400 sbc cam choice

[75Monza]

400 is the way to go for sbc. I look for the 509 blocks, most have 3 side freeze plugs, some have only 2 and look for 020 and 010 in the timing cover area, higher nickel content in the casting. Cant remember, but think the high nickel might also have squares in the lifter valley area too. I spend around 2k building a 408 with parts and machine work usually. Best bottom end kit that I like is around 1k from Skip White on ebay here http://www.ebay.com/itm/SBC-CHEVY-4...MJ-/351614440164?_trksid=p2385738.m2548.l4275
Gives you internal balance which is way better than old external balance when it comes to rpm.

 

[75Monza]

Another thing I forgot is stay away from a 4 bolt block, 2 bolt has more material in the webbing. Before you have it line bored, buy a splayed 4 bolt cap kit and install. Also, whatever heads you use if they were not 400 sbc to begin with, remember to drill out the steam holes or your going to overheat it. Real easy to do, follow this procedure http://www.gregsengine.com/converting-350-heads-to-400.html .

 

[callmewaylon]

Hey, your build is similar to the motor i just built for my truck.

I used the 10120704 lunati Advertised Duration (Int/Exh): 276/284 Duration @ .050 233/241 Gross Valve Lift (Int/Exh): .504/.525LSA/ICL: 110/106
and couldn't be happier. 12 in of vacuum at 800 rpm, has a healthy sounding rough idle but is very snappy down low and pulls hard up past 6000 rpm no problem. Very liveable and I have been driving it to work for the past month 30 miles each way. Even got it up to 11.6 mpg the last two tanks and it would be better if I could keep my foot out of it.

Motor:

400 chevy .040 over zero decked and line honed two bolt block
Stock cast crank, Eagle 5.7 rods, Speed pro Hyper 12.5cc dish pistons
balanced rotating assembly, lunati 10120704 cam, 65cc 195 cfm Performer RPM heads, Performer RPM intake, 600cfm Edlebrock, comp roller tip rockers, 10.5:1 compression and runs well on 93 octane.

Truck:

82 GMC K2500 with an SM465, 3:42 gears and 285/75/16 tires. Thorley tri Y headers into Hooker 2 1/4" exhaust with flowmaster 40's.

Yeah, the SM465 is like a grain truck trans but at least you know you'll never break it. Shifts can be reasonable swift if you are used to driving it. The gear spreads on it are what suck for performance. Still plenty fun to drive though.

 

[Green79Scottsdale]

Also, whatever heads you use if they were not 400 sbc to begin with, remember to drill out the steam holes or your going to overheat it. Real easy to do, follow this procedure http://www.gregsengine.com/converting-350-heads-to-400.html .

Thanks for this link! I always knew they needed to be drilled, but this is the first I have seen actually telling where and what angle to drill them at.

 

[Crdude]

That should make her scoot pretty good!

I'm going with a 223@ .050 .450 lift on a 108LSA cam for my 400. But I'm running 062 vortec heads rather then AL ones like yours.

Let us know how it runs when done!

 

[MikeB]

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.

Did you get a set of rings with a support rail support for the oil rings?

Also, 10.2:1 seems like a lot to me, but hopefully the tight quench will let you run pump premium or even mid-grade. Worst case, you'll have to back off total advance. However, some of the newer heads don't require the old standard of 36 degrees because the chamber shape gets the flame front moving faster.

 

[Crdude]

Did you get a set of rings with a support rail support for the oil rings?

Also, 10.2:1 seems like a lot to me, but hopefully the tight quench will let you run pump premium or even mid-grade.

10.2:1 will be fine with aluminum heads. Could easily run higher static comp on pump fuel, but what really matters is dynamic compression ratio.

 

[HotRodPC]

10.2:1 will be fine with aluminum heads. Could easily run higher static comp on pump fuel, but what really matters is dynamic compression ratio.

Exactly !!! People forget the difference in static and dynamic. You can be 11.5 to 1 and if you have a big enough cam with enough valve overlap bleeding off compression, you can get by with pump gas easily and even moreso with aluminum heads that run much cooler and much more forgiving to high compression and detonation.

 

[MikeB]

10.2:1 will be fine with aluminum heads. Could easily run higher static comp on pump fuel, but what really matters is dynamic compression ratio.

The problem with depending solely on DCR is it does not take into consideration cylinder filling (or overfilling) at higher RPMs. It's actually a static number, since all it looks at is intake closing angle, and it ignores overlap.

So while a big cam may not make much pressure at cranking speeds, it will increase that pressure significantly once the RPM range is in the cam's sweet spot. That's when the static compression ratio comes into play. Of course the intake and exhaust systems also have a lot to do with how well the cylinder will fill.

 

[HotRodPC]

That would make sense too, At high rpm the compression bleed off isn't going to be there like at lower rpm. But, will detonation be a problem at that high of rpm? I know detonation can happen at any rpm, but engine strain or load plays a part too right?

 

[1978k10]

Mike B. Yes the pistons came with oil support ring.

So I just got the truck going tonight finally. Skoots pretty good until ya gotta shift... the 4 speed is a good upgrade for now since the old th350 was getting weak. Hopefully a nice th400 with gear vendors od is in the future. Happy so far with the truck. It sounds great too.
Btw. Great cam for the motor. Lots of instant tq.

 

[HotRodPC]

With all the expense of a gear vendor, have you considered a 4L80-E swap? Even buying a controller, might just be a cheaper option with alot less headache.

 

[74 Shortbed]

With all the expense of a gear vendor, have you considered a 4L80-E swap? Even buying a controller, might just be a cheaper option with alot less headache.

They have a trade in deal(I think they still have it)find an old early core and trade it in and get half off, when I bought mine they were going for $2500, got mine for $1100 out the door, very easy to install too, love that 6 speed, lol..