D4B DC mods like the LD340 DC mods?

[go-fish]

Would it seem logical that what's good for the LD340 is good for the D48 or LD4B in regards to the Direct Connection plenum mods? I don't know the exact spec but I'm talking about the square notch.

For those that care: 1965 273 2-bbl. Changing to dual point distributor, D4B, Carter AVS 4638SA (1969 340 auto), Commando type cam grind. I will probably keep the 9:1 (?) pistons for now but if it gets opened up you know the 10.5 pistons will go in.

So, from a flow and distribution aspect is what is good for the goose also good for the gander?

 

[413]

Not at all. Many differences in the engines, cubic inches, 2bbl pistons, port sizes, etc, etc.

And max flow doesn't make useable power for a street car.

What gears? What trans? Converter? It's about the combination.

 

[RustyRatRod]

I've always thought unless you were all out racing, to leave well enough alone.

 

[jeff alder]

Another piston option for the 273. If you do open it up behold EggE isnt the only option

 

[jeff alder]

My 273 1/4 Mile Time Slip With Video

 

[go-fish]

@413

Rest of the combo is factory 904 and will be a 3.21 when the 8-1/4 goes in.

 

[go-fish]

My 273 1/4 Mile Time Slip With Video

And these.

I (well, actually my machinist) ordered 3 sets of made in the USA, Forged custom 273 pistons from Race Tek a few weeks ago. They should be ready in a few weeks, and were $700 a set. I got 2 sets for me and one for @66fs.

Would love to learn more about these.

 

[jeff alder]

And these.

Would love to learn more about these.

JD Mopar and 66fs are very helpful members of this forum. I have gotten good advice from both of them and also pay attention to what they post when it's applicable to what my goals are.

 

[jeff alder]

Contact - Rebuilder's Choice I found some .060 over which is a stretch on ebay from rebuilders choice. They are high performance 10 to 1 made from hyperkinetic aluminum with valve reliefs. I contacted builder's choice to get the info for the part number. Ill post the ebay listing in a moment

 

[jeff alder]

Mopar 273 piston set .060 | eBay

 

[jeff alder]

Mopar 273 piston set .060 | eBay

if the block would take this bore this could be an interesting build...

 

[go-fish]

FYI
Laster one is LD340 modification



View attachment 1715924130

View attachment 1715924131

View attachment 1715924132

LD340 Direct Connection mods from the manual. This is the modification I'm asking about.

 

[ch1ll]

The notch is cut in to use a thermoquad carburetor. Any way what you are doing is changing it from a dual plane to a single plane, sort of. If your not using a thermoquad carburetor, I wouldn’t do it. I’d use a larger carburetor than an AVS with a dual plane as 4 cylinders only see 1/2 the cfm and the AVS is a small carburetor.

 

[Garrett Ellison]

Unless you use the AVS2 1412 800 CFM carburetor. I'm pretty sure that a TQ's secondary blades will still require an adapter to fit that manifold. I've always heard that the notch is for the three barrel Holley carburetors that were popular at that time.

 

[toolmanmike]

Check the clearances, run it without and do the mod and run it again. But once you carve it up there's no going back unless you tig it back in and machine it. Let us know how it works.

 

[JDMopar]

@go-fish Here’s a pic of my pistons when I was assembling my 273. I used 302 heads that in the final windup had 58 cc’s and 1.88 intake valves. A little massaging, but nothing crazy. I ended up with 9.8 compression wit these pistons. More than enough for what I wanted. Mild hyd. roller cam. I ended up with 260ish HP and 280 lbs. of tq.

 

[go-fish]

@JDMopar The hydraulic rollers intrigue me. I have two LA's that have bushed lifter bores. Needless to say, I like 'em. I wasn't even considering hydraulic rollers with the 273. Are the 273 lifter bores plagued with inconsistent chamfer like the other LA's? What lifters did you use?