desi

I am doing a cam/head upgrade to my L48. Before I took it apart, the compression test showed 172-179 psi across all cylinders. Car was runnig great. I am just looking for more power. Here is what the pistons look like. I know the car was running rich before and there is a lot of carbon build up. What can I use to clean this up with? Brake cleaner? Degreasers? Carb cleaner? Once the car is running again, I will be installing an oxygen sensor to fine tune the carb on a dyno.

What do you guys think? It's not too bad, is it? The cylinder walls are very clean.

MotorHead

They don't look too bad but get some other opinions, the main reason I posted was to warn you about sraping that crap off and getting the little particles of carbon stuck down between the piston and the cylinder walls. That will really shorten the life of the motor

desi

I was thinking of cleaning with chemicals then using high powered shop vac to clean all small particles before rotating anything.

ZD75blue

Go get some GM top engine cleaner.

That stuff flat out WORKS!

Just put enough in so the pistons are covered, and let it sit for a couple hours. Mop it out with some paper towels. Then take some marvel mystery oil and flush it out until it doesnt change colors!

comp

vettfixr

I'd be afraid to clean them while they're still in the engine. As posted before there's a danger of getting particles down the cylinder walls which will score them. When I had my engine apart for it's rebuild I soaked my pistons in carb cleaner and they came out brand new with no scraping required.

joe73vette

Drop the pan, pull the pistons, do it right the first time. You can check the bearings while you're there. If the tops look like that, the rings are probably gunked in the grooves, too. Joe

jbroughton

Heh, heh, years ago in my younger days while I head the heads off replacing a blown head gasket, I just stuck a wire wheel in my drill and knocked all the carbon off the tops of the pistons. I did this with each piston at the top of its stroke, and then when I would move on to the next piston, I'd wipe the cylinder wall of any debris from the piston I had just completed. Apparently the Chevy gods were watching after me that day, because somehow I managed to end up with beautifully clean pistons, and never hurt anything. She ran great when I got it back together!!

desi

The oil pan is out, but I don't want to pull the crank or pistons. This is supposed to be a "bolt on" upgrade.

I am going to get some of the GM top engine cleaner. But what is "marvel mystery oil"? What does it do? Is it just another oil? Can I use any motor oil to clean afterwards?

munday

marvel mystery oil is good.

desi

Is this mystry oil available at parts stores or a special order?

Wrencher

Don't get all worked up about the details here. Roll the engine 'till the piston that your cleaning is up at TDC, then use a 3M rotary pad or the like to clean it. Heck, just a good carb cleaner and a rag will do pistons that are as clean as yours! If you have compressed air, blow out the piston and cylinder area when your done. Hey!, the rings seal the crap out of the lower end, remmember? If you dont have air, squirt a little light oil in the groove, roll the piston down and the all the gunk will stick to the cylinder wall (in the oil) where you can easily wipe it off.

As I look at your photos, I would first pull the two block coolant drain plugs (down on the pan rail - one on each side) just to get the coolant out of there. Also, cover the lifter galley with a rag to prevent crud from getting in the lifters. Next, clean the deck and (again using compressed air) blow out all the head bolt holes. Remember to protect your eyes! Use the air to clear all the junk laying round the work area and don't forget to chase the threads on the head bolt holes using the appropriate tap.

You'll be fine, just think clean and make sure the deck is free of any old gasket or crud. Your lower end looks good for stock and should be fine.

Hans

Wrencher

Joe, is that a Mach III Kawasaki in your avatar? That was the fastest, scariest bike I ever owned in my life (and I've had some bullets, including a turbo Z1-R) and I sure wish I had it back... Ride on.

Hans

joe73vette

Yeah, it's a 500, though. Pretty fast until the clutch started slipping. Tough to keep the plugs from fouling, too. But really fun when it all came together. Joe

wacked

I would of just let it be. Bolt on the heads and have no worrys.
Is that Rust on that piston? My bad just Carbon.

wattac2

And remember, after all that cleaning, make sure to oil down the cylinder walls. They'll rust in a flash if you leave them without oil.

Andy

Shark Racer

Run the engine at 6000 rpm under a heavy load. That always worked for me. Seriously though, I wouldn't worry about it.

-Steve

zwede

Mine looked about the same as yours. I used a blunt screwdriver to get most of it. Shopvac to suck the crap up. Be sure that it doesn't get into the water jackets. After I scraped them with the screwdriver I used carb cleaner and shop rags to get the rest. They came out spotless. As I rotated the engine to do each piston I would clean the walls.

72LS1Vette

When I used to drive an Alfa Romeo we used to give the engine an 'Italian Tune Up' by running it up to redline several times to burn off the carbon deposits. I took my Alfa to a driving school once and revved the crap out of it for an afternoon and it ran better than ever for weeks.

Rick B.

JIM

Dont bother. That extra carbon on top gives you a little extra compression and it not hurting a thing.