6.2L Winter Refresh

[RST Dana]

Now for more machine shop shenanigans possibly?
The pistons are listed on the box to have .020 reduced compression height. So you would assume down the hole slightly even after having the block deck shaved a few thou for new gaskets.

Checking piston deck height, mine measure between .011 and .013 above the deck. GM spec is .013 above the deck so good there. So to me that means the machine shop took .020 off to compensate for the piston height being -.020
So not knowing this when i dropped the heads off to get the valves done i asked if it was a good idea to take .020 to make up for the reduced height pistons. They said yes so i had that done.

Stock compression is 10.5:1.
Using summit compression calculator im coming up with 11.58:1 using a .051 head gasket and 66.5 chamber volume.
That's a bit more than i would like. I think great for me would be 11.3:1 ish as i only run 93 fuel. I really don't want to run a thicker head gasket so i don't lose too much quench.
I guess tomorrow i need to figure out a way to CC my heads so i know for sure what they are.

Aw we used to have big blocks running 12.5s on regular leaded fuel. No knocking either!

 

[SpareParts]

Aw we used to have big blocks running 12.5s on regular leaded fuel. No knocking either!

I honestly have no idea what will be ok. 0 experience with this problem. I am going with what i have read on LS1 and Yellow bullet forums.

 

[Chris2144]

You can get a piece of plexiglass drill a hole above where the chamber would be and put some grease around the chamber.
Lay it over and fill with water with a syringe so you can measure how much goes in.

That’s how I have always done my my heads works pretty good

 

[SpareParts]

Yeah. That's my plan. Just need to go buy a couple syringes at the co-op this morning.

 

[SpareParts]

Edited cuz bad info
Kinda miss the old days when ya did not know enough to measure almost nothing

 

[West 1]

Quench is the area where the flat part of the piston comes close to the flat part of the cylinder head.
You want these flat parts to come very close to each other in your build. Safe Zero quench is approximately .040 I think.

You need that .040 because parked the piston has .040 of clearance till it hits the head. At 6,000 RPM or more that distance of .040 comes close to zero due to internal parts flex and rod stretching at high RPM.

The area in the chamber does not affect quench only affects your compression.

Having all 8 chambers in the heads match for size is more like blueprinting trying to get equal power from each cylinder.

Having the block square decked is done for the same reason, get closer to blue print specs.

I think it is good that the shop did not take too much off your heads since you already had some taken off the block.

Taking off to much material from he head and block changes the angles of fit between the intake manifold and the cylinder heads and sometimes creates vacuum leaks that are very hard to fix.
Fel Pro used to sell angle gauges for shops to lay on the assembled engine before the intake was mounted to check these angles.

Can't say I have seen an angle gauge for the LS engines though.

Sometimes thicker intake gaskets are enough to get the proper seal. Sometimes you have to machine the intake for better fit and use thicker gaskets to solve the problem.

You don't want to go overboard cutting blocks and heads. You end up with new problems to solve.

 

[SpareParts]

Yes .040 is the target quench.
They could have square decked the block. Not sure as maybe the pistons are varying slightly. They vary from .011 to .013 out the hole. .013 is GM max spec.

Fun fact. Isopropyl alcohol is very hard to get a good seal with. Turns out i was not getting a good seal using it making my reading off.
70-74 cc just did not seam right to me and was too far apart between the readings. Density different them water i think.

I went back and cc'd every chamber with water and i got more what i would expect if the heads were milled .020.
67.5 to 68 cc's is the measurement im getting with water.
I could polish the chamber and that would get me back real close to 70 cc. I'm thinking that's too much tedious work i don't wanna do.

Leaving all as is yields a CR of 11.44:1 with a .051 head gasket. It will be ok with being a little conservative on timing to compensate for summer temps as long as 92 octane fuel is used. I have also read that 11.5:1 is about max for street on pump gas.
Black Bear will be tuning it when i get that far and they are an hour from me so in person tune.

I'll be at .038 piston to head clearance. IF GM has a max spec of .013 piston protrusion .038 has to be the minimum clearance GM has for piston to head clearance.

Now i can order head gaskets and then check piston to valve clearance.

Feels like im dragging everyone into the weeds posting all these minute details.

 

[SpareParts]

Ordered these head gaskets. .055 compressed. Quench not perfect but it's close enough for the work i usually end up doing + gets the CR down a small bit more.

Brian Tooley Racing BTR22033-2 BTR LS9 Multilayer Head Gaskets | Summit Racing

Free Shipping - BTR LS9 Multilayer Head Gaskets with qualifying orders of $109. Shop Head Gaskets at Summit Racing.

www.summitracing.com

 

[SpareParts]

What does everyone think about the pressure relief in the oil pan?
I'm using Melling HV pump without AFM.
With the HV pump, would you keep the pressure relief valve or block it off?

 

[j91z28d1]

I'd block it off at your level

 

[Joseph Garcia]

What does everyone think about the pressure relief in the oil pan?
I'm using Melling HV pump without AFM.
With the HV pump, would you keep the pressure relief valve or block it off?

Block it off for sure, as it is a point of failure, and there's no reason to leave something in place, with no added value, who's potential failure will result in dropping the oil pan again. I have the Melling 10355 HP/HV oil pump, and cold oil pressure on startup in the NH winter below 10 degrees F approaches 70psi at 2000+ rpms, so I baby the motor's rpms, until the oil heats up a bit. Once hot, the oil pressure stays under 60 psi at WOT.

If you decide to keep that pressure relief valve in place, as least make sure that it has the deflector improvement installed.

 

[Just Fishing]

early on with my 5.3 before I went 6.0, I went with the hv pump and the deflector.
it aeriated the shit out of my oil!!
block that mf off.

It's only there for AFM is my understanding.
Prevent pressure spikes when it's turning on and off.

 

[West 1]

No need for pressure relief valve if you do not run AFM. I think that valve opens at 68 PSI if it is working as intended. Protects the AFM system from high oil pressure. Not needed at all without AFM and may avoid failure as they can fail.

 

[SpareParts]

I figured that is the answer i would get and the direction i was leaning to.
VVT likes a steady pressure and flow. Should not have a problem with that at all with the HV oil pump.

 

[SpareParts]

Thought of this last night.
Hope the head gasket lines up with the cylinders perfect. With the bore being 4.095 and the head gasket being 4.100 there is no room to not be perfect.

 

[SpareParts]

Well i'm impressed. The head gaskets lineup with the cylinders perfect.
Tomorrow i can check PTV clearance then move on to the next thing.

 

[SpareParts]

This is discouraging and im not sure how to deal with it.

 

[mikez71]

Head or block shaved too much?
Another valve job or shorter valve seats? idk

 

[SpareParts]

Less cam lift but that means a new cam or the stock cam.

I think im measuring wrong though.

 

[mikez71]

How come it's impacting the opposite side of valve relief in piston?

You'd think it would be angled the other way and smoosh the clay near the center?