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In my engine building experience (which is admittedly very limited as far as flatheads and cast iron blocks), I always used a torque plate when boring or honing cylinders. But I've been unable to find any reference to one being used on a flathead Dodge six. Granted, there seems to be a lot a material in these blocks, but there's still going to be some distortion in the cylinder walls when the head bolts are torqued.
Has anyone ever heard of or seen a torque plate for these engines?
Dodge Flathead Torque Plate?
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Dodge Flathead Torque Plate?
“When a long train of abuses and usurpations, pursuing invariably the same Object evinces a design to reduce them under absolute Despotism, IT IS THEIR RIGHT, IT IS THEIR DUTY, TO THROW OFF SUCH GOVERNMENT...” -Declaration of Independence, 1776
Re: Dodge Flathead Torque Plate?
no need. the molybdenum and nickel content is very high back in those days. very very rigid material. and lots of it. some shops used to bore them right in the frame with the old school boring machines. 
Re: Dodge Flathead Torque Plate?
Given the weight of a Chrysler flathead 6 block, I don't doubt that it's relatively rigid. Interesting, though, that torque plates for contemporary Chrysler OHV engines - the slant six and the small block LA - are still available to purchase new.
I suspect that part of the reason for the absence of flathead six torque plates is that these engines were never performance platforms, just slow RPM workhorses, and no one much cared about cylinder distortion when boring or honing.
I suspect that part of the reason for the absence of flathead six torque plates is that these engines were never performance platforms, just slow RPM workhorses, and no one much cared about cylinder distortion when boring or honing.
Last edited by Elwood on Fri Jul 11, 2014 3:03 pm, edited 1 time in total.
“When a long train of abuses and usurpations, pursuing invariably the same Object evinces a design to reduce them under absolute Despotism, IT IS THEIR RIGHT, IT IS THEIR DUTY, TO THROW OFF SUCH GOVERNMENT...” -Declaration of Independence, 1776
Re: Dodge Flathead Torque Plate?
also in the late 60s and 70s the amount of nickel and other good stuff in engine blocks started to be greatly reduced when the bean counters took over the auto companies. another bad move of many. possibly the torque plate didn't exist until recent decades either.
Re: Dodge Flathead Torque Plate?
Hi Guys,
Funny the mention of nickel in engine blocks finds it way over here. There seems to be a general thought out there that more nickel makes a block stronger........but that just ain't so. The truth is pure nickel is about the same hardness as iron (both 4.0 on the Mohs scale). For castings it's used primarily for corrosion resistance, not to make it harder.
The key material for block hardness is Chromium. Varying it just a few percent really changes the hardness/durability of the casting. We went thru lots of discussion about the nickel content thing in an Oldsmobile forum I'm in. There was always a claim that earlier 455 blocks were stronger because they had more nickel. So one of the guys with access to a materials analysis lab and pieces of different 455 blocks started checking. The spectrometer just doesn't lie. When all was said and done the database showed the "best" blocks had the most Chromium, not nickel. We're talking something like 0.30% Chromium and 0.08% Nickel in the "good" blocks. 0.08% is truly negligible. Chromium is about twice as hard as nickel (8.0 on the Mohs scale).
Be that as it may.........I doubt the nickel content myth will ever go away.
regards,
bob
Funny the mention of nickel in engine blocks finds it way over here. There seems to be a general thought out there that more nickel makes a block stronger........but that just ain't so. The truth is pure nickel is about the same hardness as iron (both 4.0 on the Mohs scale). For castings it's used primarily for corrosion resistance, not to make it harder.
The key material for block hardness is Chromium. Varying it just a few percent really changes the hardness/durability of the casting. We went thru lots of discussion about the nickel content thing in an Oldsmobile forum I'm in. There was always a claim that earlier 455 blocks were stronger because they had more nickel. So one of the guys with access to a materials analysis lab and pieces of different 455 blocks started checking. The spectrometer just doesn't lie. When all was said and done the database showed the "best" blocks had the most Chromium, not nickel. We're talking something like 0.30% Chromium and 0.08% Nickel in the "good" blocks. 0.08% is truly negligible. Chromium is about twice as hard as nickel (8.0 on the Mohs scale).
Be that as it may.........I doubt the nickel content myth will ever go away.
regards,
bob
Re: Dodge Flathead Torque Plate?
Bob, thanks for posting that. I think it's as advertised, i.e. a plate for mounting one of the portable cylinder boring bars that Kaegi referred to (we were still using those on Harley Shovelhead cylinders a few years ago) onto some sort of six cylinder flathead. But the relatively light construction of the plate (at least compared to a modern style of torque plate) makes me wonder if it would be of much use in simulating the distortion from an actual head. Notice that the head bolt in the middle of the head on the cylinder side doesn't even have a hole in that fixture.
Unfortunately, I can only see the one photo in the listing, but there are icons as if there should be three more. It would be helpful to see the under side (I'm assuming we're looking at the top side, and that the fixture is designed to raise the boring bar above the deck to allow for boring the cylinders with the valves still in the block).
Unfortunately, I can only see the one photo in the listing, but there are icons as if there should be three more. It would be helpful to see the under side (I'm assuming we're looking at the top side, and that the fixture is designed to raise the boring bar above the deck to allow for boring the cylinders with the valves still in the block).
“When a long train of abuses and usurpations, pursuing invariably the same Object evinces a design to reduce them under absolute Despotism, IT IS THEIR RIGHT, IT IS THEIR DUTY, TO THROW OFF SUCH GOVERNMENT...” -Declaration of Independence, 1776
Re: Dodge Flathead Torque Plate?
that's why I said other stuff was reduced in later years. I am no metallurgist but have read articles where others have done analysis years ago and stuff got weaker in the 70s was the results. must have been less molybdenum/chromium and not the nickel then. been so long I don't remember the details.w30bob wrote:Hi Guys,
Funny the mention of nickel in engine blocks finds it way over here. There seems to be a general thought out there that more nickel makes a block stronger........but that just ain't so. The truth is pure nickel is about the same hardness as iron (both 4.0 on the Mohs scale). For castings it's used primarily for corrosion resistance, not to make it harder.
The key material for block hardness is Chromium. Varying it just a few percent really changes the hardness/durability of the casting. We went thru lots of discussion about the nickel content thing in an Oldsmobile forum I'm in. There was always a claim that earlier 455 blocks were stronger because they had more nickel. So one of the guys with access to a materials analysis lab and pieces of different 455 blocks started checking. The spectrometer just doesn't lie. When all was said and done the database showed the "best" blocks had the most Chromium, not nickel. We're talking something like 0.30% Chromium and 0.08% Nickel in the "good" blocks. 0.08% is truly negligible. Chromium is about twice as hard as nickel (8.0 on the Mohs scale).
Be that as it may.........I doubt the nickel content myth will ever go away.
regards,
bob
Re: Dodge Flathead Torque Plate?
So it's been awhile since I started this thread about torque plates (aka honing plates) for our Dodge flathead sixes, but after more than a few delays (life gets in the way) I've finally got my machine shop equipped with large enough tools to press ahead with making a torque plate and answering my question.
To start, I purchased a 24" x 8" slab of 1" thick, hot rolled, low-carbon steel (1018 or A37 or similar) from a steel supply house to make the torque plate from. Ideally, I would have gone with cast iron, i.e. the same material as the cylinder head, but I didn't have an unusable cylinder head to carve up, and a slab of cast iron of the necessary dimensions is remarkably expensive. So steel will have to do, and frankly, I doubt that the material will make a significant difference in the results.
I set up the slab on a Cincinnati Cinova 80 horizontal mill with a vertical attachment, and a 3" diameter roughing shell mill, and trimmed the sides until the dimensions of the slab matched those of the original cylinder head. Then, using an 8" carbide insert face mill, one side of the slab was milled flat.
After milling, the flatness was checked with a machinist's straight edge, and the variance across the opposing corners was less than 0.0015"; the manual allows up to 0.004" per foot of length.
Using some 7/16-14 transfer screws, I positioned the slab on the cylinder block, and marked the 21 holes for the cylinder head bolts. Once these holes were drilled and chamfered, I blued the machined face of the slab and bolted it to the block. Flipping the block upside down and reaching in through each cylinder bore, I scribed the inside diameter of each bore into the bluing. After removing the slab, the center point of each cylinder was scribed and center punched, and the cylinder holes were bored through the slab, using an adjustable boring head to finish the holes to a size large enough to allow for the maximum overbore (0.060") plus some room for the boring and honing tools if needed.
Final clean up included chamfering both ends of all holes, and milling a quarter round on the corners and all top edges (the bottom edges against the cylinder head gasket were left unmilled). Then the unmilled face of the slab was stamped "DODGE / PLYMOUTH" and the bolt holes were number stamped with the torqing order.
To prepare the cylinder block, the crankshaft bearing caps were installed and torqued to spec, the bell housing and front mount plate were installed and torqued to spec, and the engine block was mounted in a cradle on the regular mounting points. All of this was done to simulate the major stresses imposed on the block - ask any machinist who has had to level a large machine tool such as a lathe, and they will tell you that, yes, cast iron can and does "bend" and "twist" over time under pressure.
Without installing the torque plate, I then measured all of the cylinder bores (top, middle, and bottom, and parallel and perpendicular to the crankshaft axis, i.e. six different measurements for each cylinder). I used a good quality 2" - 6" range Mitutoyo dial bore gage and a 3.2503" setting ring. I'm not a fan of using outside mikes to set dial bore gages, and I found a setting ring to match the stock bore, and then compare from that diameter using the bore gage. I find this method gives me consistently better and repeatable measurements compared to snap gages or inside mikes.
The factory new specs for taper and out-of-round are a maximum of 0.001" for each measurement. Since I'll be using OEM rings, which include a chrome-faced top ring, the tolerance for taper especially is low, and the 0.001" maximum is reasonable. If I could find moly-faced rings, the tolerance would be less strict.
This block had previously been through a commercial machine shop, where the top had been decked, the crankshaft bearing bores had been line bored, the block had been Magnafluxed for cracks, and the cylinders had been bored and honed to 0.020" over stock, but all done without a torque plate as far as I know.
The measurement results are in the table below (the values in the green cells were measured, all other values calculated). Notice that all except one of the measurements (the middle out-of-round on No. 6) was within the 0.001" spec, although some just barely by a ten-thousandth. What surprised (and disappointed) me the most was the variance in total bore diameter across the six cylinders: more than 0.003"! Fortunately, the OEM aluminum pistons aren't exactly made to close tolerances either, so some mixing and matching to the individual cylinder bores will reduce those piston-to-cylinder wall clearances. I'm also having the pistons coated with an abradable powder coating, which will help to fill in some of that piston clearance.
To start, I purchased a 24" x 8" slab of 1" thick, hot rolled, low-carbon steel (1018 or A37 or similar) from a steel supply house to make the torque plate from. Ideally, I would have gone with cast iron, i.e. the same material as the cylinder head, but I didn't have an unusable cylinder head to carve up, and a slab of cast iron of the necessary dimensions is remarkably expensive. So steel will have to do, and frankly, I doubt that the material will make a significant difference in the results.
I set up the slab on a Cincinnati Cinova 80 horizontal mill with a vertical attachment, and a 3" diameter roughing shell mill, and trimmed the sides until the dimensions of the slab matched those of the original cylinder head. Then, using an 8" carbide insert face mill, one side of the slab was milled flat.
- 100_1550.jpg (250.18 KiB) Viewed 1264 times
Using some 7/16-14 transfer screws, I positioned the slab on the cylinder block, and marked the 21 holes for the cylinder head bolts. Once these holes were drilled and chamfered, I blued the machined face of the slab and bolted it to the block. Flipping the block upside down and reaching in through each cylinder bore, I scribed the inside diameter of each bore into the bluing. After removing the slab, the center point of each cylinder was scribed and center punched, and the cylinder holes were bored through the slab, using an adjustable boring head to finish the holes to a size large enough to allow for the maximum overbore (0.060") plus some room for the boring and honing tools if needed.
- 100_1556 (1).jpg (231.81 KiB) Viewed 1264 times
To prepare the cylinder block, the crankshaft bearing caps were installed and torqued to spec, the bell housing and front mount plate were installed and torqued to spec, and the engine block was mounted in a cradle on the regular mounting points. All of this was done to simulate the major stresses imposed on the block - ask any machinist who has had to level a large machine tool such as a lathe, and they will tell you that, yes, cast iron can and does "bend" and "twist" over time under pressure.
Without installing the torque plate, I then measured all of the cylinder bores (top, middle, and bottom, and parallel and perpendicular to the crankshaft axis, i.e. six different measurements for each cylinder). I used a good quality 2" - 6" range Mitutoyo dial bore gage and a 3.2503" setting ring. I'm not a fan of using outside mikes to set dial bore gages, and I found a setting ring to match the stock bore, and then compare from that diameter using the bore gage. I find this method gives me consistently better and repeatable measurements compared to snap gages or inside mikes.
The factory new specs for taper and out-of-round are a maximum of 0.001" for each measurement. Since I'll be using OEM rings, which include a chrome-faced top ring, the tolerance for taper especially is low, and the 0.001" maximum is reasonable. If I could find moly-faced rings, the tolerance would be less strict.
This block had previously been through a commercial machine shop, where the top had been decked, the crankshaft bearing bores had been line bored, the block had been Magnafluxed for cracks, and the cylinders had been bored and honed to 0.020" over stock, but all done without a torque plate as far as I know.
The measurement results are in the table below (the values in the green cells were measured, all other values calculated). Notice that all except one of the measurements (the middle out-of-round on No. 6) was within the 0.001" spec, although some just barely by a ten-thousandth. What surprised (and disappointed) me the most was the variance in total bore diameter across the six cylinders: more than 0.003"! Fortunately, the OEM aluminum pistons aren't exactly made to close tolerances either, so some mixing and matching to the individual cylinder bores will reduce those piston-to-cylinder wall clearances. I'm also having the pistons coated with an abradable powder coating, which will help to fill in some of that piston clearance.
- Cylinder Bore Measurements with Torque Plate.jpg (240.27 KiB) Viewed 1264 times
Last edited by Elwood on Sun Jun 06, 2021 4:11 pm, edited 9 times in total.
“When a long train of abuses and usurpations, pursuing invariably the same Object evinces a design to reduce them under absolute Despotism, IT IS THEIR RIGHT, IT IS THEIR DUTY, TO THROW OFF SUCH GOVERNMENT...” -Declaration of Independence, 1776
Re: Dodge Flathead Torque Plate?
So now we can answer the original question: will a torque plate make a difference in the cylinder bores? I bolted up the torque plate (using an OEM gasket, but shorter Grade 8 bolts - since the torque plate is not as thick as the cylinder head at the bolt holes, I substituted shorter bolts to maintain the same engagement depth in the cylinder block), and torqued it to spec.
I allowed the block to sit for ten days, and then I re-measured each cylinder, with the following results:
So, did the torque plate make a difference? Yes, it did. Notice that total cylinder-to-cylinder variance is now 0.001" less than before, or about 2/3 of the previous variance. Almost all of the taper and out-of-round numbers have improved, with the one outlier now within tolerance (barely). Also interesting is that all of the cylinders except No. 3 showed only small amounts of change, but No. 3 shows an increase in average bore diameter of 0.0017", which brings it much closer to the other cylinders. As a percentage of the factory allowable tolerance of 0.001", that change is significant. The improvement makes me wonder if the machine shop had a torque plate for this block.
After this experiment, I wouldn't bore and hone another one of these blocks without a torque plate. The tight tolerances for use with the chrome-faced rings, and the difference in the measurements from before and after, leaves little wiggle room for a sloppy bore and hone job, which could cause the rings to take a long time to seat, or not seat at all, resulting in lowered power and faster wear in the engine.
- 100_1558.jpg (248.48 KiB) Viewed 1260 times
- Cylinder Bore Measurements with Torque Plate 1.jpg (239.67 KiB) Viewed 1263 times
After this experiment, I wouldn't bore and hone another one of these blocks without a torque plate. The tight tolerances for use with the chrome-faced rings, and the difference in the measurements from before and after, leaves little wiggle room for a sloppy bore and hone job, which could cause the rings to take a long time to seat, or not seat at all, resulting in lowered power and faster wear in the engine.
“When a long train of abuses and usurpations, pursuing invariably the same Object evinces a design to reduce them under absolute Despotism, IT IS THEIR RIGHT, IT IS THEIR DUTY, TO THROW OFF SUCH GOVERNMENT...” -Declaration of Independence, 1776
Re: Dodge Flathead Torque Plate?
Impressive!
One question, these measurements could be affected by room temperature?
I work on a factory that machines engines blocks for a well known agriculture brand and the measurement room is under 20°C. Measurements under thousands are highly affected by temp variations
Just a question
One question, these measurements could be affected by room temperature?
I work on a factory that machines engines blocks for a well known agriculture brand and the measurement room is under 20°C. Measurements under thousands are highly affected by temp variations
Just a question
Re: Dodge Flathead Torque Plate?
Good point about the temperature, and how it can affect measurements. I should have noted that both the original measurements and the measurements with the torque plate installed were made with the engine block within one degree +/- of 70degF, checked with an infrared thermometer. I tried to minimize any variables other than the torque plate that could have altered the results.
“When a long train of abuses and usurpations, pursuing invariably the same Object evinces a design to reduce them under absolute Despotism, IT IS THEIR RIGHT, IT IS THEIR DUTY, TO THROW OFF SUCH GOVERNMENT...” -Declaration of Independence, 1776
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Re: Dodge Flathead Torque Plate?
Since I am getting almost old as dirt – I remember reading in a book once about engine part manufacturing in the US days before AC (Evo Controls) became common in factories.
Parts made on different weeks or even days would not fit their matching components even though they were made to the same tolerance.
So, people were employed to test fit parts together and categorize them to be matching. Makes me wonder about things being made in the Far East counties. And how much they care.
Parts made on different weeks or even days would not fit their matching components even though they were made to the same tolerance.
So, people were employed to test fit parts together and categorize them to be matching. Makes me wonder about things being made in the Far East counties. And how much they care.
47 CJ2A
53 M38A1
52 M37
51 M38
67 M416
?? M101A1
53 M38A1
52 M37
51 M38
67 M416
?? M101A1
Re: Dodge Flathead Torque Plate?
Excelent job!!
Re: Dodge Flathead Torque Plate?
excellent work thanks for posting all the results.