what carbs should i use for a 3x1 intake.

[jahearne]

"when the 200 looks lost between the fenders" ha ha ha, I know what you mean! The DUI dizzy helps fill out the engine compartment and the slightly taller/wider 250 add a bit more "meat".

My '66 Comet Cyclone and the Ranchero share the same sheet metal in the engine compartment with the exception of slightly larger hole in the core support for a bigger radiator and some cross bracing. You need a shoe horn to get the 390 in there. The amazing part is tri-Y headers fit with a 4-speed and I can still get to the starter! The spark plugs is another story. Back to the topic at hand. I said I'd have some more info:

Holley 1904 - the angle of the fuel valve and float assembly.

Since these carburetors are so picky, I thought this is worth mentioning. I think it's best if the float can move freely up & down, so the assembly should be level. You can mount a partially assembled carb on the manifold and eyeball it, then tighten the retaining screw. Make sure you have a gasket/washer on both sides of the carb body to prevent any internal leaks.

See above where the throttle lever contacts the manifold. Barely touches... had to trim off a bit.

More to come,

 

[stang65]

can someone post pics with the webers on the intake
thanks
marcus

 

[Eric Rose]

Does anyone have pics of the milling operations needed to fit the carb base to the log? How much material do you have to remove? How do you seal it? Gaskets or something more permanent?

 

[Patrick66]

so from reading this, i guess the 3x1 intake isnt the best idea for a daily driver. i think im just going to do a 2v for now.

 

[bigcatchdaniel555]

Patrick for the 3x1 setup it can be a good daily driver from whaty Ive heard f coupled with the right carbs. The 1904's and 1100's are tempermental carbs the weber 34's are very good once jetted. People on here have gone 60000 miles without a tune.

 

[addo]

Surely, for a true "daily driver" the most trouble-free upgrade would be a CFI adaption, also driving an EDIS setup.

 

[JOHN G]

with the webers, I can drive it every day,all day and get good mileage and the on demand power as well. Once you have the tuning setup properly, it's really a pretty good setup overall. On the other hand, you have increased the chance of a part failure by a factor of 3. I had a minor problem with the linkage on my main carb last year and was able to scavenge what I needed off one of the other ones and then shut down that carb till I got home-think of it as carrying spare parts!!

 

[stang65]

come on guys
some pics of installed webers
please
marcus

 

[jahearne]

Does anyone have pics of the milling operations needed to fit the carb base to the log? How much material do you have to remove? How do you seal it? Gaskets or something more permanent?

Sorry, I didn't get any pictures when I had mine apart. I thought i did, but can't find any. Both versions use o-rings. Mine uses the flat-top intake manifold and was already machined when I got it. I did away with the o-rings and cut out my own gaskets, which worked out great since it has a flat machined area for a good seal.

There's a picture in the Falcon Performance Handbook on machining a flat top.

Sealing the hex-log intake has always painful from what I understand.

 

[Junk-Falcon]

ppp

 

[Patrick66]

old thread, but whatever. now that im rebuilding my engine, im thinking about doing the 3x1 now instead of staying with the 1100. i think i was just being impatient and wanted to get it running. i was planning on using a head with a "flat top intake" when i did this, but i just spent $90 milling my C6 head (now have 40cc combustion chambers and am goin to have a 9.7-10:1 CR with .055 head gasket and stock pistons, more when the new head gaskets come out). i know the later heads have larger valves and intakes, i also know that the "hex" log can be modified for a 3x1, but the flat top is easier.

so this is the question: are the larger valves, larger intake, and possibly the easier installation really worth the cost of the new head + machine work? im trying to figure out what to do. what realistic gains can i expect with a 77+ head over the 66 head when i do the 3x1?

with the hex head i think ill have to get the offy adapter, whereas with the flat top i could do it myself. if i do it myself it will be cheaper, but im still not sure what to do about linkage

 

[jahearne]

I don't think any one is easier than the other. My thoughts are that the Offy manifold for the flat top intake is easier to seal against vacuum leaks. Trying to seal the hex log against vacuum leaks with those two o-ring is painful from what I've read. My flat top already came machined.

The performance gain between heads are minimal for a street engine, but if you're going for everything that you can squeeze out of your motor then it's worth while to invest in larger valves, intake and volume. You can install larger valves in the head you have now.

Try vintagespeed.com online catalog for linkage parts. Look under "Carb linkage - throttle shafts misc".

How would making your own 3x1 intake with the flat top easier than with the hex?

 

[Patrick66]

ok ive decided to do it, with the "hex" log. what size hole saw should i use? i got the smallest exhaust tubing i could find at advance, 1.5", just to see if it would work. it does work, and as of now that looks like the best option, anybody have any other suggestions? im going to make my own 'flanges' for the carburetors, because im having trouble finding the right exhaust flanges at napa or advance.

ok, guess the questions are: what size hole saw? (im thinking 1.25 inches because it would i think leave some material for me to work with and it is close to 34mm) <-- is that right?

And, is there a better choice than exhaust tubing? i know i can make it work, but i dont think it would look that great. then again after the welds are ground down and its painted it might look ok. let me know what you think.

(oh yeah found these and im going to bid on them: http://cgi.ebay.com/ebaymotors/ws/e...STRK:MEBI:IT&viewitem=&item=250212723074&rd=1

so how hard is it to rebuild a carburetor? what special tools will i need?

 

[addo]

I would really strongly urge a twin carb setup, rather than three.

Also, make the mount flanges of steel plate around 5/16" thick, and braze them to the manifold. After brazing, use the flange hole as a template to cut the hole right through into the log. Any small voids will be obvious now, and can be filled up with braze or silver solder. Make sure your new flanges are flat on the top after all the work, and drill/tap for the mount studs.

For the centre hole, make up a 3/32" thick partition that passes through the carb hole to mostly block the log in half. Braze a 1/8" thick steel "cap" onto it, that matches the carb base pattern.

You'll be able to run two carbs off a 170, and get plenty more airflow than the single carb arrangement permitted.

 

[Patrick66]

I would really strongly urge a twin carb setup, rather than three.

Also, make the mount flanges of steel plate around 5/16" thick, and braze them to the manifold. After brazing, use the flange hole as a template to cut the hole right through into the log. Any small voids will be obvious now, and can be filled up with braze or silver solder. Make sure your new flanges are flat on the top after all the work, and drill/tap for the mount studs.

For the centre hole, make up a 3/32" thick partition that passes through the carb hole to mostly block the log in half. Braze a 1/8" thick steel "cap" onto it, that matches the carb base pattern.

You'll be able to run two carbs off a 170, and get plenty more airflow than the single carb arrangement permitted.

why 2 carbs? i think 3 would be better because then i can use progressive linkage and run off just the center carb when i want to. this car is my DD so MPG is important to me. also i wouldnt have to block off the hole that is already in the center. it would be easy, but i think it would be ugly.

not being critical, i just want to know why twin carbs would be better.

and i have a 200 not 170. im also getting a 264/274 cam 9.7:1 or higher CR, dual out header, and a little porting.

edit: your also saying to braze everything, mig welding wont work well?

 

[addo]

I will say that MIG welding to cast iron is pretty difficult. It really requires preheating of the weld area, then slow cooling. The weld wire isn't very ductile and if the weld's overly stressed by rapid cooling, it will come unstuck.

Brazing requires less overall heat, and the braze material is soft and yielding.

170 carbs are less popular, because most people want a 200. However, two of them will way outflow a standard 200 single carb. Two is also easier to tune/synchronise than three. There's no real reason why two synchronous carbs should be less economical than three with a progressive linkage on a DD. You could always cover the centre carb plug with a fancy plate or some chromed sheetmetal...

 

[bigcatchdaniel555]

Look at Slade's site here http://www.kastang.us/offenhausermod.html
he did a good write up on the offy. I heard the 3x1 for the hex head was getting a little hard to find because of low production. Although I did find it here 144 shares the same head so its cool http://www.offyparts.com/product_info.p ... 37cff82054
Slade used 2 studs mounted the adapter then pilot drilled the holes through the outer 2 to ensure proper alignment and size. I would recommend doing that to ensure proper fitment. Carb rebuilds are no big deal just keep track of all the mall parts and get a schematic if you can. Rebuild kit will have floats jetrs etc. just clean everything and replace.

 

[Patrick66]

I will say that MIG welding to cast iron is pretty difficult. It really requires preheating of the weld area, then slow cooling. The weld wire isn't very ductile and if the weld's overly stressed by rapid cooling, it will come unstuck.

Brazing requires less overall heat, and the braze material is soft and yielding.

170 carbs are less popular, because most people want a 200. However, two of them will way outflow a standard 200 single carb. Two is also easier to tune/synchronise than three. There's no real reason why two synchronous carbs should be less economical than three with a progressive linkage on a DD. You could always cover the centre carb plug with a fancy plate or some chromed sheetmetal...

ok, right now im pretty set on 3, but ill think about it. guess ill have to learn to braze too.

bigcatch: ive been on kastang's site already, and i sent him a pm asking about the size of the holesaw, but he hasnt replied yet. offyparts.com has them for the hex and flat top, but theyre $100 more expensive there than cliffordperformance.com. but im most likely going to do it myself and already started gathering supplies.

 

[bigcatchdaniel555]

I would call and make sure cliff has them in stock. Offy only produces them twice a year once they're gone thats it. Offy parts had some when I called earlier in the year.

 

[Eric Rose]

How would one use a kickdown for an automatic trans with the 3x1 linkage? :