New project, cloning an AoK dual carb intake for 23 inch heads

[lostviking]

Since I can't buy one, and the Offy design is inferior, I've decided to do a clone of the AoK type dual carb intake for the 23 inch block. I have the Offy, but the design is kind of crappy. The passageways are squat, not the best shape or finish and the transitions, well they suck too.

 

I'm trying to get some cad drawings of the engines, but I'm not waiting for that. I took my Offy and screwed it down over some wet cardboard on my work bench. I'm just trying to get the flange outlines as well as the exact(ish) hole placements. With that I can start to model my design.

 

 

 

Once I have a nice impression, I did BTW outline the flanges with a pencil, I can draw a grid over the whole thing and start transferring coordinates to the 2D drawing. If you aren't familiar with 3D modeling, at least in Solidworks, you start with a 2D and then extrude the thickness. That's how I'll get the flanges and their locations.

 

This is a long term project, so I will come back as I make progress and update the thread.

 

I'm going to use some heavy wall 2" OD aluminum pipe for the majority of the intake and transfer plenum, then I'll use the 2" OD cast aluminum elbows to go from the tube, to each intake port. I could just cut up the Offy to use it's flanges, they would work fine, but I paid $350 for the intake and they are selling for $500 today. Might as well sell it.

Edited January 13 by lostviking
formatting and placing text under the picture

[lostviking]

To answer the lingering question, yes, if I could buy one, I would simply buy the AoK intake. I'm not trying to steal anything from Tim and George. They just don't have them to sell anymore. This would cost a lot more than $650 if I had t pay for the work, but I don't

[lostviking]

The first pattern. From this I'll get the flange design where it meets the block.

[lostviking]

Started over...didn't like the tubing walls. These have .145 thickness.

 

Edited January 16 by lostviking

[Matt Wilson]

Looks like an interesting project.  It will be cool to see the updates.

 

Also, I should mention they I'm shocked at the price of the Offy manifold.  I had to look them up for myself, to verify the price you stated.  My memory (which could be faulty) says they were being sold for around $200 just 5 - 6 years ago.  Or maybe it was closer to $300, but either way, that was much less than the current pricing.

 

I definitely remember a time when they sold for under $200, although that may have been longer ago - say 15+ years ago(?).

Edited January 15 by Matt Wilson

[Jim Shepard]

I’m doing the same thing except a triple carb setup. I’m going to have the flanges CNC’d locally and weld ‘em to steel pipe. Haven’t decided if I’ll do a “log” design like your illustration or something where each intake port has its own curved pipe and a smaller pipe connects the three intakes, making a balance tube.

[kencombs]

On 1/15/2024 at 8:52 AM, Matt Wilson said:

Looks like an interesting project.  It will be cool to see the updates.

 

Also, I should mention they I'm shocked at the price of the Offy manifold.  I had to look them up for myself, to verify the price you stated.  My memory (which could be faulty) says they were being sold for around $200 just 5 - 6 years ago.  Or maybe it was closer to $300, but either way, that was much less than the current pricing.

 

I definitely remember a time when they sold for under $200, although that may have been longer ago - say 15+ years ago(?).

Yep, I bought a new unused one off eBay a few years back, 200 bucks delivered, changed my mind and sold it several months later for 250 plus shipping.  Should of kept it I guess.

[RNR1957NYer]

I haven't built the 230 it's going on yet, but when I bought my Offy intake they were more common on ebay and I bought the best deal at the time: $300, linkage included, free shipping.  I know now Offy isn't the best performing manifold but I have it and the carbs;  if performance is what I was after there is always the dreaded LS swap.

 

For those interested in fabricated manifolds and are leery of DYI, Google "Manifolds by Moose"; he's a member of the forum and I've seen his work (Moose is fairly local to me here in Massachusetts). 

[lostviking]

There are quite a few drawbacks to the Offy design. It's probably better than a stock intake. I everything Tim Kingsbury has written about intakes for our engines. I've also studied the AoK design as much as I can from all the pictures available. I can see where it is an improvement over the Offy, and I understand the advantages of the multi-carb setup for fuel distribution. That isn't just a performance thing.

 

I don't like the idea of using steel for the intake. I'm not arguing with anyone who chose that path, and I've seen "M by M" stuff, and it's price. Not something I'd go for, but you certainly can. I'm sure the manufacturing is quite good. I just don't like using steel for intake manifolds, and for me it's only the cost of materials.

 

The log, is partly for strength and of course for the balancing of all the ports. I am currently using the 2in pipe because it makes welding the elbows and the carb flanges not yet in the design to it easier. Triple carbs IS a better design, but the cost goes up also. Just a trade-off I made.

 

I know Tim and George Asche both like and use the B&B carbs. I respect their experience over internet chatter. I chose Carter WA-1 carbs, partly because I was able to buy two identical carbs with manual chokes, but also because I like vacuum controlled metering rods.

 

I have an Offy, but I'm going to sell it.

[kencombs]

Before I decided to use a 2bbl, my plan was the little Holleys with glass bowls.  'cause the look cool and use readily available Holley jets for the inevitable tuning needs.  One can find those in really small sizes from early falcons so even a 3 carb setup wouldn't overpower a 230,

[Matt Wilson]

6 hours ago, kencombs said:

Yep, I bought a new unused one off eBay a few years back, 200 bucks delivered, changed my mind and sold it several months later for 250 plus shipping.  Should of kept it I guess.

I bought a new Offy for my 230, over 20 years ago, for under $200 and never used it.  I still have it, new in the box, with linkage and everything.  I guess I'll sell it one of these days, as I have no plans for the 230.  Instead, I'm building up a 265.

[lostviking]

I took the Offy in to work Friday so I could get some dimensions. One thing I noticed was the OD of the tubes that connect to the block facing flanges. At about 1.7" they were quite a bit smaller than the tube elbows I'd found, and put in my model. I had to find something else, so I found some 1.66" OD with the correct (for the flange) ID of 1.25". I replaced them in the model. I still have the 2" OD log, but I'm thinking I can change that to 1.75". Maybe something else, I need to look at what materials are avail. Might just keep it, but the .25 wall makes it kind of heavier than it needs to be. Here is what it looks like today. BTW, I was able to model the block facing flanges accurately after measuring everything at work.

 

 

[lostviking]

Here it is using 1.25 Sch 40 pipe. That is 1.66 OD and 1.38 ID. Plenty of wall thickness IMHO.

 

 

[lostviking]

One more shot. I think this is the basic design. I'm going to look at some reinforcement flanges, but I have to get the weight of the carbs and do FEA on it. I'll do that Monday when I'm not logging in remotely. I put the carbs at 2.5Deg.

 

Edit: I wouldn't be cheap to make. Even with getting welding for free, I figure something north of $300 for materials. As much as $400 exactly like this, single part. I know I can shave it a bit with some careful thought about the design. LOL, the Offy cost as much as the material for this, and it's not completely ready to build yet. Of course that's what I paid...$335. Now when I just checked the same source is $541. I guess mine would be a deal.

 

 

Edited January 20 by lostviking

[lostviking]

Once you have the block side flanges, you can do quite a bit. My other passion is Harley's, and I do like the CV40 carb. It's designed to work on an engine that shakes, so living on a flathead would be easy. The carb has a rubber tube that mounts it to the stock intakes, but people like myself commonly adapt them to our older engines, like my shovelhead. You epoxy a flange to the intake side of the carb, and that let's you bolt it to the two bolt flange on older intake manifolds. Hmmmm, what could be better or cheaper to make than a straight tube manifold and the best fuel distribution for our motors is three carbs.

 

Not finished, but food for thought, but this is easy to make, carbs are very inexpensive, have huge jet and needle choices. Flange adapters are less than $20.

 

 

 

This is done with 1.5" 6061-T6 pipe. It's schedule 40, so nice wall thickness to support everything. 1.66" OD, 1.38" ID.

The flange adapters are O-ring also CV40's have integrated return springs and manual "chokes". Of course with this same design you could use an SS carb also, like a Super E.

 

Edited January 21 by lostviking

[lostviking]

I had the flanges only quoted. For a single manifold it's about $36 for the center and $25 each for the side flanges. That drops to $20(ish) each if I order 10 parts. If I ordered enough to build 10 manifolds, the price for the sides doesn't go down, so about $60 for a set of flanges. The only issue is the company only works up to .500 thick, and the flanges should be .5625 (9/16). If I build them, I would machine a step in the flange washer to make up the difference, or maybe just face my manifold. It's cast iron, so I don't think taking .0625 out would hurt it.

Now, should I just order a set for myself is the real question. Wasn't planning on manufacturing intakes, but who knows, I might know someone who wants a set of 6061-T6 flanges.

[lostviking]

On a roll I guess. This is one way to reduce the cost a bit. Drops on elbow and reduced tubing. That stuff is about $1/ft, so not much savings really. On all of these, there are details for the throttle I haven't added yet.

 

[lostviking]

With, IMHO, a better option, I'm no longer going to use the Offy intake. It's never actually been installed, so I think I'll end up selling it. I am going to use the Carter WA-1 carbs, just need to put the rebuild kit's I have in them. Both are clean, but not freshly "dipped".

[FarmerJon]

Which WA-1 did you get? Most are the smaller base flange, but 413/414 are "universal" and fit both patterns. They also have an adjustable main jet and can be switched from vacuum controlled metering rods to mechanical metering rods. 

Jon (CarbKing) warned me against using these carbs as a pair due to the difficulty in tuning them, but I am going to try anyway. My plan is to run them as singles, getting both adjusted to the same vacuum, speed and air fuel ratio, then put them on my manifold.

I just installed one, and am very impressed with its performance vs the B&B. 

However, despite the throttle shaft being fairly tight, it does seem to take in a littlle too much air, so I am going to go back and make bushings and maybe Oring it on both.

[lostviking]

Don't really know for sure right now, just that they are identical and have manual chokes. Who knows, I might just sell them after all. George Asche Jr is still offering B&B carb's he setup along with the throttle linkages. 92 years young and still doing what he loves. He's a great person to talk with, and both him and Tim Kingsbury are pretty friendly and willing to share their knowledge. They actually lived and did it, so it's from the horses mouth so to speak. Unlike some who talk a lot, but don't do.

[lostviking]

You got me wondering, so I took some pictures. Maybe the larger due to the slotted flanges?

[FarmerJon]

Thats a nice looking core.  It should be a 413. I think they are the only ones with that base. The 414 is the same but has an automatic choke. 

The instruction sheet with your rebuild kit should spell out the adjustments 

Edited February 17 by FarmerJon

[lostviking]

Yep. I took some WD40 to the dirty one and sure enough, 413S on the side. They would both make a good carb after rebuilding.