Dual DCNF Manifold

CnC79X19

True Classic

Anyone have experience with this seller or already have this manifold on an X engine? It lists both the 128 and X so not 100% on the angle. It seems awful cheap price-wise but if it'll get the job done? I see in the pictures it says PBS 128 so I'm assuming it was cast from one?
 
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DanielForest

True Classic
Hi Cliff,
You are right, this is cheap. I don't know the seller. I don't like what I see in the bridge (look like a weld or something weird), but that is not a part that is submitted to much stress, so this isn't really important. This is for a 128, it's written on the manifold in the third pic, PBS 128. So to get it right for an x19 you will need to have a phenolic spacer machine to the right angle.
 

Dr.Jeff

True Classic
The eBay store name is "carb parts direct". They have been around for quite awhile and seem to have a pretty comprehensive offering. No personal experience but I've had them bookmarked for any future Weber parts needs.

To me the area in the middle (center bridge) appears to have been ground off a little, not welded of damaged. That could have been from the casting process or similar reasons.

I have the same understanding about the PBS manifolds, they made them with a compromised angle in between the 128 and X1/9 applications, to be somewhat "universal". Hopefully others have more first hand knowledge on that. Personally this would not bother me, especially for a street car that won't be running at maximum G-loads for long durations, or such like a race-only car might. I wouldn't even attempt to correct the angle any, just set the float levels accordingly.

For the price it seems hard to beat.
 

Dr.Jeff

True Classic
I ordered a rebuild kit from this sell. shipment was from Pierce
I know the locations of the two - Gilroy and Hollister - are very near one another. And the merchandise from them is pretty much the same. So that makes sense.

Pierce is well know for Webers and related stuff, so they should be a reputable seller.
 
I've been to the one in Gilroy to pick up some jets. That was in the 90s and they were located on a frontage road for US-101 not too long a ride from where I worked in San Jose. I bought from them recently via their web site. Their DCOE banjo bolt seals worked perfectly on my DCNF banjos.
 

DanielForest

True Classic
I've been to the one in Gilroy to pick up some jets. That was in the 90s and they were located on a frontage road for US-101 not too long a ride from where I worked in San Jose. I bought from them recently via their web site. Their DCOE banjo bolt seals worked perfectly on my DCNF banjos.
That's... music to my ears!
 

kmead

Old enough to know better
I would imagine that if one were going to use DCNF pattern throttle bodies for injection the angle wouldn’t be much of an issue.

Asking for a friend.
 

Dr.Jeff

True Classic
I would imagine that if one were going to use DCNF pattern throttle bodies for injection the angle wouldn’t be much of an issue.
I would agree. One exception might be for a high end race engine where you want the ideal approach for the maximum air flow, but I imagine you wouldn't be using anything like DCNF TB's and manifold if that were the case. ;)
 

artz1731

True Classic
Been using a single DCNF for 10 years with a 128 manifold. I have had zero issues, the angle means very little in my opinion.
 

Dr.Jeff

True Classic
Been using a single DCNF for 10 years with a 128 manifold.
Personal opinion, I'm a fan of a single DCNF set up. For a relatively stock'ish street engine it offers a performance improvement in the usable RPM range, rather than taking some of that away as duals will do. Makes the car more drivable under normal conditions. And one Weber is much easier to keep in proper tune than a pair. But of course it doesn't look as cool as dual Webers. :)
 

Dr.Jeff

True Classic
The throttle response is also better.
I'll debate that comment, depending on how you define things. In my experience large induction systems (like a pair of dual throat carbs) offer improved response at the top of the RPM range, but diminished response at the lower/mid RPM range. So if your application is strictly street driving under "normal" conditions, then lots of carburetion can actually lead to less drivability when compared to improved induction that is more suited in size (e.g. a single Weber). However if your application requires wide open throttle pretty much all the time (like race track use), then the big carbs will be a benefit. Personally for my street cars I really dislike things like off idle stumble, laggy low end acceleration, hesitant midrange, or a hole in the curve that typically accompany really big carbs. But everyone's situation will be different.

As for the sound, I find just about any improved carb and air filter setup offers plenty of "throttle noise" over a stock system. But this will also be different for everyone's taste.

I'm not against dual carbs. There is definitely a place for them in an appropriate application, and they do look and sound cool. To me the drivability is more important and I find a noticeable difference there - again, depending on the application.
 
The throttle response is a function of the distance between the throttle plates and the intake valve. The dual DCNF setup moves the carbs physically closer to the intake valve, and each cylinder is fed independently. I agree that there can be drivability tradeoffs with big carbs and the cams needed to take advantage of them.
 

MikeHynes

True Classic
Personal opinion, I'm a fan of a single DCNF set up. For a relatively stock'ish street engine it offers a performance improvement in the usable RPM range, rather than taking some of that away as duals will do. Makes the car more drivable under normal conditions. And one Weber is much easier to keep in proper tune than a pair. But of course it doesn't look as cool as dual Webers. :)
I'm not sure why you would make these comments. Maybe my experience is an outlier, but I haven't experienced any problems with a pair of 40 DCNFs on a warned over 1500. It's been a long time, maybe 20 years, and the car is still a JOY to drive. The carbs don't require any maintenance (probably wouldn't hurt to do some, but they don't require it). And they don't "go out of tune", what changes anyway? The jets don't change, the float level is stable. The idle and sync screws don't move around. They don't wear anymore than any one carb would. One carb or two, I see no difference in anything other than performance. :)
I do make an effort to use alcohol free gas as much as possible though. And premium when it's available. If I have to use "regular" 10% ethanol gas I try to use it up and replace it with gas sans ethanol ASAP. I only use ethanol free gas in ALL of my carbed engines (lawn mowers, weedwackers, leaf blowers, generators, chain saws, motorcycles, etc). I typically load up 3 five gallon gas cans in the frunk of my DCNF equipped X, drive it to the alcohol free gas station, and fill them all up at the same time. :)
 

carl

True Classic
My motor is stock with just a header/turbo muffler and dual 40 IDFs. The motor has razor sharp throttle response right off idle. My car is driven in a suburban environment where sitting at traffic lights for a few minutes is common. I do have my favorite sporting roads not far from the house. I agree with Mike, they stay in tune and if there is a glitch it is usually dirt in one of the jets. I will admit a single carb has a steadier idle but that's about it. I don't advocate carbs or even dual carbs to anyone. I like them and my Fiat is a toy and thus a recreational release for me...as opposed to my Miata which is just a nice little sporting convertible.
 
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