I modified my intake manifold

J

jaded13640

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I have a 1957 Dodge with the 325 CID "Poly" engine. I recently picked up a 354 Hemi from a 56 Chrysler. I'll be putting the Hemi in the Dodge but time got too tight and I already wasted much of this summer so I'm going to put my Poly engine back in for this summer and put the Hemi in over the winter. ANYWAY...

So sometime back I purchased a 4 barrel intake for the Poly but didn't have a carb for it. I figured we had one around in all the junk and I'd rebuild it. Turns out we didn't have anything that old....except for the carb on the 354 Hemi. But there was a problem, the Poly carb was shorter and squarer so the hole pattern to bold the carb down was in much closer than the holes were on the Hemi's carb. It's kind of strange because when you see the pics you'll see that they used the exact same pattern as on the Hemi intake. The Hemi carb lays over the flat surface for the carb perfectly! All I had to do in order to make it work was drill and tap 4 holes! Simple right? Famous last words...

I had some good transfer punches so I plopped the Hemi carb down on the poly intake and it turned out only 3 holes could be directly transferred as there was something on the carb in the way. It was an easy fix. I just measured the distances between the holes, plugged them into my calipers, swung an "X" and centerpunched all four. Instead of being careful and doing the drilling with a had drill I looked over at my mill and said to myself, "just think how much better that would work!" Bad idea! It turned out there were no flat surfaces other than the one the carb mounts on. I had to use a bunch of shims and clamps, had to remove my vice....what a job. It was a real pain getting it level. It wasn't until later that I realized just how NOT level the mill was. I'd been meaning to level it since I put it there 4 years ago but just never got to it. It turns out it's so far out of level I'm lucky my project worked at all and didn't ruin my very spendy intake manifold. I guess the moral of the story on this one is, "just because you have a milling machine doesn't mean you should insist on using it!" I think the results would have been much more accurate had I done it by hand!

Anyway, here's a couple of pics...

Thanks,

Wayne
 

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The poly V8,s are incredible engines!
They ARE a mostly Hemispheric combustion chamber
Nice job.
You are right about it is sometimes faster and more accurate to do it by hand.
 
Hindsight is always 20-20. With that in mind, I would drill and tap the blocked hole first and mount the carb to the manifold with that hole. Then I would use the transfer punch to mark the remaining holes.

While the setup is a pain, I would have used the mill as well. It is difficult to get truly perpendicular holes by eye when hand drilling. Also, a tap going in crooked is prone to breaking and extracting a broken tap from a valuable part is a real pain.
 
I have found a level app for my Android phone called Clinometer. It is surprisingly accurate and repeatable to 0.1°.

You can also place it on a surface and zero it to make something level to that surface.
 
If you can't get a transfer punch to fit you can make a transfer plug (wrong term??) My wood working doweling jig came with these in 3 sizes. 1/4, 5/16 & 3/8. I use them all the time.

IMG_4116.JPG

As part of my 66 Midget Toyota engine swap project I am going to have to do the same as you are doing to install a weber 32/36 carb onto the stock Toyota manifold.
 
Wow, excellent ideas everyone! I totally didn't expect this threat to blow up into all of this. This is great! I think I have a digital level now that you mention it, I'm going to see if I can find it and mess with it. I'm also going to look for that app.

Getting that fourth hole location was pretty easy, I had the distant between the other holes right there in front of me. Once I had transfer punched, and center punched the three holes I could get a transfer punch through I just took the distance between the holes, locked it into my calipers and, put one end into the center punch divot and swung the other side to scribe a little sweep line. Once both lines were swept I had an intersection to punch. Transferring that info was the easy part. The had part was mounting the intake into the machine.

Chuck, great idea. I have done that in the past. I transferred the data from an existing set of holes by taking screws, grinding them to a point , threading them almost all the way into the hole and setting the surface of what I wanted to machine over the points and tapped the workepiece with a hammer in all four corners. It worked great but was only as accurate as my ability to grind the screws to a point. I didn't use the lathe to cut points on them because I didn't want to have to smash down on the screw threads and therefor possibly damaging the threads of the piece of I was transferring from. If the screw piece is long enough/depth of hole deep enough I would put two nuts on the cut off and chuck the two nuts on up the lathe. But I would have much rather had pieces that already had points and would fit directly into the center of the hole like what you have there. What was that again and where can I find them?

Thanks,

Wayne
 
I just downloaded a clinometer app and am playing with it a little but i don't know what I'm doing it. My phone cover is a necessity in my life of work but doesn't lend itself to zeroing an existing unlevel surface. I would have to take the cover out to make this work...I think. If so it's a little fragile and wouldn't take too many time before it was broken. But I love the idea and will use it in the future. Thanks!
 
Could you use the gasket the carb uses to get holes where they belong?
 
The case on my phone is just as accurate as the phone itself. It does not matter if I am laying the phone flat on a surface or holding any of the 4 edges against a surface. YMMV.
 
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