LD340 MODIFICATION OR NOT?

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CFD244

CFD244

"THE NEW OLDSMOBILES ARE IN EARLY THIS YEAR"
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Hi Folks

Putting this on a 9.3 to 1 340 with an XE262 Cam running an auto and 3.23 gears. I am planning on running a factory TQ. Should I tastefully modify it for the spread-bore, or do I consider an adapter? Pro's and cons of each please. Thanks FABO

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The design of the pad does seem to suggest it was intended for a little expansion of the rear opening area.
 
I'd cut it for the spreadbore and at the same time smooth the transitions under the mounting plate into the runner. Port match as well, of course. Yes they don't make them anymore, but they are a car part, not art artifact. If someone down the road wants to restore it, takes an hour or two of welding and cutting to get back to square bore.
The other option would be to use an adapter which is fine too, if you have the hood clearance, and has been done for decades
 
gzig5 said:
I'd cut it for the spreadbore and at the same time smooth the transitions under the mounting plate into the runner. Port match as well, of course. Yes they don't make them anymore, but they are a car part, not art artifact. If someone down the road wants to restore it, takes an hour or two of welding and cutting to get back to square bore.
The other option would be to use an adapter which is fine too, if you have the hood clearance, and has been done for decades
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They make intakes for a spread bore. Sell the LD340 and buy a new intake and you'll have cash left over

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Open it up! LD340 is a spectacular intake for a warmed over small block. It’s not the Mona Lisa, it’s an intake manifold. Make it work and reap the benefit, haters be damned.
 
Oldmanmopar said:
They make intakes for a spread bore. Sell the LD340 and buy a new intake and you'll have cash left over

View attachment 1716091107

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Good thought but I don't think you are going to have much money left over after paying almost $400 for a new intake. They aren't falling off trees cheaper in the used market either. If you can find one and it makes fiscal sense great, but I wouldn't let that slow me down if I needed it right now. The LD340 is generally considered one of the best dual planes that was available so I wouldn't go backwards with a 318 port Performer to keep from tuning up the LD340 if I couldn't find and equal.
 
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It’s your intake. Do with it what you please. Dare I say I think the TQ crowd might be willing to pay you more for it after you modify it for spreadbore if the modifications are executed well.
 
Personally I would not modify it, I was looking for that intake down here in Ontario and if I could find one it was $600-700+ and dirty with stripped holes. I ended up buying a RPM Perfomer off of Amazon for $500 shipped. And that was with tax and shipping.

I believe that the Weiand 8007 was a little less. The LD340 is a very desirable piece and once you modify it...it worth a lot less.

Just my opinion, but it is your choice.
 
What air cleaner are you planning on running? See how much room you have for an adapter, get your throttle linkage and kickdown linkage sorted to suit as it will need figuring out. Don’t touch the intake. Unless you’re just head over heels in love with it I’d shelve it for another combo or sell it for highest dollar to the first nut that comes along!
 
Look how thin the secondary walls are in the pic in post 14. That would make my mind up not to do it right there, but I wouldn't do it anyway. In the end, it's your intake.
 
First, I'd leave it alone. Second, the is no provision for a factory choke. TQ's should be choked to start, even in California or Florida. There is enough meat to cleanly modify it for a TQ. If you want to trade even up (assuming yours has not been milled on the intake face), I have one that was not pristine so I had it modified including welding up the heat crossover, cutting down the center divider per Super Stock recomendations, and opening up the carb base for a TQ. Never ran it since it was fixed.
 
This engine was going to get the 2100 intake that it came with from the factory. I thought that this would be a good upgrade to reduce the "heat sink" effect of the original cast iron assembly. I am running the original TQ and air cleaner, with the addition of an aftermarket electric choke set-up. I was worried that an adapter would interfere with the way the divider was originally designed. No, I don't like how thin the base is after it gets hogged out. Looks like a really nice job would entail some tig welding. LOL.............Can't figure out why I keep going down these rabbit holes. I'll have more **** on my shelves that I won't use. :BangHead:
 
Oldmanmopar said:
Don't ruin the intake ! get a spacer and modify it. Or buy another intake. The LD's are to rare and work great as they are.
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I agree. But I would still fix that carb flange. The divider is usually thicker to one side and hangs into one side of the barrels a hair and it's not Square end to end or side to side. Same on the port windows.
 
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