Wake up, 400

[Gerald Morris]

The high performance manifolds are about 7-10 horse power better than logs with a mild cam and dual exhaust in the higher rpm range. Headers are the ideal choice, but have their own issues with fitment and only a small number of choices. There are also still issues with keeping gaskets in headers which is why I prefer the cast manifolds on a street engine. It comes down to a choice of how badly one wants the extra horsepower. I really hate changing gaskets on headers so I stay with cast manifolds. The cast high performance manifolds are better than logs over 4k rpms, if you have a stock street engine that usually does not rev over that, it is probably not worth the bother to change out the log manifolds.

Dave

THANK you Dave. Your cost/benefit analysis confirmed my ow less well informed by experience assessment. Since Mathilda currently only revs up to 3000 rpm when I use the passing kickdown or am rolling on the Interstate ~90 mph, I have VERY LITTLE to gain from upgrading even to HP manifolds. Your data indicates that the power gain for such an engine as my current and future ones would likely be near nil in on the by-ways of south Tucson.

Headers certainly entail more trouble than they're worth for an old junky daddy like myself. Of course, if some completely built high powered monster materialized in my dirt lot, I WOULD be TEMPTED. Thank the Lord there is little probability of such an occurrence.

 

[Gerald Morris]

My 400 already had the steel crank, and I added the 69 383 HP cam and HP manifolds, with the 1967 915 Closed chamber heads from the 440.It was not even the same engine.

This follows VERY closely my plan for my 400! Good to see I'm on the right path thus far. Thx for sharing this data.

 

[polara66hardtop]

THANK you Dave. Your cost/benefit analysis confirmed my ow less well informed by experience assessment. Since Mathilda currently only revs up to 3000 rpm when I use the passing kickdown or am rolling on the Interstate ~90 mph, I have VERY LITTLE to gain from upgrading even to HP manifolds. Your data indicates that the power gain for such an engine as my current and future ones would likely be near nil in on the by-ways of south Tucson.

Headers certainly entail more trouble than they're worth for an old junky daddy like myself. Of course, if some completely built high powered monster materialized in my dirt lot, I WOULD be TEMPTED. Thank the Lord there is little probability of such an occurrence.

Hey Gerald I heard from friends in Maricopa Arizona that the big deal now is high output engines with overdrive transmissions..
cruising at 90 under 3,000. My buddy is trying to convince me to put in a three speed /overdrive in my 383 69 Cuda.The cops around here would get to know me fast!LoL Alan was walking me thru making the 400 go on a budget
but he is crazy, as he drives around the valley in a 65 dart convertible with the top down year around! 118 degrees be damned!

 

[Gerald Morris]

Put away all those catalogs before you hurt yourself.
You can wake the engine up best by first giving it a FULL A-to-Z tuneup. Stop fantasizing.

How many younger folks even KNOW what a "FULL A-to-Z tuneup" entails? This advice is MOST WISE though. I know from having finally managed it.....I theenk.

 

[Gerald Morris]

Hey Gerald I heard from friends in Maricopa Arizona that the big deal now is high output engines with overdrive transmissions..
cruising at 90 under 3,000. My buddy is trying to convince me to put in a three speed /overdrive in my 383 69 Cuda.The cops around here would get to know me fast!LoL
but my buddy is crazy, as he drives around the valley in a 65 dart convertible with the top down year around! 118 degrees be damned!

Mathilda turns 3k and hits 90.54 mph on I-10 according to my GPS phone speedometer and my tach. (I trust this instrument.) Those 2.76 rear ends make for some long legged strolling! Your Cuda would FLY w a good Sure Grip in that banjo-pumpkin at 2.76. The 742 with these gears makes a wonderful "sleeper" rear end. Is your buddy working on you putting a MANUAL 3-speed in with such a rear end? SNEAKY SNARKY man! I LAAAHHHHIIIKE it! Why bother with a 3-on-the-tree though, which delivers the same ratios a 727 gives, unless you just LIKE clutching and shifting for the fun of it?

Do this: Get a mid-late 1970s A-833 which gives you identical ratios in gears 1-3 to the old 3 speed, and an OVERDRIVE of ~ .75! Build your "little" 383 for high revving then with THIS transmission, on the 2.76 Sure Grip equipped 742.

THEN, let me help you with your Last Will and Testament, and a Friendly Insurance policy! You should have a gratifying newspaper heading about your airborne Cuda.

 

[polara66hardtop]

That is exactly what he suggested doing. my cuda is a factory Fastback four speed, so I sent him a core to assemble that trans with the overdrive and correct case part number for the car. I kept the original in storage, and The engine is built to stock superbee specs. I imagine it will get around pretty good!Install vintage air and head down to visit him in the spring BEFORE april. I used to live there, and the heat is not my tea.
the 400 project is to replace the stock 400 In my 77 Cordoba, which already has all the police options,( trans and power steering cooler, 100 amp alternator) Including non lock 727 HD auto and 3:21 limited slip 9 1/4 rear end. That car will also be a very fun ride!

 

[Davea Lux]

WHERE did it say "stroker 400"? As I recall, all B/RB rods are the same length. Some 440 rods (i.e., 6-pack rods) are allegedly stronger and heavier. No real advantage unless greater strength (probably not needed) is desired. You'll need to get it all balanced anyway, with the aftermarket pistons. The longer stroke of the RB crank makes that taller deck height necessary. To put the RB crank in a B, the main journals will need to be turned down, which then makes getting a stroker kit more operative, so the crank comes that way rather than getting it turned-down locally. Plus the application-specific pistons.

Otherwise, the small chamber heads should hit the compression ratio area you're seeking, if my old calculations are still correct. Just put 1.74 exhaust valves in them and you'll probably be closer to "906" performance than you might suspect. From what another member did with his factory '68 383/325 Fury was a Summit-sourced cam which was a "factory HP re-imagined" Lunati cam. From the specs, it looks very good to me and he said it works well with his stock short block. Plus runs really nice.

Happy Holidays!
CBODY67

To fit a 440 crank to a 383/400 block, yes the mains need to be turned down, also need to trim the counterweights to fit in the space available, the 440 crank is a good deal heavier at the counterweights to compensate for the longer stroke. 3.375 vs 3.750. The other issue is that removing all that metal causes some pretty tricky balancing issues. Usually simpler and often cheaper to just buy a complete rotating assembly as noted.

Dave

 

[Gerald Morris]

That is exactly what he suggested doing. .... That car will also be a very fun ride!

SHO NUFF!

 

[oldkimmer]

you got me there, forgot about the rb. would just flat tops do it then?

The difference in rods is over .22o thou. So 440 rods will not fit with ur 400 pistons. If u can find a 440 + .020 low compression piston u can use that in ur 400. That will be a 2 point compression increase. Kim

 

[oldkimmer]

To fit a 440 crank to a 383/400 block, yes the mains need to be turned down, also need to trim the counterweights to fit in the space available, the 440 crank is a good deal heavier at the counterweights to compensate for the longer stroke. 3.375 vs 3.750. The other issue is that removing all that metal causes some pretty tricky balancing issues. Usually simpler and often cheaper to just buy a complete rotating assembly as noted.

Dave

When using a light piston with the 451 balancing is not tricky at all. Barely any material to remove. Usually less than 100 grams. The journals and counter weights need to be turned down .125 thou. Kim

 

[CBODY67]

For some reason, I was thinking the B and RB rods were the same ctr-to-ctr length. A check of the 1970 Dodge service manual states otherwise. 383 rods are 6.356" and 440 rods are 6.766". Same piston pin bore diameter. Sorry for my earlier mis-statement.

CBODY67

 

[commando1]

or you can just give it a total tuneup....