1973 400 wake up

Daly

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I'm looking to wake up the 400 in my 1973 Newport. It's pretty much stock with the 2 barrel carb. I'm not looking for anything radical, if I can get it over 200hp, I'd be happy. The obvious start is to swap the 2 barrel for a 4 barrel. I'm going to swap to a relatively mild cam, and port and polish the stock heads. I'm having a 2.5" dual exhaust put on it soon, as the old exhaust is a patchwork of pipes and leaking, but I'm probably going to stay with the stock manifolds, unless I can find a good set of used TTI long tubes. I eventually plan to add 3.21 gears and a sure grip.
My questions are.
What is a good mild cam?
What's the stock 727 torque converters stall speed?
Other than an electronic ignition upgrade, is there anything else I can do to wake up the 400.
 
You don't need electronic, just curve the distrbutor to what you need.
 
You don't need electronic, just curve the distrbutor to what you need.
I'm not actually planning to upgrade to electronic ignition, just from past experience everyone always recommendedit. So I put that in to limit that input.
 
I will get crap for this but unless you race and need that 1/10 of a second no reason for it points last 10K miles usually.
 
73's are a low compression engine, that right there will be your one huge factor in getting it to wake up. If you're going to do headwork at least find HP manifolds, long tubes are a PITA and for what you're doing way overkill and a waste of money. Use cometic head gaskets, if you use Fel Pro's your going to end up with even less compression than you have now. Cam, with the comp you're working with you could probably use a mild stock grind (69-70 Road Runner etc) and you should be over 200-240hp on paper. If you go that route, send your stock cam to Oregon Cams and have them do a re-grind, I'm using grind #1369 in my Fury and it's a torque monster, they do awesome work for a fraction of the price of going comp etc for what you're trying to do and you won't have to wait 6 months for inventory.
 
Before you spend $1 rebuilding and porting the heads price out the work vs 440source and Edelbrock entry level heads. They offer closed chamber to help with CR and solid flow ootb.

It's an old tech grind but the comp 268H is up your alley.
 
Totally agree with Furious, the 440 source heads are really affordable and flow well. Port/polish isn't cheap and you may end up at the same level so 440 source.

Also try to find something in this range: @.050 219/226 Not sure I would go any bigger with your setup and gears.
 
In the way of cams, look for a cam with assymetrical lobe shapes, in the 216 @ .050 intake duration range. which should generate an exhaust duration of a little bit more (longer exhaust duration helps with factory exhaust manifolds and such. I checked one of the Comp Cams 268 cams back when they were "the thing" for a good street engine. I had read of their quick open/ slow close lobe shapes but I was NOT prepared for the valve to be at TDC for 10 crank degrees in that mix too. Which means more open time than a stock cam, where max lift only happens for ONE degree of crank rotation. BTAIM

Comp and Lunati have some assymetrical lobe cams now. I'm not against re-ground cams, but to get the additional lift, the base circle of the cam is decreased a bit, as I understand it. THEN also ensure they put OEM-level Parkerizing on the reground cam, too.

With any cyl head from anybody, you might well consider taking them apart for cleaning and touching the valve seats before installation. Mopar Joe has a video comparing two brands of new "in the box" cylinder heads, which verifies why my late machine shop operative always did with new heads. FWIW

The MAIN difference between the 400 and prior 383s is the lowered compression ratio. Cams are not that different, or enough to cause a loss of power from them (basically the old 256/260 4bbl cam, with a few tweaks). USA 400s had electronic ignition standard for the '73 model year, as I recall. Our '72 Newport 400 has it, when it was optional in the later part of that model year. Generally, the 2bbl 383s and 400s had good advance curves (factory specs) which generally allowed about 36 degrees BTDC total, so a little bit more base timing and quicker off-idle timing advance might be all that's needed.

Don't worry about "stall speed" of the stock torque converter. To me, some get too excited about that, by observation. It should be in the 1800rpm range, typically, if it has the 11.75" converter. The alternative would be the 10.75" converter. You can tell from the fluid capacity which one it should have, with the smaller converter taking less fluid, if there are dual capacities listed.

Stall speeds can vary with the amount of power in front of them, with the same converter. With the smaller converter, it might be closer to 2100rpm with the stock cam or thereabouts.

To me, horsepower figures are more about bragging rights at cruise nights than anything else. That horsepower only happens past 4000rpm. Torque moves the vehicle from rest. In this case, a vehicle weighing over 4300lbs (and more with people in it). So, build a "torque motor that rpms" and let the top end power be what it is. Torque also causes the rear tires to loose traction, off-idle.

From my experiences, having an engine which comes off-idle (about 600rpm in "D", hot base idle speed) cleanly and responsive to small throttle inputs makes for a more enjoyable general driving experience, no matter how much power happens past 4000rpm. Certainly, it needs to also eagerly approach 5000rpm as it goes through the gears, too.

What you have now, in that Holley 2245 2bbl, is basically the primary side of a 650cfm 4bbl squarebore carb. How much time do you spend at WOT to need the additional power of the 4bbl? Certainly, the 4bbl might increase power above 3000rpm or so, but with the current gears and general tire size on those cars, that's close to 85mph road speed "at cruise". 75mph with 3.21 gears.

The 4bbl upgrade is easy to do with an AVS2 and related Edelbrock intake. Just also plan on getting the necessary adapters for the throttle hookup and (if needed) the kickdown rod.

Do the rear axle gears last. I like the C-body cars for their extended speed/range cruise performance, but being able to lay rubber counts for a little bit too. There are a lot of smaller 4cys with gazillion-speed automatics that will put every older car to shame in "a contest", so best to not go there! The cars were not specifically designed for that, but in "police mode", they were very credible . . . when they were produced, but not in the current world we now have. But to me, the capability to effortless cruise at 80mph (in current traffic patterns!) is more important than a smokey burnout. Highway fuel economy is important too.

Sorry for the length. Some observations and experiences,
CBODY67
 
Just looked at the Oregon Cams website. Looks good! Another source for camshafts!

CBODY67
 
Thanks guys, food for thought is what I'm looking for.
I'm not looking to build a street monster. I'm just looking to improve its motivation a little. Make merging and getting up to speed easier. I live in the county and the car spends 60-70% of it's time on county roads doing 55-60. It is pretty peppy for what it is, but sometimes it feels like the kick down isn't enough. Like I said I'm hoping to be in the 200-250hp range which I would hope puts the Torque in the 350ftlb area. I'll look into the 440Source heads, but being in Canada I'd be very surprised if I can get them cheaper than a few days at the end of a burr bit. If I find a set of late 60s 383 heads I'll pick up a set and use those.
 
Your existing cyl heads have very similar configuration and sized chambers as the '68 vintage 906 heads, so you'll need to go back to 1967 or earlier. Then put the 1.74" exhaust valves in them (with hard seats) just to get something better than you now have. Which makes the aftermarket aluminum heads a better value for what they are and you want to end up.

Enjoy!
CBODY67
 
If you don't go the 440 source route try to find a set of 516 heads. They are closed chambered and will help with compression. They will need to have hardened seats installed.
 
fyi the 73 400 2v was rated at 185 net hp / 310 torque so the net #s arent that far off what you want to get to
 
Do the rear end gears first not last. HUGE improvement there.
 
Bucks down?

Assuming the engine is sound, Factory thermoquad intake with properly sorted Thermoquad.

Recurve the factory distributor.

Get a multi key timing chain kit and advance the cam 4 degrees.

2.5" dual exhaust.

3.21 gears.

It will roast the tires at will.

Kevin
 
I agree with 2stick....and need a gear in mine. Have talked this before, but with the current 2.92 gear in my 383 4bbl fury, auto, this thing is still pretty lame. I think the motor makes OK power once the secondaries open, but still not where I want to be. Was thinking of carlisle and a third member, but based on pricing, I am now thinking of a great shop in our area, and about the 3.54........3.73 not out of the question yet. This will NEVER be a road car, unlike Frieberger and his 70 roadrunner that he wants to drive 200 miles back and forth to see Stevie. I want a better launch, and bark than I have.....and continue back to the day.
 
If you never go out of town with it 4.10's are a hoot. With 28" tires. If you have little 26" tires 3.55.
Or join the ranks of us with overdrive. Not cheap, never pays itself back, but makes the cars so much better
 
Yep, my old drag racing buddy had one of the Dodge race cars with the light front end and battery over the RR. And, he says 4.10. Have to laugh. Have not decided, but want some launch and tire smoke, not an interstate bandit. And yes, changed over to 15 inch wheels, but the 60 series tires are just over 26.
 
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