Engine Build - Where to Start

[Charger21]

Ok so I have a 73 Charger 400 4bbl with 727 and 3.55 Suregrip gears and factory high performance 440 exhaust manifolds. I also have a bare 400 block sitting in the garage. Looking to start an engine build and not sure where to start.

I am shooting for something with around 400 to 450 horsepower on pump gas for street use only (no strip use). I know my engine is low on compression so pistons are likely in my future and I will likely need to upgrade the heads. I have access to extra 906s and 452s but not sure if I should just buy some aluminum heads or try to have the factory ones worked over.

Also need a cam obviously and have considered headers but not sure about the durability and common flange gasket issues.

Any thoughts on where to start? Should I look into a stroker kits from 440 source?

Thanks!

 

[69L48Z27]

What's your budget? I think once you identify that it will help with the rest of the story.

Headers, converter, and gears are all part of the equation too.

Cubic inches are 'cheapest' way to make HP.

 

[Charger21]

My budget is pretty flexible. Would 5k get it done? Could spend more if needed.

I do also have access to a 440 block. It would need totally rebuilt though.

Thanks

 

[68 HEMI GTS]

Build the 400, 470 kit. Pretty much any upper end with a bit of head work and small cam will reach your goal.

 

[Charger21]

Thanks Hemi GTS. When you say any upper end what do you mean? Is the 470 kit a stroker from 440 source?

 

[Charger21]

Assuming maybe you mean carb and intake?

Thanks again!

 

[68 HEMI GTS]

Thanks Hemi GTS. When you say any upper end what do you mean? Is the 470 kit a stroker from 440 source?

Yes, 440 source makes a 470kit. Do you need it to make your goal? No, but it's the easiest way to make power. By the time you buy pistons, bearings, rings, rod bolts, resize your rods, grind crank (if it's needed), and balance the assembly your not that far away from a source kit. With a 470 you could easily use some stock iron heads with a bit of clean up and well surpass your goals. Although the price of new aluminum heads makes it very hard to justify resurrecting some old heads. Mild hydraulic cam, rpm intake, and a nice vacuum secdary holley would finish off a nice combo that will do what you want. Again a stock stroke 383-400 is plenty capable, i just don't see the point after you start adding up the parts.

 

[747mopar]

I agree with these guys, take the 400 block and stroke it! Sounds like your shooting for the same goal as I was, I built a 456 using a 440 rotating assembly (I had one laying around) and 452 heads bored .060" over. In my case budget was key but I'm very happy with it. The extra cubes makes it where you can meet your goal while keeping the rpm's down for a reliable motor.
As far as heads go I ported mine, installed larger valves and had them flow tested. They're right there with the Stealth's but at the end of the day cost damn near as much with the machine work, valves, guides, springs, locks, etc. From my research the 906 and 452s are very close in flow but the 452s will save you from having to have hardened seats installed vs the 906s.
With 10,000 miles on it it's proven to be a strong reliable motor.

 

[747mopar]

One thing I strongly urge you to do is determine exactly what your intentions are for this car and build the motor appropriately. Take into account the gearing, tranny, intended use then match the components so that the motor runs it's best within that rpm range. There's plenty of guys that will recommend huge lumpy cams that don't wake up until 3,000 requiring more stall and steeper gears equalling out to miserable freeway use so just do your homework and you'll be happy.

 

[doublekrossd]

for 400-450 hp I'm pretty sure just cleaning up the stock rotating assembly, 10-1 compression-ish pistons, a well thought out cam, matched to lightly touched heads, matched to the correct intake and carb, should get you that power on the rear wheels (or at least close to it). You could always spend more to get more but if 400 ish works for you, save your money for the next project.

 

[doublekrossd]

you could always put a Paxton supercharger kit on it too... great power gains, economically "cheap" power (not cheap), and really all you would need is carb intake and cam change... http://www.paxtonauto.com/product.php?id=266 just a thought...

 

[PurpleBeeper]

IMO..... first thing would be to get that 400 block checked at a machine shop before buying any parts.

 

[moper]

x2^^. Don't count chickens before they're hatched. Get the block magnafluxed and measured if you haven't. If you are considering a stroker (longer than factory stroke) have it sonic tested. Assumming it passes, the next thing is the designing. From what you say you have, and want, I would build the biggest 400-based you can. Reason being the power you want in an rpm range that is most usable for you as a cruiser is easiest gotten from a big cube engine. The 496 kits are good. The 470 kit might be "best choice" given the parts involved in each. A milder flat tappet camshaft (in the area of 250° @ .050) and a set of cleaned up and corrected Stealths will make the numbers you want on pump fuel. Budget will need around $8-10K if you are paying a pro shop to build. But - the smaller the engine the higher the power band to reach what you want. So change what you want, or build big.

 

[Charger21]

Thanks guys! You guys are awesome and very helpful. Some great recommendations and things to think about and get checked over before I start. Hoping to make some decisions soon so I can get started while the weather is still cold here!

 

[Ski 61701]

Some good info given here. If you are looking for something simple but yet reliable look at the link below. Andy is a very talented guy, and since the article was written getting the stroker crank etc should be easier now. Its a pretty simple build. Matter of fact I'm going to start saving up to do the same build up


http://www.moparts.org/Tech/Archive/bb/550hp.html

 

[rrTor-Red]

400 stroked to 470. Dyno'ed at 585 horses and 610 ft lbs of torque

 

[Ski 61701]

400 stroked to 470. Dyno'ed at 585 horses and 610 ft lbs of torque

View attachment 388843 View attachment 388844

That is a really sharp looking motor, if I may inquire, whats the specs of your engine.

 

[rrTor-Red]

That is a really sharp looking motor, if I may inquire, whats the specs of your engine.

Was going to send you a message about my motor but your inbox is full

 

[Ski 61701]

Was going to send you a message about my motor but your inbox is full

Oops sorry im going clean it out.

 

[rrTor-Red]

Oops sorry im going clean it out.

Cool, cause out of respect to the OP, I don't want to fill his post up with my stuff but will share if needed to whom ever