400 Build Ideas

[rumblefish360]

Big block Buicks can be made into a real bad bitch. There is a lot going for them when you dig into them.

 

[68 HEMI GTS]

I’ve built several low deck strokers. The 512 kit is hands down my favorite. I see people worrying about the shorter rods but keep in mind the rod ratio is the same as a 454 Chevy 1.53. If that was an issue GM would have never put them in passenger car vehicles. Cool thing about the big cube engine is the torque is unreal ( perfect for a road gear) and they typically don’t need big rpm’s. Better for longevity and even Hyd cam use if zero maint is your thing. I typically don’t see the point in reusing old heads, unless you can do all your own machine work. You’ll easily have spent enough to buy a set of alum heads by the time you do guides, hardened ex seats, valves, springs, and retainers. That’s not including if you have to pay someone to do the porting. I run a 400/512 in my street car, absolutely couldn’t imagine running anything different in it. Stay away from the source 400/499 kit, those 1.122 CD pistons are a bit short for any longevity on the street. I’ve tried it and wasn’t real impressed.

 

[m79ded]

I’ve built several low deck strokers. The 512 kit is hands down my favorite. I see people worrying about the shorter rods but keep in mind the rod ratio is the same as a 454 Chevy 1.53. If that was an issue GM would have never put them in passenger car vehicles. Cool thing about the big cube engine is the torque is unreal ( perfect for a road gear) and they typically don’t need big rpm’s. Better for longevity and even Hyd cam use if zero maint is your thing. I typically don’t see the point in reusing old heads, unless you can do all your own machine work. You’ll easily have spent enough to buy a set of alum heads by the time you do guides, hardened ex seats, valves, springs, and retainers. That’s not including if you have to pay someone to do the porting. I run a 400/512 in my street car, absolutely couldn’t imagine running anything different in it. Stay away from the source 400/499 kit, those 1.122 CD pistons are a bit short for any longevity on the street. I’ve tried it and wasn’t real impressed.

Very good point made about that 499kit 1.12CD pistons, great for track use not too good for street, wobble in bore sounds bad (Diesel) and wears quick. very good points about the 512 as well, any concerns about cap walk? on the 512?

 

[68 HEMI GTS]

Very good point made about that 499kit 1.12CD pistons, great for track use not too good for street, wobble in bore sounds bad (Diesel) and wears quick. very good points about the 512 as well, any concerns about cap walk? on the 512?

Honestly any of these engines you’re going to see some cap walk. I’ve been using studs with girdles on most. If I was going max effort on a stock block I’d recommend alum caps but by the time you do that you may as well pony up the extra and go aftermarket block. I’ve had the same amount of capwalk on stock stroke 440’s with studs as I’ve seen on the strokers. Even my MP hemi block showed a bit of cap walk. When I was working in the machine shop there wasn’t many blocks that didn’t have a little bit if they made any kind of power.

 

[70bigblockdodge]

A tremendous thread! I'm considering the same, replacing the 360 in my '73 SSP (similar weight to the OPs RR). I have my eye on an unmolested 400 near me out of a '78 Dodge van. All stock from air cleaner to oil pan. Budget build as I'm going to have to change most drivetrain components after the motor (727 vs 904, new driveshaft, 8.75 vs 8.25, gearing). Reuse as much as possible (cast crank, heads, pistons), raise the CR through machining. 1 hp per c.i. sounds good to me. Dual plane aftermarket, 650+ cfm carb. Heavy car, 15" wheel, looking for a cam that has good vacuum, not rumpity-rump. Think cruiser with balls.

360 has a longer stroke than 400. Way easier to get pistons for a 4" bore than a 4.34" inch bore. The 904 uses less HP to turn. Agree that the big block looks better and the distributor is in the front (easier to work with). If it was me I would just work with the small block if racing is not a priority.

 

[68 HEMI GTS]

360 has a longer stroke than 400. Way easier to get pistons for a 4" bore than a 4.34" inch bore. The 904 uses less HP to turn. Agree that the big block looks better and the distributor is in the front (easier to work with). If it was me I would just work with the small block if racing is not a priority.

I have a buddy who’s been a small block “A” body guy for years. After driving my roadrunner his dart now sports a 499… lol

 

[70bigblockdodge]

I have a buddy who’s been a small block “A” body guy for years. After driving my roadrunner his dart now sports a 499… lol

View attachment 1322841

I'm with you!

I am a big block guy. Just bringing up the fact that seems to get lost with 340 this and 318 that. The 360 is a much better street car engine than the smaller small blocks.

 

[Hemirunner]

1.0 hp per cubic inch can be done in stock trim. With a good set of heads and the right cam, valve train and induction system, 1.5 should be very straight forward.

 

[Lenny459]

Hello everyone,

I am in the process of sourcing a 400 engine.

The car already has a 8 3/4 489 Suregrip. It is an original big block car.

I am thinking about different build ideas.

2 main options:

1. 400 with 383 crank and a mildly supped-up build.
2. 470 stroker from 440 source.

Is it a bad idea to use the stock 400 crank for builds over 400+hp?

Thank you!

I have the same engine and this is what I did; I have never stroked an engine though some do. Stock bore 400 I ordered keith black 10.5 to 1 pistons, added a lunati cam did a gasket match and a valve job with a good head bowl debur. Other than that just a basic bearing and gasket set with a decent intake and 750 carb. This thing is WILD!!! I have built many 440 engines and this thing will compete. I put it in a 71 Duster with a 373 gear and second gear will literally slap your head against the head rest. I am so suprised and pleased with this motor........