Hot Rod Forum banner

406 sbc, build questions

7K views 53 replies 9 participants last post by  manchildau65 
#1 ·
Hi, I'm a new member and have some basic questions about a 400 sbc that I'm putting togethor. The following is the information I have about the engine:

Block
Serial Number: 330817
Bore: 0.030" over
Main Caps: 2 Bolt
Crank/Connecting Rods: Stock

Heads
Serial Number: 14014416
Intake: 2.02 SS
Exhaust: 1.60 SS
Rockers:
Push Rods: Stock
Valve Springs: Doubled? (one inside of another)
Valve Guides
Tapped/Studded Rocker studs
Combustion Chamber: I was told 64cc but the 416 head is 58cc right?

Camshaft
SUM-1107
Cam Style: Hydraulic flat tappet
Basic Operating RPM Range: 3,000-6,500
Intake Duration at 050 inch Lift: 234
Exhaust Duration at 050 inch Lift: 244
Duration at 050 inch Lift: 234 int./244 exh.
Advertised Intake Duration: 292
Advertised Exhaust Duration: 302
Advertised Duration: 292 int./302 exh.
Intake Valve Lift with Factory Rocker Arm Ratio: 0.488 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio: 0.510 in.
Valve Lift with Factory Rocker Arm Ratio: 0.488 int./0.510 exh. lift
Lobe Separation (degrees): 114

Pistons
Ring dimensions 5/64, 5/64, 3/16
Dome shape: .135 dish; 4 valve reliefs
Compression dist 1.560
Deck Clearance .025
Skirt Clearance .0015

So, I'm sorry to data dump but this is the engine I recently purchased as is. The application will be for a pickup I'm building (K30) and will be using it for fun mostly, definitely want to run pump fuel in it. I've had it running previously with 93 octane and it was very strong with great oil pressure.

First question: is this set up any good? or what should be changed?
Second question: I need a head gasket, what gasket should I get?
Third question: what kind of numbers can I expect from it?

Thanks guys for any input, I'm a novice, with very limited money (recently married) and just want something fun and reliable.

-Luke
 
See less See more
#4 ·
Those heads can't support 400hp UNLESS you take the time to port them out- then they're pretty decent. That cam looks little big for your intended use, but it will run fine, just not have as much low end as I would prefer.

My only suggestion is to port the heads. I don't believe 305ho heads had steam holes so you wouldn't need a gasket for them unless you had them drilled- which would also be a smart move.

Summit has a budget line of carbs that came out recently- I believe they have a 750 for like $250, it would be plenty for that.


LASTLY, measure your piston dish volume, your chamber volume, and set your quench distance to about .040"- you can use that to figure your compression. No more than 10:1- preferabley around 9.5:1 for a daily driven truck.
 
#5 ·
Boring the Steam Holes

What's involved with boring the steam holes into the 416 head? Is it easy enough I can do it in my garage or do i need to send them to a machine shop?

Also, I failed to mention I have roller tip Crane rocker arms with different ratios for the exhaust and intake valves... don't remember what they are but will post up tomorrow when I check.

What's involved with Porting them? again, can I do this myself or is this something i need to have a shop do?

Thanks again for the replies and I appreciate any input!

-Luke
 
#6 ·
its not hard to put the steam holes in them just line a head gasket up and drill
take you time to line every thing up i've done it a few time havent had any problems with them. now porting your head is a nother thing that alot harder to do get a good grinder alot of books and some one that has been doing it for years all in the same room you could give it a shot but start with a junk set because you will mess the first piar up
and they need the steam holes or it will over heat hard on head gaskets
 
#7 ·
Steam Holes

Nothing more besides lining up the gasket and drilling? How deep? at what angle? what size? I guess I'm nervous, these heads have had a lot of work done to them (probably too much for a simple 416 head) so I'm a little scared with just drilling some holes... Anyone have pictures?
 
#9 ·
manchildau65 said:
Nothing more besides lining up the gasket and drilling? How deep? at what angle? what size? I guess I'm nervous, these heads have had a lot of work done to them (probably too much for a simple 416 head) so I'm a little scared with just drilling some holes... Anyone have pictures?
drill the hole strate the hole should be the same size as what in the block not hard to do
 
#10 ·
Thanks!

The attached tech article is extremely informative! The only detail missing is the depth of the holes... do I just drill until I've cleared through to the water chamber?

OK, another newbie question, I've never ported a set of heads. Can you guide me to another tech article on the right procedure?

With the engine torn down, would I be better off in the long run to suck up the 80 bucks or so and buy another hydraulic cam? or do you think the one I have will produce some good power with my set up?

Thanks again - joining this site has proven to be invaluable!

-Luke
 
#11 ·
Carb and Intake

The engine currently has an Edelbrock Performer RPM, since I need a carb with atleast ~710 cfm I'm looking at staying with Edelbrock and buying the 1407 750cfm unit. Any opinions? I've had good luck with Edelbrock in the past, they seem to be the easiest to set up and maintain... to a novice.

Thanks again for any input.
 
#13 ·
So it's time to button the engine back up, and I've a couple questions prior finishing everything.

1) I thought that chromoly rings were a great idea when I first started this build years ago, however, even now as I'm in the process of refreshing the engine the oringinal cross-hatching is still present. Should I tear it further down and replace the Chromoly rings with a standard set? This engine will be a toy, meaning I won't be putting many miles on it but will be running it hard.

2) I need a set of head gaskets, in my opinion I have too high of compression so I'm looking to reduce the ratio if in any way I can. What do you think of these head gaskets for my application: SUM-111505 ?

As always, I appreciate any and all feedback.
 
#15 ·
manchildau65 said:
1) I thought that chromoly rings were a great idea when I first started this build years ago, however, even now as I'm in the process of refreshing the engine the oringinal cross-hatching is still present. Should I tear it further down and replace the Chromoly rings with a standard set?
Are the rings already broken in to the cylinders? If yes, I'd leave it as-is if they're low-milage.

BTW, the rings are either chrome or moly. While there are steel rings, they're usually not found in a street-type build.

Which type it is (Cr or moly), is important as to how they'll break in and what type of bore finish is required for them.

If you have not honed the block, and the rings are new chrome-faced rings- they'll never break in, or will take for-freakin'-ever to do so, IMO.

If they're moly rings, there's at least a chance they'll break in on an unhoned bore- but to try might well have you tearing the whole thing back down if they don't seat. Not worth the risk, IMHO.

2) I need a set of head gaskets, in my opinion I have too high of compression so I'm looking to reduce the ratio if in any way I can. What do you think of these head gaskets for my application: SUM-111505 ?
I don't know what those gaskets are (just a friendly FYI: Providing a link would help. Most folks don't want to have to look up part numbers)- but you want to balance the piston-to-head distance (you hear this called both quench and squish, depending on who you're talking to) with the CR- too much of either isn't good.

You might get away w/as much as .060" "squench", but many people will say (rightly so, in many cases) this is too much; 0.040" is the target for a SBC in most cases.

But things being as they are, this is about all the options as to lowering CR and keeping squench within reason. With it at the max, you about have to live w/whatever CR that gives you, unless you want to machine the pistons, or change them altogether.

Good luck! :)
 
#16 ·
Thanks for posting your question Manchild... I am in the process of building a 408 using a 400 block with the same casting as yours, but bored over .040"... I will be checking your progress; I also just posted a question about my build recently. Hopefully some of your answers will help me. Good luck!!!
 
#17 ·
Cobalt, thanks for the reply and suggestions. The rings themselves are Moly and as far as honing is concerned I'm not sure what you mean. The bore was increased by 0.030" and the resulting finish was 'cross hatched'. The concern I have is whether or not they'll break in... I've had the engine running in the past (not for long... maybe 20 miles or 2 hours) and they still show the cross hatching as if they just came from the machine shop.

The head gasket I'm looking at: SUM-111505

Brand: Summit
Product Line: Summit® Copper Head Gaskets
Part Type: Head Gaskets
Bore (in): 4.155 in.
Bore (mm): 105.537mm
Gasket Material: Copper
Compressed Thickness (in): 0.062 in.
Lock Wire: No
Quantity: Sold as a pair.
Notes: These gaskets are not drilled for steam holes. Installation of these copper head gaskets requires O-rings.
 
#18 · (Edited)
That cam looks little big for your intended use, but it will run fine, just not have as much low end as I would prefer.
A 406 will swallow up that cam quite easily, and it will have plenty of TQ in the bottom. Might be a good thing to soften it up a tad so the tires don't wear away too fast. Even with a dish that bore/stroke and small chamber will yield some good compression, probably enough to worry about. A smaller cam will not help in this sense.

You will not want to use those copper gaskets unless you are going to o ring the block or receiver groove the heads or both. JMO

You should stil see the hone after 100k miles. That's where the oil stays until it's wiped down the cylinder. I think your hone is probably still good. Any glazed brown walls, or other maladies to indicate a problem - other than seeing the crosshatch pattern??
 
#19 ·
manchildau65 said:
I've had the engine running in the past (not for long... maybe 20 miles or 2 hours) and they still show the cross hatching as if they just came from the machine shop.
If there was no problems with the rings from this first build, why did you replace them- or are they the same rings you had in the engine that was run for a couple hours?

What I'm getting at is those 2-hour-old rings would (or should) have been fine. If you changed them, "just because", I wouldn't have- but what's done is done.

I'm a proponent of honing a cylinder before using new rings, if the cylinder has been broken in to another set of rings.

At just 2 hours run-time, the cylinders might still have enough "tooth" to break in your new moly rings- those rings are made to run on a comparatively smooth cylinder finish. I don't think anyone can say with 100% certainty that they will or won't break in.

The head gasket I'm looking at: SUM-111505
You do not want those gaskets.

Look into measuring how deep in the cylinder (at TDC) the pistons are. This measurement along with the gasket thickness wants to be as close to 0.040" (no less) as you can get, and still retain the CR needed.
 
#20 ·
Wow! Great information, Thank you.

To answer some questions:

1) The rings are the original Moly rings I installed during the first build (2hrs.) old. The reason the engine wasn't run longer was because I split the tranny in two the first time I had it out (SM465...) and it's sat ever since. I now have ambition again so I thought it would be a good idea to tear it down, drill the steam holes, and to try and improve my compression ratio.

2) Again, I'm not sure what honing means... the cylinders have the cross hatching (nothing a fingernail will pick up) does this mean the bores were honed? - there were no glazing marks present, just some carbon in the combustion area.

3) It looks like I'll need to keep looking for the right head gasket... Cobalt, when you say to measure the distance from the deck to the top of the piston, should I simply use a vernier and go to the highest point? and if so, I know there is visually a deck to top of piston gap so 0.040" seems to already be consumed... I think I'm confused
 
#21 ·
P.S. all I originally built the engine with was a Fel Pro gasket that came with the rebuild kit... Engine started hard (stock starter - 1000 CCA battery) but ran well with 93 octane, no pinging, however, I didn't push it hard, because I wanted to break it in properly (well except when I split the tranny housing...)
 
#22 · (Edited)
manchildau65 said:
1) The rings are the original Moly rings I installed during the first build (2hrs.) old.
GREAT!!! The rings will be fine as-is, and my earlier concerns are not valid- good deal!

2) Again, I'm not sure what honing means... the cylinders have the cross hatching (nothing a fingernail will pick up) does this mean the bores were honed? - there were no glazing marks present, just some carbon in the combustion area.
If the engine showed no signs of excessive blow-by (smoke from the breathers, etc.) or tail-pipe oil smoke (blue, oil smelling smoke with an attendant high rate of oil used from the engine), the rings/bore is fine.

Quick FYI- "Honing" is an operation done after the cylinders are bored, it brings the final dimensions and finish of the cylinders to what's needed for the type of piston and rings being used- it's a standard machine shop operation and was surely done to your engine, so you need worry about it no more- it's all good!

when you say to measure the distance from the deck to the top of the piston, should I simply use a vernier and go to the highest point? and if so, I know there is visually a deck to top of piston gap so 0.040" seems to already be consumed... I think I'm confused
What you need to measure, is the distance from the top of the block (where the head's bolted) down to the highest part of the piston, with the piston at TDC.

This can be done w/the depth function of a dial or veneer caliper but is more easily (and accurately) done w/a micrometer that bridges the bore. But it doesn't have to be accurate down to 0.0001", either.

Better than me struggling to describe the deal, here's a brief description along w/a calculator to figure what it is: HERE.

I know there is visually a deck to top of piston gap so 0.040" seems to already be consumed.
This wouldn't be too surprising. Often the pistons are made "short" on purpose- this is to compensate for the decking of the block that's often done on re-manufactured engines, usually 0.020" is cut from the blocks, so the rebuilder-type pistons are made 0.020" short to match.

"Squench" should be close to 0.040" as is possible, but sometimes this figure isn't possible w/the parts that are on hand.

To significantly chance the deck height, you can use gasket thickness (you would prob. need one of the thinner ones that are available) and/or change pistons.

EDIT- there are at least three different thicknesses of 400 head gaskets, four if you count the OEM steel shim that's out of production by GM, IIRC.

There may well be other manufacturers who make shim gaskets, and other thicknesses of composite gaskets- you'll just need to research it is all.

I'd suggest checking w/all the manufacturers to see who has what you need. The gaskets I listed earlier were for a 4" bore.
 
#24 ·
can always get one made... I found a local place to make me a few gaskets a while back when I was fooling around with a pontaic 151 (never do that again), actaully wasn't as expensive as I thought it would be. They did NOT specailize in auto products though, more of an industrial supplier, give them enough money and they can make anything for you.
 
#26 ·
Deck to Piston Clearance

OK, so I finally got my hands on a pair of depth mic's (.0001" resolution - overkill) and measured a couple different pistons on both banks of the engine and found the tightest/shortest to be 0.025". I'm assuming they are all close within a margin, the problem I was running into was determining when the piston was exactly at TDC.

So, as Cobalt had said earlier, I want the 'squench' to be around 0.040"... does that mean that I want a head gasket that adds only 0.015-0.020" compressed? Why is the magic number 0.040 for the squench?

Thanks again for all of the help, the project is actually starting to move forward again!
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top