welding framehead advice

[HankScorpio]

As you can probably already see my frame head is not in great shape. I'm a knowledgeable but inexperienced welder (worked as a manufacturing engineer so I know good welds just not necessarily how to actual make them). I've got the little Hobart 140 that everyone on here recommended. (only have 120V in garage) I got some rough estimates from the pros for this repair and my poor 72 wouldn't be worth that much money in showroom condition. So I'm trying this myself.

I have a new frame head and napoleon hat from Wolfsburg west. The new frame head looks equivalent to the original. The napoleon tunnel is pretty sloppy looking at the tunnel.
I'm trying to show with the photos that the seams at the bottom of the napoleon hat and tunnel section of the frame head are super rusted.

Here's my 'plan' please punch holes in it and tell me how to do it better.

First try to clean off as much paint and guck as I can in the affected areas (that body pan seal goop is a mess, any tips removing)

I'm afraid alignment will be F'ed up if I try cut off back at the firewall. I'm thinking I will cut off the bottom 1/3 to 1/2 of the frame head. Try to make the same cut on the new frame head. tac them together and bolt the beams to make some measurements in an attempt to verify the alignment. adjust if necessary Weld to complete. Then maybe add some sheet metal patches over my welds where possible for a little extra insurance

The napoleon hat is rusted through where it meats the pan and the triangle under the frame head but still looks strong around the tunnel and the fit of the new part look terrible. I'm thinking remove all the rot I can the cut up the new hat for patches to go where I've removed material...

The only up side is the pan looks rust free from the napoleon hat back.

It's like the below image all the way around the frame head and hat

Also what's recommended for 'delicate' cuts? I have a sawzall & 4" angle grinder with cutoff wheel which I assume will do most of the heavy work but some of the inside corners are pretty tight. what's recommended. (I don't have a heavy duty air compressor at this time) Plasma torch is probably not in the budget.

[Derek Cobb]

Personally I would call a wrecking yard in the dry desert and have them cut one from a rust free car. I struggled with poorly made aftermarket junk and finally gave up and got a good used one. My 110 Lincoln did a fine job laying a strong bead. The key to getting this one right is to measure fifty times, lay a few small tack welds then re-check your measurements. keep doing this until it is very solidly tacked in, then finish weld that booger, good and solid.

[HankScorpio]

[wcfvw69]

x2 on returning those parts to WW. As you've seen, the napolean hat is not even close to fitting. I used the same one and had to REALLY cut it up and tweak it to get it to fit. I was NOT happy, at all. The other advantage with having a original piece is you can cut the extra's off the donor and have a pretty good template as to where it goes and sits.

There are LOTS of rust free pans out there for you to get those original pieces off of. The metal is thicker and you know it will fit. If it was me, I'd make a simple jig that aligns all the right distances and holes before cutting off your frame head. Obviously, it needs to be dead perfect before you weld it in place.
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[kman]

Cut the old one all the way off. Line up the new one as best you can and tack with 3 or 4 small but good welds. Bolt on the front axle beam and take measurements to make sure it is even and straight. Even put on the wheels and rear wheels if you can and measure distances. Cut through tack welds and re tack as needed until its lined up. When satisfied, start welding thoroughly in different places a little at a time so as not to overly shrink an area.

No point in trying to make a graft of two frame heads.

[eyetzr]

Measure it before you cut. Put the axle back on & make sure front to rear is the same on both sides. Get someone to help to measure corner to corner. Remove the old one, drilling out the spot welds. Fit new part on & screw it on or some nice tack welds. put axle back on & check your measurements. Finish welding.
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I think he meant "rare", as in "not well-done"

[beetlenut]

Assuming your existing framehead is still square on the frame, the best way to ensure you get the new one on, whether it be after-market or OG off a donor, is to build a jig!
Just get some lengths of angle iron or flat stock or bar stock or whatever metal reaches from the frame head to the part of the pan that will remain, and drill holes in them to attach to all the important mounting points on the frame head and to the tunnel or pan. Then bolt them up tight to all the mounting points, and weld them together where they intersect or come together to connect the frame head to the tunnel and pan. Now measure the new part, and cut-off the old part leaving about a 1/2 of extra old metal. Put the new part in the jig, and while offering up the new frame head, trim off the remaining old metal until the holes in the jig mate up with the remaining tunnel and pan holes. That should at least ensure you get the new part on with the same fit as the old one.
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scrapyards are for quitters
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[HankScorpio]

Maybe I'm misunderstanding the jig tips but it sounds like the recommendations are to put the entire new frame head on, cut off everything at the firewall. This makes me very nervous even with a jig. (Any pictures of such jigs would be helpful)

I was trying to communicate in my original post that I was thinking of cutting the existing framehead horizontally and keep as much good original metal as I can so say the top two suspension mounting holes are original and the bottom two would be new. I would still do jigging. I'm assuming fittment would probably be trickier my way,. cutting old and new just right to mate up won't be easy. Also a bit riskier that I ruin my new head with a bad cut but I'm still not sold on cutting everything off.

[beetlenut]

[miller0358]

Give Dave a call at Bug City in Berlin, Ct. Get a used original. I got a new aftermarket and killed myself trying to make it work. Good luck. Jeff