briannutter

hey there, just deck the block if you already have rods. .020 off the deck isn't nearly enough change to cause a problem with intake manifold alignment. cutting .035 off decks is done 1000 times a day...most small block chevy aftermarket pistons are set to 8.990 and factory deck height is 9.025.

Also, someone had a statement about the truck blocks being 9.240 rather than 9.230. There may be a few blocks that hit the 9.240 spec, but there's plenty that aren't even close due to production tolerances. It's the engine builders responsibility to measure, but we put a cautionary note in anyway to keep people at .036" piston to head clearance at a minimum. Better to have more clearance than too little.

Also, someone made mention of our catalog having bad flow. I take that personally. I do it in excel and there's only so much info you can stick on a page. We give a range of 4 different comp ratio's for 4 different chambers and give deck heights with the 2 different standard rod lengths. Check out the other piston companies catalogs to see if they bother to keep their customers out of trouble as much as we do. The next thing the tech geeks are going to want in our catalog is dcr calculations with the 4 most popular Comp cams

JimMueller

iTrader: (9)

I checked with the machine shop and it'd cost $110 to deck the block, but the owner wasn't in yet to advise on scheduling. As soon as I can get an answer from him I'll make a decision.
Can you have that information published today?

PREDATOR-Z

I wouldn't deck that block if allready assembled. 8.6 DCR is better than 8.9 with the fuels out there. That .3 SCR is gonna give you maybe 5 rwhp.
I say forget it.

briannutter

Jim, I'm glad you appreciate the humor in this business.

Thrifty engine builders used relatively inexpensive sbc 6.125 x .927 rods when the LS1 market first started and the piston companies followed suit. We now have to deal with it because the piston and rod companies have too many part numbers already created. Besides, if we made our pistons for 6.100 rods only, we'd get guys saying..."I won't use Wiseco's because they're built for 6.100 rods and my engine won't even turn over with a 1.525 rod ratio without shoving a piston through the side of the block."

We did actually make 1 new piston for our 2008 catalog with a 1.140 compression height expressedly for a 6.100 rod and big nitrous applications where additional land thickness is appreciated. I expect a LS1 tech post out next year that says this:

Title: Piston slap with Wiseco's?

Message: "My engine seems to be making a loud clacking sound above 2000rpm, water is spraying everywhere and my head studs are becoming elonagated, could it be that my .015" piston to head clearance wasn't enough?"

Keep me updated on the build. Hopefully your post will edumacate others when it comes time for them to piece together a rotating assembly.

-Brian

...p.s. We'll see about that dcr calculator

JimMueller

iTrader: (9)

How did you get a difference of .3 SCR? Am I using the wrong numbers?

I'm using this site: http://www.kb-silvolite.com/calc.php?action=comp

Cylinder head volume: 59
Piston volume: 2.2 (-2.2 raises the compression, so I'm figuring it must be positive for valve reliefs)
Gasket thickness: .040
Gasket bore: 3.910 (per Cometic)
Cylinder Bore 3.905
Deck Clearance: .02 (guesstimate)
Stroke: 3.622

That yields 10.7 SCR. If I change only the deck clearance to -0.007, then SCR changes to 11.5.

I'm not sure which number to put in the IVC field to calculate DCR.

xssive

iTrader: (123)

You need to have everything dynamically balanced to within 2-3 grams max I would say spinning to 7500 rpm. I try hard to get everything within half a gram.

JimMueller

iTrader: (9)

OK, I'm taking the assembled block to the machine shop to get an accurate measurement of how much it's in the hole. They implied they can deck it just as quick as I need it, so I guess I'm measuring it, disassembling it, decking it, then re-assembling it. He said since the block is assembled not to mess with new rods as he doesn't consider it worth the cost and time.

He also said my block was basically balanced perfect, less than a 1/2 gram, and I won't have any problems with those RPM's.

Beaflag VonRathburg

iTrader: (176)

That's why it's so important to run the correct rods. Either 6.125 on center rods with a .927 pin or 6.098 stock replacement pieces with a .945 pin. Along with the correct piston combination.

Irocss85

iTrader: (1)

yeah, it makes a big dirrerence when getting up in rpms like that. BUT, the weight penalty will offset the strength of the Hbeams. if nitrous is possibly in the future, stick with the Hbeams for sure. thats alot of weight to shed off the rotating assembly though. Id check into the differenc it'll make with the balancing. but changing the rods is def. the way Id go if your goin to fix this. I would not want to deck or mill any more if you can help it.

as for quench, you take the piston height, add it to the compress gasket thickness and there's your quench. .035 is like ideal. too tight is BAD, but larger then that and you'll loose fuel mileage/burn quality/detonation resistance.

you could just go for the .035" cometics and call it a day. but for me, Id look at it like this. you dont want to go in there again, your spending TONS of money to do this, you'll regret leaving ANYTHING on the table later.

chris

PREDATOR-Z

I tell you what, just get that deck height measured correctly, also get your chambers measured as well. Basically get all your figures right then contemplate your decision.

All else is speculation.

mrr23

iTrader: (3)

it's 9.240 - 9.213 = 0.027. this is the number right where they measured your block today. 0.026 - 0.031.

mrr23

iTrader: (3)

that was me. and you should take it personally. that means you take pride in your work. let me qualify what i mean by it doesn't flowchart well. i wasn't privy to the conversation jim had with the person at wiseco, but here's a problem i see with the online catalog. and i'll only contain this to my own experience, as i bought the K394A3 for my own 408 motor. without having this book in my possesion to view, i had to rely on your techs at wiseco. when i called, and i like to call and hear a human voice over a computer email, i gave my specifics. 6.0L iron block being bored .030" over, eagle 6.125" rods, eagle 4.00" stroke crank, 63CC heads and i was looking for 11.3:1 compression. tech said to me, with a stock thickness head gasketand piston coming up about 0.005-0.007 out of the hole, the K394A3 is the one that will net me 11.3:1. technically it looks to be correct. until you actually try to flowchart my combination.

now, here's my concern with the flowchart of the book. your inital thought is well laid out, to a point. for simplification, you should be able to read straight across from left to right and come up with the compression desired. so, let's use the K394A3.

http://www.wiseco.com/PDFs/Catalogs/AB05_chevy.pdf
bore ---- stroke ---- rod ----- deck ---- compression
4.030 --- 4.000 ---- 6.098 --- 9.230 --- 11.3 @ 63cc
4.030 --- 4.000 ---- 6.125 --- 9.240 --- 11.3 @ 63cc

now, my combination of parts do not flow left to right without jumping from one to the other.
4.030 --- 4.000 ---- 6.125 --- 9.230 --- ??:1 @ 63cc
with my rod being longer, it puts the piston further out of the hole by 0.027", unless i'm reading incorrectly. and i was lazy and didn't measure mine after assembling the block. i noticed they were sticking out and that was good enough for me. i got lucky and have higher compression. and i'm lucky that i went with stock thickness head gasket. jim isn't so lucky.

now, my reasoning for saying it doesn't flow well, is because some people won't look at it in the manner as i described, which is the correct way. some will go and look at it as a yes/no column. match bore? yes/no. match stroke? yes/no. match rod? yes/no. match deck? yes/no. if all are yes, this is the one to use. now, you might can see why i say it doesn't flowchart well. i didn't say it didn't flow well. you tried to condense as much as possible into the catalog to simplify it. unfortunately, with it's current configuration, it leaves one to make errors in judgement in choosing the correct pistons for a desired compression and piston positioning in/out of the hole.

another question. what thickness head gasket was used to determine the compression? it is not written on the online catalog. and these are reasons why i call.

then, we have the 3.905 bore pistons mixed in with the 4" bore pistons. going through the flowchart and the nicely red highlighted deck height explanations, the 3.905 bore pistons would never come into the 9.230 deck height as the LS1 are 9.240 decks.

back to jim's dilemma:
bore ---- stroke ---- rod ----- deck
3.905 --- 3.622 --- 6.100 ---- 9.240

K398A07
bore ---- stroke ---- rod ----- deck ---- compression
3.905 --- 3.622 ---- 6.098 --- 9.230 --- 10.7:1 @ 63cc
3.905 --- 3.622 ---- 6.125 --- 9.240 --- 10.7:1 @ 63cc

using the intended flowchart method, it would've been caught right away that in jim's case the piston is going to be in the hole 0.027", instead of out by about 0.005" - 0.007".

using the yes/no column method as was used:
bore match? yes
stroke match? yes
deck match? yes
so, K398A07 is the correct piston to use.

your idea for the catalog was a great idea. because you knew that it was meant to flowchart left to right with no up down changing. on paper it didn't translate.

JimMueller

iTrader: (9)

I realized I miscalculated that earlier this afternoon. So as Robert alluded, the pistons were in the hole:

Cylinder 1: .028
Cylinder 7: .026

Cylinder 2: .029
Cylinder 8: .031

Machine shop might be open on Sunday, so I'll pickup heads tomorrow AM and deliver Sunday and have them cc'ed before anything else is done.

All the guys at the machine shop were adamant that it was silly to throw more money and time at .025 longer rods, maybe bearings, and balancing when I already have a balanced assembly that could be easily rectified with a very minor decking. I'll be honest guys, I'm really leaning towards just decking the block, but I haven't 100% decided on how much I can get away with. I'd love to have it out of the hole .005, but that would be a huge cut.

Pending verification of the chambers, I've removed ~.014 from the gasket (stock compressed is .054, right?), and ~.020 from the heads. So if .055 is the practical maximum before alignment issues arise, I could still deck the block at most .020. That should leave me an average of .009 in the hole, and a SCR of 11.0 and DCR of 8.6, but the quench would be a little high (albeit much better than now!).

So my quench right now is .040+~.028. I think I'd be happy with quench around .040-.045. I could have the machine shop deck the respective bank the average of the two bank values (i.e., deck odd side .027 and even side .030) to get them all close to the deck as possible. It seems that would give me an SCR of 11.3 and a DCR of 8.8. So is the increase in compression worth the chance of milling an extra .007-.010 more than the .055 practical limit mentioned earlier?

Brian Nutter: So your opinion is that even after taking a combined .034-.037 off the bottom of the head, I can still deck the block .020 and not have any LS6 intake manifold alignment or fitment issues?

racer7088

We have had some 6.0s with as much as .020 difference in the decks so it's nice to have something to work with. Most aftermarket pistons are made to allow some cleanup with the deck. They give you the compression height and that is what tells you everything else.

PREDATOR-Z

Well from looking at true data now, yeah that is a bit much in the hole. But I wouldn't change the rods with a nicely ballanced unit as you have.
deck .025, that should get you like .005 in the hole with .040 gasket, that is a .045 quench (still nice).

JimMueller

iTrader: (9)

If I use .005 in the hole, the quench will be .045, but I'm coming up with a DCR above 9 using the remaining values in post #25 above with J-Rod's formulas. Can someone check my math? What's a nice balance of quench vs. DCR in my scenario?

Chamber volume (cc) 59.000
Gasket compressed thickness 0.040
Gasket Bore 3.910
Deck clearance (in) (+ below the deck, - above the deck) 0.001
Stroke (inches): 3.622
Cylinder Bore Diameter 3.905
Piston disk volume (cc) (+ for dish, - for dome) 2.200
Connecting Rod length 6.100
Advertised intake duration 277.500
Advertised Intake Centerline 108.300
Advertised Intake Closing timing (angle) in degrees ABDC 63.600

briannutter

Mrr23, I appreciate your input. We've got the "0 deck at" and "standard deck height" columns in there, but we usually rate compression ratio with about .045" piston to head clearance total. Most good machine shops are going to deck the block as necessary to get between .040 and .050 quench..if given a different number, they might tighten it up a bit.

There was a question about whether to take the deck the heads or the block. Definitely the block. You can get the compression ratio either way, but you still won't have any quench if you take it off the head and it will have more of a tendency to detonate.

Also, because of a restriction in room, we'll target the bore size in the middle of a series: k392's range from 3.905 to 4.030 for instance and we'll target the 4" size to get the best average number.

Hope this helps.

JimMueller

iTrader: (9)

From my calcs, if my piston is higher than .005 in the hole then I'm rubbing up against that reported limit of .055 causing fitment problems.

I suppose I could play with retarding the cam 1-2* to lower DCR, but the 2* advance was intentionally ground in and I'd prefer not to do so. I see what I did wrong on the formulas - I wasn't including the piston cc's.

When we deck the block, it measures from the crank centerline, right? So it'll take off a little bit more on one end of the block than the other to get the deck clearance the same across the head?

***uming the chambers are indeed 59cc, I'm not convinced I can deck the block more than .021 and avoid excessive DCR and/or incur fitment problems.

Will the high DCR require better cooling? Bigger radiator, oil cooler, etc?

PREDATOR-Z

Give me the .006 advertised durations, intake and exhaust, LSA and ICL, I'll see what your DCR is like.
With .045 quench, and colder plug like TR6 gapped a bit tighter (.040>.045) you shouldn't have any issues with premium.

JimMueller

iTrader: (9)

https://ls1tech.com/forums/showpost....59&postcount=6

I do have the TR6's currently gapped at .045.