on that intake is much wider than that holley spread bore...It wont bolt right too it with out a plate.....I ran into the same thing..and it didnt cover that grove around the front and i couldnt use the stock plate....the carb wouldnt even open...It turned into a nightmare just to mount a carb...I finaly gave up and got a aftermarker intake to match....And stuck the stock one in a box...You can save your self a little head ache if you go stock 4300D carb i think...Plus if you ever stick ram air on..No issue with stock carb and intake.

 

[Jeff73Mach1]

Only the 4300 D will fit that intake properly.

The stock intake isn't the best performer and is very heavy. If you are going to use it the Stock carb makes sense.