Im goin through this 350 olds I bought and had running last summer and i pulled the heads and saw this pitting around the water jacket area. I’m pretty sure I can’t get the block decked anymore cause the piston damn near comes up flush w the block. I planned on using the fel pro head gaskets but should I use sealant in these pitted areas if it’ll seal at all? Someone told me the fel pro would seal it just fine but I don’t know if I believe them

 

The reason you see pitting there is that a gasket didn't cover that area. The gasket left a stagnant area (a slot between the head and the block) that allowed water to stay in contact with the iron.

If that area affected sealing, the gasket maker would have covered it originally.

You have done a good job of removing rust in that area, so even if your next gasket covers it, there will be no problem.

 

Agree, it won't be a problem.

 

Make sure you use Roloc discs to clean the block and heads (if your not having them machined).

https://www.3m.com/3M/en_US/p/d/b40064719/

 

I would buy a cheap "stone" or two and run it over the head and block gasket surfaces using a light oil (Kroil, WD-40, etc. and gentle finger tip pressure. You'll find the high spots around threaded holes and imperfections.. Start with the coarse side and finish with the "fine" side.
https://www.harborfreight.com/combin...SABEgK1avD_BwE

 

Please do not. ............ This is from my web site:
https://www.enginerepairshop.com/abrasive-disc.html

That one was aluminum but I have seen just as much damage on cast iron. Plus the abrasive from the Roloc discs is deadly to bearings.

Use a very flat sanding block with 100 grit sandpaper or better yet a 2" x 6" knife sharpening stone.
https://www.harborfreight.com/combin...one-62852.html

 

I fully agree with Bill in the previous post. I have successfully used a long flat file, long enough to span well beyond the width of the deck surface, with one inch wide 80 grit fabric backed abrasive to remove the "crap" from the deck surface and also the head surface followed by light touch of the bare file. It is imperative that the flat file is indeed flat and that you do not apply pressure to the middle or ends of the file if you choose to use one; let the abrasive do the work. Most machine shops will have rolls of the one inch wide abrasive in various grits and should be happy to sell you a few feet.

 

BillK, you provided a good example of the damage a Roloc disk can do. I witnessed a power plant steam turbine that was opened up and showed the damage done by a previous turbine repair contractor using Roloc's.

Your knife sharpening stone is the same as what I posted and call a cheap stone.
.

 

I missed that Thats what I get for reading too fast. I was surprised at how cheap it was at HF. I have been getting them at Home Depot for $20 or so.

GM actually had a service bulletin back years ago about using the Rolocs for cleaning intake manifold surfaces. Apparently the abrasive was getting into the engine and killing bearings. I imagine some of it had to do with guys not being very careful

 

Good to know about the 3M surfacing disks. If I do use them from now on, everything will get covered and a very good cleaning before install. My 350 still had minor pitting after being decked .016". As long it won't compromise the head gasket sealing surface, it should be fine.