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Discussion Starter #1
Well, i got news back from the trans shop on the dak and it's getting all redone with some "beefy" parts.

I decided to stray from the idea of building an R/t ad just build the 318 dakota.

My question to you guys is, what is the difference between a 408 and a 390 (besides base motors) Is it really that much of an edge to build a 408 over a 390?

The reason i ask is because it makes alot more sense for me to build a 390 from the 318 i already have vs getting a 360 to build and then have a 318 to try and sell.
 

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The cost of the 390 rotating assembly will be more as the parts are less common. It depends on how cheap you can get a 360 block...
 

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the blue blur...
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yep...pricewise, 408 will be cheaper, but neither are a cheap build. if price isnt a concern, both are gonna be stout engines HP wise. IIRC, the 390 will be more of a revver and will shine at higher RPMs....but i guess it still depends on how you build it....either way, cant go wrong really. just depends on what you are looking to do as far as how you will build it.
 

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If your trying to do a budget build just go with the 408 so you can take your time and build it up right while still driving the truck.
 

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keep your stick onthe ice
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If you can find a 360 a 408 would probably be a better engine. Bigger bores unshroud the valves and let the heads flow a little better. 408 parts are more common and easier to find. They both use the same stroke and are pretty close on size so power and RPM range should be pretty close but the 408 is bigger and there is no replacement for displacement. It also gives the ability to drive you truck while building the engine and just take a weekend and swap it out.
 

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Discussion Starter #6
I have a v6 dakota i will daily drive during the build, as well as after the build. I don't plan on DD'ing a stroked dakota.

Where is a good site / place to get parts for a 390 build?
 

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Discussion Starter #8
ebay dealers, cambell enterprises, or summit.

JMS is local to me and have good ebay rep:
http://cgi.ebay.com/ebaymotors/318-...d7cQQitemZ200426052988QQptZRaceQ5fCarQ5fParts
How much of a boost is a 390 over a 318?

I dont need a huge load of power for the truck, just more then it has now.

Do you think i would be better off just doing the 318?
Heads, cam, intake, headers, new exhaust, a little more beef in the fuel dept.

Anybody got some good recomendations on the above items for the 318?

If i decide to stroke a motor, i am going to do a 360, but i think i will be happy with a 318 for now.
 

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Blown and Squirted
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I would get the displacement up one way or another if you're going to build it.
 

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the blue blur...
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How much of a boost is a 390 over a 318?

I dont need a huge load of power for the truck, just more then it has now.

Do you think i would be better off just doing the 318?
Heads, cam, intake, headers, new exhaust, a little more beef in the fuel dept.

Anybody got some good recomendations on the above items for the 318?

If i decide to stroke a motor, i am going to do a 360, but i think i will be happy with a 318 for now.
here's where you weigh your options...if you do the 318, but dont wanna get into payin so much for a stroker crank for it, just have it bored out and use the stock crank and rods with some .030 over pistons. build the rest with aftermarket parts without going too extreme. examples: P&P heads(gonna have to stick with stockers unless you wanna pay for some eddies or r/ts), M1 intake, rr's, cam, exhaust, headers, bigger injectors, and bigger TB. doing all that will make a very considerable difference in power and is pretty well within budget for an overhauled engine with more power in mind.

or you could do a 360 to a 408. IF you can get a good price on a 360 this might be cheaper in the long run. have it bored .030 over, you can get a complete balanced rotating assembly for around $1000 (from what i've seen, but i havent looked around in 3 years...thats cast crank and rods...forged is more). again, you can get a P&P on the heads you have or save your pennies for eddies or r/t's. get rr's and pushrods, decent headers with a nice flowing exhaust, a mild street friendly cam, M1 intake (used ones on here have been had for around $300), injectors, etc.....

it really comes down to budget. a 408 is cheaper for the ratio of power to money spent. another factor is what are you wanting out of it? just more power for daily driving, something you can play on the track with on weekends, or an all out beast that will get your heart out of rythm when you go WOT? also, with a 408, you can build it slowly while having a brand new bottom end in it. as long as your heads will flow good enough for the cam you will be able to pace yourself with it while being able to drive it in the meantime....same thing with the 318, but you'll be spending more on a bottom end for it if you dont wanna use the stock crank and rods b/c of the odd journal size of the mains. think about what you really want, decide, and do your homework and you'll be alot better off financially. and if you just want a little more power than you do now, the 318 can do that stock with some heads, exhaust, intake, rr's, and damn good tune. weigh all your options and you'll be golden. good luck.
 

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Loud is NOT Fast
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Think outside the box, and put a mild built LSx motor in it.
 

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the blue blur...
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Ugliest Truck on here!!!
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The cost of the 390 rotating assembly will be more as the parts are less common. It depends on how cheap you can get a 360 block...
At Summit the price difference was quite minimal the other day when I looked.

id rather buy an fbody or vette then drop a ls1 or lss6 into my dakota...
LS9 :D
 
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