Wake up, 400

[Helpmeunderstand]

So ive finally figured out how to post and can finally get to ordering parts. my plan is to put 440 rods, flat top pistons and a summit cam into my 400 to make more sense of the big tires on the back. Im wondering if those blueprints would work or if theres a better way to up the compression to around 9-9.5.

 

[Ripinator]

So ive finally figured out how to post and can finally get to ordering parts. my plan is to put 440 rods, flat top pistons and a summit cam into my 400 to make more sense of the big tires on the back. Im wondering if those blueprints would work or if theres a better way to up the compression to around 9-9.5.

 

[Samplingman]

So ive finally figured out how to post and can finally get to ordering parts. my plan is to put 440 rods, flat top pistons and a summit cam into my 400 to make more sense of the big tires on the back. Im wondering if those blueprints would work or if theres a better way to up the compression to around 9-9.5.

Would 440 rods fit in a 400? I thought the RB block was taller, thus longer stroke/rods.

 

[tallhair]

I thought the RB block was taller, thus longer stroke/rods.

it is

 

[Helpmeunderstand]

Would 440 rods fit in a 400? I thought the RB block was taller, thus longer stroke/rods.

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

 

[tallhair]

If I recall correctly you use 440 crank with the 400 rods and special shorter pistons

 

[Ripinator]

If I recall correctly you use 440 crank with the 400 rods and special shorter pistons

If you gotta do all that, you might as well try and find a good 440 core engine, and go from there. . .

 

[tallhair]

Here’s an article that outlines a 451 build. Hopefully others with more engine buiding experience will chime in.

Looks like I was wrong about the rods.

451 Mopar Stroke Engine Build - Hot Rod Magazine

 

[tallhair]

If you gotta do all that, you might as well try and find a good 440 core engine, and go from there. . .

the idea is smaller engine, less weight, bigger cubes. But you could stoke out a 440 to ~512

I’ve thought about going the 451 route in my 70 Road Runner actually. Original engine long gone. It has a 70 440 U code in it presently and will probably remain.

 

[Helpmeunderstand]

Here’s an article that outlines a 451 build. Hopefully others with more engine uiding experience will chime in.

Looks like I was wrong about the rods.

451 Mopar Stroke Engine Build - Hot Rod Magazine

thanks

 

[Davea Lux]

The 400 is a de-tuned smog engine with a low comp ratio that was designed to run clean. There is an aftermarket stroker kit for the 400 based on the 440 crank and rods with custom pistons. By the time you throw a stroker kit in a 400, the weight savings will be minimal if weight is a consideration. For a street engine, probably more practical to invest in some quality pistons to bump the comp ratio up to about 9.5-1 as that is about all you can get away with running pump gas. Most of the factory 400 engines ran a ratio that was rated at 8.2 but most struggled to get even 8.0. For the start of any serious street build, be sure to use a steel crank, not the iron one found in many of the 400 series engines. The 383 steel crank is a bolt in, but if the vehicle currently has an iron crank, you must also change out the harmonic balancer and the torque convertor as part of the conversion to the steel crank. 400/383 engines share the same rods. A lot of 400 engines were also equipped with log manifolds and single exhaust which meant that there was a lot of restriction in the exhaust, converting to high performance manifolds and dual exhaust will give you a good bump in performance with the higher compression pistons. Many of the 400 series engines also had the lean burn system installed and that is not a good choice for any type of a performance build.

My advice to you is to run the engine as is until it is ready to be rebuilt. Then consult a local engine builder with what you want in terms of horsepower and go from there. You have a lot of options in terms of camshaft selection, port work on the heads, aftermarket heads, carbs etc. The 400 is capable of decent horsepower numbers, it just takes some work to get there.

Dave

 

[Gerald Morris]

The 400 is a de-tuned smog engine with a low comp ratio that was designed to run clean. There is an aftermarket stroker kit for the 400 based on the 440 crank and rods with custom pistons. By the time you throw a stroker kit in a 400, the weight savings will be minimal if weight is a consideration. For a street engine, probably more practical to invest in some quality pistons to bump the comp ratio up to about 9.5-1 as that is about all you can get away with running pump gas. Most of the factory 400 engines ran a ratio that was rated at 8.2 but most struggled to get even 8.0. For the start of any serious street build, be sure to use a steel crank, not the iron one found in many of the 400 series engines. The 383 steel crank is a bolt in, but if the vehicle currently has an iron crank, you must also change out the harmonic balancer and the torque convertor as part of the conversion to the steel crank. 400/383 engines share the same rods. A lot of 400 engines were also equipped with log manifolds and single exhaust which meant that there was a lot of restriction in the exhaust, converting to high performance manifolds and dual exhaust will give you a good bump in performance with the higher compression pistons. Many of the 400 series engines also had the lean burn system installed and that is not a good choice for any type of a performance build.

My advice to you is to run the engine as is until it is ready to be rebuilt. Then consult a local engine builder with what you want in terms of horsepower and go from there. You have a lot of options in terms of camshaft selection, port work on the heads, aftermarket heads, carbs etc. The 400 is capable of decent horsepower numbers, it just takes some work to get there.

Dave

Dave,

HOW much performance gain IS there in the Hi Po manifolds vs logs? I've got older logs on my 383 for now, and having got a mild performance bump by going to dual exhaust on this engine, (~ 1 mpg gas mileage is a good metric available to me.) I'm curious about whether getting HiPo manifolds or shorty headers would be the better investment. Mind you, I've got my 400, an extra 383 Commando w steel crank, balancer and sundry internal parts to work with, but am always strangled by monetary limits.

I've read that manifolds, including HiPo manifolds, are limited by their basic nature, and for low rev torque, short headers probably are the best bang for the buck. What do you think? I LIKE manifolds from the viewpoint of CONVENIENCE, when working on the engine, but for sufficient gain, wouldn't mind a few more bloody knuckles.....

 

[commando1]

So ive finally figured out how to post and can finally get to ordering parts. my plan is to put 440 rods, flat top pistons and a summit cam into my 400 to make more sense of the big tires on the back. Im wondering if those blueprints would work or if theres a better way to up the compression to around 9-9.5.

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.

 

[Turboomni]

HOW much performance gain IS there in the Hi Po manifolds vs logs? I've got older logs on my 383 for now, and having got a mild performance bump by going to dual exhaust on this engine, (~ 1 mpg gas mileage is a good metric available to me.)

I did some research on this long ago and what I remember it wasn't much ,5 to 10 hp. But going from a single exhaust to dual and the HP manifolds would waken it up I would guess. Even just going duals with logs for that matter.
In any case the HP's do look cool.

 

[Davea Lux]

Dave,

HOW much performance gain IS there in the Hi Po manifolds vs logs? I've got older logs on my 383 for now, and having got a mild performance bump by going to dual exhaust on this engine, (~ 1 mpg gas mileage is a good metric available to me.) I'm curious about whether getting HiPo manifolds or shorty headers would be the better investment. Mind you, I've got my 400, an extra 383 Commando w steel crank, balancer and sundry internal parts to work with, but am always strangled by monetary limits.

I've read that manifolds, including HiPo manifolds, are limited by their basic nature, and for low rev torque, short headers probably are the best bang for the buck. What do you think? I LIKE manifolds from the viewpoint of CONVENIENCE, when working on the engine, but for sufficient gain, wouldn't mind a few more bloody knuckles.....

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

 

[polara66hardtop]

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.

 

[tallhair]

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.

Probably felt like a 383 Magnum plus

 

[polara66hardtop]

Mopar guys I know in Phoenix suggested the mix, and considering the crappy gas available there, they felt the heads add 1 point of compression. not quite an original HP engine, but respectable. it beat trying to buy Higher compression pistons. In this area I can get regular ethanol free, and premium ethanol free,,,,,,,,

 

[CBODY67]

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

 

[tallhair]

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

That’s probably why I was thinking the main thing you need for the stroker is the RB crank and custom pistons.