GPW Block Pitting

[Michael_G]

Hi All,

I have a GPW block I'm trying to save, however, deck has some pretty bad pitting. Does anyone have any good methods to fix this? I'm not so much worried about pitting in areas that are not sealing surfaces such as inside the combustion chamber. I think I should mainly focus on the head gasket sealing surface and valve seats. Some ways I've considered repairing before machining the deck:

1) Spray welding

2) Use Lock-n-Stitch pins in pitted areas

3) Weld up pitted areas with nickel rod

-Michael

[Adam]

Talk to your machine shop, or a good machine shop that works on old engines, dont get out the buzz box and go at her with some NI99 unless you want a boat anchor.

Adam

[Jerry Hudgens]

I have the same problem but for a Willys engine. I am hoping my pits ae not too deep for the block to be shaved. Will find out at the machine shop.

Jerry Hudgens

['42 Peep's Motorpool]

That poor GPW engine has seen better days.

You need to find a good machine shop that does this sort of thing regularly (works on these OLD flatheads). Some of the shops out there may say they can do it, but a GPW block is really sensitive. I don't like taking chances with a GPW block, they were somewhate frail to begin with. There is a lot of work needed in there. The seats are no good, definitely pitted a lot anyway. So you will be looking at not only determining how thin the deck is where the deepest pitting is, but also how new seat inserts (probably the way the machine shop will go) will affect a deck in that condition. Personally before having any work done, I'd have it cleaned completely and then pressure tested. It may be that the block is already a boat anchor. Now people have saved some bad blocks from the trash heap, but it becomes an issue of not can it be done, but how long would it last and should you just because you can?

Good luck

[Adam]

am i seeing .080 pistons? You may think about resleeving that to std, another 400 bucks up here. You can deck it .050 or so and some of that will clean up too, gotta do some measuring, then chop the top off the pistons to get it back to stock compression or use a thick copper gasket. or get it back by machineing the big end of the rods.

Is that a heli coil sticking out? that needs replacing too.

Why do you need to save this block? special numbers or something?

Adam

['42 Peep's Motorpool]

am i seeing .080 pistons? You may think about resleeving that to std, another 400 bucks up here. You can deck it .050 or so and some of that will clean up too, gotta do some measuring, then chop the top off the pistons to get it back to stock compression or use a thick copper gasket. or get it back by machineing the big end of the rods.

Is that a heli coil sticking out? that needs replacing too.

Why do you need to save this block? special numbers or something?

Adam

It does look like it has .080 over pistons. .060 is my personal limit in a GPW due to their noted thin castings. Sleeving a GPW block can be dicey for that reason. I've heard of people boring out the cylinders for sleeving, only to find the casting was thin and they've gone through to the water jacket void.

But definitely agree, the cost can make or break a block as much as it's condition. Some are better put away for a rainy day. This block wouldn't be cheap to overhaul (which is normal), but he condition issues are so severe that it raises questions as to condition. It's right there, and could go either way. Only a good machine shop and testing can help make that determination, but when you start sinking money into an iffy block, you have to ask what the goal is? If matching numbers I understand the desire, and if this is a show jeep that would probably be saveable. But if this jeep is to be driven a lot, clean it, preserve it, and source another block depending on what the machine shop says. It may not fail under light use, but might fail under heavy use. Some of those valve seats concern me, because of the pitting right up to them. If there isn't sufficient metal left there, an insert might come loose. At best it would rotate in the bore, at worse it would really ruin your month.

I'm on the fence with this one. I think it might be saved, but being a GPW block it's iffy without more detailed testing. And the lack of testing would make me think twice about trying to save this one as a running engine. If this isn't a matching numbered engine, you might sink twice it's value into it and still end up with a situation where it would have been better to source another block. Tough call.