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Ford 9N, 2N & 8N Discussion Forum
Show Parts for Model:

head bolt question

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heybusdriver

01-28-2013 14:01:36
70.71.96.170



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I'm replacing my head gasket on 9N 222933 , I found that the head has more gap than might be acceptable, I have another head off another tractor that I salvaged that shows less gap than the one that was on there. The one on there show about a 20+mm gap , the one I am putting on shows about 5mm. 9N 222933 has studs with nuts , I prefer bolts , I found 14 of the 18 bolts I took off the salvaged tractor, I bought 4 grade 8 bolts for the remaining , would there be anything wrong with putting grade 8 bolts to replace the missing head bolts?

Stan
9N 222933
2N with 8N motor 8N345567
8N 146710
8N 179555
8N 197904
8N 199000
8N 254079
8N 362039

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showcrop

01-29-2013 04:01:43
75.67.231.80



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 Re: head bolt question in reply to heybusdriver, 01-28-2013 14:01:36  
I am glad to have learned today what "head gap" is.



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TheOldHokie

01-29-2013 03:34:33
74.110.75.46



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 Re: head bolt question in reply to it me again, 01-28-2013 14:01:36  
Quoting Removed, click Modern View to see

It's a definitive an informative bit of testing and well worth adding to your site.
TOH



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John Smith8N

01-28-2013 20:47:02
75.23.125.17



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 Re: head bolt question in reply to Hobo,NC, 01-28-2013 14:01:36  
Quoting Removed, click Modern View to see
No, that's one picture from a half dozen on a webpage I made up several years ago expressing my opinion on the subject of when to mill the head ( surface imperfections and fire ring grooving) and when not to (warped), clearance problems, gaskets, etc. I don't think I ever did finish it and put it online. It's in the dusty part of the harddrive somewhere with all the other things on the "list".

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John Smith8N

01-28-2013 18:12:28
75.23.125.17



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 Re: head bolt question in reply to Wes(MI), 01-28-2013 14:01:36  
Quoting Removed, click Modern View to see

I fully agree with Zane. If there are no defects in the surface it's a complete waste of time and money to mill a N head. Absolutely not true for OHV engines, but for a N flat head it's pointless and causes more trouble with clearance than it helps. The amount of force used to flatten that 1-1/2" thick hollow head is so small it's insignificant. It can be engineered to death by smart guys, but I've tested it in the real world.

This head was bowed upward in the center like most of them. About .008" bow and .003" twist. It's placed on a flat table with just one (1) bolt right in the center of the head and an indicator to read the movement.



Tightening the single bolt to 5 ft lbs bends the head down nearly .010" and eliminates all the twist. Tightening to 10 ft lbs bows the dead down nearly .020". That's just one bolt in the center with a slight amount of torque. The N head normally uses 18 bolts all torqued to 65-70 fl lbs each. At 65 ft lbs each bolt is exerting roughly 8,940 pounds of clamping pressure. At 70 ft lbs each bolt is exerting roughly 9,600 pounds of clamping force. These numbers are for dry threads. Since the head bolts are normally lubricated with some sort of sealer, the actual clamping pressure will be up to 25 to 30 percent higher. The 4-5 ft lbs of force needed to flatten this head will be spread over the half dozen or more center area head bolts. which means the "lost" torque from flattening the head isn't more than a couple of INCH pounds per bolt. A lot of people won't agree with this, but that's ok. If it gives you a warm fuzzy feeling, have the head milled flat.

.

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Bulldozer

01-30-2013 08:54:51
24.165.92.6



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 Re: head bolt question in reply to John Smith8N, 01-28-2013 18:12:28  
Also agree with ZANE that surfacing the flat head cylinder cover is not required, even if there is evidence of warp using a machined straight edge.

However, do believe that surfacing is required if the cover has been subjected to overheating of the engine causing a leak between the cylinder and the coolant jacket.

Believe overheating of this engine is quite unlikely since the maximum rated rpm is 2000 and the compression ratio is only 6.7:1, unless the engine is run when low on coolant or no coolant.

Consider when the cover is manufactured as a sand casting, it cools non uniformly, creating temperature gradients in the cooling process. These thermal gradients result in a residual stress state in the cover. Now, the cover is machined flat and installed on the engine. The engine is run at normal temperatures. The cover is not at a uniform temperature and temperature gradients are developed. There is stress developed in the cover from the thermal gradients. When the engine cools to ambient temperature a portion of the stress developed at normal operating temperature still remains as residual stress in the cover.
When the cover is removed the residual stress developed at normal operating temperatures causes the cover to warp. If the warped cover is reinstalled from warp to flat condition additional stress are added to the residual stress so the cover is back to the original stress state before it was removed The the cover is now bolted down flat on the flat deck and seals at the fire ring and coolant jacket openings with no problems. The cover was sealing all right before it was removed.

Another condition
The engine is overheated and causes a leak between the cylinder and coolant jacket opening from warping between the bolt holes.
The leak can easily be detected by removing the radiator cap when the engine is first started before it is hot. Small gas bubles can be seen rising to the top of the coolant surface. The gas source is from the combustion chamber.
This type of warp between the holes is permanent.
Removing the cover and re installing it will not seal the passage between the cylinder and the coolant opening. A re surfaced cover or new cover is then required.

Note:
In addition, when the gas is present in the coolant jacket ,the gas bubbles decrease the film coefficient between the coolant and the radiator surface reducing the heat transfer and resulting in an even hotter running engine creating more permanent warp.

If the cover is removed for general engine overhaul like rings and valves and the engine was not overheated, believe the cover can be reinstalled, even if it shows warp with a straight edge off the engine. The cover will again bolt down flat against the block deck and seal. Believe this to be 99% of the cases for removing the cover.

Again, if the engine was overheated and gas bubles showing up with the radiator cap removed
the cover must be surfaced or replaced with a new one. Believe the probability of overheating on this engine to be remote, as evidenced by a 3 psig radiator cap.

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JMOR

01-30-2013 10:57:35
72.181.173.171



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 Re: head bolt question in reply to Bulldozer, 01-30-2013 08:54:51  
'Believe overheating is remote " Clearly you never mowed/bush hogged tall weeds & had chaff/etc. clog radiator.........they do overheat!



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Bulldozer

01-31-2013 08:33:47
24.165.92.6



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 Re: head bolt question in reply to JMOR, 01-30-2013 10:57:35  
Thank you for the clarification.

Understand overheating is likely with heavy PTO load and clogged radiator.

Understand the fan is a push type rather pull type ,so as to minimize pulling depris into radiator.



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heybusdriver

01-28-2013 18:52:16
70.71.96.170



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 Re: head bolt question in reply to John Smith8N, 01-28-2013 18:12:28  
Thanks John ,

I don't recall saying I was going to have the head milled, I thought I said I was going to use the head with less gap. The only other flathead I had was back in the mid 60's with 59 Dodge pick-up truck flathead 6 cylinder , I put in many head gaskets in that never did get it planned. Last gasket I blew was I used too much either too start the truck in cold weather, wouldn't start.

Stan
9N 222933
2N with 8N motor 8N345567
8N 146710
8N 179555
8N 197904
8N 199000
8N 254079
8N 362039

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TheOldHokie

01-28-2013 18:31:52
74.110.75.46



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 Re: head bolt question in reply to John Smith8N, 01-28-2013 18:12:28  

John Smith8N said: (quoted from post at 22:12:28 01/28/13)
TheOldHokie said: (quoted from post at 02:22:19 01/29/13)
I'd like to address Zane's point. You can bend any cylinder head including a big thick warped cast iron OHV V8 head an awful lot by tightening down the head bolts. If you have any doubt just ask a machinist that has to clamp them to a machine table to resurface them. If the table surface isn't dead flat the head will bend when it is clamped down. Then after its machined and the clamps are released it will spring back and the freshly machined head won't be flat anymore.

So if we can easily bend any head when we tighten teh head bolts what's the big deal with being flat to start with? Simple - every pound of head bolts force that is used to bend the head back down towards flat is a pound of clamping force lost at the head/block junction. In other words using a warped head reduces the gasket clamping force and increases the potential for a head gasket failure. OK you say - why not just use a little higher tightening torque to up the force from the bolts and compensate for the loss diue to warpgae? Maybe but the standard head bolt torque value is already close to the limit the bolts can handle and you are now blindly guessing about how much more you need. That risks coming up short or over stretching and permanently deforming the head bolts making matters even worse. You can wind up with a warped head AND even less clamping force where you actually need it.

That's the engineering issues. In practice a flat head does as Zane says bend a lot easier than a big thick OHV head so it can tolerate a bit more warpage. How much more is the million dollar question. The "official" warpage tolerance on a cast iron OHV head is usually about ,005. I have never seen an official Ford specification for the flathead but .020 is more than I personally would risk. In other words you pays your money and you takes your chances using anything that isn't very nearly factory flat from the git-go. You are re-engineering Fords carefully calculated clamping numbers while flying in the dark - how lucky do you feel today?

TOH


I fully agree with Zane. If there are no defects in the surface it's a complete waste of time and money to mill a N head. Absolutely not true for OHV engines, but for a N flat head it's pointless and causes more trouble with clearance than it helps. The amount of force used to flatten that 1-1/2" thick hollow head is so small it's insignificant. It can be engineered to death by smart guys, but I've tested it in the real world.

This head was bowed upward in the center like most of them. About .008" bow and .003" twist. It's placed on a flat table with just one (1) bolt right in the center of the head and an indicator to read the movement.



Tightening the single bolt to 5 ft lbs bends the head down nearly .010" and eliminates all the twist. Tightening to 10 ft lbs bows the dead down nearly .020". That's just one bolt in the center with a slight amount of torque. The N head normally uses 18 bolts all torqued to 65-70 fl lbs each. At 65 ft lbs each bolt is exerting roughly 8,940 pounds of clamping pressure. At 70 ft lbs each bolt is exerting roughly 9,600 pounds of clamping force. These numbers are for dry threads. Since the head bolts are normally lubricated with some sort of sealer, the actual clamping pressure will be up to 25 to 30 percent higher. The 4-5 ft lbs of force needed to flatten this head will be spread over the half dozen or more center area head bolts. which means the "lost" torque from flattening the head isn't more than a couple of INCH pounds per bolt. A lot of people won't agree with this, but that's ok. If it gives you a warm fuzzy feeling, have the head milled flat.

.


Ok - that is good hard data from a smart guy and I fail to see how anyone could disagree with your analysis. Empirical measurements always trump engineering theory so I defer to your testing ;-) Did you just set that rig up for this discussion or is that something you conducted previously?

TOH
This post was edited by TheOldHokie at 18:42:14 01/28/13 2 times.

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ZANE

01-28-2013 15:37:52
98.83.66.106



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 Re: head bolt question in reply to heybusdriver, 01-28-2013 14:01:36  
Are you sure you didn't mean thousands of an inch???????????

Many an N head has been ruined by someone thinking that cast iron can't bend. I've been repairing N engines for at least 50 years. Probably in the hundreds and never had a head milled. Head bolts will pull it down to the block deck. Or nuts on studs.

Zane



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Bob Harvey

01-28-2013 15:28:53
209.121.225.183



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 Re: head bolt question in reply to heybusdriver, 01-28-2013 14:01:36  
Stan, I think you will find that your 9N is in fact a late '46 or early '47 2N. All 9N's and 2N's start with 9. HTH



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heybusdriver

01-28-2013 16:09:06
70.71.96.170



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 Re: head bolt question in reply to Bob Harvey, 01-28-2013 15:28:53  
Yes , you pointed that out before, however I already knew that ,it's a 46 but serial# still reads 9N 222933. That is how it is identified by serial number. Thanks

Stan
9N 222933
2N with 8N motor 8N345567
8N 146710
8N 179555
8N 197904
8N 199000
8N 254079
8N 362039



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TheOldHokie

01-28-2013 15:10:44
74.110.75.46



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 Re: head bolt question in reply to heybusdriver, 01-28-2013 14:01:36  
Quoting Removed, click Modern View to see

What else would you use? Now about that gap - 5mm = .196 inches. Exactly where is that gap? If it's between the mating surfaces that is WAYYYYY to much and I can't even begin to imagine what the head with 20 mm gap looked like!

TOH



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heybusdriver

01-28-2013 16:23:54
70.71.96.170



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 Re: head bolt question in reply to TheOldHokie, 01-28-2013 15:10:44  
I laid it on my bench in the dark with a flashlight shining , I measured the light gap with a square .Sorry meant 5/ 1000 , not 5mm , old head measured 20/1000. Since I took a closer look at the salvaged head in the daylight and find out the spark plugs are seized in the hole, I am soaking now with +deep creep", if that doesn't loosen them I'll try heat from my torch tomorrow. Stan
9N 222933
2N with 8N motor 8N345567
8N 146710
8N 179555
8N 197904
8N 199000
8N 254079
8N 362039

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TheOldHokie

01-28-2013 17:22:19
74.110.75.46



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 Re: head bolt question in reply to heybusdriver, 01-28-2013 16:23:54  

heybusdriver said: (quoted from post at 20:23:54 01/28/13) I laid it on my bench in the dark with a
flashlight shining , I measured the light gap with
a square .Sorry meant 5/ 1000 , not 5mm , old head
measured 20/1000. Since I took a closer look at
the salvaged head in the daylight and find out the
spark plugs are seized in the hole, I am soaking
now with +deep creep", if that doesn't loosen them
I'll try heat from my torch tomorrow.
Stan

9N 222933

2N with 8N motor 8N345567

8N 146710

8N 179555

8N 197904

8N 199000

8N 254079

8N 362039


Measure the gap with a feeler gauge.

I'd like to address Zane's point. You can bend any cylinder head including a big thick warped cast iron OHV V8 head an awful lot by tightening down the head bolts. If you have any doubt just ask a machinist that has to clamp them to a machine table to resurface them. If the table surface isn't dead flat the head will bend when it is clamped down. Then after its machined and the clamps are released it will spring back and the freshly machined head won't be flat anymore.

So if we can easily bend any head when we tighten teh head bolts what's the big deal with being flat to start with? Simple - every pound of head bolts force that is used to bend the head back down towards flat is a pound of clamping force lost at the head/block junction. In other words using a warped head reduces the gasket clamping force and increases the potential for a head gasket failure. OK you say - why not just use a little higher tightening torque to up the force from the bolts and compensate for the loss diue to warpgae? Maybe but the standard head bolt torque value is already close to the limit the bolts can handle and you are now blindly guessing about how much more you need. That risks coming up short or over stretching and permanently deforming the head bolts making matters even worse. You can wind up with a warped head AND even less clamping force where you actually need it.

That's the engineering issues. In practice a flat head does as Zane says bend a lot easier than a big thick OHV head so it can tolerate a bit more warpage. How much more is the million dollar question. The "official" warpage tolerance on a cast iron OHV head is usually about ,005. I have never seen an official Ford specification for the flathead but .020 is more than I personally would risk. In other words you pays your money and you takes your chances using anything that isn't very nearly factory flat from the git-go. You are re-engineering Fords carefully calculated clamping numbers while flying in the dark - how lucky do you feel today?

TOH
This post was edited by TheOldHokie at 17:26:54 01/28/13.

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heybusdriver

01-28-2013 17:48:11
70.71.96.170



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 Re: head bolt question in reply to TheOldHokie, 01-28-2013 17:22:19  
"measure the gap with a feeler gauge"

that's exactly what I did, I measured the gap with a feeler gauge by laying my square against the head. I could clearly see the amount of light shining through the gap.

I thought I was being quite clear about what I meant.
I thought 5mm is the same thing as 5/1000. I thought mm is 1000. When you say 20/1000 is a lot , hmm I gap my front mount distributor @ 15 ,side mount distributor @25, spark plugs @25 , doesn't seem like a lot to me. I may be wrong, I'm just a back yard N tractor mechanic.

Stan
9N 222933
2N with 8N motor 8N345567
8N 146710
8N 179555
8N 197904
8N 199000
8N 254079
8N 362039

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ASEguy

01-29-2013 04:01:37
68.186.162.134



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 Re: head bolt question in reply to heybusdriver, 01-28-2013 17:48:11  
Stan, No disrespect intended here, but you need to use a straightedge (machined flat) to measure gaps like you mentioned. A square is not flat enough for precision measuring. Again no disrespect intended. Gerard



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TheOldHokie

01-28-2013 18:04:28
74.110.75.46



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 Re: head bolt question in reply to heybusdriver, 01-28-2013 17:48:11  
Quoting Removed, click Modern View to see

Sorry but I misunderstood your explanation of how you measured the gap. If .020 sounds OK to you go for it. The worst that can happen is you will get a chance to do it over again.

TOH



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