What will wake up a 400 engine?

[MarPar]

An Edelbrock more tuneable than a Holley?
Okay.

In my world, yes. Sorry fer offending your delicate sensibilities. I was just offering my solicited opinion.

 

[Myasylum]

you can also buy gears Brand new for the 8-1/4 dirt cheap..
i still have a set of 4:10s laying around from yukon,i think they cost less than 200.
the key to those rears is to rebuild using Spacers instead of a crush sleeve.
buy the aftermarket kit of Spacers,that has all diff sizes then use those instead of the crush sleeve.
with the factory crush sleeve,you get 1 shot at getting it right,correctly torqued to set.
whereas with the spacers,it will be easier to get right and Stay right because theres no sleeve to fail.

as far as your motor goes,from the start figure out the condition of the motor,ie timing chain,plugs water pump valve stem seals,compression for each cylinder,etc etc.

after that,either get your distributor recurved or buy an aftermarket performance<< one,thats curved for your Application.
ditch that holley you have,and look for either a street Demon or an edelbrock.
if you are going to street cruise this car,then get a 625
if you plan on beating it senseless then go for the 750.
heres a link to the Demon 750,and keep in mind this is Next Gen version of the Thermoquad design too.

https://danaport.com/products/demon..._content=sag_organic&utm_campaign=sag_organic

Is that 750 Demon still streetable? I'm sure I'll be doing a bit of both.
Yea the Holly I have seems kind of rigged just to get it to start. It does start right up. So it does its job. Other than that though it's popping and not real healthy. Not even sure it's getting full throttle.
Thanks!

 

[rumblefish360]

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!

Having owned a ‘78-400…
What holds it back?
Everything!
EZ way out? Torque storm super charger, headers, cam, a plus with a RPM intake and good blow through carb.

Ported iron heads (452) of those years and be really good.

 

[rumblefish360]

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.

Cheap mods to improve the mill?
Headers, carb, intake, small cam.
Hedman, Holley, RPM, a SFT is the style I’d look for & if a rocker upgrade is within your wallet. Otherwise, I’d use a Road Runner cam.
Things that will help compliment the engine & car, more converter and gear.

 

[66Satellite47]

IMHO, an Edelbrock carb is a lot more user-friendly than a Holley. Much more tune-able.

Let the flaming begin. lol

MarPar, I'm on the opposite side. My efforts with the Carter style have not gone well. I'm a Holley guy because I understand what it takes to tune them. I had a new aftermarket Carter AFB that worked great OTB and for quite a while on my 360 van tow vehicle. But all my drag race carbs have been Holley's. All parts to tune them are readily available. MHO.
For you Carter guys, keep going.

 

[Mopar Hunter]

X3 Supercharger!

 

[Hemirunner]

Here you go just over 3 grand plus the cost of a fuel system upgrade.
View attachment 1213453

Single plane intake, VS racing 80mm turbo and a used blow through carb. Half the price, twice the fun

 

[Nate S]

Not a performance part per-se but I suggest downloading perf expert and getting a windshield mount. Weigh the car (or guess with some backing data), plug in axle ratios and tire sizes, plug them into the program then go do a few 1st gear dyno runs on a flat quiet street.

With the data from this you’ll have a reference. How much horsepower today (don’t expect much, this will give you net and won’t lie) and then as you tune / alter you can see what each step has done (or undone). Without a reference like this you will miss a bunch of power opportunity, mostly in the area of tuning.

 

[Darter6]

Now I'm starting to think about the "popping" you are talking about. Possible burnt valve ?
Sounds like a compression check along with a leak down test should be first on the list before throwing any parts at it.

 

[Myasylum]

I think it's just backfiring due to improper timing/carb set up.

With this supercharger does that mean new pistons and all that, or will that work on a relatively stock engine?

 

[69hemibeep]

75cc Eddy heads and as thin a head gasket as possible.

 

[Hemirunner]

I think it's just backfiring due to improper timing/carb set up.

With this supercharger does that mean new pistons and all that, or will that work on a relatively stock engine?

Anything under 10psi would probably be fine. There’s probably enough wear on that engine that ring gap won’t be an issue.

 

[Myasylum]

After all that I have read the stroker with the 440 crank seems to be the way to go. For now though I just want it to run good. So I'm getting RPM intake, headers, and some kind of 750 Carb. Still looking into the carb. That 750 Demon looks interesting as long as its streetable. and a recurve.

 

[68 HEMI GTS]

+112 cubes.

 

[BeatersRus]

After all that I have read the stroker with the 440 crank seems to be the way to go. For now though I just want it to run good. So I'm getting RPM intake, headers, and some kind of 750 Carb. Still looking into the carb. That 750 Demon looks interesting as long as its streetable. and a recurve.

the rpm,is that the tall air gap one??
best to ask what will fit under your hood Before you buy.<<<<<<<<<<<<<<
yes,the street demon is a street carb and a performance carb.
i use them on small blocks and big blocks.

final thought,dont we have a distributor guru here,im not sure if he does the recurves tho ?? @HALIFAXHOPS

edit: i wouldnt throw your exhaust manifolds away either...
headers are a pita to work around,get installed,and Really heat up the whole engine bay,even if wrapped.
ive seen a lot of people very quietly switching back to stock/or stock honed/extruded.

 

[Curiousyellow71]

Our 400 is stroked to 542...
It is true..the 440 crank 452 combo is beloved by many. It was the go to combo back when the aftermarket didn't make affordable stroker cranks. Now doing a 512 is a bit of a no brainer.."nearly" a bolt in combo for the same money.
If you went with a turbo...everything else would look slow. The best part is driveability, driving around boost drives like its stock, you can make big power wo a wild cam and big heads. We did a turbo on a 318 years about 25 years ago, cast pistons, Technology has changed so much since then. We never melted a piston, mainly cause we would blow a head gasket first

 

[hunt2elk]

With a Performer RPM intake, you will need a drop base air cleaner to fit under a stock hood.....

 

[rumblefish360]

With this supercharger does that mean new pistons and all that, or will that work on a relatively stock engine?

Anything under 10psi would probably be fine. There’s probably enough wear on that engine that ring gap won’t be an issue.

Probably so! LMAO! But in all honesty, pulling the engine apart to re gap the rings is an easy mod but it is a long road to get there. OH! I did use a Holley Street Dominator on my 400 with a TQ. I tried an electric choke model. It was good. I swapped out it out for a larger primary TQ from a 440, tuned it up w/metering rods pretty nicely. Much nicer on the power return. It really felt great.

(Yea, it looks like hell but it worked really good. Lokar cables makes things easier FWIW.)

 

[Myasylum]

How do you fix this compression problem??
(Glad I have off this week, lol)

 

[Hemirunner]

Probably so! LMAO! But in all honesty, pulling the engine apart to re gap the rings is an easy mod but it is a long road to get there. OH! I did use a Holley Street Dominator on my 400 with a TQ. I tried an electric choke model. It was good. I swapped out it out for a larger primary TQ from a 440, tuned it up w/metering rods pretty nicely. Much nicer on the power return. It really felt great.

(Yea, it looks like hell but it worked really good. Lokar cables makes things easier FWIW.)

View attachment 1213657

It’s definitely the way to know for sure, but under 10psi and it’s not a big issue, so why pull it down if you don’t have to? I have a low mileage 400 block in my shop now and it’s got .005 wear in the bores which roughly translates to .015” additional end gap. Add that to the factory end gap and it has more than my 4.500 bore twin turbo hemi...