Mild 400, What gear and converter?

[TetanusShot]

Choose a rear gear and spec a converter according to your own tastes and what you would do with the car.

The engine isn't built yet, feel free to critique the build.

400
9.6:1 Compression (KB240-030 pistons)
915 heads 2.08/1.74, unported clean slate
Flowtech Headers (1.75" into 2.5") full dual exhaust
Summit 6401 cam (282/292, 224/[email protected], .465/.488, 114LSA)
Edelbrock TM6 intake
Holley 750cfm vac secondary (3310-2)
B&M external balance flex plate for neutral balance torque converters
stock rods/crank/damper

Axles and gears I have on hand:
8 3/4
-3.23 SG & 4.57 SG
Dana 60
-3.73 SG & 4.10 SG

Stock chassis with 383-4bbl suspension, 3680lbs with me in it. Your choice of 26.5" street tires or 28" slicks.

 

[PRHeads]

Comp XE 268 or 274

Performer rpm

I’m not a big fan of the way the VS carbs “feel”. I’d use a DP...... like a Brawler 650.

3.23’s, 11” hemi style converter.

4.10’s for a more track oriented package.

 

[Don Frelier]

With 9.6 cr and that wide lobe separation angle, you may run into predetonation problems after you run it a few thousand miles. I like the Mopar .455 cam, a roadrunner cam or one of the nostalgia series.

 

[727]

Which head gasket? Head shim will give you more compression.
There are better cams
ARP rod bolts.
RPM intake

 

[TetanusShot]

Which head gasket? Head shim will give you more compression.
There are better cams
ARP rod bolts.
RPM intake

Here are the dimensions I used to figure compression:

4.372" bore
3.375" stroke
6.358" rod
1.908" compression height on the pistons
5cc valve reliefs
9.98" deck height
80cc chamber volume
.020" gasket thickness
4.38" gasket opening

I won't know true CR until mock up, but if the compression ended up being too high, I could easily switch to a fel-pro .039" head gasket.

I appreciate the engine suggestions and advice guys..... how about rear gears and a good converter choice?

 

[RJS]

I know I'm not really answering your question but here is my 2cents: Pick a different intake manifold, a TM-6 is a horsepower open plenum. I would use an old Holley Street dominator intake.
As far as gearing 3.55 minimum and a 2500-2800 11" or 10" convertor. I would speak to PTC for the convertor.
Ron

 

[Bighead440]

Edelbrock DP4B or Performer 383/400 intake or Weiand dual plane (Action #8008?), 2500 stall 11" converter and 3.55 gears should be perfect.

 

[Bighead440]

FWIW, I ran a freshened '77 400 from a Newport (stock pistons) with .060" milled "906" heads (.072" off the intake face so the manifold lines up again), and a Comp 275DEH (219/235*@.050", .462/.482" lift, 110LSA) cam with a DP4B and a 750 Edelbrock carb. That cam is biased towards iron exhaust manifolds, so I used my HP E-body manifolds and 2.5" full exhaust with Hooker turbo mufflers. With a "Break-A-Way" TCI shelf converter and my '70 Challenger R/T's 3.23 gears, it was a hoot!! I eventually sold the whole shebang to a guy who swore it was a 451 it ran so good!! LOL

 

[BSB67]

With 9.6 cr and that wide lobe separation angle, you may run into predetonation problems after you run it a few thousand miles. I like the Mopar .455 cam, a roadrunner cam or one of the nostalgia series.

Wide LSA = less cylinder pressure = less detonation.

I do like that cam. And I think the Summit cam is okay too.

Dual plane intake, and 750 DP.

 

[BSB67]

3.23’s, 11” hemi style converter.

4.10’s for a more track oriented package.

and this.

 

[TetanusShot]

About the engine build:
Most of the parts going into it are leftover stuff on the shelf. In fact, the only parts I don't I already have from the list in first post are the B&M flexplate and the KB pistons. I'd be hunting Hemi parts if it wasn't so darn cheap to build this 400.

I'm not in love with the TM6, on the hunt for a cheap aluminum dual plane. I really like my Holley 3310 though.

To clarify, the gears and axles I have on hand are:
3.23 suregrip & 4.57 suregrip for 8 3/4
3.73 in a Dana 60 with an extra set of 4.10's

Based on suggestions, I think I'll go for the 3.73 Dana.

 

[TetanusShot]

So here are some converters from A&A transmission I'm looking at:

2276MX, 11" 2600-2800, $450
22769, 11" Reproduction Hemi, $595
22312LSXHD, 10" 3000-3400, $695

They have milder ones and more aggressive ones available too.

 

[dvw]

PTC Will set you up with an excellent converter in the $500 range. I think I'd use a stock intake before the TM6 in this build.
Doug

 

[383man]

We run a mild 400 in my sons Dart which is a street car. Its a .030 over 400 with a 383 forged crank (406 cubes). Its a stock 400 block with .030 over KB pistons. We use Eddy RPM heads that were shaved to give it 10.6 pump gas friendly comp. He runs the MP .557 cam and Crane ductile iron adjustable rockers. Has an Eddy RPM intake with a Holley 750 DP. CPPA 2" headers and 3" exh. Uses a stock Mopar electronic dist I recurved and MSD 6A ign. Runs a 727 with a A & A reverse manual valve body and uses a Luppo Dynamic 9.5 converter that will flash about 4000 rpm and drives like a normal car on the street. I also use a Dynamic 9.5 converter in my street car and we love their converters as they work very good in our cars. He runs 3.91 gears and is now using M/T SS drag radial tires. His Dart is not lightened any as it weighs 3640 with him in it and about 1/2 tank of gas. His best et driving to the track and racing in street trim is 11.41 @ 117. Hope this helps you some and if you want any more info just PM me or email me at [email protected]. Ron

The 400 eng.

His Dart.

 

[383man]

Wide LSA = less cylinder pressure = less detonation.

I do like that cam. And I think the Summit cam is okay too.

Dual plane intake, and 750 DP.

Not trying to be smart at all but the wider the lobe separation angle the less overlap and more cyl press the more prone to detonation. Ron

 

[BSB67]

Not trying to be smart at all but the wider the lobe separation angle the less overlap and more cyl press the more prone to detonation. Ron

Ron, intake valve closing point plays a key role in cylinder pressure and detonation. If you take two cams with identical lobes, put one on a 114° lsa and the other on a 108° lsa, the one on the 108 (I.e. larger overlap) will close the intake valve 6° earlier and generate higher cylinder pressure. This of course assumes the the are installed the same way, such as straight up, or 2° advanced, etc.

Go ahead and plug the numbers into your favorite dynamic compression calculator.

FWIW, my motor is nearly 11:1 CR, and have 52° overlap (actual is probably less considering how loose I set my lash

 

[TetanusShot]

We run a mild 400 in my sons Dart which is a street car. Its a .030 over 400 with a 383 forged crank (406 cubes). Its a stock 400 block with .030 over KB pistons. We use Eddy RPM heads that were shaved to give it 10.6 pump gas friendly comp. He runs the MP .557 cam and Crane ductile iron adjustable rockers. Has an Eddy RPM intake with a Holley 750 DP. CPPA 2" headers and 3" exh. Uses a stock Mopar electronic dist I recurved and MSD 6A ign. Runs a 727 with a A & A reverse manual valve body and uses a Luppo Dynamic 9.5 converter that will flash about 4000 rpm and drives like a normal car on the street. I also use a Dynamic 9.5 converter in my street car and we love their converters as they work very good in our cars. He runs 3.91 gears and is now using M/T SS drag radial tires. His Dart is not lightened any as it weighs 3640 with him in it and about 1/2 tank of gas. His best et driving to the track and racing in street trim is 11.41 @ 117. Hope this helps you some and if you want any more info just PM me or email me at [email protected]. Ron

The 400 eng.

View attachment 673456


His Dart.

View attachment 673457

You're making me awfully tempted to dump these iron heads and put in a solid lifter cam like I wanted to do in the first place! Thanks for the build and converter example, that dart is a nice street package!

 

[383man]

Ron, intake valve closing point plays a key role in cylinder pressure and detonation. If you take two cams with identical lobes, put one on a 114° lsa and the other on a 108° lsa, the one on the 108 (I.e. larger overlap) will close the intake valve 6° earlier and generate higher cylinder pressure. This of course assumes the the are installed the same way, such as straight up, or 2° advanced, etc.

Go ahead and plug the numbers into your favorite dynamic compression calculator.

FWIW, my motor is nearly 11:1 CR, and have 52° overlap (actual is probably less considering how loose I set my lash

Yes you are right and I agree that the intake closing is one of the most important things in cyl pressure build. I was just thinking in general that when a cam has a higher LSA # (say 114 vs 108) is will have less overlap and usually less duration and an earlier closing intake. But I was thinking in general and not actually comparing #'s to the same cam. But I believe we both understand what we mean that in general more overlap and later intake valve closing gives less cyl pressure in general. But I do agree the intake valve closing makes the most difference since it is when the piston is on the comp building stroke. Course more overlap can cause more dead inert exh gas to be pulled into the cyl which of course wont ignite and can also lower cyl pressure some. But I am no wizard on this just keep trying to learn all I can which I have been doing all my life and still feel like a real dummy some days. Ron

 

[BSB67]

Thanks Ron. I figured that was what you meant. You've certainly been around the horn a few times. But I do think its worth being clear for those that might not fully understand. Intake valve closing is what has some impact on cylinder pressure and detonation, and until you do the math between different cams, you cannot say for sure which has more detonation potential.

 

[wyrmrider]

ron dude
no e-mails in posts
thanks
On topic
If you use a 904 profile instead of an .842 profile you can open the intake later and close it sooner and have the same area under the curve and less overlap
same with the exhaust
timing around BDC is more sensitive with a long rod motor so using a 904 profile is even more important
some worry about .904 being more radical
it does not have to be
it can be a mild profile just using more lifter diameter
many .842 chevy profiles are pushing the acceleration envelope for chevy lifters
and do not live will when put with the heavier Mopar valvetrain