Fun day today - and a consensus needed

[Dan]

I went over to my Father-in-Law's shop today to get my first look at my "new" 1939 9N block I acquired and he picked up for me. The block was in great shape - but had most of the head studs still installed. Two were removed, two were sheared off, and all of the remaining studs had marks on them like someone tried to remove them but did not go far enough to snap them off. My Father-in-Law fired up the big torch and we heated each area up real good, then heated the stud to red hot. Once the color came back to the stud I would put a stud remover to it and attempt to remove it. Unlike the last time were I sheared off 12 - I would stop if it did not seem to come out and we would heat it up again. At the end of the job - we snapped off 4 more, but was able to remove one using the welding trick with a nut. So, I am down to five I have to deal with - not too bad considering how stuck they were in the block. We got all of the manifold studs and water pump studs out though with no breakage so that was positive.

However - this pic shows what I found while cleaning the top surface up tonight. I have this same crack on two cylinders - #2 and #3 on the intake valve area. The crack goes all the way through to the sleeve bore about the same length as this side. I see no evidence of water leakage, and the crack is not into the seat. I found where John Smith had the same crack - so I am wondering if this is fairly common. Could it be from installing new valve seats? Should I be concerned?

The rest of the block is primo so far and I am pretty happy to have found a 1939 9N block in this great of shape. The serial number is 9N 4405 and is very clear to read including both stars. Best of all - NO freeze cracks!

A nice day to work on old iron.

Dan

John Smiths thread

 

[Sean (TX)]

I had a email conversation with John the other day. According to him those cracks are caused from over heating.

 

[Dan]

Would make sense as there is no water jacket around there. Did he give any idea as to if it will cause any issues on a running engine?

Dan

 

[Anonymous-0]

I think I know the answer, but to keep from making a total fool of myself,was the over heating caused from the torch or the actual engine overheating in the past?

 

[Sean (TX)]

He didnt say. He was comparing freeze cracks to overheat cracks. He did say one out four turns out to be crack free. Maybe he will chime in..

 

[Anonymous-0]

Sean, I asked the question to find out from you more experienced guy's how sensitive that motor is to the torch. If the motor is not sensitive to the torch, he may want to heat both around the stud and then heat the stud red hot, then walk away and let the whole thing cool down completely. Then go back and heat the cast around the bolt, trying to heat more of the cast than the bolt,putting steady pressure on bolt (do not hit it with a hammer) and it will often times break the bond from years of the engine going from hot to cold.

 

[Anonymous-0]

Dan, what you have is a metallurgy problem, we often say the bolts are rusted in the head, when in fact the bolt or stud being of a soft metal and the block being of cast iron,two metals that are related, over a period of time the two have"welded" themselves together, they are not rusted unless by some unlikely situation they have been exposed to water, in that case we can use heat to break that weld. If you have patience you can save this piece of history. First read my note to Sean,find out how sensitive this engine is to the torch. If it can take some abuse,consider my post to Sean. The studs that sheared off did so because when you heated them the bond was only broken to that point. I would suggest you drill a hole in the broken stud making sure you do not drill clear through. Then heat the stud red hot,then let it cool all the way down and try to remove with an easy out, I have had to use a left handed tap and die with a left handed bolt on the tougher ones, patience is the key you have to seperate the molecules of mild steel from the molecule of the cast iron thus breaking the bond. ts0000000000000000000000000000000000000000000000000000000000000000000000000000000000000

 

[Dan]

Not that I doubt your directions - but I have never heard of drilling into the bolt but not through it before and I like learning new stuff. Why do you want to not drill through it?

Dan

 

[Klatch]

Long long ago in auto mechs class I was told that aera in flat head engines was refered to as the devels triangle. This is due to the cracking potental from cold intake gasses next to the hot ehaust gasses. The area looks like a triangle from the piston to exh valve and intake valve. I really dont think an engine has to be over heated for this to occur, as I have seen it on many engines.
Klatch Laura Ohio

 

[Anonymous-0]

The main reason I suggested you not drill clear through, is you want the heat to concentrate on the mild steel in the bolt. If you drill all the way through into any open area under the bolt,it will let the heat you want on the bolt to escape to another piece of metal and it takes more time to get the bolt heated. You also can get filings in places you don't want them. What you are trying to do, is get the molecules in the two metals to stop holding hands. Now on the studs that are broke off you may have rust problems if the stud broke and was exposed to water,in that case the old WD40 may also be of help. Remember don't try to wrench the bolt or stud until it has cooled,and the steel in the bolt has become stable. You may have to repeat the heating process, what you are trying to do is (walk) the heat all the way down the shank of the bolt thus causing the softer mild steel to release from the cast. If you try to heat a long bolt all at once you could jepordize the integrity of the head. Just heat the head,then back off while the heat crawls down the shank,then reheat, continue this process until the bolt comes out. When you get the bolt out you will find that the threads feel like they have small sand particles on them, that is what was holding your bolt. GOOD LUCK!

 

[Dan]

Makes good sense. Another bonus to not drilling all the way through is you can still soak the stud in penetrating oil between heating cycles.

The part about the metal bonding and not by rusting does make a lot of sense. Those 68+ year old threads in the block were all nice and shiny on the holes we got the studs out of.

Thanks,
Dan

 

[Sean (TX)]

Dan, you need more patients. I been soaking my studs for over a week. A couple more days and Ill put a torch on them. Then soak them some more. Like yours my exposed thread are shot. Couple a nuts were rusted to almost nothing LOL Had to split them with a cold chisel. My left rear axle has a couple nuts like that too..

Hey what size studs do I need to look for? I have a stock head 9N6050-B

 

[Dan]

The stock studs for a 9N is 7/16" - 18/20 (18 pitch to the block and 20 on top). You need 16 that are 2 3/4" long and 2 that are 3" long. Or, if you are like me a bugger a few threads on the block - use 3" long studs and screw them in 1/4" deeper into the block ;-)

As far as patience - yes, that is by far my biggest flaw in working on old iron. However, since the block was at my FIL's shop and my only access to a big torch and a MIG welder was there - I thought it was a good idea LOL

Dan

 

[Anonymous-0]

One other little secret,if you maintain the same temp. on your torch and time the length of time it takes for the head of your bolt to get red hot, When it takes the same amount of time for the head to get red hot two or three times in a row, thats a good sign the shank is heated all the way, now as Alton Brown on the Food Network would say "WALK AWAY, just WALK AWAY" come back when it cools down, cross your fingers and it should come out. Now don't forget, get ALL new bolts and clean out the threads.

 

[Matt L]

Dan, next time you decide to remore some studs or something....


Try this trick: Heat the stud up till it gets about red then let it cool a touch and put some parafin wax on it. As it cools it will suck the wax in. If ya dont do it right the wax will just turn to smoke. It takes a couple tries to do it right. Sometimes you can unscrew the studs by hand.............