400 sbc cam choice

[1978k10]

Well I'm trying to find the right or perfect cam for my 400 small block build. My 350 decided to dump all the coolant in the oil. I ended up with a cracked block and a bad crank. So I'm starting over with a 400 I picked up. Trying to get my truck going on a budget but without cutting corners. So far my plan is to build a 400 sbc that's .030 over. Useing stock 5.7 rods. New pistons and rings. 18cc d shape dish. Motor will have 10.2:1 compression. I have Promaxx 195 aluminum heads and comp 1.6 roller rockers. I would like to see around 450 hp and similar tq. The truck has a 4 in lift and 35s. Sm465 trans. This is my daily driver put a rough idel and lower vacuum is ok. I was looking at the lunati 10120410 cam. Would this work well? Would a different cam work better? Thanks for your help.

 

[vkh]

I've been eyeing the lunati voodoo series myself, based on their compression recommendation 10120704 would work for you. If you can justify the cost I'd suggest going roller, don't have to worry about zddp in your oil and more performance. But above all else I suggest getting a recommendation from the companies themselves. http://www.lunatipower.com/FindMyCam.aspx is lunati's. May as well get a recommendation from comp and a few others to see what they suggest for you.

 

[1987 GMC Jimmy]

What are you trying to do with the truck? I understand wanting more power, and it sounds to me like you want something that'll hold its own on the street, but that gearbox... To me, that's like having a racehorse for a motor and a mule for a transmission. You'll have all that power, and it'll still shift like a Mack. Again, I don't know what you're doing with it, but it's just a lot of money to spend if you want a street truck, and you may not be happy with the trans situation.

 

[1978k10]

Yea it doesn't make the greatest combo with the 4 speed. What kind of power should this motor make?

 

[Rusty Nail]

*250-275? Stock was 190? Tops?

There's no reason to NOT run 6.0 inch rods with a stock crank....

1.48 rod/stroke ratio with STOCK 5.56 inch 400 rods and a LOT of side-loading that is easily correctable.
Increasing to a 5.7 inch 350 rod yields a 1.52 ratio, which is still dismal.
A 6.0 inch rod lands you a respectable 1.6 rod/stroke ratio and that is MAXxXING out your benefit PER DOLLAR using a stock 3.75 stroke crank.
Let's be real, youre wasting time with those pistons (literally).
According to the late, great , Smokey Yunick, the most desirable, perfect rod/stroke ratio is 1.75.
This is most cheaply accomplished (in a sbc400) with an offset ground, 3.50 inch stroke 350 crank, spacer bearings and 6.125 inch rods. Now we're talkin destroked 377-ish...382 with a 1.75 rod/stroke ratio.
Im not into roller , can't justify the cost. More parts to fail in more, worse places..pass. Too many better spots to spend dollars on machine work. My 400 has a 268H Comp cam in it that I didnt buy but it seemed 'adequate' for a slow motor street cam BUT I was able to run it out of breath before I was finished spinning it. Too much torque too low in a very thin and narrow power band. No legs!
Definately tell it was there but I thought it was "lazy". The power was all too low to suit me. Really slow. Like those 325 vortex guys? SOUNDS fast and GOING fast are wildly different things! Screamed like a banshee. but fails to deliver at the big end where it REALLY counts.
Boils down to FEET PER SECOND.

Will not run again. I'd rather spin an OE L46 cam for cool points but it's not perfect (for you maybe) Great pick for the street

Youve got great heads, sad to see them cheated with limp-dick pistons. You're talkin less than 8.5:1 with a 76cc head....8.2 with a 12 or 15 cc dish? Are you sure 18cc? That's a LOT. Run flat tops, pliz.

THE 3.50 CRANK is around $250 or less.
The 6.125 RODS are around $250 or more.
The 4.155 PISTONS are around $250
$750+deck+line hone =$1000+

More research is necessary to meet your power goals cuz I don't think your plan is gonna do it, even with those great heads, but mine will get pritty close. (with fewer cubes). PLUS i'll see a 7k+ redline, reduced oil/engine operating temps as the result of less parasitic, frictional horsepower loss.
Meaning: greater power at every , more rpm. An easier, faster revving, cooler, happier engine for longer. Not to mention it's way better suited for your transmission.... Super piston speed with barely any travel, comparatively. Think about it!

Or you can run the 18cc dish with 5.7 (5.5) rods on a 3.750 crank.
How do you figure 10.2 with an 18cc dish, exactly? Even if your heads are 64s....5.7 with 18cc is WaY DOWN IN THE HOLe and that quench height is teh suk!
It is NOT uncommon for old-school, low-compression, smog-motor stockers to have over 0.060-inch quench at TDC when you're shootin for more like 0.040 with steel rods. That difference is HUGE!!!! x8?!

What you're calling a 5.7 rod is actually 5.56 in a 400...more research is necessary. Because NOW with a 3.50 stroke crank, it's internally balanced, so a new flywheel and harmonic dampener are necessary.

Youre gonna have to deck that block if you wanna win. 400s are notorious for uneven or 'inconsistent' deck heights between cylinders. Blame the Siamese. Camshaft choice is like an afterthought.
Don't wonder how I'm buildin mine!

.060-.040=0.20
.020x8=.16 OF AN INCH!

6.125-5.56=.565
.565x8=4.52 INCHES!

That's HUGE. HUUGGGEEEE.
(that's wat she said!)

[yt]lw3WhSD2nMQ[/yt]


^great post!

 

[Honky Kong jr]

Awesome read.

 

[HotRodPC]

Another very loaded question. What gear ratio you running? What are your intentions with the truck other than daily driver? Towing? Mostly highway driving or around town driving? Where do you want the power band? Way down low or mid range? This 450hp you want.. Is that to the ground or the flywheel?

 

[Honky Kong jr]

Another very loaded question. What gear ratio you running? What are your intentions with the truck other than daily driver? Towing? Mostly highway driving or around town driving? Where do you want the power band? Way down low or mid range? This 450hp you want.. Is that to the ground or the flywheel?

I think OP was scared off by Rusty Nails post. There is a lot of info there.

 

[Rusty Nail]

ahahahaha,wah.

Did it sounds like I know what im talking about though?
I have been doing rather extensive research into the subject of sbc 400s and you can bet that I'ma build a baddd mother.
Nobody replied. I was sad. Still am I reckon. OP will show back up, right? One payment left for the K5 and I can start saving for the build!
I haven't even taken the heads off yet, it's chillin and already .040 over. If the bores are good, I'ma make it a 388! AND run the 350/350 cam. Should be okay. 11 years old and 3-400 miles supposedly.
1hp/cube be NO PROBLEM.

Dude was talking 450hp ... hate to tell ya the bad news but I speak the truth brother.....That ain't cheap.
Anybody heard of a "GSU" 400 block? I know where one is.
$300 bucks!
GSU 1974 400CI 175HP 2 Bolt Main NB2
NB2 = CA vehicles with A.I.R. and longer valve overlap camshaft. In '74?
Motor code GSU: 1974 out of a truck, 2 bolt main with heads.
Engine casting is a 817, heads are 333882. ?
BUT! I made a deal to buy a rebuilt,complete,265 for $250 first. Dude put an Opti in my Caprice and it started. OFC now he wants to keep it.
He hooked me up with an engine-only though so I'm not mad.
I'm really gonna have a 3.00 inch craaa-aank and 5.9 pm rooo-ooods!

It was 37° last weekend, I'm still locked inside.

I saw a set of 6.125 rods sell on eBay for $180!
http://r.ebay.com/mSk2i7
That crank price is accurate..$225 NEW.
http://www.adperformance.com/index.php?main_page=product_info&products_id=654
I emailed them about running 6.125s on this crank - no reply yet and I want it! I hear Scat cranks are hard to balance though?
Same for 9.(something) hyper pistons -$240ish.
Closer to <10.5 is do-able with aluminum heads...
350 mains are smaller than 400 mains - parts posted I found quickly for example.

Those rods can easily fetch $350 though.

Balancing all that will run $200+easy.
About 1k ROTATING is a safe bet. (following this build) Sure it can be made cheaper.

 

[Honky Kong jr]

Long rod is why I haven't dumped my tall deck not a big fan of laying a rod over that hard. Not conducive to good rpm. Far to common these days to look in a catalog and start adding hp numbers and all of a sudden you got a 600 hp small block with parts that won't work together and be lucky to produce 275 at the crank and a mismatched piece of **** that is so unbalance and only sounds cammed and mean because it's ready to fly apart at any given moment.

 

[HotRodPC]

What gets me, seems these days people don't care about performance anyway. They just want it to lope and they want a loud exhaust as if louder is better. I'm the opposite. I like element of surprise and don't need all the noise to say, "Look at me, I have a little dick" Jus Sayin' !!! I don't mind the lope IF IT'S JUSTIFIED and you actually have the hp/torque to go along with it. In short, if it's going to be choppy, you better have something, and why go loud on the exhaust? I'd want to keep it quiet as possible to hide the lope so that punk kid in his Honda that's blowing smoke out of every orifice gets his ass spanked from light to light.

 

[Rusty Nail]

Lol.
190 was too much. 175 stock hp. I gave 40 very generous hp for the unknown CC heads, and another generous 25+ for assumed intake and exhaust improvement on a fresh build.
18cc (dished) pistons kills it.
5.5 rods finished it off. 400sbcs work HARD. Can't overlook very basic and inherent 400 issues while seeking the "perfect cam". No such thing, it's all give and take.
It's really not that big of a deal especially if the rest of the build is legit. All cylinders must be the same. That cannot be overstated. First person that says it can is the last person ima listen to.
The aftermarket never got geared for the different bearing sizes between 350&400 but it's easily remedied in most cases, now.

In example, when I picked up the K5, I was asking very specific questions about the engine. They told me .040 over "stock replacement" pistons(8.2:1) and it wasn't decked with stock rods and stock 882s but they were all about that cam.....****.
Okay fine. at least I know it's WAY uneven between cylinders,heads and a slow p.o.s goin in. Yeah, sounds cool! But in reality it's not been built to make any power.
The hard part is to NOT blow it up before I can set it straight!

Best thing I can do is swap in a 350 and save a bunch of money.
The 350 prolly goes faster right now!

OP I'm NOT trying to talk ****, none of these guys are. You asked for our help and that is the intention. We genuinely want to see you succeed. At least I do.

Guys that want to run 400s are THE REAL bad asses because it's hard and expensive plus they are rare..

Really. Wrap your head around how much it costs to make a 400 go fast...Gotta have new rods.gotta be decked.gotta be line honed. For starters, no cutting corners!.

If you have a tall enough TIRE -not wheel- your 40 year old truck ought to take the shock of real power "okay". Big sidewall will eat the "hit" on concrete and your parts will live long,happy lives.

I'm finished with this thread. My answer is the GM L46 camshaft.

Those engines were 11:1, don't forget! Aluminum heads are good for an additional FULL POINT of compression over iron.

http://r.ebay.com/eYZsbD + Rhoads lifters.

I'll collect my parts,have the machine work completed, and based on THOSE near-finished measurements, select the pistons and head gaskets LAST. Gonna be hyper SPEED-PRO.Gonna be coated.Installed CH is vital a vital measurement! Gonna run the Holley 300-36 intake and 1.5/2.5 inch headers. Prolly a SA770.

I don't have a horsepower goal , I want 7,000 rpm ability with a "511" block. Maybe I'm asking for trouble...Maybe I need a different block. I've had one machinist for 23 years and whatever he says, I'll do. The 362 we built in 2002 still lives today and​ sees almost 6500 every time I turn it on plus it's faster than whatever you got...
More on machine work than you think.Parts can be had cheaper than you think. Create a well thought out engine with parts that compliment each other, instead of stuff that is forced to work together.Your cam isnt much different from mine, you're on the right track. Different strokes for different folks, get it?

Thank you and good luck.

 

[68post]

OP
The Lunati 10120410 cam would be close to as large as I'd want for a truck and 407 ci, it'll work with your 4 speed. BUT , if you have the stock K10's 3.08 gears I wouldn't like them combined with your 35" tires at all ! (But 4th gear would feel like overdrive to me) You already know how this combo drives.
The cam's 109* LS and single pattern will work to the benefit of this combo, especially if you have a great exhaust system. Don't use too small of a carb, an 800 Qjet would be **** if setup correctly.

Don't worry about using 5.7" rods if that's what you have , they're an improvement over the stockers.

 

[4WDKC]

Well I'm trying to find the right or perfect cam for my 400 small block build. My 350 decided to dump all the coolant in the oil. I ended up with a cracked block and a bad crank. So I'm starting over with a 400 I picked up. Trying to get my truck going on a budget but without cutting corners. So far my plan is to build a 400 sbc that's .030 over. Useing stock 5.7 rods. New pistons and rings. 18cc d shape dish. Motor will have 10.2:1 compression. I have Promaxx 195 aluminum heads and comp 1.6 roller rockers. I would like to see around 450 hp and similar tq. The truck has a 4 in lift and 35s. Sm465 trans. This is my daily driver put a rough idel and lower vacuum is ok. I was looking at the lunati 10120410 cam. Would this work well? Would a different cam work better? Thanks for your help.

hope op is still around, thats a lot of dish, rough calculations put you just under 10:1 if the pistons is -.005 from the deck. Ideally for our heavy trucks 6" rods would be best but you already have your heads. Cam selection depends on intended usage, gears and tire size.

 

[1978k10]

Wow guys thanks for the info. I didn't even realize I got so many replies. So I ended up ordering a full scat rotating assembly with 6.0 rods cast crank and hyputectic pistons. Static compression will be 10.2:1. Yes the block is getting decked. I'm going to use a .039 gasket and that will leave my with .039 quench. Pistons will be flat with the deck. I did end up getting the lunati 292 230@ .050 .480 lift cam. As for my truck it has 3:73 gears in it now but I plan on swapping in a set of 3/4 axels I got. They have 4:10 gears in them. Again thanks.