Building 406 cu. in - Team Camaro Tech
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post #1 of 23 (permalink) Old Oct 8th, 09, 06:56 PM Thread Starter
Apprentice
 
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Building 406 cu. in

I have visted this forum over the years and noticed there are many 400 cu. owners here. I don't have a Camaro but do have a chevy. Just posting here to get some input from the 400 sbc users and or others who have first hand experience on this mighty mouse or maybe it's a clone of a mouse/rat.
So, have a 57 chevy and just decided to do a 406 cu. with a "509" block for it. Block is virgin.....never been bored. Taking it to the machine shop to be magnafluxed and sonic test before doing anything to it.
I'm well experienced at most any build with sbc (I'm out of the 60's muscle car era) except the 400. Do have most info what to look for as far as cracks, block prep, etc. Other sherlock holmes inspections by 400 cu. owners would be appreciated.
Understand 50% of most guys do the steam hole drill etc. for street use. What do some here think of having the need to drill the heads for street use. Understand a bypass or dedicated water supply from the water pump to the twin cyl. is a favorable improvement for helping any temperature issues. I'm looking at a non sprayed engine with use of pump gas. Will probably do a roller cam and this car will see street, cruise, and rare show up at the strip. I look at changing the rear ratio for strip use. Expect hp to be say in the 450-550 range. 4.11 gears with a 5 speed. With the use of the 3rd members I have ratio's available in 3.36, 3.73, 4.11, 488 ...all easily removable out of the housing.
Replies appreciated. Thanks in advance
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post #2 of 23 (permalink) Old Oct 8th, 09, 08:25 PM
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Wes
 
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Re: Building 406 cu. in

If you have a not-bored 400 block, good for you. They're rare as an honest politician. Have it all checked out by your favorite machine shop.

Steam holes,..never understood the arguement for not drilling them. It costs almost nothing and if GM thought they were needed to prevent hot-spots (vaporized coolant) in Granny's 75 Caprice, you can bet they're needed when HP is added (HP = heat). Also, a good hi-flow water pump and an upgraded radiator are good investments for a 406.

It's said the 2-bolt blocks are actually stronger but use whatever you have. Regardless, a good stud kit for the mains is a worthwhile investment.

You likely know this but a stock 400 is externally balanced. So, make sure not mix and match internally balanced components with external (harmonic, crank, flywheel). You'll need to pick one or the other (internal or external). Given the choice, I'd go internal unless you want to reuse the stock cast crank as a budget consideration. It should be good to 500 hp.

Also, get heads that are big enough for your 406,..something in 210cc range would work well here.

1-3/4" headers are the ticket here and get a Carter 'Street' mechanical fuel pump (flows 80 gph) or similar alternative.

Good luck with your project,..sounds like fun!
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post #3 of 23 (permalink) Old Oct 9th, 09, 11:12 AM
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Sean
 
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Re: Building 406 cu. in

The reason to not drill the steam holes? They are not needed (especially in a performance oriented build)....they are an extra expense.... and I do know guys that were sorry they drilled the holes when they drilled them wrong, but I have yet to meet someone that wished they had in the real world. The only reason GM did it was for idling for hours in 100+ degree heat in a taxicab you might get steam pockets and overheating.
You have to ask yourself why none of the aftermarket siamesed blocks don't have steam holes, and of all the guys that I know that race with 406's exactly 0 have drilled the heads. Just run a good pump and all the other cooling system items any performance block needs and you will be OK. But for people that are going to sweat over it, I say go ahead and drill them if it makes you feel better, they just are not needed.

As for the rest of the stuff, I would build it just like any other motor just keep in mind it has more cubes, so a slightly bigger cam and slightly bigger heads are in order for your performance goal. I would keep the gears in the 4.11 range, but as I'm sure you know that's more of a cam spec driven deal.
I agree go with an internal balanced assembly.

Good luck with it, you'll love it!

Sean

1968 rs with an old school 354" SB2.2 pump gas motor.

Repetition does not transform a lie into a truth.

Franklin D. Roosevelt
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post #4 of 23 (permalink) Old Oct 9th, 09, 03:21 PM
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Wes
 
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Re: Building 406 cu. in

Quote:
Originally Posted by 68rs406 View Post
The reason to not drill the steam holes? They are not needed (especially in a performance oriented build)....they are an extra expense.... and I do know guys that were sorry they drilled the holes when they drilled them wrong, but I have yet to meet someone that wished they had in the real world. The only reason GM did it was for idling for hours in 100+ degree heat in a taxicab you might get steam pockets and overheating.
You have to ask yourself why none of the aftermarket siamesed blocks don't have steam holes, and of all the guys that I know that race with 406's exactly 0 have drilled the heads. Just run a good pump and all the other cooling system items any performance block needs and you will be OK. But for people that are going to sweat over it, I say go ahead and drill them if it makes you feel better, they just are not needed.

As for the rest of the stuff, I would build it just like any other motor just keep in mind it has more cubes, so a slightly bigger cam and slightly bigger heads are in order for your performance goal. I would keep the gears in the 4.11 range, but as I'm sure you know that's more of a cam spec driven deal.
I agree go with an internal balanced assembly.

Good luck with it, you'll love it!
Disagreement with GM engineers is dicey business. If the arguement is "none of my race buddies drill the holes into the heads so they're not needed" for a street build, then forgive me and most others that yield to the R&D at GM.

If the arguement is, steam holes are less needed for a "performance oriented build", then there's a small understanding of heat and HP.

Again, if the engineers believed they were needed on detuned 70's 400 engines with 8:1 compression that never saw the dark side of 3000 rpm, it makes sense they'd be needed on a performance build with 10:1 (or more) engine that will see some real rpms (3000 could be the cruise rpm); not to mention, removing another .030" from the bores on rebuild which further reduces the meat between the siamesed cylinders.

HP creates heat. Steam pockets happen though your temp guage shows to be nice and cool at operating temp. Steam can't cool like liquid coolant.

Drilling the holes cost next to nothing and provides insurance against steam pockets. Again, there's no arguement for not drilling the holes.
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post #5 of 23 (permalink) Old Oct 9th, 09, 05:49 PM
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Re: Building 406 cu. in

Street motor (as the OP is building) drill the holes !

Street/Strip car (sees little street time) high stall,tall gears,ect. is optional IMO.

Strip only, no need for the holes.

BTW, no holes here (sees very little street) and no issues in over 2 ? years.

Again, to the OP... just build torque and the rest will come.
My motor has morphed from a mild rebuild (9.5:1,5.7" rods,stock crank,.030 over bore,home ported stock 400 heads--> (went 13.5 @ 102)
Then 200cc Protoplines with bigger valves,smaller cc chambers (Comp now 10.2:1) with no other changes went 12.3 @ 110...
Went to a solid roller cam,heads were shaved a little (Comp now 10.6ish:1),bigger valves installed and new times below (still needs dialed in and very low vacuum for brakes...not good for the street).

68 Camaro~LSx ~all motor
1.54 60'--6.95 @ 98.45 660'--10.96 @ 121.53
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post #6 of 23 (permalink) Old Oct 9th, 09, 07:00 PM
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Sean
 
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Re: Building 406 cu. in

Quote:
Originally Posted by Straight-line-69 View Post
Disagreement with GM engineers is dicey business. .
How about disagreeing with the manufacturer of EVERY SINGLE SIAMESED AFTERMARKET BLOCK? None that I know of have steam holes.

Remember these blocks were built in the 1970's, you know, around the same time as the Vega.... what was that about the GM engineers again?

Quote:
If the arguement is, steam holes are less needed for a "performance oriented build", then there's a small understanding of heat and HP.
Perhaps your confusion is a "small understanding" of why the holes are even there... Steam pockets don't develop due to horsepower or anything else, the theory is at idle, in steaming hot weather, whith Grandma idling at 800 rpm, the flow is reduced enough (remember water pump speed is directly proprtioanl to RPM) that steam pockets *may* occurr in the area of the siamesed cylinder. Thats it, no magic.

Quote:
Again, there's no arguement for not drilling the holes.
Well if you say so....
57 Belair, see my reasons above in my first post, and if you feel you need to drill holes in your heads for personal reasons, hey, they are your heads right? But they are not needed in any kind of mild performance motor, street or strip, that sees most of it's time above 1500rpm.

Sean

1968 rs with an old school 354" SB2.2 pump gas motor.

Repetition does not transform a lie into a truth.

Franklin D. Roosevelt
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post #7 of 23 (permalink) Old Oct 9th, 09, 07:10 PM
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Re: Building 406 cu. in

Quote:
Originally Posted by DOUG G View Post
Street motor (as the OP is building) drill the holes !

Doug, did you see what his goals are? 450-550 horse. While he may be driving on the street, that qualifies as a bit more than a "street motor" in my opinion, and with gears in the high 3's, low 4's, and a cam that will support that horsepower, how much time do you really think it will spend in the rpm range steam holes are needed?
My 406 was right in that range, about 500 horse, and I ran a stock radiator and nothing more than a good pump, and the car NEVER overheated, 180 in all weather. I spent 95% of my time on the street with it.
I assure you mine was not just an anomoly. 7 years before I just took it out this summer.

But, as this debate always ends up, I really don't care how people run their motor, but the guy asked and I replied (knowing it would turn into the draeded steam hole debate..... ). I didn't arrive at my conclusion not to drill them randomly, and I and many folks I know (and apparently everyone running aftermarket 4.125 blocks..) have never had a problem.

Just sayin'

Sean

1968 rs with an old school 354" SB2.2 pump gas motor.

Repetition does not transform a lie into a truth.

Franklin D. Roosevelt
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post #8 of 23 (permalink) Old Oct 9th, 09, 07:56 PM
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Re: Building 406 cu. in

Sean, yes.... but then again...

How many real 450-500+ hp SB motors are out there ?

His "street" motor may not quite be there and a 500hp SB motor isn't something for everyone

68 Camaro~LSx ~all motor
1.54 60'--6.95 @ 98.45 660'--10.96 @ 121.53
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post #9 of 23 (permalink) Old Oct 9th, 09, 08:58 PM
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Re: Building 406 cu. in

Quote:
Originally Posted by DOUG G View Post
Sean, yes.... but then again...

How many real 450-500+ hp SB motors are out there ?

His "street" motor may not quite be there and a 500hp SB motor isn't something for everyone
I hear ya Doug, but I'm only working off the info he gave us...
Quote:
Will probably do a roller cam and this car will see street, cruise, and rare show up at the strip. I look at changing the rear ratio for strip use. Expect hp to be say in the 450-550 range. 4.11 gears with a 5 speed.
And even at that, unless he says "I'm building a completelty stock motor that will be going in my Taxi cab and I live in Arizona....." I'm still saying steam holes not needed.
But as we ahve both seen, this is just a matter of opinion, and arguing gets no where. He asked and I told him the same thing I would tell any of my buddies that asked for my opinion, they can decide from there I figure. There is just so much mis information about 400's out there, it's crazy.

Sean

1968 rs with an old school 354" SB2.2 pump gas motor.

Repetition does not transform a lie into a truth.

Franklin D. Roosevelt
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post #10 of 23 (permalink) Old Oct 9th, 09, 09:22 PM
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Re: Building 406 cu. in

68rs406,..since you've a small opinion of the Chevrolet engineers and their R&D, how about some guy named Lingenfelter?

http://books.google.com/books?id=GUC...0Chevy&f=false

Also, if a new aftermarket 400 block isn't drilled for the steam holes, that's hardly evidence they're not needed for the street. New aftermarket blocks aren't drilled for much of anything unless requested; things like a clutch stud, bosses for a mechanical fuel pump, four bolt mains, etc., usually have to be ordered and drilled, and of course, paid for.

Err on the side caution; might save you from a cracked head or block.

Also, still awaiting one good reason why drilling the holes is a bad idea.
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post #11 of 23 (permalink) Old Oct 9th, 09, 10:30 PM
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Re: Building 406 cu. in

I will not waste any further of my time debating this, but the Dart SHP block (and I believe almost all aftermarket iron blocks) has every single accessory hole drilled and is marketed as, and I quote
Quote:
Dart's new Special High Performance (SHP) small-block meets the need for an affordable, precision-machined cast-iron block with superior features. Designed for high-performance and heavy-duty applications producing up to 600 horsepower, the SHP block is the ideal starting point for hot rodders, drag racers, circle track competitors, off-roaders, and high-performance marine enthusiasts.
Not performance only, but ideal for everything from hotrodders to marine applications. It's not 'race only' and your assumption thats why they are not drilled is plain incorrect. The fact is they are not needed unless your car will see exrended periods of under 1500 rpm in the heat, seriously. Thats why the engineers built them that way. And since my answer was based on the OP's original question, that does not apply.

A good reason? How about, because you don't need to in even a mild performance application? Again as I have said I know many stories about guys drilling the heads incorrectly, so I figure the fact they are not needed, they are subject to screwing up, and are an additional cost if a shop does it, thats reason enough for me. Plus back when I worked as a mechanic the reason the 400 had a bad rep was heads cracked at the steam holes. If you want to drill holes in your heads, by all means have at it, it's not going to hurt my feelings.

Sean

1968 rs with an old school 354" SB2.2 pump gas motor.

Repetition does not transform a lie into a truth.

Franklin D. Roosevelt
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post #12 of 23 (permalink) Old Oct 10th, 09, 05:20 AM
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Re: Building 406 cu. in

Quote:
Originally Posted by Straight-line-69 View Post
68rs406,..since you've a small opinion of the Chevrolet engineers and their R&D, how about some guy named Lingenfelter?

http://books.google.com/books?id=GUC...0Chevy&f=false

Also, if a new aftermarket 400 block isn't drilled for the steam holes, that's hardly evidence they're not needed for the street. New aftermarket blocks aren't drilled for much of anything unless requested; things like a clutch stud, bosses for a mechanical fuel pump, four bolt mains, etc., usually have to be ordered and drilled, and of course, paid for.

Err on the side caution; might save you from a cracked head or block.

Also, still awaiting one good reason why drilling the holes is a bad idea.
I have used Dart little m & shp also Motown blocks and all of the holes were drilled for the acc.
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post #13 of 23 (permalink) Old Oct 10th, 09, 09:04 AM
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Re: Building 406 cu. in

Quote:
Originally Posted by Straight-line-69 View Post
If you have a not-bored 400 block, good for you. They're rare as an honest politician. Have it all checked out by your favorite machine shop.
How much would a rebuildable short block or whole motor not yet bored be worth. there are some for sale around here for between 400$ and 600$.Iwas also wondering how much hp and rpm can a stock crank handle?
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post #14 of 23 (permalink) Old Oct 10th, 09, 10:30 PM
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Re: Building 406 cu. in

As the owner of a 76 K5 Blazer that came with the 400 from the factory, Steam Holes or not if the Heads are going to crack they are going to crack.It happened in my case going across the desert at 65mph (around 2500 rpm).There was no sign of overheating nothing out of the ordinary.That was at roughly 80,000 miles.I pulled the heads,found out the damages,got some new heads,had a valve job done,"Steam Holes" drilled(the Machine Shop/Engine Builder)insisted they were necessary,(no extra charge).Engine went to 126,000 and finally died with a couple of failed pistons (from the leaky cracked heads)Cast pistons do not like water injection....LOL.Just my experience.I hope it helps in your decision.
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post #15 of 23 (permalink) Old Oct 12th, 09, 04:06 PM Thread Starter
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Re: Building 406 cu. in

Read all of the post up to now and very good info and debates. i can agree that drilling holes in $1000 dollar heads makes one nervous. Always could wait/see without the holes. Will give it carful thought though.
Thinking maybe boring only to .020 over to save some cyl wear for future rework. The block cyl are only .005 max over! the engine was clean inside, no gunk build-up etc. the only problem I encountered into tearing the engine down was two of the intake bolts were rusty so bad that most half of the bolt hex head was gone. But internally the block was clean all through including the heads.
Had a double chain at the crank/cam sprocket.
Believe this block will be right for the project if it magnaflux's repor comes back ok.
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