What will wake up a 400 engine?

[Myasylum]

What HP gains would I get with just a Holly 4bbl, intake and headers?

Really need to wake this thing up! I think I read that the heads on the 400 is what really holds it back?

Thanks!

 

[Pikser]

Replace it with a HEMi …

 

[Jerry Hall]

Stroke it, 451 comes to mind.

 

[Myasylum]

Thanks, but I was running relatively cheap mods for now. I just bought this car, and just want to wake it up it bit for now. I'll get into tearing it all down at some point, but for now just want to enjoy driving it.

 

[MarPar]

Taller rear gear?

 

[mopar jack]

Taller rear gear?

Check timing. Many cars during the 400 era had very low initial advance. I bought a 70 Chrysler 300 with a 440 from a friend and it wouldn't spin a tire cause it was set at 2 degrees initial, bumped it to 10 fried the tires and broke a motor mount. That 440 was trying to climb out of the engine compartment.

 

[moes]

Re-Curve the Distributor

 

[1968rt]

Compression, camshaft, intake

 

[Darter6]

The 400 2 bbl cams weren't much. You may want to look into a cam that is made for a low compression engine.
Heads should be the 451,Maybe 356.Either will be fine for now. That should be your last worry for now.
Now you are looking at cam,lifters,timing chain,valve springs,gaskets.Along with a carb and headers.
The budget has just increased by a large sum.

 

[streetmachine]

The question(s) I have for you is define "waking up?" Basic bolt ons will get you some power but, not a ton depending on where your power goals lie. But, it also depends on the year of the 400. Is it an HP engine or not? Sounds like a 2bbl version?

Also, I'm assuming you want to keep it somewhat daily driver friendly? Most 400s suffer from lower compression. Gears would help depending on what you're running now. The other question is what is the engine in?

 

[PRHeads]

If it’s a 2bbl now, then a 4bbl/intake, headers, recurve distributor will make a nice difference.

The next steps require some real $$$ to be spent....... cam and heads.

 

[66Satellite47]

My '70 383 2bbl low compression motor really responded to a basic DP4B intake and Holley 3310-1 with cheap 1 3/4" headers.
I'm sure the 400 would do the same. A basic aluminum intake, good 4 bbl, and headers will "wake it up". Recurving the distributor would help.
The really BIG gains come from a bigger cam combined with a basic pocket porting on the stock heads. It's amazing what a little pocket porting gives you. But start with the intake/carb & headers.

 

[33 IMP]

Search here for "the slug 400 on the dyno" by IQ52. Step by step how to get a low compression 400 to run.
The search will bring up all kinds of 400 builds and threads.

 

[Myasylum]

It's. 72 Satellite with a 400. It does have a stockist 4bbl intake on it now ( someone must have put it on) and a rigged up Holly. It works but definitely needs a tune. Backfires and stuff. I was actually thinking about getting Snipper Fuel injection. I would think maybe that would solve a lot. I think that hooks up to the timing as well?

 

[4mulas]

1-Not much with those additions. Maybe 30

2-a crankshaft (440 crank for 451 end game), pistons and rods, a cam and aluminum heads will change the characteristics of it dramatically

 

[hunt2elk]

What gears are in your rear end? If you have 2.76's now, a swap to 3.55's would wake it up for not a lot of money.

 

[Runcharger]

Almost zero gain changing from a factory 4 bbl manifold to an aftermarket in your application.
You need a properly running and tuned carb. No performance advantage going to injection.
A camshaft designed for low compression would help but is a bit pricey.
Optimized advance curve in distributor is really the most bang for the buck for you along with a properly tuned carb.
Rearend gears will help for sure, no doubt you have a 2.76 or 2.94 ratio and that will hold it back.
I don't see headers helping much with your mild engine either.
You do have dual exhaust I hope?

 

[RemCharger]

Compression.
I would like to build a top notch 400. Seventy one hundred rods and 13 to one hockey pucks... mmmm.

 

[Myasylum]

It is Duel exhaust.

 

[barbee6043]

Gears is the first choice. like said, go to 3:55.
Then as said, get the dist. curve where it needs to be.
If a 2 bbl, a 4 bbl, dual exhaust.
Then spend $$ for compression, cam, etc.