Holley 94 adapters/spacers + some

I figure I might as well throw something on here for tech week. I bought a nice used Offy 3 carb manifold for the flathead I'm putting in my 40, problem is I have a box of 94 cores, no 97s. I like the 94 ok but they won't fit the Offy manifold, the carb spacing is too tight. I didn't want to pop for the 97s so I decided to build some adapters to make the 94's fit and maybe trick thing up a bit by making risers out of them.
Like everything I build they are done with basic tools, I don't have the luxury of mills and lathes or all that good stuff. About the only thing I used that might not be in most home garages is a tig to weld up the aluminum. This would still be doable if you can't weld aluminum, you could do all the fitting then send it out to be welded or they could be made out of steel and painted.
First step is to build a jig. I took some chunks of 1/2" by 4" steel and using a old carb base for a guide drilled the 3 bolt carb pattern in the middle of each. On one plate the holes are drilled and tapped for a 5/16 bolt and the other just drilled 5/16. I also drilled a small hole marking the center of the carb bores. You don't really need to but I also used these plates as a drill guild for the aluminum bases I'm about to make.
Bolting the two plates together I then drilled a hole near each corner but inboard some on the long side. Unbolting the two plates I the slid the top one 3/8" foward, clamped it and drilled thru the holes making another set of holes in the bottom plate, then slid it back 3/8" from the first set of holes and drilled 4 more in the bottom plate. I'm afraid this sounds confusing but hopefully the pictures will explain. What you end up with is two plated that can be bolted together in 3 posisions with the carb bolts either offset 3/8" front or back or centered.
I bolted the 2 pieces together with some pieces of all-thread to space them apart the distance that I wanted risers to be, in this case 3 1/2" apart.



You'll want to mark the plates so one doesn't get flipped later on and your holes arn't perfectly square. That would throw the carb holes off.
Now I can start building the risers.

 

I started by cutting up some 4" x 1/2" aluminum plate into the basic carb base shape (like on the manifold). I use to cut this stuff up with a hand hacksaw but I finally inherited my Dads old Jefferson power hacksaw. Not fast but it sure works good on aluminum. I cut out six of these and drilled them out (sorry, I don't have a picture of them drilled). Besides the 3 bolt holes I drilled out the carb bores with a 1 1/2" hole saw. The 1 1/2" holes will overlap about 1/8", thats ok. One 3 plate the carb bolt holes are drilled and tapped to 5/16 course thread and the other 3 are drilled to 11/32.

I then took some 1 1/2 inch x 1/8" wall aluminum tubing and cut it into 6 3 1/2" long pieces.


Sanding a flat into the side of each piece of tubing till 2 of them would fit into the sieamized holes in the plate, I then clamped them together and welded them up, ending up with 3 sets of double tubes.
I went ahead and dressed the welds on them now with a sanding roll in my die grinder, a lot easier then it would be later.

Now I'm readdy to actually build the risers.

 

I assembled the pieces in the jig . The first one I use the center holes on the plate for the all-thread. this centers the 2 carb plates in a staight plane.
Using a caliper I make sure all 4 corners are spaced the same 3 1/2 " apart.

I start welding the 3 sections together. I do as much welding as I can while it is still in the jig to keep things from moving with the heat. Removing the riser from the jig, I finish welding it up including around the top and bottom.

The next set I move the jig plate to the foward hole. This offsets the carb plates 3/8" foward. You have to hog out the bore holes in the plates with a die grinder and sand an slight angle to the tubes to get it to fit. Hog out the plates on the inside only, not the top or bottom or your bores will not line up with the carb or manifold. Once it all fit together weld it up like the first one. On the last set, move you plates to the back hole. This offsets your plates 3/8" backwards. Grind, fit and weld as before.
Please note. I just realized all the pics are of the riser jiged up in the offset mode. I hope you can still grasp the concept!



You now have 3 risers, one straight, one leaning foward and one leaning backward. All thats left is to dress them out. The top and bottom I file flat witha large flat file, the one I call my "arm strong" milling machine. Take the time to get it as flat as possible, they are gasket surfaces. The rest is dressed with a combination of sanders and die grinders and a little hand sanding, none of it much fun. I take it down to 320 grit then hit it with the buffing wheel. Thats it, 3 custom risers that are offset so the 94's willfit the manifold.
R to L raw, sanded, polished

While I was at it I decided to incorperate a fuel log into it. They a pretty simple, Cut a leanth of 1" 1/8 wall tube, weld some 1'2" tick plugs in the ends. Drill 3 5/8" holes spaced the same as the carbs and weld in some shote pieces of 5/8" solid bar. Add some mounting tabs that fit to some of the manifold bolts. Dress it all out, drill and tap some pipe treads in each end and each of the 5/8" bosses and polish it up.

 

Nice work! and a clever jig. getting an aluminium capable tig is next on my list..

for the record, I have fitted 3 94s to an offy 3 carb,needed some judicous filing(with an armstrong mill!) they touch, but they fit.

 

Time to put it all together. I was quite pleased by how it turned out, I hope it runs as good as it looks!




This picture shows the offset of the carbs well.

Final note. Polishing aluminum is not my favorite past time, just doing the spacers and carbs tests my patence. Many thanks to Tom at Squeaky's Metal Polishing in Logan, Kansas for the killer job he did polishing the manifold (and the heads as well), resonable priced as well!
There you have it, hope it's helpfull. Keep in mind it would be easy to build almost ant type of carb adapter this way, say a 4 bolt carb to a 3 bolt manifold.

 

Great stuff. I have a Powerhacksaw similar to yours I bought at an auction. The motor took a shit the first time I used it. (raining at outdoor auction+open motor=short life)

If you were to make these again would (could) you drill holes in the steel plates so you
could get access to weld the insides while still in the jig? Just a thought.

Awesome work.

Jeff

 

Very cool idea. I like your thought about adapting different bolt pattern carbs to a manifold. That COULD save someone the expense of buying a new manifold when they already have one but not suited for the carbs they want to run.

Frank

 

If Thickstun had made a tri-carb manifold, it probably would've looked a lot like this.

 

Very sweet !

 

I guess it's possible to drill the jig and weld the insides while the riser is still bolted to it but it would be tight to get the nozzle and rod in there. Really all the jig is for is to keep the upper and lower plates square and level with each other. You can weld enough of it while it's still in the jig things arn't moving while you finish welding out side. Besides, the nicer you can weld the top and bottom (easier = nicer welds) the less work with the file.

 

Nice work and I'm diggin' that old hacksaw!

 

I've done that too, but these adapters are a much better looking solution!

Nice work.