Thread: Removing carbon deposits with water???

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Whoa, whoa. Let's take it from the top.

You have a motor with 9.1:1 compression ratio. You are planning to install a cam that made best power in a 9.5:1 motor. Do I have that right?

Are you going to pull the heads off the motor or not?

..........

Originally Posted by techinspector1

Whoa, whoa. Let's take it from the top.

You have a motor with 9.1:1 compression ratio. You are planning to install a cam that made best power in a 9.5:1 motor. Do I have that right?

Are you going to pull the heads off the motor or not?

Sorry for the late reply,

YES and YES.

After serious thought, I think I need to at least get thinner on the gasket to compensate for the loss of DC. I was thinking a MR. Gasket with .18 to .20 compressed thickness??

Oh yea, whats the deal with all the different bore sizes for gaskets that are supposed to be for a 350CID?? Arnt all 350CID standard 4.000 bore???? The Mr.Gasket that I want only comes in 4.100. Will that work.

Dont mean to get ahead of you, just have questions that I dont want to fail to ask. Thanks Tech.

"After serious thought, I think I need to at least get thinner on the gasket to compensate for the loss of DC. I was thinking a MR. Gasket with .18 to .20 compressed thickness??"

You need to get the heads off and check the deck height before you make a decision on the head gasket you're going to use.

" Oh yea, whats the deal with all the different bore sizes for gaskets that are supposed to be for a 350CID?? Arnt all 350CID standard 4.000 bore???? The Mr.Gasket that I want only comes in 4.100. Will that work."

It all depends on what the final bore is and how much chamfer the machinist leaves at the top of the bore. You don't want the gasket overhanging the bore at the top because it could become a hot spot to support detonation. You also don't want the gasket so big that it leaves a dead space between the top of the block and the head.

Originally Posted by techinspector1

"After serious thought, I think I need to at least get thinner on the gasket to compensate for the loss of DC. I was thinking a MR. Gasket with .18 to .20 compressed thickness??"

You need to get the heads off and check the deck height before you make a decision on the head gasket you're going to use.

" Oh yea, whats the deal with all the different bore sizes for gaskets that are supposed to be for a 350CID?? Arnt all 350CID standard 4.000 bore???? The Mr.Gasket that I want only comes in 4.100. Will that work."

It all depends on what the final bore is and how much chamfer the machinist leaves at the top of the bore. You don't want the gasket overhanging the bore at the top because it could become a hot spot to support detonation. You also don't want the gasket so big that it leaves a dead space between the top of the block and the head.

Wow,
I was hoping that there was some kind of industry standard on bore tolerances for GM Crate engines that havent been machined. If I gather this right, there is no standard deck height to be assumed? This engine has not been disassembled before, it is the same today as it was when it came out of the crate, not counting years and mileage.

Here are the specs out of the box:

Engine Part Number: 12355345
Displacement: 350 Cubic Inches (5.7L)
Horsepower: 300 @ 5000 RPM
Torque: 369 Ft. Lbs. @ 3500 RPM
Maximum Recommended RPM: 5500 RPM
Compression Ratio: 9.1:1
Block: P/N 10105123 Cast Iron with straight four-bolt bearing caps, late model 1-piece rear main seal design.
Bore and Stroke: 4.00” x 3.48”
Crankshaft: P/N 14088527 Nodular cast iron, 1-piece rear main seal design.
Piston Material: P/N 12361371 Cast Aluminum
Connecting Rods: P/N 10108688, 1053 Forged Steel
Cylinder Heads: P/N 10159592 Bare Head, Cast Iron 64cc Chambers [Old P/N 12356026]
Valvetrain: Overhead Valve with Pushrod
Camshaft: Hydraulic Flat Tappet Design
Intake Valve Dia.: P/N 10093027 1.94”
Exhaust Valve Dia.: P/N 14088641 1.50”
Advertised Lift (Int/Ext): .435/460
Rocker Arm / Ratio: P/N 10089648 / 1.50 Ratio
Valve Lash: Zero
Engine Idle Speed: 650 RPM
Spark Plugs: R44TS
Spark Plug Gap: .035
Oil Pressure (Normal): 40 PSI @ 2000 RPM
Fuel Pressure Required: 5 to 8 PSI
Spark Timing: 10 BTDC @ 700 RPM

If it is a stock GM block, then the deck is 9.025" above the centerline of the main bearings. If we assume half the stroke is 1.740" and the rod length is 5.700", that leaves 1.585" from the centerline of the pin end of the rod to the top of the deck. Problem is, we don't know the compression height of the piston. I've searched for the last 30 minutes trying to find it with no luck. I suspect that it is around 1.540", which would leave a deck height of 0.045", but unless you can find info on the compression height of the piston, you'll have to wait until you get the heads off to measure it yourself. Don't worry about the finished bore dimension or the chamfer at this time. Find out what you have first.

Thank you for your research on this Techinspector ,

Give me a little while to check on this. Might contact the local GM parts and see if they have the piston information.

BTW, When you speak of compression height, is that the same as piston to deck???

Originally Posted by s10streeter

Thank you for your research on this Techinspector ,

Give me a little while to check on this. Might contact the local GM parts and see if they have the piston information.

BTW, When you speak of compression height, is that the same as piston to deck???

Check out this link:http://www.kb-silvolite.com/calc.php?action=piston_comp


Will this calculator work??

"BTW, When you speak of compression height, is that the same as piston to deck???"
No, compression height is the distance from the centerline of the small end of the wrist pin to the piston crown.

Deck height is the distance from the crown of the piston to the flat surface of the block deck.
I suspect your deck height is about 0.045"

Originally Posted by techinspector1

"BTW, When you speak of compression height, is that the same as piston to deck???"
No, compression height is the distance from the centerline of the small end of the wrist pin to the piston crown.

Deck height is the distance from the crown of the piston to the flat surface of the block deck.
I suspect your deck height is about 0.045"

Did you see the link in the previous post? What do you think?

product called seafoam works great,NAPA carries it some autozones etc. Most Marime/Jeep website talk about it , I have used it saved me $$ on M.B. diesel injector replacement, cleaned out gum in boat carb etc. 31 5w

Yes, I saw that calculator, but it assumes that the piston is exactly even with the deck at TDC (zero deck) and we do not know that yet, so the calculator is useless right now without knowing how far the piston is down in the hole at TDC. I can guarantee that the motor is not assembled at zero deck. None of the OEM's have ever built a motor like that.

On the water/carbon. I heard this from my auto-shop teacher who was dang smart in my opinion.. Just pour some water down the carb as the engine is running. He suggested a couple cups of water over about a minute.

I promptly tried it on my mildly cammed 283. It seemed to work fine. In my typical youth I decided if a little is good, more should be good-der. I drug out the garden hose to try an experiment. I got the hose running at, I would estimate, about 3gals/minute. I kinked it in one hand, climbed on the engine and started dribbling it into the carb. As I dribbled more and more, the engine slowed down. This required more throttle. I eventually had the garden hose unkinked (fully open) running into the engine pegged at full throttle. The engine was running at about 1,800rpm. Clouds were coming out the back and I later detected a large black, (soot), puddle behind the car.

Anyway I thought I'd pass this on. I wouldn't recommend it NOW just on principals, but a running engine can ingest a whole lotta water, without harm.

Rotflmao :lol:

Originally Posted by techinspector1

Rotflmao :lol:

he should be "ROTFLAMO" if he still got any pistons left. must have some sorry a** water pressure, or the luckiest man alive.