Looking for some information that I cant seem to find. I have been reasearching the web for simple upgrades to a 400 ci dodge rv . Seems that everyone is looking to get peak hp. In the upper rpm range. I would like to get more torque in the lower side of the tach. I would like to just cruise along at 55-60 mph pulling my jeep and quads on a trailer. The 400 that I have is a 1978 b300 van 4 x 4 ..I guess this was one of their " smog " motors. It has a two barrel carb and gets horrible gas mileage and I know that it is capable of more low end power. But how ??? Any suggestions ???

 

Here are a few things I found out. Someone with some mopar big block knowledge please chime in...

Ok first swap intake manifold with stock 4 barrel manifold.

4 barrel carb.

Headers

Windage tray

Heat riser block off gasket

Does anyone know what smog stuff can be removed for extra power. ??

I plan on doing some upgrades in two weeks, so I need to know what to start buying.

 

If you put headers and dual exhaust put a balance tube between the 2 pipes....Towing cam would also help with the above that you mentioned...The air pumps and "Smog" stuff will go away with the headers and intake..I would use aluminum Intake with no EGR if I were you and a 600 Holley vacuum secondary carburator...Also there will be no heat riser if you put headers on...Windage tray you will have to pull the oil pan and they use special bolts on the main caps...The gain there is min. so I would not do that as you said it is not a HP application so no real gain...Bill

1) You didn't mention gear ratio...
2)Timing???
3)Vans will never be a power house to heavy and with 4X4 it will be worse...
4)Both of the things you are towing are heavy...

 

These had Horribly low compression..... Thats why they where gut less....
This would be my suggestion if you can swing it...
Get the compression bumped up to around 9.0.1 or 9.5.1
Good valve job and port match only to the heads.
Lunati High Efficiency cam or comparable Cam lifters ans springs for the heads
Eddy or Holley Single plan Manifold... Add a 1" spacer if you can..
Thermoquad or a Holley Vac. sec. 650 CFM or 750 CFM
Upgrade to the orange ignition box and re-curve the distributor.
Install fresh air intake air cleaner to get fresh air from the front side of the core support.
Headers for sure.
2-1/2" Dual Exhaust system

Good Shift kit for the trans and a nice tight converter....

Use the Lucus fuel treatment on the long hauls....



Should tow real nice.....

 

Easy. Google around and determine the specs on a six-pack. Then take those specs and "translate" them into modern cam numbers

(For years, cam manufacturers played with numbers to make their cams "look bigger" by playing with the way they are measured)

Then cross check that against recommendations. Comp, other, cam makers often have recommendations.

The other thing you might consider is swapping in a 440. You can also get stroker kits for low block engines.u

 

Thanks ... I was afraid off some of yor answers. Lol

I like the header idea and removing some of the smog stuff, and don't get me wrong, when it's time for a rebuild I will be looking into a 451-500 striker kit... Butttt, for now I wanted to get a little more oomph for a camping trip we have planed for next month..

Okay, so on allpar there are some numbers..


400 with 2 bbl carb is 190 hp 305 tq.
400 with 4 bbl is 225 hp 340 tq
400 with 4 bbl cold pack ?? Is 265 hp 345 tq.

Can I just put a 4 bbl manifold and carb and headers to achieve the 265 numbers ??

 

Here is the beast ....

 

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No for the 265 hp you would need to raise the compression and change the cam

 

woo hoo.. i found out how to attach pics...

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So Would I see any benefit for swaping the manifold , carb, and headers ???

Is it worth it ? cause I found a guy with the mani/carb 4bbl from a dodge 400. Good deal also.. ???

 

it all depends on how you are going to use it. on the cam thing. you can shift some torque from the high end to bottom end by setting it 2 degrees advanced. you do NOT gain any total torque. cant remember if you can go 4 degrees. BUT i CAN tell you do NOT try 6 degrees advanced. you dont want to hear that story.

 

What carb comes with the manifold? Dual plane 4 barrel spreadbore carb with a recurved or new adjustable distributor and headers are the easy bolt ons to get what you want.

ThermoQuad, QuadraJet or Street Demon with very small primaries is the way to go. I like the Street Demon's triple primary boosters.

 

many many many years ago i had 1977 dodge 100. 318 stock. i found a carter 2 bbl WGD from a chevy. it had a triple boosters. i put it on the 318. it was not powerful. but off idle it VERY quick.