No, read on below.
No, read on below.
There is a caveat to this all. Read below.
Spacer or notch. If notch, no.
Junkyard hero, Bingo!!!!!!
Not all LD-340’s came with the notch. Mine didn’t. (Ch1ll)
Moving on…
The MP engines bible suggests cutting the plenum divider down to a (IIRC) 3/8ths height with rounded edges and front to back to more or less line up with the forward edge - again, IIRC.
This was the “Legal Cheat” on class racing that demanded a dual plane be used. Opening up the plenum as large as described basically turns the intake into a single plane intake. But that’s basically since the intake still has uneven length runners that travel twisted paths. This retains some of the dual plane characteristics.
If you put a spacer on an uncut intake, do note that the depth of the plenum is more or less what is needed to be matched in order to - SORT OF - recreate the missing wall.
MoPar suggests making use of a cam with .600 or greater. Here, you will have to read between the lines some and go back in history to see just exactly what a .600+ lift cam is in duration wise. I’ll cut the homework for you and just say, it’s a big *** cam. A cam your going to RACE with. It will be north of [email protected]. The MoPar cam, the 312 duration, .590 lift cam is [email protected] as they say to do the math. IDGAF what anybody else comes up with, I’m just sticking to the book and what they say to do to convert. Carrying on….
The next MP cam is 324/.620. That would be [email protected] duration.
There are a scant few who would run this in the street while actually taking full advantage of the cams power engine and chassis wise. The next MP cams are solid rollers.
I did the divider mod and it was worth it even on a small cam 318 w/low compression. I also did the TQ opening mod. This was also worth it. There wasn’t a lack or notable/noticeable torque loss even in the 318 I had. It certainly picked up in the mid range and top end.
If you have this intake already modified or in a condition that won’t command any resale value & you want to use it, absolutely go for it. If you want to make a sleepy looking day two engine that’ll rock some socks off, this is a go!
Further more, port the intake runners as deep as possible the size of the heads window. Follow the TQ mods in the book and by users on here at FABO. I wouldn’t do the “Club” mod on the rods.
Just remember, these LD-340 mods are designed for racing. The effectiveness in the street is limited to the power produced by engine size, rpm, cam size and a proper combo. Do not use this modifications with small cams and low lifts. IMO, a good example would be a cam under 255@050.
I do not know how this mod would work on modern intakes.
I’d do it to a Weiand Action Plus or Stealth. IDK about a RPM. That’s pretty darn good as is and better with runner porting.
IDK about the notch mod.
Anyway, this old DC book mod was the forerunner and a big help to today’s F.A.S.T. Class racing. Those guys that are deep into are knocking down low 10’s and high 9’s on the OEM iron intakes.
Whew!
