400 sbc piston advice needed - at the machine shop

Okay, my next question is...

Who told you that you'd be good with going to a total of .040?

A machine shop? Were all the cylinders mic'ed?

You see the reason why I'm asking is many times when you have multiple bore issues you need to go .020-.030 just to clear up the issues. With your block already being at .030 I'd double check if another .010 will clear things up before persuing the build.

If all cylinders will be fine after just a .010 cut then, go for it! But I'm starting to feel a little uneasy at this point.

 

They checked several cylinders, but it was only a quick initital check. I will not know until tomorrow, what the actual measurements show. I did find out the thrust bearing is worn from someone riding the clutch (it was in a rock climber jeep). I had .012 end play in the crank.

 

Thrust wear can be caused by many things. GM had problems with thrust wear when certain engines were mated to 400 turbo trans. Be aware that "rebuilders" pistons are short by .020" out of the box. This combined with the normal factory .020-.025" will have the piston quite a bit in the hole. Bad for quench. Will build carbon. Which, worse case scenerio, can lead to octane sensitivity.

The stock length 400 rods load the cylinder walls pretty hard when used in hi-perf applications. Probably the cause of out of round in mid cylinder. Front cylinders tend to wear more at the top of ring travel. Due to coolant flow thru block/heads. .040" overbore should be ok for your intended use.

The debate on 383 vs. 400 will go on forever (or till dwindling 400 block supply drys up).

On the dyno. Street/stock block type engines. The 383 shows almost the same power/torque as similarly prepped 400. 383 advantage is a much more stable block, better rod angle.

I have 40+ years performance machine shop.

 

The thrust wear was not a huge concern to the machine shop. They said they could correct that.

I still don't know what is the best piston choice for my 400? (Assuming it will hone clean at .040.) Should I run the 882 heads and flattop pistons? Will it be run good in the truck on 87 octane, OR do I go with stock dish pistons and run the 882 heads for now and hope to change to vortec heads later? As-is, the old piston set .045 down in the hole. I wonder if new pistons will do the same? If they will, then that will effect the CR.

 

I've done a little more research and came up with two new piston choices:

SpeedPro H601P-40 (76 cc head CR - 9.11) Hypereutectic
Speedpro L2352F40 (76 cc heads CR - 8.94) Forged

One is Forged the other is Hypereutectic. Is there a difference for a street motor?
What about quench? How far down should a piston be below the deck?

 

You don't need a forged piston for your application. The Hypereutectic piston does not need as much wall clearance compared to a forged piston. The two pistons listed have a 0.005" difference in compression height, which will affect how far down in the bore they sit. For general street use like you have described, try to get the quench at or below 0.060". Higher performance applications will go less - maybe 0.040-0.045 - but you need to take into account wall clearance and piston rock. A dished piston changes the quench situation some as well. I'd use the 9.1 CR piston you listed and get it 0.015" down and use a 0.040" headgasket.

 

And yes, when you deck the block to adjust the piston height your original 9.1CR will come up a point or two. You can do all of the math after you finalize the machine work if you need to know, and even do the math on .039, .040, and .041 headgaskets if you care. I'd just build it because you'll be in a good place with those parts.

 

Heres a build up of a 400.
They had problems and the end result was less than spectacular.
Good read so you know what to avoid
http://www.carcraft.com/techarticle...ck_chevy_torque_monster_for_2500/viewall.html

Heres another one with better results.
http://www.chevyhiperformance.com/techarticles/148_0306_chevrolet_406_big_block_torque/

 

What is the GVW on the truck it's over 6000 lbs I'd stay below 9 to 1.

 

If you're going to buy pistons, go with the hypereutectic, especially for your low rpm application. I don't like the 9.1-1 compression figure, but that's me. If you go that route, I would highly suggest to do the math and zero deck the block to get your compression up to around 9.5-1, and run a good quality head gasket. The earlier comment about many aftermarket pistons being around .020 "short" is true, so you may have to take that into consideration when calculating deck and quench figures.

The earlier comment about many 400 cranks having excess thrust is true. Of all the 400s I have been around, many (most) of the cranks were unusable due to excessive thrust. A Scat crank is cost effective option if the stock crank doesn't pass inspection.

I know what you're going through with all the options. There are dozens of ways to go, and each one has it's pros and cons. It all comes down to money, because it's harder to build a reliable engine on a tight budget than most people think. You can easily build an el cheapo, but most of them are potential time bombs that will decide to explode at the worst possible time, like when you're 100 miles from home.

 

Did I miss something here?

Who ever said the block needed to be decked?

There we go again building the ultimate engine when it's not needed or wanted.

Shit I'm running 5xx horse in a .040 over 400 (408) and my deck wasn't touched! Oh and for the record, my engine was built at Oddy's.... yeah that Oddy's.

Check it! If it passes leave it alone!

 

There are so many choices, combinations and costs to consider. Do I buy a kit with pistons, but a re-ring kit and separate pisons, buy this and that, and have parts left over for another engine build...yikes. It all adds seems to add up to about the same amount of $1500 for basic machine work and parts. That price does not include balancing. Where it starts to gets out of control is changing to 5.7 rods, then I have to add in $275 for balancing and $200 for new rods. Also the lower 9.1 CR compression pistons cost double.

The least expensive option is the N.A.P. kit with the 9.6 CR flat top pistons on the stock rods. I could also buy these 9.6 CR pistons on new 5.7 rods for the price of the lower 9.1 CR pistons alone (but then there is an additional balancing costs).

The machine shop guy said the .006 excess thrust issue can be corrected with an oversize rear bearing designed to be machined to the correct thickness.

The truck weight is unknown at this time, but I'd guess 6500# or more.

I'll read the links listed on 400 builds.

 

"Deck the block and spend more money...fa la la lal la." (My new favorite song)

FYI - I noticed the old flattop pistons (9.5 CR) were very heavily covered in carbon. They were .045 in the hole and had .039 gaskets.

 

Ha Ha Ha!!!

That's fuckin' hillarious!

 

Did I miss something here?

Who ever said the block needed to be decked?

He asked about quench, and if he cares to do anything about getting it out of the smog era dementions and to a better range for his intended use with the pistons he listed in post #35, he will need to deck the block. He could also get a different piston with a different compression height - but he didn't talk about that.

 

Am I to understand that I can buy pistons that will be higher in the cylinder and be say, .012 down from the deck? How do I figure out which pistons will fit like that?

 

In some cases, yes. You need to check the compression height listed for the piston. I know for the 5.7 rod 400- which I know you are not using - there are several that sit .008 or .010 higher than the customary -.025 down. Take 1/2 your stroke + rod length + piston compression height to find top of piston. Stock SBC deck height is 9.025. The difference betwen those two numbers is how far the piston is down with a stock deck height.

 

If you got the dough, they will make you whatever kind of pistons you tell them to.

 

The Car Craft article from post 35, talks about how far off the actual deck on their 400 was from the 9.025 and how it got worse on different cylinders.

 

The Car Craft article from post 35, talks about how far off the actual deck on their 400 was from the 9.025 and how it got worse on different cylinders
Yes, but not uncommon from the factory. With your intended budget and use, figure out the best use of your money, and live with the result. A good machine shop should be able to steer you in the right direction.

 

One of the worst I have seen was a block that I was building for myself.

While I was setting the block up for deck height. I couldn't believe what the instruments read. .027 front left cyl. .029 on next. .034 next and .045 back side of bore on last hole. Almost the same on the other side only reversed. Like the block was twisted on its locator pins as it went thru the factory deck broach. I wondered how this thing had ever held a head gasket?

 

I'd check the rod bigends, expecting to find some out of round or with cap shift, with the end result some or most will need to be rebuilt. Those rods will be several thousandths shorter than they were.

It used to be that folks would swap rods and pistons around to try to equalize the deck heights. A worthy goal.

Even if the block needs to be decked for flatness or finish reasons, I'd get a handle on what the deck heights at all 4 corners are likely to be, so a uniform height, with tighter squish/quench would be the end result.

 

At this point I am down to two possible engine kits. The Northern Auto kit has the advantage of by spending $50 extra I get an extra "performance" cam, lifters and timing chain for my 350 in my 41 pickup. The trade off is the higher compression ratio.

Both kits make the calculated quench more than it should be. (.064 and .066) Is it worth decking the block? How much can it be decked before it effects the head alignment?

Is it worth spending $20 more to get Clevite bearings with the Northern Kit?

Here are the kit differences:

<TABLE style="WIDTH: 184pt; BORDER-COLLAPSE: collapse" border=0 cellSpacing=0 cellPadding=0 width=246 x:str><COLGROUP><COL style="WIDTH: 92pt; mso-width-source: userset; mso-width-alt: 4498" span=2 width=123><TBODY><TR style="HEIGHT: 12.75pt" height=17><TD style="BORDER-BOTTOM: #ece9d8; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: transparent; WIDTH: 92pt; HEIGHT: 12.75pt; BORDER-TOP: #ece9d8; BORDER-RIGHT: #ece9d8" class=xl24 height=17 width=123>Summit</TD><TD style="BORDER-BOTTOM: #ece9d8; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: transparent; WIDTH: 92pt; BORDER-TOP: #ece9d8; BORDER-RIGHT: #ece9d8" class=xl24 width=123>Northern</TD></TR><TR style="HEIGHT: 12.75pt" height=17><TD style="BORDER-BOTTOM: #ece9d8; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: transparent; HEIGHT: 12.75pt; BORDER-TOP: #ece9d8; BORDER-RIGHT: #ece9d8" class=xl24 height=17>MHP138-411</TD><TD style="BORDER-BOTTOM: #ece9d8; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: transparent; BORDER-TOP: #ece9d8; BORDER-RIGHT: #ece9d8" class=xl24>EK-1162</TD></TR><TR style="HEIGHT: 12.75pt" height=17><TD style="BORDER-BOTTOM: #ece9d8; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: transparent; HEIGHT: 12.75pt; BORDER-TOP: #ece9d8; BORDER-RIGHT: #ece9d8" class=xl24 height=17></TD><TD style="BORDER-BOTTOM: #ece9d8; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: transparent; BORDER-TOP: #ece9d8; BORDER-RIGHT: #ece9d8" class=xl24></TD></TR><TR style="HEIGHT: 12.75pt" height=17><TD style="BORDER-BOTTOM: #ece9d8; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: transparent; HEIGHT: 12.75pt; BORDER-TOP: #ece9d8; BORDER-RIGHT: #ece9d8" class=xl26 height=17 x:num="442">$442 </TD><TD style="BORDER-BOTTOM: #ece9d8; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: transparent; BORDER-TOP: #ece9d8; BORDER-RIGHT: #ece9d8" class=xl24>$425/$473 w/cam</TD></TR><TR style="HEIGHT: 12.75pt" height=17><TD style="BORDER-BOTTOM: #ece9d8; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: transparent; HEIGHT: 12.75pt; BORDER-TOP: #ece9d8; BORDER-RIGHT: #ece9d8" class=xl24 height=17></TD><TD style="BORDER-BOTTOM: #ece9d8; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: transparent; BORDER-TOP: #ece9d8; BORDER-RIGHT: #ece9d8" class=xl24></TD></TR><TR style="HEIGHT: 12.75pt" height=17><TD style="BORDER-BOTTOM: #ece9d8; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: transparent; HEIGHT: 12.75pt; BORDER-TOP: #ece9d8; BORDER-RIGHT: #ece9d8" class=xl25 height=17>9.1 CR</TD><TD style="BORDER-BOTTOM: #ece9d8; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: transparent; BORDER-TOP: #ece9d8; BORDER-RIGHT: #ece9d8" class=xl25>9.7 CR</TD></TR><TR style="HEIGHT: 12.75pt" height=17><TD style="BORDER-BOTTOM: #ece9d8; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: transparent; HEIGHT: 12.75pt; BORDER-TOP: #ece9d8; BORDER-RIGHT: #ece9d8" class=xl25 height=17>H601CP-40</TD><TD style="BORDER-BOTTOM: #ece9d8; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: transparent; BORDER-TOP: #ece9d8; BORDER-RIGHT: #ece9d8" class=xl25>H400CP-40</TD></TR><TR style="HEIGHT: 12.75pt" height=17><TD style="BORDER-BOTTOM: #ece9d8; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: transparent; HEIGHT: 12.75pt; BORDER-TOP: #ece9d8; BORDER-RIGHT: #ece9d8" class=xl25 height=17>.025 deck</TD><TD style="BORDER-BOTTOM: #ece9d8; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: transparent; BORDER-TOP: #ece9d8; BORDER-RIGHT: #ece9d8" class=xl25>.025 deck</TD></TR><TR style="HEIGHT: 12.75pt" height=17><TD style="BORDER-BOTTOM: #ece9d8; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: transparent; HEIGHT: 12.75pt; BORDER-TOP: #ece9d8; BORDER-RIGHT: #ece9d8" class=xl25 height=17>Moly Rings</TD><TD style="BORDER-BOTTOM: #ece9d8; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: transparent; BORDER-TOP: #ece9d8; BORDER-RIGHT: #ece9d8" class=xl25>?</TD></TR><TR style="HEIGHT: 12.75pt" height=17><TD style="BORDER-BOTTOM: #ece9d8; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: transparent; HEIGHT: 12.75pt; BORDER-TOP: #ece9d8; BORDER-RIGHT: #ece9d8" class=xl25 height=17></TD><TD style="BORDER-BOTTOM: #ece9d8; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: transparent; BORDER-TOP: #ece9d8; BORDER-RIGHT: #ece9d8" class=xl25></TD></TR><TR style="HEIGHT: 12.75pt" height=17><TD style="BORDER-BOTTOM: #ece9d8; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: transparent; HEIGHT: 12.75pt; BORDER-TOP: #ece9d8; BORDER-RIGHT: #ece9d8" class=xl25 height=17>Hi Vol oil pump</TD><TD style="BORDER-BOTTOM: #ece9d8; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: transparent; BORDER-TOP: #ece9d8; BORDER-RIGHT: #ece9d8" class=xl25>Std Oil Pump</TD></TR><TR style="HEIGHT: 12.75pt" height=17><TD style="BORDER-BOTTOM: #ece9d8; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: transparent; HEIGHT: 12.75pt; BORDER-TOP: #ece9d8; BORDER-RIGHT: #ece9d8" class=xl25 height=17></TD><TD style="BORDER-BOTTOM: #ece9d8; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: transparent; BORDER-TOP: #ece9d8; BORDER-RIGHT: #ece9d8" class=xl25></TD></TR><TR style="HEIGHT: 12.75pt" height=17><TD style="BORDER-BOTTOM: #ece9d8; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: transparent; HEIGHT: 12.75pt; BORDER-TOP: #ece9d8; BORDER-RIGHT: #ece9d8" class=xl25 height=17>Full gasket set</TD><TD style="BORDER-BOTTOM: #ece9d8; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: transparent; BORDER-TOP: #ece9d8; BORDER-RIGHT: #ece9d8" class=xl25>Fel Pro Gasket set</TD></TR><TR style="HEIGHT: 12.75pt" height=17><TD style="BORDER-BOTTOM: #ece9d8; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: transparent; HEIGHT: 12.75pt; BORDER-TOP: #ece9d8; BORDER-RIGHT: #ece9d8" class=xl25 height=17>.041 head gasket</TD><TD style="BORDER-BOTTOM: #ece9d8; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: transparent; BORDER-TOP: #ece9d8; BORDER-RIGHT: #ece9d8" class=xl25>.039 head gasket</TD></TR><TR style="HEIGHT: 12.75pt" height=17><TD style="BORDER-BOTTOM: #ece9d8; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: transparent; HEIGHT: 12.75pt; BORDER-TOP: #ece9d8; BORDER-RIGHT: #ece9d8" class=xl25 height=17></TD><TD style="BORDER-BOTTOM: #ece9d8; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: transparent; BORDER-TOP: #ece9d8; BORDER-RIGHT: #ece9d8" class=xl25></TD></TR><TR style="HEIGHT: 12.75pt" height=17><TD style="BORDER-BOTTOM: #ece9d8; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: transparent; HEIGHT: 12.75pt; BORDER-TOP: #ece9d8; BORDER-RIGHT: #ece9d8" class=xl25 height=17>Brass Freeze plugs</TD><TD style="BORDER-BOTTOM: #ece9d8; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: transparent; 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BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: transparent; BORDER-TOP: #ece9d8; BORDER-RIGHT: #ece9d8" class=xl25>camshaft stock</TD></TR><TR style="HEIGHT: 12.75pt" height=17><TD style="BORDER-BOTTOM: #ece9d8; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: transparent; HEIGHT: 12.75pt; BORDER-TOP: #ece9d8; BORDER-RIGHT: #ece9d8" class=xl25 height=17></TD><TD style="BORDER-BOTTOM: #ece9d8; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: transparent; BORDER-TOP: #ece9d8; BORDER-RIGHT: #ece9d8" class=xl25>$50 perf cam</TD></TR><TR style="HEIGHT: 12.75pt" height=17><TD style="BORDER-BOTTOM: #ece9d8; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: transparent; HEIGHT: 12.75pt; BORDER-TOP: #ece9d8; BORDER-RIGHT: #ece9d8" class=xl25 height=17></TD><TD style="BORDER-BOTTOM: #ece9d8; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: transparent; BORDER-TOP: #ece9d8; BORDER-RIGHT: #ece9d8" class=xl25></TD></TR><TR style="HEIGHT: 12.75pt" height=17><TD style="BORDER-BOTTOM: #ece9d8; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: transparent; 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I'm glad your thread has survived. Whenever I ask a big block chevy question, it gets pulled, stomped on and thrown in the trash. The reason from Ryan..."we like to keep things pre 64 here" Maybe now that he has told the world that his favorite car is a 65 riva, things might change.....one year anyway.

 

I'm glad it survived and for the advice. This is the engine for my 41 Ford COE. I know little about engines past cam swaps and really take the advice the guys here give a lot of attention. The engine was suppossed to installed already. My COE is now "hanging" in the garage and in a million pieces. It is amazing how hard the motor swap is when it is under the bed. The one picture is of the metal fragments I discoverd in the oil pan.

 

Ha Ha!

Ya' do know yer talkin' 'bout 'da Boss don't ya'?

 

I'm sure you have a good machine shop that has torque plates. These plates distort the cylinders so after the heads are torqued they will be round. If you go .030 to .040 I would ask them to bolt there torque plates to the deck and hone the whole amount. When you bore the block you set up off the deck, and if you deck the block it might throw off the bar. I know you correct the deck, lining it up with the crank centerline. The trouble is if the deck is off and you have to correct the cylinders you might have to go .060 or scrap the block.

If you want torque don't do it with compression. Run dished pistons but open the heads up for 2.02 and 1.6 valves, and little pocket porting. You're pushing alot of truck down the road. I beleive anything over 9 to 1 will be to close to running on the edge. Most of these guys are getting away with higher compression because they have light cars. You go by different rules on truck engines.

 

Hey waddayacare...can you take a look at post 54 and give me your opinion, thanks. I was thinking that I could choose one of the alternate cams from the N.A.P. kit and run that in the 400 if my .427/.454 torque cam is too small for the 9.7 CR.

 

54???

The one about Ryan???

 

In case you haven't heard, Ryan is the BOSS, the Grand Wazoo, El -Capitan, and we are grateful for all he does. Go with the flow, it will keep you from getting vaporized.