Magnum intake drilling plate project

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Stephen Hotz

Stephen Hotz

Youtube channel Stephen Hotz Just Drive It!
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So started this project by borrowing a LA head core. Thank you Rick at Park's Engine Service, Seguin Tx.

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Made a pattern with a fiber paper and ball peened hammer.

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Did the same thing with a Magnum head. Here you go.

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One problem I see already are the end bolts.

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The brass pipe nipples will be installed into the steel plate I have. You bolt the ends up and that allows you to drill the center bolt holes. Then swap to the other plate and drill the last two.
 
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Trying to do these so they can be mailed around as needed. Will see how to get past the end bolt hurdle.
 
Just so I understand....you're making a fixture plate to drill Magnum heads so LA intakes will fit? Somebody on Moparts made one years ago, and loaned it out, and it supposedly worked well. It got lost between loan outs, and has been MIA ever since!
 
Sounds like it's drilling Magnum manifolds to LA pattern.
 
318willrun said:
I believe he is drilling Magnum Heads to accept a LA intake
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Yep. I can do it without the plates as I have a flat bed milling machine. Wanted to make up one to loan out and another for myself for field use if needed.
 
I was going to ask why but I know there isn't too many choices for Magnum intakes out there.
 
Figured this is something that comes up every so often so why not help out. I have already received a good amount of help from threads and members.
 
so how are you going to assure the proper hole angle - provide transfer punch for marking location
 
toolmanmike said:
I was going to ask why but I know there isn't too many choices for Magnum intakes out there.
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Correct. Either Eddy RPM air gap, or Chinese knock off air gap. Mopar performance made a nice dual plane (non air gap) and a single plane, but they messed up by making them too early, meaning magnums were fairly new and nobody was swapping them into older vehicles. Mopar got out as sells were down, so we have our two choices - unless you drill :) I asked Johnny Mac to make a nice dual plane (non air gap) that sells for 200 bucks, and it would go. More magnum swaps than ever, and not everyone wants a air gap
 
dodge71demon said:
so how are you going to assure the proper hole angle - provide transfer punch for marking location
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Going to install standoff nipples that allow you to run the drill straight down the pipe. You would install a stop on the drill bit. The first plate will have standoffs on the end bolts so the plates bolt down as per factory in order to align the center bolts. Then tap and install the second plate to drill the ends.
 
Considering that most used magnum heads are cracked, I would be surprised if it gets used much. You can buy a new, much better EQ casting bar with the LA pattern already in it.
 
I've got the real fixture from BHJ. Planned on drilling my Magnum heads but found a set of Edelbrock too cheap to pass up.
 
Another modern issue is that working AC is now more popular and the Mag intakes aren't too friendly with vintage compressor locations.

I gave the OP a "thanks" for this labor of love.
 
The other two plates do what, bolt to the head deck surface? What happens if the head has been surfaced?

I was going to make one of these and like everything else around here, "no"
 
Guess with either of the style plates if you bolt it up and its been surfaced you could be in trouble.
 
Stephen Hotz said:
Guess with either of the style plates if you bolt it up and its been surfaced you could be in trouble.
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I had intended to use a known unsurfaced LA head as a pattern, and index the jig on the top of the head, as tops of the head bolt holes. I've forgotten, I had taken some prelim measurements between some junk heads, and the measurement of the tops of the head holes to the surface of the head were fairly uniform, as I recall. I don't remember, I guess the Magnum head bolt "height" is different so you'd have to adjust the jig to that.
 
Picked up the proper drill bit today. Got the ends drilled and tapped before I got in trouble for working on car stuff instead of roasting coffee.:lol:

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