Here I go with a long post, sorry! Please help me think about a street 400 block build for my antique truck.

Details and The intended chassis:

I have been looking for a 400 block for a while and finally scored one complete carb to pan with all accessories and brackets. Perfect candidate to stuff into my 1954 3/4 ton dodge pickup truck! The truck already has a jeep grand cherokee rear axle, new suspension and kingpins, a nice aluminum radiator, and four wheel power disc brakes. I heard I would need to do an oil filter relocation, electric fans, and re-work the steering. The steering box is beat anyway but otherwise the truck is pretty roadworthy and ready for a little v8 power. The rear is 3.55 limited slip and it has all terrain 12”x31” rear tires.

Goals/limitations:

I know this block is going to get a rebuild but I would like to keep the iron exhaust manifolds and probably the 452 casting # heads for now too. I want to keep the stamped rockers and use a hydraulic cam, probably flat tappet for economy. I want to make power from idle to 5000 with neck snapping torque from any speed under 40mph. I want to lay stripes at will from a roll. I don’t want to do more than 80mph or do any real racing over 45mph. I don’t want a lazy pig of a motor! If I got bored with the initial result then stealth heads and headers could probably uncork it later. I’m definitely doing pistons, a cam and intake but I’m unsure about stroking it.

Build options I’m considering:

-400 with rods, 9:1 pistons, cam, intake. This one would give up some power from a stroker but I’m sure a de-smogged 400 could put out 350hp/400tq without being too revvy and wouldn’t cost much if I could find stock weight .030 over slugs maybe hyper not forged. I could probably get power like a smallblock 408 pretty easily with the huge bore.

-470 stroker kit. The 440 source 512 kit is a sexy number but their 470 kit offers lower compression ratios. I have a feeling that I couldn’t possibly put a big enough cam in with the limitation of stamped rockers to get poor idle or street manners with a 470-512 eating up duration?

Would a big CID kit just be an ego/bragging rights thing all corked up with stock heads or would it have that big flat torque curve from idle to 5000? I don’t need it to rip from 5-7k, all done well before 6000 is fine. I also don’t want it to feel like a tow truck all power no giddyup- the decently light vehicle should come into play there?

What do you all think? I’ve seen some shredding low deck builds on here- I’m trying to do something way simpler but that 512 is calling me hahaha

Thanks for reading and as always any type of constructive or non constructive commentary or discussion is welcome!

Radar

Just copy a big Detroit engine and you should be close. Take a look at the specs for a Caddy, Olds, Buick type of engine and copy the cam specs and compression ratio. It sounds like that is what you want. A 470 inch short block will give you the cubes then use a mild hyd flat tappet and you should be good to go. You won't want a very big cam, take a look at the cam that Chevy uses in their 502 street rod engine and you'll be surprised at how small it is. If you use the same cam specs in your 470 you should be fairly happy.

Go big now,505,511 or 512 C.I., and not have to wish you had done it later
On the camshaft look at Comp Cams grind #s 270H,XE268H and 275DEH.
Any of those three should put a big grin on your face from idle to a 35 MPH roll to shred those big tires with that pump gas stroker motor in that pickup Make sure to degree the cam in from 3 to 6 degrees advanced like Comp recommends, they suggest 4 degrees advance but 3 to 6 degrees advanced will work well, especially with the larger stroke
Last thing, first thing before starting any machine work, is to make sure and have your block sonic tested and magnaflux checked for cracks before boring it One of the first 400 stroker motors I assembled had very thin cylinder walls on the driver side of the block on the cam side due to massive core shift on that block, it cracked the #1 cylinder wall on the dyno and was not repairable

Wow the heavies weighed in already! Cab you’ve steered me right over the years and Andy I bought your big block book when it came out to support you and to drool over all that horsepower- it’s your fault I bought a big block! I was literally re-reading your book and wondering why I’m still awake when I looked at moparts to see if anybody chimed in.

I think I like both of your ideas- make it big and use the caddy 500 or bowtie crate motor specs as a starting place for big reliable torque. I will check out those grinds- I think I used a 268 comp in a smallblock it was kind of the biggest I would go in a street 318. It worked out well. I just remember Andy talking big duration #s getting soaked up by cubes in his book but that’s probably aimed more at the 600+ hp crowd.

So far I opened up the valvecover to check casting #s and started stripping down the front of the block. I’ll get it bare and down to the machine shop asap to get the walls checked out and to find out how much bore it will need to clean up. Hopefully this 78 block doesn’t have much core shift or any damage. It looks well cared for so far- no sludge under the valve covers.

Thanks again and if anybody else built something like this I’d love to hear about it! The hot rod guys did one on you tube but they kind of cruised it around and did a powerbrake burnout- a warm 273 could do that...

if you only want 470 cubic inches. just get a 440, you're most of the way there and with limited power demands and wanting to keep stock rockers, the 3.75 stock stroke will do just fine. save the expense of stroking the engine.

Build the biggest shortblock you can afford. If you're using iron heads, use quench dome type pistons. If you ever want to swap heads to closed chamber type the squish pads can be machined down to zero deck.

R.

Go Big, spend your money right the first time...514ci 4.25 stroke 4.400 bore aluminum rods,half cement the block 12.5 pump gas..make sure the cam has alot of over lap so that you can run pump gas....

Invest in a set of pistons that come to the top--use Summit K6401 cam
new valve springs and other than that 100% stock as a rock even your old used rod bolts sweet valve job---It will be cheap and if you tune on the distributor with an FBO plate it will run fantastic!!!

manifolds everyone he wants manifolds

400's are like 360's no performance history because they were all low compression---

That recipe will run amazing and be cheaper than a concert ticket

I love my low 6 mid 9 second 470 in my 72 Dart.............

I would build a 470ci. More bang for your buck than a 451 and less chance of going boom with a 512.

Good luck with your build.

Since you put a limit on rpm, i would follow Andyf or Cabs' advice and go big. It depends on what you are willing to invest in the shortblock, but my preferance is go big, 512. This is the best situation that the statement YOU CAN'T BEAT CUBIC INCHES works in. If you have 25 percent more cubic inches than a 400, (512) you should be able to build 25 percent, or close, more torque way down low (2500 rpm?) where you say you want it. A custom set of pistons designed for the good heads down the road would be my choice. Then when you upgrade, the gains will be very well worth it.

As others above have hinted at, there's no replacement for displacement. Do the 512 it's a great combination. Build a big mild motor, it will be reliable, make tons of tire shredding torque, and you won't have to rev it to the moon.

I've built several different combinations of 400 stroker motors for pump gas and race gas.
I would bore the block first after having it sonic tested and then decide on the piston and rods and compression ratio with your current heads, bore it as big as needed to straighten up the bores only.
Don't go to the maximum bore to start with If it will clean up at 4.360 use that, if not it might clean up at 4.375 or it may need to go to 4.380
My current bracket motor is a 230 thick main cold weather block I bought from Andyf and it cleaned up at 4.350
I have had several new 4.150 BB stroker cranks with Mopar rod journal sizes offset ground down to 4.300 stroke with 2.200 rod journal sizes and used forged steel BB Chevy H beam rods in 6.800 and 6.700 rod length The pistons are really light and the motors make a hoop of torque and HP
The more common crankshafts available are 4.25, 4.150 and the old shorter 3.91 stroke, they work very well also, especially for a pump gas motor
OP, good luck on your build, be ready to enjoy or have the crap scared out of you the first time you go to WOT
AKA aside, these motors can make a bunch of power is built correctly for the application so be safe until you get use to the new found power

No replacement for displacement!

My 493 is just shy of 9:1 and made 600 ft/lbs at 4000. It was making 500 ft/lbs by 2000 RPM. MP509 cam, TBI and Edelbrock RPM heads with 1.7 rockers. That's the magic of cubes. That cam in a 440 is a stone off idle.

It's happy on all but the hottest days on 87 regular and if my timing curve was a little less aggressive, it would likely be OK on 87 all the time.

Kevin

Darn it- ‘project creep’ strikes again!

I got the manifolds and heads off this morning- the heads are not looking too great and the heads and exhaust manifolds weighed a TON!

So...
I already ordered a set of stealths. I’ll have to weld up some headers after I shoehorn this thing in my old truck too- no need to cart around a thousand pounds of iron manifolds. I’ll be doing an rpm manifold too- it looks pretty easy to shave 75+ lbs off a big block.

Wrenching on my first big block mopar I am not sure if I am impressed by how all the BB systems and parts are independent of each other and easy to service, or how the LA combines many items to save weight and space haha- water pump/timing cover,oil pump/rear main/ rear main seal, intake/valley pan

I’m definitely going 512. There is really no reason not to! I still am still planning on a mild cam and low powerband. The heads will get checked out before installation and my block will go to the machine shop this week.

Thanks for all the input you guys are great

Sounds awesome! I am looking at cams one step milder than the 509 but I’m not buying a cam until I finish collecting a lot more parts.

Does all that torque move a factory high stall type converter up a few hundred rpm? What are you running for a converter?

Pretty sure it's a 2800 stall. It's a Turbo Action that I got at Mancini's.

The first time I tried to check the stall it ripped the left motormount apart about the time the tach approached 2400. I put in a set of Polylock Schumacher mounts which it stretched but the brakes would never hold it and it didn't have enough traction to get a flash stall reading either.

The car was a 66 New Yorker, 4800 lbs.

Kevin