Steam holes. Do they pose any problems using Iron Eagles, Sportsman 2s, AFRs, or Edelbrock RPMs?

Friend of uncle offers trade of .060 over 350 4-bolt block for our 400 4-bolt block. Everything else is the same as far as clearances, cam (xe268h!) intake etc. Must buy rods, pistons in any case.

I'm under a lot of pressure to decide, any thoughts? Any worries about 400 4-bolt block web cracking? (will use main studs instead of bolts)

Thanks!

Dave H.
Houston

The 350 is bored .060 which is considered by most folks, including myself, undesirable for a street motor. A .030-.040 is the preferred max overbore for any 327 or 350. So that, by itself, would discourage me. If the 400 has a virgin bore, then that settles it. Most people know that next to a healthy BB, I am a SB400 fan (I have them in 4 vehicles). Unless you are going all out, full bore racing, don't even give the 4bolt main a second thought (build the engine as a strong 6000rpm motor and you will be fine). Three of the 4 that I have are 4bolt, the 2bolt has studs. With that extra 50inches you need a set of heads (alum or iron) that have the biggest ports on the market. I always mention that a SB400 and a 396/402 are the same displacement but the BB will always blow the doors off a SB400. The main reason is because BB heads WILL OUTFLOW ANY SB head.
So your SB needs to be able to breathe.
And definitely use at least a 350 rod (5.7, 6.0 is better).

As far as steam holes go, don't buy anyone's head that will void the warranty if you drill steam holes. In fact, some head sources will pre-drill the holes for you if you ask at the time of ordering.

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Tom Parsons

[This message has been edited by DZAUTO (edited 03-05-2000).]

Okay, I stay 400 block, which as far as I know has a virgin bore, and will use studs.

I have a presumably virgin 400 cast crank as well. If it tests positive in a magnflux test, is it okay for 5500-6000? I have heard it is, but bow to your obviously superior knowledge.

So all I must do is grind a bit on the cam side of the rod bolts? And is it any more trouble to use 6" rods? Cost about the same 5.7 or 6 and pistons about the same too. KB Silvolites okay? Or TRW forged?

Have you got aluminum heads on any of your 4 engines? Detonation tolerance is important! And yes, I know about quench, and hot spots.

The crummy 361 actually runs pretty good, a properly cammed and headed 406 should ROCK!!!

Wish you lived nearby Tom!

Dave H.
Houston

First, let me touch on pistons. The KB hypers are (as far as I know) a good piston (I have them in one SB400). But I have switched to Federal-Mogul hypers. Here is why. The KB hypers require a huge top ring gap (when you buy the pistons they contain instructions and a table for which gap to use). I JUST DON'T LIKE THAT BIG GAP! I called F-M and talked to the tech person. He ASSURED me that a standard ring gap was OK, but it would also be OK to go .002-.003 bigger if I wanted. My last 3 SB400s have had the F-M hypers with a dished top and 5.7 rods. This combination with a .030 bore and 64cc heads gives 10.14 comp ratio and 9.08 with 76cc heads. If you go to flat top, you get 10.84 and 9.62. I use stock 350 rods (because I have a box full of them), blast them myself, install ARP bolts, grind about a 45deg clearance on the cam side bolt head, and then have them resized. All my engines have 64cc heads and I have only one with a set of Trick Flow Twisted Wedge alum heads (READ THE INSTRUCTIONS FOR CORRECT HEAD BOLTS). That engine is a 420SB and I am very pleased with it. IT DOES REQUIRE 93 OCTANE, otherwise it knocks at full throttle.
Myself, I have never built a full on, hard core, SB400 race motor designed to turn 7000+, but there are plenty of people who have, and they live. All the 400s I have built (12-15 over the years) have had the factory cast crank with a good balance, are 6000rpm engines and none that I have heard about have broken. My 4 run great, but basically they are ocassional street performance engines. I am not afraid of 6000rpm with this combo and a cast crank.
Hope this helps.
Let me mention one last thing. I have and I like SB400s. But, look closely at what you are going to spend, because it is possible that for close to the same, or a few hundred more, you could have a bad BB (especially if you already have a core to work with). If you want to go SB400, OK, do it. Don't let anyone change your mind. Just keep this last point in mind. But for a SB400 to work, it NEEDS to breathe. This means AFTERMARKET heads, as I mentioned earlier. DON'T WASTE YOUR MONEY HOGGIN' OUT STOCK CASTINGS. You need to be pushing a .500 lift cam, a roller would be better.

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Tom Parsons

#1 - Tom knows what he is talking about, so listen to him.

#2- This is the setup I will be running on my 400. My 400sb (which I will be rebuilding when I get it back from the machine shop) will be set up to turn up to 6800 RPM, stock crank, 5.7 rods (mag'd and shotpeened), and with JE forged racing pistons (flat top w/ valve reliefs). I went with forged aluminum as I will be running nitrous later on, and hyperutectic pistons are too brittle (or so they say). I think I will be installing a comp cam 280H (235 duration, .48 lift), or the next larger cam. Compression will be around 10.5 with cast heads and run on pump gas. 3000 RPM stall.

Should be fun! I must say though, that this is not a daily driver, this will be my go out on friday and saturday night and kill some mustangs vehicle (and a certain 66 chevelle here in Calgary with a 505 ci BB and a hefty nitrous system, not naming any names http://www.chevelles.com/forum/redface.gif). He He, jsut kiddin RH

Hey DZ, which manifold are you running, single or dual. I think I will slap a single on for looks, since they perform about the same above 3000 RPM anyways.

L8R.



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Keane
1970 Canadian Chevelle Malibu (undergoing partial resto)
1977 Canadian Chevelle Malibu Classic
1970 Canadian GMC Jimmy Daily Driver

Keane,
Three of my 4 SB400s have the old original very hi-rise Z/28 intake. NO QUESTION AT ALL that there are better intakes on the market. I just like it. I run that intake and the finned alum LT-1/Z28 valve covers. Chev orange painted engine and factory finish on the alum parts. Although, instead of a Holley, I use an adapter plate to convert to a Q-jet (very trouble free carb). All brackets are factory black. I just like the clean, plain factory engine look (although I do have ceramic coated headers).
My 4th SB400 is in my 56 Vette (lots of chrome and show). That 400 has an old rochester FI unit that is highly modified. It was one of the units that was cut in half and ported out by Bill Thomas/Hayden Proffit back in 1961 (I have Hayden's written statement on that). This old injector works perfect, but is limited because the air meter only flows about 6-650cfm. I run an M-21 Muncie, 3.08 posi and it will light up the tires without banging the clutch.

Also, I totally agree with your choice to go forged, if N2O is in the future. Since I no longer race, and don't use N2O, that's why I always go with hyper pistons.

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Tom Parsons

[This message has been edited by DZAUTO (edited 03-06-2000).]

True, the KB hypereutechtic pistons use a large top ring gap. The top ring is higher on the piston than most, and therefore runs a bit warmer. Because it expands more, it requires a larger "cold" gap...but the gap when actually running is no larger than any other piston.

KB pistons tend to "knock" when (very) cold, but it seems not to hurt them, and it doesn't get worse with additonal milage. More of an annoyance factor than anything. Nice and quiet when warm. In my case, the engine rattles for about thirty seconds during North Dakota winter starts, but I didn't notice it knocking in the summer or fall.

The knock problem is solved by coating the skirts with the do-it-yourself anti-scuff coatings sold by Eastwood, among others.

Okay, Tom...

Cast Crank it is, if MagnaFlux checks out.
You still didn't say if a 6 inch rod is a pita more than a 5.7.
I'll try to get F-M pistons, don't think N2O is in my future.
Will go flat top large chamber, probably DartII's at 215cc.
Big Block would be wicked, but an '81 engine compartment can't have BB and A/C, and I ain't doing without A/C!!!!!

Will a single plain intake make it a little soft off idle? Hate to have to pedal it like a Funny car!!!

Guess that covers all my questions, THANKS!!!

Dave H.
Houston

actually 81 Elcamino I know a guy that has a LS7 in his 81 elky and it fits just fine. Apparently the AC box allows even more clearance for the motor. The biggest PITA is laying out the cash for the headers. I think it costs like $700 for a set of coated headers for that application. But they do fit! Just ask Mike Crosby... I'm sure he's still lurking around here somewhere...

J.J. Fig



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MCC member #256
http://www.clark.net/pub/chevelle/mcc.htm

Dave,
You should be OK with a 6.0 rod, but my F-M catalog ONLY lists pistons for a 400 with 5.565 or 5.7 rods. If you decide to go with 6.0 rods, make sure you have located pistons to suit your needs FIRST.
I agree with the AC!


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Tom Parsons

Hmm, the top ring gap thing..... KB do have 6" rod pistons.....

I really can't believe I could do a decent BB for the $$$ I'm gonna spend. Unless you don't automatically have to buy heads like I will.

And an LS7 in an Elky... How on EARTH can you hook up? Unless of course you have mega bucks and have AL block and heads, the weight distribution stinks!!!

And since the pig that's in the car runs so suprisingly well, 406 a little soft off idle should be a riot!!!

Dave

Hey guys, I'm really liking this thread. I'm currently running a stock '74 400 in my '68 Chevelle cause I liked how it ran and my other engine was about to need a rebuild and it was nothing special. One thing I really like about the 400 is that it's a torque-monster. This brings me to what I'd like to add out of curiosity.
Adding in the longer rods lowers the ability of the 400's peak torque, as expected. What kinda hp/torque does the 406 produce if anyone knows, and what kinda cash it take to get there including heads, machine work, etc
I'm not ready to rip out the engine yet and redo it, as cash is short and there's much other work to do on the car, but I wanna see about how much reward/cost at making the 406 is.

Tony
'68 Chevelle 400

Tony,
If you have a SB400 complete engine (other than external brackets, accessories, valve covers, etc), all you are going to save for rebuilding is the block/crank/balancer/flywheel. Period. That is if you want to really have a strong 400 (406). As far as rod length goes, you won't hurt anything at all by going longer, 5.7/6.0. For example, look at how long the BB rods are, and a well built 396/402 is torque mother compared to a SB400. Also, as I have mentioned elsewhere, poor flowing BB heads outflow hi-perf SB heads. That, if nothing else, is the key to a BBs superior torque/power over an equal displacement SB, IT CAN BREATHE! Not to mention that the BIGGEST valve that you can put into a SB is still SMALLER the smallest BB valve. So if you really want your SB400 to haul, you're going to have to provide air to it's lungs. If you want a really good street SB400, use a good, 76cc head with at least 2.02/1.6 valves. But if you want it to kick a$$, go for the BIGGEST aftermarket head/valves/roller cam money can buy. And when you're done spending all this money on a SB400, check to see how much it would have cost to build a nice 454. Yes, I am a user of 400s plus one BB. I chose the 400s because of several things. Budget and practicality, mainly. For example, A SB400 is a drop in bolt in with the 56 Vette (a BB requires butchering).

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Tom Parsons

This IS turning into fun isn't it?
Okay Tom, I see what you mean about bucks. If I get a deal on everything, having a block and crank and NOT wanting a full race baby, it's about 2000 for a long block. Better rods, pistons, and heads could easily drive it up to 3000-3500....
WHEW!!!!

I'm looking for a motor that has a big fat torque curve, and revs maybe 6000 (maybe only 5500) Looking back to 5.7 rods, and while AL heads would be nice, Iron Eagle 215cc's look likely (or Sportsman II 200's)

Can't imagine a BB in there!!! Have fond memories of '64 Malibu two-door BB 433 however!!!!

Just gotta meet you one day Tom!!!

Dave H.
Houston

I see what ya mean DZ. It'd be awhile before I built up cash enough to build up the 400. Maybe when I get to that point I'll leave in the 400 and start building up a BB to drop in, and also enough to redo the suspension to back it up, probably tranny too.

Thanks,
Tony
'68 Chevelle 400

I love my 406 in the 69 Malibu. I have flat tops with 2 valve reliefs and 64 CC Sportsman 2's with 200 cc runners. Compression is 11.00 to 1 and cranking compression is 230 psi. That Comp Cam Extreme Energy 274 really builds a lot of pressure in the cylinder. Cast crank with the stock 400 connecting rods has been balanced, the shop that did it said it was pretty safe to 6,000 rpms after that it could break something. On the engine dyno it put out 380hp at 5,000 and 480ftlb. of torque at 3,500.

------------------
69 SS 454
69 Malibu 406
ACES Member #3635

Plain69,
Just out of simple curiosity, why did you go back with stock 400 rods rather than longer 350 rods? I have always been told, read and heard that the longer the rod that you can use in an engine will help build more top end hp.

By the way, if anyone needs some stock SB400 rods, I have a ton ot them. I have no use for them, but they are too good to just throw away.

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Tom Parsons

[This message has been edited by DZAUTO (edited 03-08-2000).]

>(and a certain 66 chevelle here in Calgary
>with a 505 ci BB and a hefty nitrous
>system, not naming any names http://www.chevelles.com/forum/redface.gif). He He, >jsut kiddin RH

Keane, QUIET! I still have 283 emblems on my '66... that's what is under the 4" cowl hood! The sound? It's an RV cam and glasspacks... http://www.chevelles.com/forum/rolleyes.gif

RH

DZ when I built the motor I was thinking about doing that but I was not for sure if you had to have the right wrist pin height and the like. The next one I build will have the 5.7 rods. How will those rods affect compression as compared to the stock 400 rods?

Plain69, I know the answer to this one!!!!
You will have to get pistons made for 5.7 or for 6.0 rods. I think a 5.7 with a stock 5.565 piston would clobber the head!!!!

Dave H.
Houston

Plain69,

Pistons made for a 400 and 5.7 rods, will compensate for the longer rod in the compression height (wrist pin location). If you have a longer rod (5.7"), then the wrist pin location will be moved closer to the face of the pistion to compensate, therefore, no change in compression.

If you went with a stock 400 rod, and a piston designed for a 5.7" rod, your compression ratio will drop, because you are effectively creating a larger compression chamber area. Same if you went with a 6" rod and a 5.7" piston.

Like Dave H. said, if you have 5.7" rods or 6" rods, and stock pistons, you will run into problems with clearance with your cylider heads and valves.

When you look in the parts catalogues, they take out all the quesswork, by listing engine size (400 sb), rod length to be used (stock, 5.7", or 6"), and flat top, domed, or dished piston, and will list the compression range from 64cc heads to 76 cc heads.

Hope this helps,

Cheers,

Keane

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Keane
1970 Canadian Chevelle Malibu (undergoing partial resto)
1977 Canadian Chevelle Malibu Classic
1970 Canadian GMC Jimmy Daily Driver

Darn Keane, I love being right once in a while!
Man my 406 is on hold for a bit.
A: I just got a "new" truck, took all disposable income for several months!
B: The 36? (350 + .060) is running so darn good right now, I fear it's like a candle burning brightest before going out. It's FUN running this good!

Will I see any Houston guys at Battleground Monument show sunday?

Dave H.
Houston

I have run a 406 combination in my 79 Malibu for about 4 years now. I have been very happy with the reliability. I just want to go faster.

I have about $4500 invested in the 406 I ran. That was with bowl blended dart Sportsmans, 2 bolt studded block, GM 5.7 race prepped rods, Speed Pro 12.75:1 pistons, and Crane .625 lift roller valvetrain. This engine makes about 450 HP. In my 3200 lb (w/driver) car, the combination runs 11.30's at 120 mph.

I consider that to be a strong runner for a mild combination and small $$$ investment. I just sold this engine for $2500. I myself am finishing a conversion to a BBC that I was able to buy completely rebuilt. I should have about $6500 invested in the BBC. My plan is to run some low 10's in the 1/4 mile.

To get a smal block to be in the 600+ HP area, be prepared to spend at least $2k on a set of heads and another $4k in a strong bottom end. When I added up the parts and peices, I came up with $8-10k every time. For me, the BBC was a cheaper alternative.

I hope to fire the new engine today if the rain clears out.

BTW, Fig was right...Hooker S/C's (#2241) are about $700 after having them coated.

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Todd Geisler
79 Malibu
11.27@120mph
Malibu Muscle
http://www.qis.net/~tgeisler

Arrgghh!!! My candle comment has born fruit!

Can you say knock? Light knock at idle, not noticeable at accelleration or decelleration, but at steady cruise (up next to a wall) pretty noticeable.

And 406 bucks aren't available. Looks like a 305 my uncle has goes in for now. Argh!

Dave H.