[bajamedic]

I am rebuilding a big block GM for a Marine application. In the past I have just sent the motor to be remaned. This time I am gonna do the rebuild myself. In the past I have used scotch bright disks and a 3" high speed right angle die grinder to clean the block surface. I have been told its better to just scrape it with a gasket scraper.
Thanks

[willowbilly3]

I love those 3M surface prep discs, use them all the time.

[BOBCRMAN@aol.com]

EVERY week I see the damage done by Scotchbrite discs. You just have no idea of the cutting power of these things. Most blocks/heads have to have a mill cut of at least .005" to repair the damage.

[Blazin72]

Originally Posted by BOBCRMAN@aol.com

EVERY week I see the damage done by Scotchbrite discs. You just have no idea of the cutting power of these things. Most blocks/heads have to have a mill cut of at least .005" to repair the damage.

Absolutely agree. They work great but you have to be very careful with those things. I'd stick with a gasket scraper.

I've had guys at work try to use scotch brite flap wheels trying to clean dried grease and salt deposits off bronze bearings. More than a few had ho be replaced because they weren't careful.

[OneMoreTime]

What a lot of guys do not get about those things is that they shed grit in use and of course that grit winds up in the engine and causes all sorts of problems..kinda like dumping polishing compound in your crankcase..

Sam

[Irelands child]

Why not go to your local big box store and pick up a couple of packs of single edge razor blades then stop at your favorite parts store and get a can of Permatex 80646 Gasket Remover or similar. Yeah, in the course of doing an engine project it might add a few minutes or maybe even an hour or so, depending on how much of a job you are doing, but a heluva lot faster not to mention less expensive then having a specialty machine shop (if you can find one) straighten out those rounded edges and corners.

Dave W

[CNC BLOCKS NE]

Originally Posted by BOBCRMAN@aol.com

EVERY week I see the damage done by Scotchbrite discs. You just have no idea of the cutting power of these things. Most blocks/heads have to have a mill cut of at least .005" to repair the damage.

I have repaired a few blocks because of guy using those disks, We run our engines at zero deck height so in some cases we have to cut the pistons to keep the decks at zero because of rules.

In the end the customer spends alot of money because of those disks.

[ogre]

Originally Posted by BOBCRMAN@aol.com

EVERY week I see the damage done by Scotchbrite discs. You just have no idea of the cutting power of these things. Most blocks/heads have to have a mill cut of at least .005" to repair the damage.

i always wondered about using scotchbrite disks on a machined surface. this is good to know. i usually scrape and then use the scotchbrite sparingly. i may reconsider this too.

[Jake_Dragon]

I don't use SB on anything close to an open engine. But I did use one to clean up an intake gasket surface but I wiped everything down with solvent and used and air hose on it several times before taking it back to the engine.

[chucksrt]

they sell less abrasive disc! Are you talking about the brown disc? They also have disc made for weaker metals that to describe them have about 100 little fingers that do the work and they get the surface clean pretty well.