638 cid Big Block in a 69 CST/10 Shortbed

[bhunt31]

I'm wanting to build a Big Block for my 69 CST/10 and badge everything up like a 396 to fool the untrained eye. I'm looking at a Dart Big M block that is capable of 4.625" bore and 4.75" stroke. I'm wanting to keep a mild cam in it and iron heads so it runs and looks close to a stock engine. Preliminary runs on my Dyno program comes up with around 750lb-ft of tq@2K RPM and 502hp@4500RPM. The question I have is: has anyone done anything close to this power range in one of these pickups and what has to be done in ways of rear end, transmission,...etc. to handle this kind of power? Also, if anyone has any parts suggestions to stuff in this engine, please advise, remember I want to keep it stock appearing and idling.

[weasel29gm]

Why? Thats alot for the street nothin' wrong with a BB but you can go to much with one.

[Farmtruck71]

i have a 502 in my truck and it made close to 700 hp to the back wheels and i havent had a problem with anything other than killing the tires when it leaves,and it has been 10.11@130mph weighing 4050. I also have a dart big m block,it's brand new still in box,it has billet splayed main caps

[bhunt31]

mostly bragging rights, and I want to go with something that noone else has, I know it's a lot, which is why I want to keep it tame in the cam. There's too many crate 572s being dropped in everything these days, I want something different, something that's as custom as the rest of the truck is going to be. It's not meant to be a street racer and I know I'll never be able to hook it up on the street, but I might get up the nerve to take it to the strip every now and then, to quote the infamous Carrol Shelby "Too much Horsepower is just enough" =)

[special-K]

Somrthing cool about an old truck with way more power than you "need."
In a simular subject.I bought a truck a while back that was an origunal big block truck,still very original.I restored it all original but used an LS6 crate motor using all the 402 stuff on top and painted everything factory colors and used factory stickers.It was powerful,reliable,yet I showed it as original.

[bhunt31]

Originally Posted by Farmtruck71

i have a 502 in my truck and it made close to 700 hp to the back wheels and i havent had a problem with anything other than killing the tires when it leaves,and it has been 10.11@130mph weighing 4050. I also have a dart big m block,it's brand new still in box,it has billet splayed main caps

Wow, that's a lot of horses to the back wheels. That's the block I'm looking at, so you're running the stock rear end, gears, and suspension and it holds it? What kind of tranny are you running? Does your 502 idle smooth or not? How does it get around on the street, like from stoplights and such during normal driving? I want to be able to drive the thing, I just want the "impressive factor" there when I need it. I live in a small town and people around here are scared to death of anything that has a big block in it, let alone a 638cid Big Block, so it'd be the top dog around here when I get it built.

[powell72]

I can't imagine anything rearend or suspension wise would break until you try to make it hook up. As long as the tires are the weakest link you SHOULD be o.k.

[beater69]

Originally Posted by powell72

I can't imagine anything rearend or suspension wise would break until you try to make it hook up. As long as the tires are the weakest link you SHOULD be o.k.

exactly what i was thinking. if you go and put a big set of slicks on the back or put a lot of weight out back you could have some issues. I do agree with carol shelby though but we are talking about enough money to buy a small third-world country

[mnunn454]

Gotta love those BBC SWB C-10's. You're singing the song I love to hear.

No experience with an engine that big, but (but I'd love to). One thought though. Due to the "swept volume" of the cylinders that have to be filled, what would notmally be a very radical cam on a smaller engine would be tamer on a huge engine like the 638. So, don't underestimate how much cam it needs to even be "tame". Talk to the cam experts with your requirements.

Regarding the anticipated performance, please let us know if you'll be using a neck brace or high back bucket seats.

Thanks.

[rage'nrat638]

hello heres a picture
dart big block 638 ci 10:1 comp $20,000 engine

clink the link in my signature thats what one sounds like

[bhunt31]

Originally Posted by beater69

exactly what i was thinking. if you go and put a big set of slicks on the back or put a lot of weight out back you could have some issues. I do agree with carol shelby though but we are talking about enough money to buy a small third-world country

Yeah, I'm not wanting to tub it all the way, but a little would be ok and yeah, it's enough money to buy a small 3rd world country, but the only starving person I'm gonna have to worry about while I'm building it, is me,

[ThatOneBlue67]

Wow, that 638 is coming to eat people! That thing sounds like a beast.

I believe someone said "Everybody is dropping in a 572 these days, I want to do something different."

Well, I admire your drive to go larger, but I know I sure as Hell don't have a 572! I wish! So... hook a brotha' up if you have any lying around.

[bhunt31]

Now you've gone and done it. Now I'm gonna have to have the smile surgically removed from my face after hearing and seeing that 638. As for the 572 comment, I'm just saying that the 572 is a very popular custom vehicle engine these days, I don't want anything about this truck to be the "norm" It's easy to say, "I've got a 572 crate engine in there", lots of custom car builders choose that engine, and I'm not saying it's a bad engine, cuz I love the 572, I'm just saying that it's cooler to push it to the limit and say "it's a 638 cubic inch Big Block that I built in my garage" But at the same time, badge it up as a normal 396 so the untrained eye won't know what it really is.

[kenm78]

Good luck on your project!!! hope you don't break your pocket book on it

[rage'nrat638]

get ready to spend some cash i spent $10,000 fixing stuff i broke

[bhunt31]

What all did you break with that engine? Have you ever had it on a dyno to see how much it puts out? As for breaking my budget...yeah, it's gonna be a while, I'm gonna do a close to stock 350 or a nice 500hp 406cid SBC for now and do the body and interior up, then we'll start on the dragon's breath under the hood. Maybe that's what I'll name the truck "Dragon's Breath" Lay down a black basecoat, then spray green glitter paint lightly over the top, then seal it all with a good covering of clearcoat. Then I'll have to have the thunder under the hood,

[bhunt31]

To Ragen' Rat638, if you wouldn't mind could you send me a mod list of what's in your 638? That'd get me started in the right direction anyway. Have you ever had that 638 on a dyno? If so, how much?

[bhunt31]

I finally got my avatar and everything up!!!! Doing this to check on the signature.

[C10-Driver]

Well all I have to say is .

Holy crap RAGENRAT, the motor sounds wicked. Gave me goosebumps listening to it.

Good luck with your project bhunt31. Anything would be cool with a 638 cid engine in it, especially a Chevy truck.

[underdog8704]

just my opinion- if your going to spend that much coin on a motor of that magnitude, why wouldnt you try to get all the power out of it you could? You can make 500hp easy on a supercharged 350 for a fraction of the cost. again, just my opinion.

[C10-Driver]

Originally Posted by underdog8704

just my opinion- if your going to spend that much coin on a motor of that magnitude, why wouldnt you try to get all the power out of it you could? You can make 500hp easy on a supercharged 350 for a fraction of the cost. again, just my opinion.

I agree but, come on, a 638 cubic inch big block???

Just my opinion but when someone hears the roar of your truck pulling into a parking lot, comes over to check it out and asks "Oh my god, what have you got in that thing?" What is going to sound cooler?

A Supercharged 350

or

A 638 cubic inch big block

[bhunt31]

Just something about a Big Block. Plus I won't have the whine of the charger giving things away. Just the shaking of the asphalt when I roll up. Also, the way I am, if I'm gonna build a big block, I'm gonna build a BIG block. I wanna keep the cam tame so I can actually drive it. I've got a monster cam in the 350 in my 84 Silverado right now and it's nothing nice to try to drive around. It puts the idle at 1200, so yeah...it's coming out soon. Cool thing about it is it'll slide the back end sideways at 90 in 2nd gear, , but it's my daily driver, so that's no good, and with the 3" pipes and FlowTech Afterburner Mufflers and small tube headers...it wakes cops up when I drive by(not good)

[ThatOneBlue67]

How about a 638 Supercharged?

[bhunt31]

you're gonna get me in a lot of trouble....that's a really good idea though....what am I saying? am I ? haha, yeah, I'll have to set the shortblock up to stick a blower on at a later date......

[Bishops Trucks]

Originally Posted by rage'nrat638

hello heres a picture
dart big block 638 ci 10:1 comp $20,000 engine

clink the link in my signature thats what one sounds like

Damn, that rat sounds great.