'57 GMC (on going progress) Ram Air? aluminum intake plenum

Fellas....How goes it.
Got busy in the garage so thought I'd show whats up like always. There's still a few things that need to get done before I roll this thing out to the weekend hangouts and shows. When the front flip was planned I welded some tabs on the radiator support to mount a plenum behind the big hole in the GMC hood. I figure the hole would make a nice air intake. I bought some 1/8" 5052 aluminum and set out to fabricate the intake.


These pictures show the hood opening and the support with the tabs.



I measured and bent an upper and lower pieces with a 20 degree profile around the sides. The lower piece is wider and deeper as the hood slopes forward and the opening is wider on the bottom. I left a little extra in the front to roll up and ready for the nose opening. This picture shows the top bottom and back tacked together. You may notice this somewhat matches the aluminum carburetor scoop on the engine.

I made up a thin gauge sheet metal opening template and cardboard center support in the newly fabricated pieces and checked the fit. I adjusted the rolled ears on the front of the pieces.

Next the nose side's. Some hammer work on piece of pipe in the vise and the anvil shaped them out. I scribed some angled lines and cut the lower angle first. I worked up to the top curve around the template and finaly scribed and fit the top.




After tacking the right side I did the same process for the left side.





A quick measurement check on each side to be sure it's even.

Tack weld and remove the cardboard support.


Looking good so far. Check the fit in the opening and get ready later for the other sides. Enough for now. Keep on truckin'


 

allright now...gettin' back to it.

The sides are somewhat compound angle and curve at the front nose. Once the top, back and nose pieces are in place the sides are shaped to fit as close possible. The best tool I have to do the shaping is this mini angle with a rasp bit. The aluminum didn't choke it out and it cut quick. This is a few pic of the sides cut out at the compound transition and the tool mentioned


The most important thing is clean metal. The pieces are cleaned with acetone and wire brushed with a stainless brush dedicated for aluminum only.


My machine is an old Miller 330bp. It works good for me but if I where "in the business" I would invest in a modern machine. For now I can only read on the web how nice they are compared to the copper piles of the past. I also use a coolant setup for heavier welding if needed.

I'm using a 5% magnesium ER5356 filler rod in both 3/32 and 1/16 sizes. This goes with pure tungsten green band electrode. I set the welder as needed for this and adjusted to give the pedal a bit more than producing a puddle on the metal.

The beads I ran out are by no means as professional as one who welds this stuff allday but the results are good. Welding aluminum is a difficult process. I am happy to see the rod flow out like solder. If I can get the consistant rod dipping down the bead would be uniform. As you can see some spacing and thicker puddles show here and there. Only practice will produce perfection here but since the intake cleaner on the carb is smooth I'll more than likely be sanding these out and polishing to finish.


A few times the tungsten contaminated by touching the puddle or I touched it with the filler rod. A quick remove of the cup and a hit with a hammer on an edge of the anvil breaks of the contaminated tip of the tungsten. After resetting the tungsten I just reballed the tip with a quick arc strike and 3 second hold on a scrap piece of 5052.


Patience is a virtue! Anything that can go out of control will. One of the important things is to use some heat sink pieces. I used some blocks of aluminum to help soak up the heat and keep the edges straight. The aluminum likes to warp if not clamped to position.
The curve transition isn't exactly tight so some heat with the acytelene torch and a ball peen works it in some.


At this point this side is tacked into a good position. I can take my time welding the outer corners and get ready to make an inner member to support the GMC emblem.  

Fella's.....How do?.... Just wanted to share some more of the aluminum work with the intake so here goes.
I did some side work and put together a few green backs and got some more front pieces chromed like I mentioned before. I'm keeping things close to orig as possible. I kept the wing windows, orig mirror arms and such and so forth and the grill and emblems will stay too. These pieces are die cast and could't be chromed by Tri City so I called Hanlon near me in Virginia and arranged for them to plate 'em.
Hanlon did a fair job but I really can't complain because they only charged me $200.  Here's a shot of the pieces.

I got the support bracket painted and mounted the center grill piece. The grill looks nice without it but the bars are flimsy. I noticed just with the engine running the bars vibrate and I know before long a nasty crack would be stupid bad.

I completed the welding on the sides and sanded the tig welds smooth. WD-40 on a 4" sanding disc works good. Later I'll start fine sanding ready for polishing. I made 2 center uprights with stepped edges. I notched open the plenum for the stepped edges. There's no way to get the torch inside for a corner weld. This way I can run a bead across the top and bottom then sand it out.


I traced out the GMC hood emblem on a piece of aluminum and cut it out for a mounting backer.


 

Thanks a very nice build Hotrod...dinot know I was in such company......!  

Thank you Rich but really it's an average home grown garage build over nearly two decades in the making. I've been blessed with health and a stable job for now so I've been able to buy a few things to help it along. What amazes me most is what one can do with very little but hand tools or common shop stuff. It's easy for shops to make nice brackets with CNC water jets but that's not practical for you or I. I enjoy seeing someone pound out something by hand the old school way. For me, the end result in a projects looks from a high end value isn't as important as the passion that one puts into it. Keep things going on your project and post as you can. It's about the enjoyment and fun of it all.  

Made up the inner support brackets and welded on some tabs

The '57's didn't have a screen grill behind the emblem so after the holes are drilled the eblem will go on next.

Made a cardboard template for keeping things uniform and marked for the back outlet to carb passage.

Cut and shape flange piece.





I cut the outward flare from the old filter scoop housing to keep things straight.


Nice thing here is I don't need to make up or but another filter. Keepin' it simple.


Next few are of the blank off plate in front of old scoop housing.




I'll put a couple of fasteners on the bottom half. The top will come off easy for filter service.


Make up of center tube.
 

Looks great Hotrod.  

A shot here of the weld on the inside. Both sides are done and will get sanded out to finish.

Shows the inner brackets in the cut out grooves ready to weld. I alreadt sanded the rough scratches and corner welds down. The piece will be buffed and polished out later. The next photos are just showing the rough in and all will be taken apart to polish.

Left groove ready

Right groove ready

Welding in now

Top welded and back plate clamped to keep straight.

This shows the 1/8" rubber edge. At final assembly I'll use a 3m adhesive.

Shows my plan for mounting. The grommet has an 1/8" groove for the plenum thickness. The inner spacers are cut from the 3/8"ss tube shown and the plenum will get drilled 5/8" for the grommet to be placed in.

Shows the grommet placement.

Showing the backer plate and chromed GMC emblem loosely bolted for mock up fitting.

Showing the silicone sleeves and ss clamps with plenum and center tube placement.
Next time I get back to this I should have the final welding, sanding, buffing and placement done to post.  

Thats going to look really cool, nice fab work!  

Fellas,
Hope all is good for everyone. I been busy with everything but found some time to finally get this plenum done. Thanks for all the compliments.

Sanded with 220 then 320 then used the Makita buffer with a 8" cotton wheel. After some time the green compound began to buff up a shine. The next pics just show the final product.





 

Ace, you are a true craftsman! that is just awesome WOW! Great job... now can you do mine? just kidding...