78 620, L20B foreign matter in combustion chamber.

[Atikin9000]

You should be able to see your reflection. :lol: :lol: :lol:

 

Not really, if you can run your had over it and have it feel smooth then your likely alright, but you have to be honest with yourself,

if you think you felt anything then your not done yet.

 

Everything is smooth but there’s clearly residue spots that are smooth and flat, I even went at some of the tougher spots with a razor blade. I just don’t know when it’s good to go.

 

 

 

 

 

[datzenmike]

It's etching from the gasket and two different metals. Notice the rust in the coolant holes? Make sure you use a good quality antifreeze/coolant.

[wayno]

The only way to get rid of the stains is to have it decked, and I would not do that unless it was not level.

[Atikin9000]

The only way to get rid of the stains is to have it decked, and I would not do that unless it was not level.

It's etching from the gasket and two different metals. Notice the rust in the coolant holes? Make sure you use a good quality antifreeze/coolant.

Should be good to slap a gasket on, and check on good coolant.

 

Also I might add, i used a can of permatex gasket remover and just went over it with a plastic scraper, then hit a couple of spots with a metal razor. The can I bought was expired or something came out all runny, went back and exchanged for another, same thing. Still did a pretty good job.

[Atikin9000]

Anybody have a measurement for the studs that the exhaust manifold hangs on that I mentioned before? I know the thread pitch just need the length.

[distributorguy]

Looks like a rough surface finish to start with, then corrosion set in over time.  It should pretty much pass the razor blade test as well as the white towel test with brake cleaner.  You can even knock down high spots around stud holes with a fine file if you are VERY careful!  I use a scraper that's got a solid carbide edge and it will shave cast steel if you're heavy handed.  

 

Due to the condition of the block deck, I'd use Permatex #2 sealant around all the head stud and water jacket holes on the deck and the head.  Don't apply gasket sealant to the fire rings on the head gasket, and don't use enough for it to squeeze out into any of the holes.  Lett it just help bond where gasket pressure may be a little light from corrosion and age.  

[Atikin9000]

Looks like a rough surface finish to start with, then corrosion set in over time. It should pretty much pass the razor blade test as well as the white towel test with brake cleaner. You can even knock down high spots around stud holes with a fine file if you are VERY careful! I use a scraper that's got a solid carbide edge and it will shave cast steel if you're heavy handed.

 

Due to the condition of the block deck, I'd use Permatex #2 sealant around all the head stud and water jacket holes on the deck and the head. Don't apply gasket sealant to the fire rings on the head gasket, and don't use enough for it to squeeze out into any of the holes. Lett it just help bond where gasket pressure may be a little light from corrosion and age.

Just gonna stick to my little thread, ventured to Facebook and the 620 group and all I got was people pointing out #1 piston lol.

 

Anyway I’m gonna give some scotch brite a try as well.

 

Thanks guys.

[datzenmike]

The gasket remover is thick so it sticks and won't run off vertical surfaces.

[wayno]

Pointing out where the valve seat hit the piston, that's funny as it is so obvious that it really doesn't need to be pointed out, how could that be missed.

[racerx]

Anybody have a measurement for the studs that the exhaust manifold hangs on that I mentioned before? I know the thread pitch just need the length.

...51 mm or about 2 inches.

[Atikin9000]

...51 mm or about 2 inches.

Thanks man, happen to know the length of the spacing in the middle part?

[datzenmike]

You want less than the thickness of the exhaust flange. I think they are 1/2" so 3/8"?

[racerx]

Thanks man, happen to know the length of the spacing in the middle part?

not sure what u mean

[racerx]

You mean how much to screw it it?

[wayno]

not sure what u mean

 

He is talking about the un-threaded part of the stud.

[racerx]

Not sure if this helps but i measured the 3 studs on an L16 head and its about 1" that sticks out.

[wayno]

Thanks man, happen to know the length of the spacing in the middle part?

 

It really depends on how far the stud screws into the head, the exhaust/intake gasket is 1/16th of an inch thick, the stock exhaust manifold is 7/16ths of an inch thick, and the washer is a 1/16th of an inch thick, so is the lock washer, so if the stud threads all the way in to where you cannot see any threads a 1/2 inch would sound about right but I have some studs and it appears to be 5/8ths of an inch, anyway you look at it the stud should start having threads about a 1/2 inch away from the head surface.

If you don't have threads till 3/4s of an inch from the head surface you will have to start using thick washers or start stacking them which you do not want to do.

Here is a photo of a couple studs I have, the end with the most threads goes into the head.

Here is the stud in the head.

 

Here is the stock manifold on the head, with an exhaust/intake gasket less threads would show.

 

Here is the washer and lock washer in place, with a intake/exhaust gasket in place it would be better.

And here is the nut in place, it is not quite tight, but with another washer to simulate the gasket it is tight.

[datzenmike]

Get studs that are threaded all the way.

[Atikin9000]

It really depends on how far the stud screws into the head, the exhaust/intake gasket is 1/16th of an inch thick, the stock exhaust manifold is 7/16ths of an inch thick, and the washer is a 1/16th of an inch thick, so is the lock washer, so if the stud threads all the way in to where you cannot see any threads a 1/2 inch would sound about right but I have some studs and it appears to be 5/8ths of an inch, anyway you look at it the stud should start having threads about a 1/2 inch away from the head surface.

If you don't have threads till 3/4s of an inch from the head surface you will have to start using thick washers or start stacking them which you do not want to do.

Here is a photo of a couple studs I have, the end with the most threads goes into the head.

Here is the stud in the head.

 

Here is the stock manifold on the head, with an exhaust/intake gasket less threads would show.

 

Here is the washer and lock washer in place, with a intake/exhaust gasket in place it would be better.

And here is the nut in place, it is not quite tight, but with another washer to simulate the gasket it is tight.

Thanks for the pics, that’s exacltly what I needed.

 

 

Also mike is this what you’re talking about ?

 

 

 

I found some of these in m8 1.25 but I thought the manifold would beat up the threads from hanging on it.

[Crashtd420]

Thanks for the pics, that’s exacltly what I needed.

 

 

Also mike is this what you’re talking about ?

 

 

 

I found some of these in m8 1.25 but I thought the manifold would beat up the threads from hanging on it.

It might but you'll never use that part of the stud anyhow.... And once tight nothing will be moving around so you should be just fine.....

[Stoffregen Motorsports]

McMaster Carr sells studs - https://www.mcmaster.com/#standard-threaded-rods/=1a8m9ua

 

And you can also get them through Summit - https://www.summitracing.com/parts/rnb-966-333?seid=srese1&cm_mmc=pla-google-_-shopping-_-srese1-_-dorman&gclid=EAIaIQobChMIvtDYzYO81wIVz2F-Ch096wBFEAQYAyABEgJIz_D_BwE

 

https://www.summitracing.com/search/brand/dorman/product-line/dorman-double-ended-studs/top-thread-size/m8-x-1-25mm?N=401115%2B344901%2B4294908646&SortBy=BestKeywordMatch&SortOrder=Ascending&autoview=SKU&ibanner=SREPD5

 

If you have a good auto parts store in your area, they ought to sell Dorman studs and the book will show many different sizes to chose from.

[racerx]

Is there a stud finder fee..hahaha.

[Atikin9000]

Machine shop guy found the factory studs, happy about that. Thanks for all the help.

[BOZO]

The Z-Store has a set of studs and nuts for $31. I can't remember where I got my stud

set, but they even came with Allen wrench holes in the end for screwing them in. Used the studs for all my intake/exhaust clamping and had some left over. They worked excellent. You can put a bit more torque on them when you aren't afraid of stripping out the aluminum threads.

[d.p]

I’m missing these two johnnies too, timing cover bolts, and a lower manifold bolt.

 

Wondering if local hardware store will have something similar? Any suggestions for hardware?

 

 

 

What happened to that #1 piston?  Was that from the broken valve?