You will need a TQ adapter to run a TQ on a D4B or LD4B intake. There is not enough meat to just bore the intake for the TQ secondaries like a LD340.
D4B DC mods like the LD340 DC mods?
- Thread starter go-fish
- Start date
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You will need a TQ adapter to run a TQ on a D4B or LD4B intake. There is not enough meat to just bore the intake for the TQ secondaries like a LD340.
I think the notch on the one in pic is original? All the ones I've seen have that, or divider is milled down.
JDMopar
Well-Known Member
It should be able to be cleaned up on a mill to look decent. If nothing else, it can be a spreadbore intake. I need to dig it out, take it to my buddy with a mill and 60 years of machining experience and tell him...."I doubt you can fix this, but see what you can do."
I've seen some REALLY good jobs on some of those to a spread bore, you'd think Edelbrock made a run, but they never did. There are even instructions in the MP engine book on how to do it.It should be able to be cleaned up on a mill to look decent. If nothing else, it can be a spreadbore intake. I need to dig it out, take it to my buddy with a mill and 60 years of machining experience and tell him...."I doubt you can fix this, but see what you can do."
I got one for a 383 but I guess it was the same as the 340 carb. I figured that and a Racer brown or E4. I hope to find a cam that will work with the pistons that are in it. That also depends on if I can get a thinner head gasket (MLS?) to bring the compression up that much more. I'm thinking this could be a good mpg engine, have a wide rpm range, and still be able to efficiently pass a semi with a 3.21 SG.
The MLS gaskets aren't all that thin. These are good ones. .028 compressed.
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Yes, but I would go with a larger carburetor, 850 cfm at least.
junkyardhero
Well-Known Member
i recently just did a little road trip in a 68 dart with a 273 2bbl and a no-grip rear end. zero-point-zero problems passing semi's, keeping up with traffic or tackling the mountain pass to get back home. all while clicking off high teens/low 20's mpg.
keep the cam small, keep the carb reasonable, bump the compression to a moderate amount and it'll be a ripper, have great street manners and return decent mileage.
That's what I'm shooting for.
junkyardhero
Well-Known Member
i'm sure that many will take umbrage at this, but looking back on your spec and ideas i'd forgo the "commando cam" or the E4. don't get me wrong, it's a cool cam if you're going for that type build but i think that there's many improved, more modern grinds out there that would suit what you're doing a lot better.
the stock 9:1 will be plenty for a broad range of use and should run on pretty much any fuel should you get jammed up while out and about. if you wind up needing to open it up, then i'd burn that bridge when you get there.
double check the primaries/secondaries on the carb to confirm that it's a "small" rather than the bigger 750, which i think would be too much carb for what it seems like you're trying to accomplish.
The best thing to do for us right now is probably to call Jim at Racer Brown and tell him my compression, gear, intake and carb, and intentions. We'll keep the heads on but replace the cam and lifters when the intake goes on. Dual point distributor as well
junkyardhero
Well-Known Member
100% agreement. Jim will steer ya right!
on a 273?
66340SEDAN
FABO Member #3649
That is correct, that’s what the notch is for. The mod is also to allow the use of a TQ carb, grinding is for the larger secondaries and the carb will them fit. I have an LD340 intake that’s been modded just like this.
Yes, vacuum secondary. Each cylinder is effectively only seeing 425 cfm with a dual plane manifold if the center divider is not cut down in the intake manifold.
A stock 4 barrel on a 273 is about that cfm for all the barrels wide open.
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fat fingered "is"
Oh, and stock was a single plane manifold on the commando engine, right?
Yes, a very flat, low profile, open plenum. This is a aluminum prototype cast from the iron molds and blueprints.
Well truth be told, I prefer a thermoquad on any street engine and that would require notching clearance in a dual plane manifold or a spacer, but then your more than likely going to run into hood clearance problems.
@toolmanmike @ch1ll
How about a new AVS2 800 cfm with the D4B and a Racer Brown cam suited to the stock piston and 4 bbl automatic, 3.21 gear? I guess I'll ask Jim. I almost called today but I was driving and didn't remember till after 5pm Eastern.
The 19129 is factory refurbished and only $400 when they're available. I liked the 500 cfm AVS2 on a 318 smog motor I had.
AS far as the cam goes I'm looking to make the most of the stock compression. I get good gas here, real gas $2.95/gal. for 91. I just want this thing to be an average engine. Good to excellent fuel mileage. Mild street. Good vacuum. Easy on valvetrain. A cam that takes advantage of the Mopae lifter too.
How about a new AVS2 800 cfm with the D4B and a Racer Brown cam suited to the stock piston and 4 bbl automatic, 3.21 gear? I guess I'll ask Jim. I almost called today but I was driving and didn't remember till after 5pm Eastern.
The 19129 is factory refurbished and only $400 when they're available. I liked the 500 cfm AVS2 on a 318 smog motor I had.
AS far as the cam goes I'm looking to make the most of the stock compression. I get good gas here, real gas $2.95/gal. for 91. I just want this thing to be an average engine. Good to excellent fuel mileage. Mild street. Good vacuum. Easy on valvetrain. A cam that takes advantage of the Mopae lifter too.
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I replaced the worn out stock carb on my 273 with a 600 AFB. It worked great right out of the box with no tweaking. Just idle speed and mixture adjustments.
Having done the DC mods to a LD-340, I would not do the mods to that intake unless your really cranking up the power with a large cam of at least 248@050 and .575+ lift.
If you’re “Going There,” go for it. Otherwise, leave it stock.
Go to a RPM instead and then add a spacer for more plenum if need be.
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