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Need help building a 400 big Block

victa15

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Sep 21, 2016
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tucson, AZ
I picked up a parts truck and it has a 400 big block. date coded 77. I got it fired up but it sounds like a warn lifter or spring. wont know till I take it apart. It came with a edulbrock performer, new edulbrock 1406 carb and some old headers that look like they were patched poorly at one time. I want to make close to 350-400hp on it. What would you recommend? I will be taking it apart and if it needs to be machined I will bring it to the shop to have it done right.
 
Shouldn't have to do much. Get the compression up around 10:1, mild cam that has plenty of low and midrange grunt, clean up the bowls in the heads, get a good dual plane intake (the Performer should do but the RPM version is better) and a good carb.... I personally would ditch the Edelbrock for a Holley, Quickfuel, Demon or the likes but that just me. This is all assuming its going in a truck, keep the rpm's in mind... a truck that only performs in the upper rpm's isn't much of a truck.

If you can score a 440 rotating assembly build one like I've got in my Charger (451 stroker)..... easily pass your goal.
 
Shouldn't have to do much. Get the compression up around 10:1, mild cam that has plenty of low and midrange grunt, clean up the bowls in the heads, get a good dual plane intake (the Performer should do but the RPM version is better) and a good carb.... I personally would ditch the Edelbrock for a Holley, Quickfuel, Demon or the likes but that just me. This is all assuming its going in a truck, keep the rpm's in mind... a truck that only performs in the upper rpm's isn't much of a truck.

If you can score a 440 rotating assembly build one like I've got in my Charger (451 stroker)..... easily pass your goal.

Ok cool. so bump pistons? or mill the heads. I could have a 440 that need to be rebuilt. What would I need or do to make it a stoker? Thanks for the info
 
You would use the 400 block and the crank and rods from a 440. Really all that's needed is the crank needs turned down to the 400 main sizes and some clearancing done on 4 throws. The clearancing is easy, I did mine using a lathe but you just cut at 45 degrees until the width of the cut measures 3/8"... done. This will require a special piston that is readily available threw Keith Black. Reason being, the 440 crank and rods move the wrist pin further up the piston where it actually passes threw the oil ring making it a short stubby piston that uses a support rail to bridge the wrist pin hole in the oil ring.

Here's the basics of why a 451 is so popular. Unlike building a Chevy 383 stroker where you rob a crank from a 400 to build a 383 and end up with less cubes and no other gains the 451 gains in a few ways.

#1 Your taking the 400 which has the largest bore of the big blocks and combing it with the 440 which has the longest stroke... win, win.
#2 The 400 being a BB instead of an RB means it's deck height is 3/4" shorter = lighter and slightly smaller.
#3 The stubby pistons free up rotating mass making for a peppy reving motor.

This combo is getting less popular with companies like 440 source offering affordable kits to turn 440s into 512's but it's hard to beat budget wise if you have access to both a 400 and a 440. The beauty of it is if you do this it leaves you with a 440 block.... making the most logical decision for the next build to be a 512 hehe. I think you get the idea on what my next engine will be.
 
Oh yeah, it needs balanced after the crank work. As for compression, I used cast 452 heads that cc'd out @ 88, flat top pistons (The KB's need the tops milled) and the deck milled to zero deck height. Man my memory stinks... I'm wanting to say it ended up around 10:1 but I'll have to go back and look. It's perfectly happy on 92 octane.
 
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Good info "747Mopar" . I like reading about "real world" builds . I've been wanting to do a 451 build for a while now and just haven't gotten the chance yet . At one point I got all the parts together , including the block . But then my work area at the time got broken into and it was all gone . I personally thank you for sharing . :cool:
 
Good info "747Mopar" . I like reading about "real world" builds . I've been wanting to do a 451 build for a while now and just haven't gotten the chance yet . At one point I got all the parts together , including the block . But then my work area at the time got broken into and it was all gone . I personally thank you for sharing . :cool:
No problem, this motor has proven to be both a blast to drive and extremely reliable. It's been to both Canada and Carlisle and back both being 12+ hour round trips and gets around 4,000 miles per summer put on it. Most of my headaches have been fuel related thanks to this junk fuel but I've got a solution for that as well.
 
Wow that doesn't sound to hard. Yeah my friend has a 440 sitting in his yard. That sound pretty sweet. Thanks for the info. I have a good trusted machine shop too
 
451 was the stroker build before strokers were common. First one I ever heard about with Mopar.
 
No problem, this motor has proven to be both a blast to drive and extremely reliable. It's been to both Canada and Carlisle and back both being 12+ hour round trips and gets around 4,000 miles per summer put on it. Most of my headaches have been fuel related thanks to this junk fuel but I've got a solution for that as well.
It's just that whenever I read about or watch any sort of engine build . It's always take this big bundle of cash and throw it at some machine shop , Hope they know how to build a Mopar and what parts are best for it , and tada you've got this motor that's "hopefully" half as good as they say it is and the owner of the car really doesn't know for sure . In the real world , we all have a budget and most of us do the work ourselves or hopefully know someone we can trust to help us with it . I grew up in a time period that you worked with what you had and in my case I worked at making the best , the strongest and the fastest with what I had .If you where building a mopar , there was very little off the shelf parts for you . When I was building the Charger I had , I was a mechanic for a good size speed shop and there was nothing on the shelves for it . I even had to order the dam cam for it because we didn't stock it . Stuff like linkage's for the tunnel ram I had fabricate , ect. ect. . So long story longer , I appreciate just a straight up Mopar build like yours and you putting it out there . As far as the fuel thing you mentioned , I agree . The fuel that's at the pumps now is garbage . As of towards the end of last season , I've been doing a custom mix for the 440 in my Warlock . I think I've almost got the ratio right , I know I'm on the right track because my millage has almost tripled and a noticeable power increase . I'll be playing around with it more this season as soon as I start driving it more .
 
451 was the stroker build before strokers were common. First one I ever heard about with Mopar.
Think about it . A B block is also roughly about thirty pounds lighter then an RB block . Power to weight . ;)
 
It's just that whenever I read about or watch any sort of engine build . It's always take this big bundle of cash and throw it at some machine shop , Hope they know how to build a Mopar and what parts are best for it , and tada you've got this motor that's "hopefully" half as good as they say it is and the owner of the car really doesn't know for sure . In the real world , we all have a budget and most of us do the work ourselves or hopefully know someone we can trust to help us with it . I grew up in a time period that you worked with what you had and in my case I worked at making the best , the strongest and the fastest with what I had .If you where building a mopar , there was very little off the shelf parts for you . When I was building the Charger I had , I was a mechanic for a good size speed shop and there was nothing on the shelves for it . I even had to order the dam cam for it because we didn't stock it . Stuff like linkage's for the tunnel ram I had fabricate , ect. ect. . So long story longer , I appreciate just a straight up Mopar build like yours and you putting it out there . As far as the fuel thing you mentioned , I agree . The fuel that's at the pumps now is garbage . As of towards the end of last season , I've been doing a custom mix for the 440 in my Warlock . I think I've almost got the ratio right , I know I'm on the right track because my millage has almost tripled and a noticeable power increase . I'll be playing around with it more this season as soon as I start driving it more .
Not me, I'm not anywhere close to rich so a lot of thought goes into best bang for the buck when I start piecing together an engine. This particular one cost me around $4,500 and is around 500hp. For his goals it will be less, I spent extra $$ putting larger Ferra valves in the heads along with the extra machine work involved but a list of the work done by the machine shop would be.

Hot tank block and heads.

Deck block to zero deck height.

Install cam bearings... it is very important when taking it to a shop that doesn't do Mopars to point out that the cam bearing placement feeds the rockers (2 of them).. put them in wrong and you have no oil upstairs.

Resize rods... for those not familiar with the term this doesn't mean changing the size, they simply remove a small amount from the clamping surfaces then re-machine the bore to remove any out of round from years of use.

Hone rods for a floating pin (not necessary)

Turn crank

Surface the heads

3 angle valve job.

Install bronze guides.

Set up the springs.

Bore and hone with deck plate.

Balance rotating assembly.

Check main alignment. (Checked out good)

I'm running a solid lift Comp Cam camshaft, Comp Cam Magnum rockers, a Quickfuel 750 DP, Edelbrock Performer RPM intake and Hooker Super Comps. Knowing it was going to have a Viper 6 speed pulling the rpm's down on the freeway I built the motor with an RPM range of 1,800-5,800 rpm. I can't stress how important it is to know the intended use and build the engine around that.

I'd recommend this book, lots of great info. Going off of what I learned from this book I was able to port my factory 452 heads to support a .550-.600 lift cam.
Screenshot_20170512-134644.png
 
I can't stress how important it is to know the intended use and build the engine around that.

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You "HIT" the nail on the head with that statement ! You don't realize how much trouble and how often I have to "try" to explain that fact to people . For instance you don't want this killer race motor with say a tunnel ram in a 4x4 truck that gunna go out wheel'in . I used that example just because it wasn't that long ago , I had to try and explain that to someone and tell him what I thought would be best . But your a 100 % right "747Mopar" , you build it for what your going to use it for .
 
You are all right. I am very budged at the moment and took the engine apart. I looks really clean inside that I'm just going to put it in my truck how it is for now and save up for the parts. I did order the book because I need to learn more about big blocks and all the stuff You guys told me really helped.
 
I'm a 400 fan and don't think they get enough respect. I had one in my 66 Charger, originally a 361 car, same basic block as a 400. My motor was bought used with a 510/292 Racer Brown cam. It sounded great but was not very streetable with that cam. I used the 516 heads from the 361 and added new SS valves and used the 510 springs. 516s are closed chamber and are good for about 1 compression ratio. I also bowl blended, smoothed runners, and gasket matched the heads. I recently did a 360 for a 75 Chrysler Cordoba that I did not want to sound like a grandpa's car. I bought a Whiplash cam from Hughes Engines. It has high lift but a reasonable overlap on the valves. They profile the grind to be more like a roller than a normal hydraulic cam. They also set it up so that this cam will actually increase your CR by around 1. I loved it but sold the car to finance the truck in my avitar. You can go to YouTube and search for Whiplash cam to hear how they sound. It was a very nice compromise between performance and driveability. Don't over carb it, bigger isn't always better. Don't get too crazy unless you're looking for 2 tenths of a second on a 1/4 mile strip. Cars are just more fun when they are reliable. Have fun getting dirty.
 
They also set it up so that this cam will actually increase your CR by around 1.
How does a cam increase compression ratio? The 516 heads I can see raising compression some, but those small exhaust valves aren't doing any favors in terms of flow.
 
When I changed the valves I went with 2.14 intake and 1.84 exhaust, slightly bigger than stock 906 heads. The cam doesn't actually change CR but the motor thinks it has by changing timing. As near as I could tell the profile puts you around 1/2 a tooth on the distributor gear. They don't recommend using this cam in motors much over 8:1. Or I might be way off in what's happening but I liked that cam and it's designed to take advantage of mopars large lifter surface diameter. I was seriously considering a 400 and Whiplash for this truck but I'm wanting to try a Cummins swap.
 
The cam doesn't actually change CR but the motor thinks it has by changing timing.
I figured that's what you meant. I couldn't put the words together when I asked earlier. I know you can build an RV engine with low compression to some serious power levels with a stock bottom end, a .509 Purple shaft cam, ported 516 heads, Super Victor intake and either an 850 or 950 CFM carb. Made like 588hp or some crazy number. The 400 is the little step brother engine. It's definitely the best choice for an engine that's built to last with it's thick main webbing, etc.
 
It's funny , I was talking to my boy about maybe him doing a 400 and that I always wanted to do the 451 . I got a call the other day and he just scored a 400 and he say's there's an HP stamp on it . With that motor he also got two early stuck 440's . Guess what he's thinking now ! lol
 
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