Unsure which new Carb to pick

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PanzerschreckLeopard

PanzerschreckLeopard

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So, I'm wanting something a little bigger than a BBD on my 225 slant. I don't want to do anything too huge, though, since I don't plan on changing engine internals unless they break.

So, the main choices I see online seem to be a Weber 38/38 and 32/36, the 350cfm Holley 2300, and the 390cfm Holley 2300, and the 390cfm Holley 4160. I was wondering how these would all compare on an otherwise stock 225 slant, in both the work required for the conversion, and actual performance. The 4160 would require a 4v intake, I know, but for the other ones, a previous owner already put the Super Six 2v manifold on there. The kickdown is a lokar cable, which I added because whoever put the 2v manifold on didn't.

Also, can anyone tell form this photo whether the BBD is the V-8 or /6 version? I have to nudge the choke rod for it to engage properly, and it's not due to a weak spring.

IMG_20170704_203744371[1].jpg
 
It is hard to go wrong with the Holley for parts availability.

If you really are tuning a carb precisely, the Weber has more adjustments and variables to the play with. But it is not a quick learning curve, and probably is not needed on a stock /6.

The performance increase is going to be pretty darned limited (unless the present carb is just not working right). The cam and it's breathing are the limiting factors. Without going inside the engine, a bigger exhaust would be of more benefit than a different carb at this point.

What year of engine do you have?

And how did you come up with that interesting forum name? LOL
 
Go with the 350 Holley. Plenty of volume for a stock motor, and only one side to jet/tune.
Eliminate the PV, and screw a set of 64's in, and it should be just about perfect.
 
nm9stheham said:
It is hard to go wrong with the Holley for parts availability.

If you really are tuning a carb precisely, the Weber has more adjustments and variables to the play with. But it is not a quick learning curve, and probably is not needed on a stock /6.

The performance increase is going to be pretty darned limited (unless the present carb is just not working right). The cam and it's breathing are the limiting factors. Without going inside the engine, a bigger exhaust would be of more benefit than a different carb at this point.

What year of engine do you have?

And how did you come up with that interesting forum name? LOL
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whitepunkonnitro said:
Go with the 350 Holley. Plenty of volume for a stock motor, and only one side to jet/tune.
Eliminate the PV, and screw a set of 64's in, and it should be just about perfect.
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Car is 71 but I don't know if engine is original: it does have 5 BTDC timing though, as opposed to the horrible ATDC settings of the later cars.

For name? Comes from when making my deviantart (while SFW for the most part, you probably won't like what's there), and had named it after a fancharacter from the dumb days of HTF fandom.

As for the 350, what all work would be needed for the conversion? (Someone also suggested thermoquad/quadrajet due to their tiny primaries, but...800cfm seems a bit much for a 225ci engine .. The 390 Mustang only has 600cfm!)
 
whitepunkonnitro said:
Go with the 350 Holley. Plenty of volume for a stock motor, and only one side to jet/tune.
Eliminate the PV, and screw a set of 64's in, and it should be just about perfect.
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I am curious why to block the PV? Just not needed with the flow volume with a stock cammed 225?
 
That's a V8 BBD you've got.

Before you decide on a carb, consider a Motorcraft 2100/2150; see this thread and this one. That would wind you up with a good-running setup and an appropriate air cleaner would be easy to find.
 
Perhaps I'll do that. Which would be the max CFM recommended for an otherwise stock 225 slant?

Also, in your second link, the part where you go " if you don't feel like doing all the adaptation work yourself, check with this guy." is a dead link, it just goes to ebay's front page.

To be honest I'm on the line with whether to upgrade other areas like cylinder heads and such as well, but I've never done work inside a the engine, so I don't know how long that sort of work would take. But if I did do stuff like that, how would it affect the above?
 
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What other modifications have you planned besides a bigger carburetor? Just putting a bigger carburetor on will be backing up.
 
RustyRatRod said:
What other modifications have you planned besides a bigger carburetor? Just putting a bigger carburetor on will be backing up.
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Not sure actually, I only started looking it up. What would you recommend? Seems that cylinder heads could be better breathing, but I'm not finding any non-stock ones.
 
PanzerschreckLeopard said:
Not sure actually, I only started looking it up. What would you recommend? Seems that cylinder heads could be better breathing, but I'm not finding any non-stock ones.
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For a stock engine, the best carburetor is the stock one. Unless you change more than one item, just a carburetor change will net you nothing.
 
PanzerschreckLeopard said:
Yes, that's why I asked the other stuff as well.
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I like the idea of a staged carburetor on a small cube engine. In other words, one that has a primary barrel(s) and a secondary barrel(s) and opens them progressively.

If sticking with a two barrel, a Weber would be a good choice. For a four barrel, a small Edelbrock AVS would be good.

Either way, upgrades to the intake and exhaust will be necessary to take advantage of any improvement.

A good, high flowing intake manifold and a good free flowing header and larger than stock exhaust will be mandatory.

Otherwise, you're pissin in a fan.
 
RustyRatRod said:
I like the idea of a staged carburetor on a small cube engine. In other words, one that has a primary barrel(s) and a secondary barrel(s) and opens them progressively.

If sticking with a two barrel, a Weber would be a good choice. For a four barrel, a small Edelbrock AVS would be good.

Either way, upgrades to the intake and exhaust will be necessary to take advantage of any improvement.

A good, high flowing intake manifold and a good free flowing header and larger than stock exhaust will be mandatory.

Otherwise, you're pissin in a fan.
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Fair enough...why ARE staged 2v's so rare? I mean, surely it'd give better mileage, and manufacturers are not required to make the primary smaller...is it just cheaper that way?

As for exhaust upgrade; would a good one mean modifying the pipe as well, or would a good manifold be able to bolt to existing one? What could one use to heat a non-stock intake?
 
I wouldn't worry about intake heat. But then, I also live in Georgia. But I wouldn't worry about it anywhere. Although it will be somewhat cold natured, it will warm up fine and run fine, especially with a larger, richer carburetor.

Yes, I would go with whatever size pipe the header collector is and not make a reduction there. Never been a fan of reducer collectors. After all, headers are a performance mod and if you're reducing the size of the pipe, how can that help performance?

I know all the exhaust experts will start talkin about back pressure this and that blah blah blah, but they don't their *** from a hole in the ground. Want more power? Bigger exhaust. Period.

Maybe the only exception being with a turbo build.



PanzerschreckLeopard said:
Fair enough...why ARE staged 2v's so rare? I mean, surely it'd give better mileage, and manufacturers are not required to make the primary smaller...is it just cheaper that way?

As for exhaust upgrade; would a good one mean modifying the pipe as well, or would a good manifold be able to bolt to existing one? What could one use to heat a non-stock intake?
Click to expand...
 
Don't pick carbs by CFM numbers. In the first place, many of the numbers thrown around are fictional. In the second place, even if you have accurate numbers, they're often not comparable between different kinds of carbs (1bbl, 2bbl, 4bbl).

Link: This guy.

If the engine is in basically sound condition, it's usually best and most cost-effective to focus on external upgrades and save the internal ones until there's a good reason to open up the engine. The semi-exception would be if your timing chain has enough wear to have developed slack; this will retard the cam timing and take a big bite out of performance and efficiency. Check it as described here.

Other external upgrades that give good value for money/time/effort invested: better ignition (with a distributor thoughtfully recurved to match your driving conditions; get with DusterIdiot over on slantsix.org about that), exhaust system upgrade as described here, and non-engine upgrades described in this post.

Oh, one other thing: Yes, "worry about" (make/keep provisions for) intake heat. It's not a hot/cold weather thing. See here and here.
 
RustyRatRod said:
I wouldn't worry about intake heat. But then, I also live in Georgia. But I wouldn't worry about it anywhere. Although it will be somewhat cold natured, it will warm up fine and run fine, especially with a larger, richer carburetor.

Yes, I would go with whatever size pipe the header collector is and not make a reduction there. Never been a fan of reducer collectors. After all, headers are a performance mod and if you're reducing the size of the pipe, how can that help performance?

I know all the exhaust experts will start talkin about back pressure this and that blah blah blah, but they don't their *** from a hole in the ground. Want more power? Bigger exhaust. Period.

Maybe the only exception being with a turbo build.
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slantsixdan said:
Don't pick carbs by CFM numbers. In the first place, many of the numbers thrown around are fictional. In the second place, even if you have accurate numbers, they're often not comparable between different kinds of carbs (1bbl, 2bbl, 4bbl).

Link: This guy.

If the engine is in basically sound condition, it's usually best and most cost-effective to focus on external upgrades and save the internal ones until there's a good reason to open up the engine. The semi-exception would be if your timing chain has enough wear to have developed slack; this will retard the cam timing and take a big bite out of performance and efficiency. Check it as described here.

Other external upgrades that give good value for money/time/effort invested: better ignition (with a distributor thoughtfully recurved to match your driving conditions; get with DusterIdiot over on slantsix.org about that), exhaust system upgrade as described here, and non-engine upgrades described in this post.

Oh, one other thing: Yes, "worry about" (make/keep provisions for) intake heat. It's not a hot/cold weather thing. See here and here.
Click to expand...

Okay. Say I only get the 2150 Carb conversion from ebay link, and nothing bigger. How much would I have to modify the rest to get good use from it?
 
Don't click/buy from the eBay link -- contact the guy (just dug up his email address for you, that is [email protected] ) and have him put together an optimal setup for the Slant-6. That'll be the 1.08" venturi carb with ported vacuum for spark advance, manifold vacuum for PCV and to operate a thermostatic air cleaner, and an integral automatic choke you can and should convert to electric by contacting the folks who sell these.

You will not need to make any other modifications to benefit from this induction upgrade; it'll run well with everything else in stock condition. Of course, it'll run progressively better with other upgrades such as those I linked (ignition, exhaust, etc).

(And one other, other thing: Yes, there is definitely such a thing as too big an exhaust pipe, which will cost you torque. More is not endlessly better; you don't want to create backpressure, but you also want to keep exhaust velocity up, and a giant exhaust pipe kills velocity.)
 
slantsixdan said:
Don't click/buy from the eBay link -- contact the guy (just dug up his email address for you, that is [email protected] ) and have him put together an optimal setup for the Slant-6. That'll be the 1.08" venturi carb with ported vacuum for spark advance, manifold vacuum for PCV and to operate a thermostatic air cleaner, and an integral automatic choke you can and should convert to electric by contacting the folks who sell these.

You will not need to make any other modifications to benefit from this induction upgrade; it'll run well with everything else in stock condition. Of course, it'll run progressively better with other upgrades such as those I linked (ignition, exhaust, etc).

(And one other, other thing: Yes, there is definitely such a thing as too big an exhaust pipe, which will cost you torque. More is not endlessly better; you don't want to create backpressure, but you also want to keep exhaust velocity up, and a giant exhaust pipe kills velocity.)
Click to expand...

I see, thank you. On a side note, any recommendations for manifold gaskets? The one I have was new (replaced earlier this year) But has two leaks, and the gasket where exhaust manifold connects to pipe leaks too (right in the middle, where it's furthest from the two bolts) In the case of the manifold-to-block gasket, could it simply be an incorrect torque sequence? (I did, at least, torque all the bolts to the block before torquing the the intake-to-exhaust ones)
 
Those stupid stamped-metal intake-to-exhaust gaskets do a lousy job at best. It is very much worth your while to get the good gaskets for the manifolds-to-head, intake-to-exhaust, and exhaust-to-pipe junctions. Hardware: read this and this.
 
I'd go with 390 4bbl it's a little more cfm than the 2bbl 390 and has smaller bores to help with velocity. Best of both worlds, but not much gain if all else is stock.
 
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