400 SBC .040 rebuild...need some help getting started - Team Camaro Tech
Engine General Engine Discussion.

 5Likes
Reply
 
LinkBack Thread Tools Display Modes
post #1 of 41 (permalink) Old Nov 24th, 16, 05:22 PM Thread Starter
Senior Tech
 
Join Date: Oct 2011
Location: Edwards, CA
Posts: 316
400 SBC .040 rebuild...need some help getting started

Had a great running 406 until the fuel pump rod ate itself and deposited metal shavings throughout the motor. There's a bit more to the story than that, but the punchline is that the motor is getting bored and honed .040 over, and I'm spending Turkey Day ordering parts. Here's my engine specs:

- 400 SBC .040 over (511 block, 4-bolt main)
- stock heads - 76cc (1.94/1.50?)
- stock rods (5.565)
- flat-tappet cam- 222/222 @ 50, .447"/.447"
- Typhoon manifold (edelbrock performer knock-off)
- either Edelbrock 1406 600 or Holley 750 (both are set-up, ready to go)
- Hooker Super Comp 1-3/4"

Someone mentioned I should strive for a 10:1 comp ratio. It's a street car normally driven on weekends. Might see the strip once or twice, but definitely nothing serious on that front. I don't need to maximize performance at this point. Maybe 5 years down the road I'll want to upgrade the heads and cam, but for now I'm not looking to drop high $$ to squeeze out every ounce of power. That being said, if there's small things I can do now that just "make sense"...let me know!

Looking for advice:

1. Pistons. I plan to get KB172KTM-040 hypereutectic, piston/ring kit (flat, 5/64" rings, $414). https://m.summitracing.com/parts/uem-kb172ktm-040. Does anyone see a reason to go with anything different?
2. I was told to have the machinist mic the rods. I assume this is worth the cost?
3. For the life of me I can't find how long the wrist pins should be to match the Pistons above. Do all Pistons come with wrist pins? Do I need to buy retaining clips separately?
4. Should I get new rod bolts? I have no idea how old the current ones are.
5. Recommendation for head gaskets? Should I chooses the thickness to fine tune a specific compression ratio? Should I really be shooting for 10:1?
6. Any specific brand of bearings?
7. I would love to have a leak proof SBC when I'm done with this. What gaskets should I be looking at?
8. I'll be rebuilding the heads. Are there known parts I'll have to replace during the rebuild?
9. Is assembly line all the same or should I lean towards a specific brand/type?

Any guidance is appreciated. I'm trying to order Pistons tomorrow...other stuff can get kicked down the road a bit.

Thx,
Boucher
Boucher421 is offline  
Sponsored Links
Advertisement
 
post #2 of 41 (permalink) Old Nov 24th, 16, 06:49 PM
Senior Tech
Dave
 
Join Date: Dec 2005
Location: Tampa, Florida
Posts: 4,681
Re: 400 SBC .040 rebuild...need some help getting started

Funny you should ask ...

1.) I plan to get KB172KTM-040 hypereutectic, piston/ring kit (flat, 5/64" rings, $414). Does anyone see a reason to go with anything different?

No not on a street engine.

2.) I was told to have the machinist mic the rods. I assume this is worth the cost?

He will need your block, and bearings as well. He is looking for verifying bearing clearances after crush.

3.) For the life of me I can't find how long the wrist pins should be to match the Pistons above. Do all Pistons come with wrist pins? Do I need to buy retaining clips separately?

Hyper pistons do not normally use retaining clips they are pressed into the small end of the rod once your old piston is removed using a gas torch to heat the small end. All pistons ship with wrist pins. You only buy an aftermarket piston Tool Steel or Tapered Wrist Pin to either obtained a stronger or lighter part; then you find yourself discarding the stock wrist pin that shipped with the piston.

4.) Should I get new rod bolts? I have no idea how old the current ones are.

Yes I would buy new ARP rod bolts (no need for 2000 series) because the stock ones are the weakest link in a stock bottom end. Just be aware of the cost of the parts and having the rods resized to accept the new rod bolts will be close to if not more than the cost of brand new SCAT or Eagle replacement rods (which are going to be offered at 5.7" at their shortest length requiring you to change your piston order) to match the longer rod.

5.) Recommendation for head gaskets? Should I chooses the thickness to fine tune a specific compression ratio? Should I really be shooting for 10:1?

I use FelPro stainless steel bead composite for most builds, or Cometic Multiple Layer Steel gaskets if I am running above 10.25:1 compression. I also deck the block to be sure it is flat (usually removes 12-15 thousandths from the deck to get it flat and square). If you are paying to deck the block why not zero deck it (bringing the top of the piston flush with the deck) so that you can choose your compressed height of your head gasket to control quench (aka squish).

Personally I think anything above 9.2:1 with a cast iron head is asking for trouble with today's gas quality.

6.) Any specific brand of bearings?

I have used Clevite 77 bearings for over forty years without a bearing failure. But once again it is the attention to detail and cleanliness that will determine reliability. Too tight and they will burn up, too loose and they will hammer themselves paper thin.

7.) I would love to have a leak proof SBC when I'm done with this. What gaskets should I be looking at?

One piece Fel-Pro oil pan gasket and a couple of tubes of RTV (one black, one blue) will stop most leaks. With stock SBC tin it is usually bent out of shape from being over tightened (there are torque specs even for the valve cover screws). Usually if I am reusing stock tin I hammer it all flat reform the lips then paint them to get a good seal. A cast aluminum valve cover will seal better as the clamping force is more uniform. I also use Moroso soft rubber over a steel core with stand offs for a valve cover gasket (they are pricey, but reusable, so one pair last the life of the engine).

Finally offset the rear main seal about fifteen degrees so that the gap isn't on the main cap parting line, and lube the front seal before installing the damper.

8.) I'll be rebuilding the heads. Are there known parts I'll have to replace during the rebuild?

That depends upon the condition of the heads. Cast iron factory heads hammer the seats and they will sink down into the head upon multiple valve jobs. This impedes their ability to breathe even at stock levels. Oil getting into the combustion chamber from worn valve guides combined with high static compression is an invitation for detonation. Verify your guides are in good shape and buy Perfect Circle valve stem seals (requires machining the head to accept them). Bigger swirl polished tuliped valves are lighter and flow more air than the same size valve from Chevy (which is flat faced and heavy).

9.) Is assembly line all the same or should I lean towards a specific brand/type?

No idea what you are asking here.

Big Dave
zdld17 likes this.
Larger Dave is online now  
post #3 of 41 (permalink) Old Nov 24th, 16, 07:15 PM Thread Starter
Senior Tech
 
Join Date: Oct 2011
Location: Edwards, CA
Posts: 316
Re: 400 SBC .040 rebuild...need some help getting started

Thx Dave. "Line" autocorrected from "lube" in #9.

I didn't realize detonation would be a problem at that low of compression. Even with Shell 93 gas? Won't zero-decking make this problem worse? Or is there enough choices in gaskets to get compression from the range between low 9s up to 10:1? (I figure I'll get new heads years from now...it'd be nice to raise compression later.

Will all new rod bolts require machine the rod? I'm surprised ARP wouldn't make a bolt specific to 5.565 rods.

Thx.
Boucher421 is offline  
 
post #4 of 41 (permalink) Old Nov 24th, 16, 07:54 PM
Gold Lifetime Member
Don
 
Join Date: Jan 2005
Location: 2 Dog Town in West Texas
Posts: 11,154
Re: 400 SBC .040 rebuild...need some help getting started

Quote:
Originally Posted by Boucher421 View Post
Thx Dave. "Line" autocorrected from "lube" in #9.

I didn't realize detonation would be a problem at that low of compression. Even with Shell 93 gas? Won't zero-decking make this problem worse? Or is there enough choices in gaskets to get compression from the range between low 9s up to 10:1? (I figure I'll get new heads years from now...it'd be nice to raise compression later.

Will all new rod bolts require machine the rod? I'm surprised ARP wouldn't make a bolt specific to 5.565 rods.

Thx.
Hope you don't mind ,
I know this was directed to Dave but I would like to comment on your zero decking concerns.

What Dave may be getting at is that once your machinest trues up block/head surface with crank center-line, he does remove the deck material of your block to true this up. Meaning the piston decks are now flat with block face surface. The piston to head flat surfaces are called quench areas.

In doing so, you can also reduce the amount of piston quench ( piston flats that mate close to your cly head flats).
By reducing quench areas, you are able to control detonation while running 10:1 compression ranges..
To get this quench ideal, you run a thicker head gasket say .035-.045 range. This will be your quench area as well as your piston to head clearance. Make sense?

Lets see if Dave agrees with my comments. He has been doing this longer and deeper than I have. I am still learning .

Don
TC # 349
Zdld17:69 Z/RS,306, NOR141111, 9N554XXX, 12A, X3G, 59/59,723, AFR 195,CCC282/290HR, TKO 600, BU1122B1E Owner since Dec 1968

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

Last edited by zdld17; Nov 24th, 16 at 08:10 PM.
zdld17 is offline  
post #5 of 41 (permalink) Old Nov 24th, 16, 08:23 PM
Moderator
John
 
Vega$69's Avatar
 
Join Date: Sep 2010
Location: Vegas NV/Wesley Chapel FL
Posts: 12,683
Garage
Re: 400 SBC .040 rebuild...need some help getting started

Zero decking will put the piston at the top of the hole. With head gasket thickness and head volume you'll be able to determine which pistons to buy to yield desired compression.

Detonation can be caused by not having ideal quench. (Space between the flat part of the piston an the flat of the head) zero deck and the quench will be equal to the compressed head gasket thickness.
Vega$69 is offline  
post #6 of 41 (permalink) Old Nov 25th, 16, 10:32 AM
Senior Tech
Dave
 
Join Date: Dec 2005
Location: Tampa, Florida
Posts: 4,681
Re: 400 SBC .040 rebuild...need some help getting started

John and Don are correct.

Ideally you would control this volume by changing the compressed thickness of the head gasket. The factory shot for a range of -0.018" to -0.025" plus 0.013" to 0.015" inch of compressed thickness in the head gasket to control static compression. As you can see that is a wide variance which was fine for a street motor running on regular gas back when regular gas as 94 octane with 100 to 106 octane being available at the pump as high test gas back in the sixties when these motors were built.

The available octane rating of gasoline is the biggest factor you should consider when building your engine (unless you are building one for race gas, alcohol, or propane). The octane rating changes with the season of the year, and the area you buy it in. Brands are not as different as you might think since usually every brand gas you buy in your area uses the same base stock and the different distributors (brands) just add their own proprietary additives to make it "their" gas.

Like I said above oil contamination, under hood air temps, humidity, and shape of your combustion chamber as well as what the material your head is made of all affect detonation; with any fixed static compression ratio. So it may run fine one day with your ignition lead set and the same gas in the tank as it ran yesterday, and still go into a death rattle today due to some other environmental change.

The factory likes to keep static compression down for reasons of reliability. In a computer controlled car (EFI) you can pull out ignition lead, change the cam timing and fatten the fuel mix in a fraction of a second if the knock sensor hears something in terms of detonation. You can not do that with fixed cam timing, and a vacuum only advance curve and a carburetor. You have to tune the car to stay out of detonation. You can tune it to the edge of detonation for the trace rack but you have to reset it to street settings unless you trailer the car home. Having the ability to change a head gasket to raise or lower your static compression ratio can be a tuning aide or just a way to build your car (fuel cars carry ten to fifteen different thickness solid copper head gaskets to tune the car for changes in altitude, barometric conditions and humidity all measured on race day between rounds).

With cast iron heads 9.4 or so is the max on STATIC compression, for a SBC which changes dynamically with any changes you make in valve timing. That big rumpitty rump cam noise we all love is the sound of the vales being held open while the pistons are pushing air and fuel that should be being compressed up through the carb. You can not build compression with an open intake valve, and as such it reduces your effective dynamic compression ratio and the actual displacement of your motor.

It is for this reason you can not accept the over the internet claim that I have a static ratio of X:1 in my car and I have never encountered detonation. You would have to consider where they lived, the head he had and the gas he was running to know if he told the truth or just couldn't hear the ratting over the noise of his exhaust.

Big Dave
zdld17 likes this.
Larger Dave is online now  
post #7 of 41 (permalink) Old Jan 1st, 17, 09:28 AM Thread Starter
Senior Tech
 
Join Date: Oct 2011
Location: Edwards, CA
Posts: 316
Re: 400 SBC .040 rebuild...need some help getting started

It's been slow going, but finally got everything delivered. Two questions:

1) do I need new cam bearings after hot tanking the block?
2) would you recommend I completely disassemble and clean the cylinder heads? Is there really a possibility that contaminates would get above the valves?
Boucher421 is offline  
post #8 of 41 (permalink) Old Jan 1st, 17, 11:51 AM
Senior Tech
Dave
 
Join Date: Dec 2005
Location: Tampa, Florida
Posts: 4,681
Re: 400 SBC .040 rebuild...need some help getting started

First question, do you need new cam bearings after a hot tank? The answer is yes you do.

The sodium hydroxide in the hot tank removes not only grease grime and carbon build up but the Cadmium, Lead and Tin from the cam bearings that the cast iron core of your cam rides upon. The bearings will look charcoal grey in color as the metals have all been chemically altered.

Would I recommend completely disassembling and cleaning the cylinder heads? Yes; but not because I am worried about foreign materials above the valves but because I would want to lap in the valve faces again and replace the valve springs because I consider valve springs to be a consumable.

Big Dave
Larger Dave is online now  
post #9 of 41 (permalink) Old Jan 1st, 17, 11:53 AM Thread Starter
Senior Tech
 
Join Date: Oct 2011
Location: Edwards, CA
Posts: 316
Re: 400 SBC .040 rebuild...need some help getting started

Even after just 500 miles on the motor?
Boucher421 is offline  
post #10 of 41 (permalink) Old Jan 1st, 17, 12:04 PM
Senior Tech
Dave
 
Join Date: Dec 2005
Location: Tampa, Florida
Posts: 4,681
Re: 400 SBC .040 rebuild...need some help getting started

500 miles would be about about 14 years of time for a trailered race car. So it all depends upon how you drove those 500 miles!

Springs that are pushed by high RPM operation should be checked about every five hundred miles to verify they are still holding within ten percent of their installed open pressure (I do that on the head with a spring checker that mounts to the stud in place of the roller rocker). But then I run a big block and they eat valve springs for breakfast because of the pressure, and that they are running through all three axis of motion on compression and expansion due to the canted valve angles. So yes I have detected bad springs at five hundred miles (actually all I would need is about ten miles if all ten miles were at wide open throttle).

Though I suspect your springs are fine. I would still check them because I am paranoid about breaking valve springs, which leads to sucking a valve which leads to a rebuild and a lot of head work if they can even be salvaged.

Big Dave
Larger Dave is online now  
post #11 of 41 (permalink) Old Jan 1st, 17, 04:40 PM
Senior Tech
Doug
 
Join Date: Jun 2016
Location: Hopewell, Va
Posts: 216
Re: 400 SBC .040 rebuild...need some help getting started

You are rebuilding your engine and you want it to last for a while. I would replace the 35-40 year old rods with the nice forged steel rods from Scat. https://www.summitracing.com/parts/s...make/chevrolet pistons- https://www.summitracing.com/parts/u...make/chevrolet, rings-https://www.summitracing.com/parts/pcr-40141cp-040/overview/, Head Gaskets-https://www.summitracing.com/parts/fel-1003/overview/make/chevrolet, have the machinist check the heads to see what they need. Camshaft-https://www.summitracing.com/parts/lun-10120318/overview/make/chevrolet, call for Valve Spring recommendation. Head Improvement Kit - Head Improvement Kit, Chev SB, 1.94-1.50" Valve, Hyd/Mech FT - Competition Products
camarodriver67 is offline  
post #12 of 41 (permalink) Old Feb 23rd, 17, 05:42 AM Thread Starter
Senior Tech
 
Join Date: Oct 2011
Location: Edwards, CA
Posts: 316
Re: 400 SBC .040 rebuild...need some help getting started

Okay guys. I have everything but the head gasket, so I'm gonna start building this weekend. Plan A is to YouTube "how to build a sbc" and go from there. Any advice for good tutorials on-line? I know there's a better-than-even chance I could screw something up...so I'll take things extra slow. Any advice is appreciated.
Boucher421 is offline  
post #13 of 41 (permalink) Old Feb 23rd, 17, 09:17 AM
Apprentice
Brad
 
Join Date: Sep 2016
Location: Michigan
Posts: 25
Re: 400 SBC .040 rebuild...need some help getting started

I'm a newbie too - planning my first engine rebuild for this spring - and I'd be interested in what others had to say. I've found several good "channels" where they do easy to follow step-by-step rebuilds. Eric the Car Guy has a great series at a machine shop. He's rebuilding a Ford with turbo but there's a lot of good advice there. Pete's Garage has a number of builds - some SBC some others. Myvintageiron7512 also does a lot of Chevy builds. After watching a bunch of these videos I've definitely got my courage up to try a rebuild - although we'll see if that's a good thing once I've actually done it!

Sent from my SM-G920V using Tapatalk
Brad Keuning is offline  
post #14 of 41 (permalink) Old Feb 23rd, 17, 10:00 AM
Gold Lifetime Member
Don
 
Join Date: Jan 2005
Location: 2 Dog Town in West Texas
Posts: 11,154
Re: 400 SBC .040 rebuild...need some help getting started

Still planning on running those heads? I would consider them a little too small, port wise. But is getting groceries are your only concern, then stay with them.

I would use a Holley 750.

Don
TC # 349
Zdld17:69 Z/RS,306, NOR141111, 9N554XXX, 12A, X3G, 59/59,723, AFR 195,CCC282/290HR, TKO 600, BU1122B1E Owner since Dec 1968

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
zdld17 is offline  
post #15 of 41 (permalink) Old Feb 24th, 17, 11:56 AM
Senior Tech
Anne
 
Join Date: Jan 2013
Location: Eddyville KY
Posts: 1,470
Re: 400 SBC .040 rebuild...need some help getting started

Quote:
Originally Posted by Boucher421 View Post
Okay guys. I have everything but the head gasket, so I'm gonna start building this weekend. Plan A is to YouTube "how to build a sbc" and go from there. Any advice for good tutorials on-line? I know there's a better-than-even chance I could screw something up...so I'll take things extra slow. Any advice is appreciated.
I've built two smallblocks using this book :

https://www.amazon.com/How-Rebuild-Y...ll+block+chevy

Government's first duty is to protect the people, not run their lives.
Ronald Reagan
Lawrence454 is offline  
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Team Camaro Tech forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address.
NOTE we receive a lot of registrations with bad email addresses. IF you do not receive your confirmation email you will not be able to post. contact support and we will try and help.
Be sure you enter a valid email address and check your spam folder as well.



Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome