In need of a new carb..any suggestions??

[B-Co Kid]

87' B-Co Fullsize, Rebuilt 351W 5.8L Bored over.060, came stock with Holley 4bbl., Edelbrock Performer intake

rebuilt C6 trans, Gibson shorty headers, tru duals, soon to upgrade to 35x12.5x15 BFGs tires

6" pro comp lift (Stage II), 3" body lift (although my rig doesnt look like it has 9" of lift)

Warn premium hubs, saginaw pump conversion, Non-egr

So, with that said, im in the market for a new carb but i cant seem to decide on a carb. I originally bought

a Holley 670 cfm, but the guys who rebuilt my engine told me that when they tried installing it, on the Edelbrock intake,

that it wouldnt fit. As of now it has a remanufactured holley 600 (4180) installed. My rig is not a daily driver. i'll

be using it on road and mild to moderate off road.

Would like a carb with electric choke and vacuum secondaries. Im pretty sure my selection will either be Holley or Edelbrock,

just dont know which one. Previous experiences with either carb, opinions, and any/all help would be appreciated.

 

[Krafty]

I would be most interested in why that other carb you bought would not fit unless you have taken it back and got your money back already.

 

[Seabronc]

Do you know what the max CFM the engine is now capable of sucking in? You need to size the carb based on that. If you under size it then it will be starving for air and if you oversize it too much, the secondaries won't pull in right. Those vacuum secondaries probably won't even open when off road which is OK since you probably want it to be able to scream when you stick your foot in to it. My 4160 sounds like it is sucking the hood in on the very rare occasion that I do stomp on it.

Also, like Krafty, it is curious that the 650 wouldn't bolt up. Did you check the bolt pattern against the 4180's. I would have expected both to have the same pattern.

Good luck,

 

[Rons beast]

I have attached a link to a carb calculator.

http://www.4secondsflat.com/Carb_CFM_Calculator.html

A few things to remember: Only full chat race engines are gonna be at 100% volumetric effeciancy. You will probably be at 85 to 90% with modifications.

As Seabronc said, it is not good to be over carbed, so go with something that is slightly smaller in cfm if you calc. in between sizes.

Also if you are going off road, it may be important to choose a carb with center pivot floats. Otherwise, if you get into a trail that has your Bromc tilted a little too much you could be left with a starving or flooded engine.

 

[B-Co Kid]

Do you know what the max CFM the engine is now capable of sucking in? You need to size the carb based on that. If you under size it then it will be starving for air and if you oversize it too much, the secondaries won't pull in right. Those vacuum secondaries probably won't even open when off road which is OK since you probably want it to be able to scream when you stick your foot in to it. My 4160 sounds like it is sucking the hood in on the very rare occasion that I do stomp on it.

Also, like Krafty, it is curious that the 650 wouldn't bolt up. Did you check the bolt pattern against the 4180's. I would have expected both to have the same pattern.

Good luck,

It was the 670 that wouldn't bolt up properly, not the 650. i wondered why the 670 wouldnt bolt up correctly either, but i was replacing the intake with the Edelbrock intake, so i really didnt question it. The shop that rebuilt my engine installed the intake and carb,

so i didnt get the chance to match the bolt pattern.

 

[B-Co Kid]

I would be most interested in why that other carb you bought would not fit unless you have taken it back and got your money back already.

When i first bought the B-Co, i replaced the stock carb with a 650, and it matched perfectly. But that was with the stock intake manifold.

it has the Edelbrock manifold on now, so i just assumed thats why the 670 wouldnt bolt on properly. They found a remanufactured 4180

and installed it on the edelbrock. which is why i didnt understand why the 670 didnt match, but then again, it was a engine rebuilding shop

so who knows..my problem is, i dont want to buy a holley 570,650,or 670 and they dont match up. Im sure the edelbrock carbs will match up with the edelbrock

intake, but im not very familiar with edelbrock carbs. Plus, i think you have to install the additional A/T kickdown link to go on the carb

 

[Seabronc]

Im sure the edelbrock carbs will match up with the edelbrock intake, but im not very familiar with edelbrock carbs. Plus, i think you have to install the additional A/T kickdown link to go on the carb

That is not a problem, you even have to install that kit on a Holley. The 4180 as with most Holley carbs, are not great for off road usage due to the internal float bowl design, in fact most people would say they **** for off road. Holley is primarily designed for flat track racing and that is also why they run so rich, it is by design. I'd go for one of the off road designed carbs if you plan on doing any steep angles like the Edelbrock http://www.edelbrock...ors/intro.shtml .

The best off road system is an EFI set up.

Good luck,

 

[Rons beast]

Your carb fitment issue may be because of the difference between a spread-bore design, (like the GM quadrajet) and a square-bore design, (like most old carters and Holleys).

many manifold manufacturers have both designs as options. Look on the underside of the carb that fits your manifold. If all the throtle bores are the same size, you have a square-bore. If the secondarys are bigger it's a spread-bore. Other than that and the bolt spacing there is no other difference, or reason the carb would not fit. (edelbrock carbs only on edelbrock manifolds, etc.)

when ordering the carb the service tech will want the design,and bolt spacing. Then the options of auto choke (if not standard), trans kickdown, etc can be discussed.

As Seabronc said, off road can be a misserable thing if the carb is not suited, (Got to have center pivot floats)

I ran a Holley 780 on 396 with headers and mild cam and torquer mannifold in a 72 Blazer. I did alot of off roading,and hill climbing. The carb worked great for that and ran well on the road too.

I don't remember the conversion in my head....what does the CI calc. to with your 351 at .060 over?

 

[B-Co Kid]

Your carb fitment issue may be because of the difference between a spread-bore design, (like the GM quadrajet) and a square-bore design, (like most old carters and Holleys).

many manifold manufacturers have both designs as options. Look on the underside of the carb that fits your manifold. If all the throtle bores are the same size, you have a square-bore. If the secondarys are bigger it's a spread-bore. Other than that and the bolt spacing there is no other difference, or reason the carb would not fit. (edelbrock carbs only on edelbrock manifolds, etc.)

when ordering the carb the service tech will want the design,and bolt spacing. Then the options of auto choke (if not standard), trans kickdown, etc can be discussed.

As Seabronc said, off road can be a misserable thing if the carb is not suited, (Got to have center pivot floats)

I ran a Holley 780 on 396 with headers and mild cam and torquer mannifold in a 72 Blazer. I did alot of off roading,and hill climbing. The carb worked great for that and ran well on the road too.

I don't remember the conversion in my head....what does the CI calc. to with your 351 at .060 over?

The edelbrock performer #2181, the one i have, has a square bore. From what i am told, 351w bored .060 is 362 c.i.

Im pretty sure im gonna go with a Holley carb, but with the max rpm range at 5000-5500, shoud i be looking at a 570, 600, 650, or

try again with the 670?

 

[Seabronc]

The 570 will be plenty big enough or keep the 4180. Here is a calculator http://www.buicks.net/shop/reference/carb_cfm.htm and info on the 4180 and 4160 http://ddilts.net/mustangs/holley_4180/index.html

Good luck,

 

[B-Co Kid]

The 570 will be plenty big enough or keep the 4180. Here is a calculator http://www.buicks.net/shop/reference/carb_cfm.htm and info on the 4180 and 4160 http://ddilts.net/mustangs/holley_4180/index.html

Good luck,

Thanks for the info!

 

[B-Co Kid]

Thanks for the info!

 

[B-Co Kid]

Just a thought..im leaning toward the holley 570. But the 570 is not offered with the spring loaded needles and seats (truck avenger), which from

what i am reading, is a good idea for off-roading. Would it be possible to install spring loaded needle/seats in the 570 to make the ultimate

street/off-road carb??

 

[B-Co Kid]

After much deliberation, i went with the Holley 570 SA. I havent been able to fire it up yet because the dual inlet hose kit

that i purchase has a AN fitting on the end, which is not supplied in the kit, and apparently is unavailable anywhere! so im waiting

for that fitting so i can hook up the fuel line. I did, however, find out why the dumb*ss engine rebuilders told me the holley 670

would not fit. There was a 2.5" tall ported vacuum switch at the back side of the intake manifold, which prevented the back side of of the carb from lowering onto the intake manifold. One trip to homedepot to find a plug. removed vacuum switch, and installed

the plug. problem solved! The funny thing is, all of the ports were blocked off! Im not a trained mechanic, but sheesh its not rocket science :-B