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Why You Want to Use Standard Size Bores

4K views 26 replies 7 participants last post by  RussZTT 
#1 ·
One of the more frequent and emotionally charged PM questions I get on a regular basis is why can't I bore my block 0.020" over. Some have even asked about a 0.030" or 0.060" overbore. The simple answer is there is insufficient cylinder wall available to support those overbore dimensions. That is usually followed by a proof point being offered that my good friend has bored his block that much and he makes XXX RWHP and is very happy.

The statement begs two questions;

1.) If you are so comfortable, why are you PMing me asking for my blessing to do the same thing?
2.) How frequently and how long has his engine run at max power with this overbore?

The simple truth is that when you have an engine with 100mm bore centers and a 90.22mm bore size, there is precious little material left to support any bore size increases, let alone bore increases on supercharged engines that are asked to perform at power levels several times Ford's original advertised power level.

Let's look a little deeper into the how and why side of the issue using some Ford data. The image below is the Ford cylinder bore dimensions on a typical Aluminum Modmotor block.

Human body Slope Font Line Parallel


As you can see from the drawing, the cylinder bore centers are set at 100mm. The combination of the liner and the supporting aluminum register the liner is located in come to 3.15mm or 0.124". The Ford print calls out a 3.5mm (0.138") gap between the outsides of the two supporting aluminum registers.

When we start to do the math, beginning with the 100mm bore centers and then subtracting 6.3mm (for liner and register), we come down to 93.7mm. From the 93.7mm we need to subtract an additional 3.5mm (1.75mm on each side) for the coolant gap between the two aluminum cylinder registers, which brings us to our standard bore size of 90.2mm or 3.551" in imperial units.

Now let's go back to the 3.15mm liner and liner support between cylinders. Remember, 3.15mm is 0.124 inches. Let's say we leave a 0.062" thick aluminum register to support the cylinder liner. That means the iron cylinder liner is 0.124" - 0.062" or only 0.062" thick on a side! The aluminum register is actually thicker than 0.062. Let's be conservative and hold to only 0.070", which means our cast-in-place sleeve has 0.124" - 0.070" or 0.054" thick walls.

Imagine boring that block 0.020 oversize, let alone larger. At 0.020" over, you only have 0.044" of liner wall left! For a daily driver you might be OK. For a mild 650 WHP car, you are in the deep end of the swimming pool, and you don't even know you have to swim! A 650 RWHP car is essentially a 750+ FWHP engine. That works out to a little over 3HP per inch, and it only has a 0.044" thick cylinder containing all that power!

On high-powered, supercharged engines, thin-walled liners like that distort under power allowing combustion gases past the rings and into the crankcase. Repeatedly doing this to the liners will ultimately cause them to crack. For any supercharged engine, you want to maintain the best ring contact possible and the most rigid liner possible. That means the least overbore.

It is also the reason I always encourage a new engine builder to find the worst cylinder in the engine and use that as the guide for piston and finished bore sizing. My suggestion will always be to go just large enough to clean up the bore top to bottom and then no more. The challenge with this historically has been that piston manufacturers only make standard, 0.010, and 0.020 oversize pistons.

The reason I originally contacted Gibtec to ask them if they would consider offering a ModMotor line of pistons was that CNC-manufactured pistons cut from billet stock had none of the limitations that forgings brought to the design table. It was possible to start with a clean sheet of paper and, without compromise, build the exact piston the engine needed!

The fact that the CNC process would allow custom pistons to be built in 0.001" increments to any size was a huge plus! Equally as attractive was the ability to order replacements that would match the size and weight of the originals to a gram and a thousandth of an inch.

The reason that having pistons in 0.001" increments is so valuable for OEM blocks is the preservation of the already oh-so-thin cylinder walls in the OEM block. The real fix for the problem is the use of an aftermarket liner like LA Sleeve offers.

Product Rectangle Font Screenshot Parallel


The LA Sleeve Modmotor liner has a outside diameter of 3.793 inches. Using a 3.551 inch bore will provide a cylinder wall thickness of 0.121 inches or just shy of an eighth of an inch!

The near eighth inch liner wall thickness and improved nodular iron liner material provides a substantially stronger liner than the thin less than a sixteenth inch OEM liner wall alternatives. The more robust liner stays round under high boost and high power and if necessary can be easily replaced on an individual basis. Additionally the full flanged approach to registration provides the necessary real estate for a receiver groove allowing copper gaskets and a stainless o-ring to be used for a dramatically improve head gasket seal.

Could you go 0.020" over on a replaceable liner - sure. You would still have 0.111" of cylinder wall left but it begs the question why? If you do, you need eight new pistons, a new set of rings, a complete boring and honing and a rebalance because the rotating assembly has just changed. This is a look from the crankcase side where you can see just how heavy the LA sleeve cylinder walls are.

Photograph Automotive tire Product Black Motor vehicle


The replaceable liner lets you replace just a liner if it gets wounded and reassemble. Worst case you order a single replacement piston from Gibtec and it will arrive identical to your original including weight. Better yet order ten pistons from Gibtec on the initial order - it is less expensive. Slide the new piston in the new liner and you are good to go. There is no need to rebalance the crank or any of the other usual rebuild monkey motion.

This is what a block looks like from the top with aftermarket liners installed.

Photograph Automotive tire Black Rim Font


And here is a picture of the block with liners and a few pistons installed

Automotive tire Automotive lighting Motor vehicle Bumper Automotive design


When you add head gaskets this is what they look like on the deck,

Photograph Automotive tire Motor vehicle Automotive engine gasket Font
 
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6
#3 ·
As usual..... excellent little article. So is there a particular block that those liners would work best in? And how much power do you feel a block with l.a. sleeves is good for? Streetable? Just a few small questions.

Sent from my SM-G955U using Tapatalk
From what I can find Nick, it appears any of the aluminum 4.6 blocks use essentially the same liners and liner support approach which means the LA Sleeve approach would work well regardless of block. Teksids and Aluminators reportedly did a better job of attaching cylinder banks to the engine block's crankcase which is presumably part of their better suitability for performance builds, story. The Aluminator blocks weigh in at 90lbs or 5 lbs more than a Teksid and WAP blocks weigh in at 5 lbs less than a Teksid. 5 lbs of aluminum is a lot of aluminum so that speaks volumes about the additional strength available in the Teksid and Aluminator blocks.

In terms of how much additional power the sleeved block would be good for, I don't really have a good way to measure that metric. It sort of comes down to something similar to the difference between the original Manley Pro Series I-Beam rods and the follow-on heavier beam version of the same rod. Both are strong rods. That notwithstanding, there is no clear line of demarcation, power-wise, where the change from one rod to the other is suggested or mandatory. Nonetheless, most of the guys at the top of the power pyramid opt for the HD beam version. It is noteworthy that before the HD versions were available, those same guys ran the lighter beam rod - some probably still do. Obviously others do not. My personal preference is to run the strongest stuff you can buy — just because.

There is no reason the sleeved version of the block would not be steetable. It is still a dry sleeve implementation so the coolant control issues associated with wet sleeve versions of the block would not be an issue. There is no reason to run the copper head gaskets on a street version of the engine. I would still use the MLS gaskets. For a race version of the block, I would just as quickly default to the copper gaskets and stainless o-rings for their superior sealing characteristics.

I think I would not build a sleeved version of the block for the street if I had an otherwise good block to start with. Street-driven cars, on the street, can not hook up as well as race cars can at a race track. The street simply does not provide that sort of traction. Additionally, you can not run a street-driven engine at the same performance level that you can run a race-only version of the same engine. You just can't load the block as hard as a race car implementation can. A good standard bore block will live a long time as long as you can keep it as a standard bore or less than 0.010" overbore.

Where it would make sense to run the sleeves on a street version of the block is if you found a block that is already 0.010" or 0.020" oversize or you find one with a cracked cylinder. Buy the block for cheap money (<$100), sleeve it, and have a very strong, very high-quality standard bore block as the basis for your build. That could be a shortcut to a nice high-quality solution.
 
#5 ·
Great info as usual, Ed. The over-bore concept almost goes down as a "rookie mistake" when so many guys arbitrarily jump on the "0.030" value since that is "...what they were told" by so-and-so or another so-and-so. It's up there the advice that floats around about how an engine needs be pulled to install head studs since all ten "must" be threaded in before setting the heads down on the decks;)

It reminds of how I almost got dyslexic with Gibtec when my order was placed knowing the bore was going over just 0.002" - came close to telling them 0.020" since it was one value thrown around so much, but glad you caught me on it back then. There are probably plenty of blocks out there that could have much more life in them rather then becoming one-more-time use. Save the Aluminators, I say!
 
#6 ·
Your build was done so long ago, I had forgotten about the bore sizing discussions, Joe. Now I remember the anxiety I was having over boring a brand new Aluminator block 0.020" over. I recall how keenly focused I was on arresting that sacrilege prior to execution. :) I don't remember where the suggestion to go that large came from. Was that the machine shop's recommendation?

In any event, seeing the real numbers that Ford used in the engineering and design of the cylinder portion of the block helps clear the air of a lot of urban legend that, at best, is misleading. It also points up some interesting opportunities to get what some people think of as a throw-away block for next to nothing and revive it, making it even better than the original — which is always a happy ending.
 
#7 ·
Ed this is Great information, For this subject you have answered many questions I've had and hit points that I've been thinking about going as far back as to 2001. Joe also brings up a good point about the common old engine builder 0.020" & 0.030" over bore as a standard procedure for doing a build. I think this comes from the decades of sbc and even more so probably the 100,000 SBF 306's & 347's motors that have been built by your local engine builder over many years. I had a 342 standard bore hehe. Ed going back to your first statement when you said you get a ton of PM's with guys saying "my buddy john smith bored his block x.xxx over an it works fine blah blah".

What I have found is that most engine builders are stubborn and don't do mod motors, most don't want to, probably because its not what they are use to they are a little tougher to do, builders like to do what's easy which is what they already know. Whats even worse is when I hear a guy say so&so engine builder built my engine He builds Pro Stock Engines for IHRA racers blah blah. Once I was asked to fix a mustang, the entire car was built by some big time engine builder, it ran like garbage. Mr. Famous engine builder said the mass air was bad. When he said it was bad he should of said he put it on backwards, he also had the fuel system and FMU backwards.

This brings me to another common statement I've heard from many engine builders, which is that you can't run copper head gaskets on the street. I proved this to be wrong. Now I'm not talking about a daily driver that sits in hot traffic for an hour or so every day, I'm talking about a weekend and cruise night car. For 2 summers I ran clark cooper gaskets that I sealed by hand using the cooper silicone, I had no coolant leaks and ran 20lbs of boost, I cruised it all over. I had an oring block, receiver groove heads and half inch heads studs. How do all those crazy 3000 HP cars that run Hot Rod week last cruising from track to track? they aren't changing head gaskets every day, or are they? I'm not saying that anyone should ever run cooper head gaskets on the street especially not on a daily driver, But I'm saying that it can be done on a weekend and cruise night car that also gets some track use a few times a year. I would always recommend using MLS gaskets first and foremost unless your power level exceeded the limits of MLS gaskets. What power level that is I have no Idea haha. Personally I have seen MLS gaskets on cars making 900whp. I would love to hear what veteran big power mod motor guys think the limitation of the MLS gasket is and at what power level would be time to switch to cooper. Side note, back when I ran cooper no one was really using MLS yet it was just coming on the scene to engine builders, other wise I would have used MLS.

Ed getting back the topic of the LA sleeves, which I think is a great idea, especially for peace of mind and keeping the cylinders from going out of round, what do you think the average cost for a shop to do this is? I think it will run about $2000. for a block you send them.
Another question I had, on a build that is not using a sleeved block, like with a used 05+ GT or Aluminator block are You and Joe saying that 0.002" over bore is the safe standard to use to clean up the cylinder?
 
#8 ·
Ed this is Great information, ...

I would always recommend using MLS gaskets first and foremost unless your power level exceeded the limits of MLS gaskets. What power level that is I have no Idea haha. Personally I have seen MLS gaskets on cars making 900whp.
In my experience it is less horsepower related and more combustion pressures related, Matt. Your combustion pressures are determined by the engine's effective compression ratio, ignition timing, fuel and engine load. If you use an 8.5:1 mechanical ratio and 25 psi of boost (39.7 absolute) you will be at approximately a 23:1 compression ratio in the chamber prior to ignition. The math for that number looks like this; 25 psi +14.7 ambient = 39.7 absolute. 39.7 absolute divided by 14.7 = 2.7 atmospheres. 2.7atm * 8.5:1 c/r = ~23:1 in chamber compression. An in chamber 23:1 c/r is over the top for all but the very best gasolines. The alcohol fuels can easily accommodate this level of compression.

The 23:1 in chamber compression is the beginning of the challenge. When you add load and ignition timing, should you get frisky, you can raise the temperature of what is called the end gasses in the combustion chamber. Those gases are the combustible mixture farthest from the flame front and up against a chamber wall. As the fuels closest to the ignition event at the plug begin to burn they radiate heat energy. They also raise chamber temperatures because of the rising pressures they create, just like and for the same reasons boost creates heat. The radiant heat and the increased pressure rise related heat cause the end gases to spontaneously ignite because the environment they are trapped in has exceeded their autoignition threshold. That sudden and spontaneous ignition produces the ping we associate with detonation.

If you load the engine by pulling it down in the 3500 to 6500 rpm range you increase the amount of time, heat and pressure these end gases "see". As soon as the end gases reach the autoignition point the rest becomes history. You can detonate the engine with too much compression, too much boost, too much timing, and too much load. What works fine in one application with a 4.10 gear detonates in another with a 3.55 gear because as you increase the load with the 3.55 gear you also increase the dwell time the end gases are exposed to the rising temperature and pressures in the chamber.

Even when you do not detonate the engine you raise the chamber pressures sufficiently high that you push the design limits of an MLS head gasket, especially one with only a four bolt head bolt pattern, like a Modmotor. Once you cross that invisible line, incipient gasket failure begins and it only becomes a matter of time before the actual failure occurs.

With both a compressive and also a mechanical interference type seal, as a result of the stainless wire and corresponding receiver grooves in the liner flange, the dead soft copper gasket seal can sustain much higher combustion pressures without failure. While they can be used on the street with proper cautions (like you did) they are, for all intents and purposes, a race engine not a street engine modification.

Ed getting back the topic of the LA sleeves, which I think is a great idea especially for piece of mind and keeping the cylinders from going out of round, what do you think the average cost for a shop to do this is? I think it will run about $2000. for a block you send them.
Depending on who you use the prices can move around a bit but you are close to dead center on the likely pricing, Matt. Well maybe a whisker high, depending on geographic location, but I would doubt if you could find anyone to do the job correctly for less than $1,800. This not insignificant cost of resurrecting the block is why you want the purchase price on the used up block to be as close to zero as you can get.

Another question I had, on a build that is not using a sleeved block, like with a used 05+ GT or Aluminator block are You and Joe saying that 0.002" over bore is the safe standard to use to clean up the cylinder?
Not at all, Matt. I have seen many old Teksids with mileage in the 100K arena clean up at that number or slightly smaller. On a new block you simply look for the largest bore and order your pistons 0.0005" to 0.001" larger so the hone can clean up and size each bore exactly to each piston.
 
#9 ·
Turbo car here, but I am running 34-35lbs boost with fel-pro black MLS head gaskets 26187PT and 26222PT. Haven't had one issue with these gaskets in the over 2 years this engine has been alive. My block is a .005" over teksid
 
#10 ·
God bless, Tony!

Turbo cars and PD blown cars do work gaskets differently at different points in the engine's operating rpm range though. PD blowers usually beat up the gaskets more at the bottom of the operating range and turbos get their licks in higher up in the rpm band. That said the thread was focussed on the reasons to embrace standard bore builds and shy away from big overbores like 0.020".

The commentary about the dead soft copper gaskets and stainless o-rings was directed at track cars not street cars and was intended to illustrate some additional upside benefits that came with a decision to go with a replaceable flanged sleeve solution.
 
#11 ·
Nicely written article Ed. Once I start my "Manley 300M 01 Cobra Over Kill Engine Build" I will only hone my OEM Teksid block enough to remove taper and thats it. So I'm hopefully I'm looking to hone no more than .002. On a side note, I am one of those lucky original 2001 Cobra owners to sport a Taksid block. I guess Ford purged their stock of Teksid blocks some time in 2001 before switching over to the less desirable WAP block.
 
#14 ·
Not to side track bore size, but I have heard from people that the mains caps start to walk around 1200whp on Teksid blocks. First, is there any truth to this? And what are the fixes/reasons why?

Sent from my SM-G955U using Tapatalk
I don't know the horsepower threshold that it begins at, Nick, but the movement is real. I suspect it is more related to the engine torque than the horsepower. What essentially is happening is the downward push on the crank by the connecting rod begins to approach the clamp loading the main studs are capable of providing. Once that threshold is reached, it is fairly easy for the caps to move around incrementally. The certain indicator it is happening is a fretting of the mating faces between the cap and block.

One of the approaches Ford used on the original FGT blocks was to use a 10mm outboard main stud instead of the original 8mm studs. I know ARP made 10mm outer studs for the Hyland blocks because I have a set. I don't know with certainty, but they may also make a 10mm outer stud for the FGT (and GT500) generation engines - it would be the same stud. If they do, the studs are a pretty easy install for a shop, and that would go a long way toward helping with main cap movement. The final step in securing the main caps are the 10mm side bolts from John M. and they are truly impressive.

If an engine still showed signs of cap-to-block fretting, then I would consider asking ARP to make a custom set of ARP 2000 or ARP 625+ studs. One of the members on the site had previously asked ARP to make some custom ARP 625+ head studs for him. I am certain they would also do the main studs if someone asked for them. The issue is pricing and quantity. I believe the head studs had to be purchased in minimum quantities of three sets. If I remember correctly, they came to something like $1,000 per set, but I don't have a clear memory anymore. When I did a quick search, I couldn't turn up the original thread, but I might have been using the wrong search criteria.
 
#13 ·
We are on the same page with respect to bore sizing, Nick. This literally turns out to be one of those cases where less is more.

I had wanted to do this thread for some time now, but as always happens, things turn up that push the thread prep to the back burner. I am glad I finally got my butt in gear.

I think your block will clean up really nice at 0.002" over. I have seen a number of the older daily drivers, un-abused Teksids with 100K on the clock, and they cleaned up very nicely around the 0.002" oversize mark, often even less. You should have a pristine, like new starting point for your build. Your 2001 Teksid is easily the most desirable of the various Teksid years. It had all the Teksid good points, and I also believe the WAP-style main caps and 9mm side bolts.

That just reminded me. John M. has a set of ARP 2000, 10mm side bolts he has custom-made for him by ARP. I had seen them in an old magazine article about his Cougar (that's how old they are). When I called him, he said he still used them, and they were available for resale if I wanted them. I bought a set from him and put them in. When John said, 'You will like them,' he wasn't kidding! They are an excellent replacement for the 9mm OEM fasteners. Here is an older pic of them,

Household hardware Fastener Auto part Nickel Metal


John's current generation has a reduced thread length and increased unthreaded shank length.

If you elect to use them, they require careful resizing of the 9mm hole to leave enough material to form the 10mm thread. I elected to use a thread-forming tap to do the new 10mm threads. The thread-forming taps use a slightly larger hole than a cutting tap because they literally move the material around to form the thread; there are no chips. The slightly larger hole for the thread-forming tap allows you to clean out all the 9mm thread vestiges and leave a clean hole for the new 10mm rolled thread. When you are done, the threads are stunning! Be sure to use a high-pressure lube for the forming process, and take your time. The side bolts torque to 62 ft/lbs and comes up to torque very crisply.

One thing to be aware of is the depth of the side bolt hole to the outer main stud and the length of the bolt - it is different from side to side. John will alert you to the side-to-side difference so you don't hit an outer main stud with the side bolt. I used hardened washers of 0.060" and 0.100" from McMaster-Carr if I remember correctly. The different thickness washers allowed me to use the same side bolt on either side of the engine. The washers had a black oxide finish on one thickness and a silver finish on the other, so you could do a quick visual check to be sure they were on the correct sides.

Almost forgot. If you use the 10mm side bolts after the caps have been retapped, be sure to use a chamfering tool and something like an Arkansas Stone to remove the material that has been pushed up around the newly threaded hole. If you don't, it will gouge the sides of the block where the caps register as you push them into place.
 
#16 ·
Apologies on the name miscue, Nick. We have another site member that has a screen name quite similar to yours and my brain flip flopped the screen names and real names.
 
#17 ·
Ed,
I went ahead and purchased as set of ARP 9mm side bolts to replace the 8mm side bolts on my Teksid. Should I just let the machine shop tap the main caps or tackle this at home? That's what I was thinking of doing. Think I decided to partially fill my block. I have been speaking to someone that is almost in the 1,300rwhp mark. He said at that level he had issues with the main bearings getting ate up. Since he partially filled the block he hasn't had any issues with the bearings. Going to order a set of Gibtec's after I get the block cleaned up of course with as close to standard bore as possible. Haven't decided on rods yet so if you have any opinions on that let me know :) Cams should arrive in the next week or 2. Heads are done by Kris S.
 
#25 ·
Ed,
Haven't decided on rods yet so if you have any opinions on that let me know :) .
The Manley 300M is one of the strongest rods available for the 4.6 so that would be my choice if you are looking for unquestioned reliability.


This is the first thing we think of when putting high compression and 52 pounds of boost in the same sentence.
But what's really important here is the impressive connecting rod--a Manley tool steel, A-beam, Pro Series 300M Lightweight measuring 5.933 inches
and weighing a muscular 650 grams--and the bearing, which is still in ready-to-run condition. Fred attributes the lack of bearing damage to the 6.0-liter oiling mod.
John had Manley develop this tough-as-nails rod for him; its main claim is its extremely hard material. Fred says it's so tough that it tears up the production tooling,
but it's proven bulletproof, even after abuse such as this. In fact, although the piston pin is frozen, the rod and bearing are otherwise usable.
 
#18 ·
Any time you go up only a single metric bolt size, i.e., 8 mm to 9mm, you face a challenge with major and minor diameter metrics between the two fasteners and recommended tap drills for the respective threads, Russ. Let's compare a Class 6g M8 x 1.25 fastener with a Class 6g M9 x 1.25 fastener.

M8 Fastener

Major Diameter ...... 7.972 mm - max, 7.760 mm - min
Minor Diameter ...... 6.619 mm - max, 6.272 mm - min
Recommended Tap Drill size 6.9 mm

M9 Fastener

Major Diameter ...... 8.972 mm - max, 8.760 mm - min
Minor Diameter ...... 7.619 mm - max, 7.272 mm - min
Recommended Tap Drill size 7.9 mm

The tap drill size for the 9 mm bolt is within 0.01 mm (0.0004") of the major diameter (7.972mm) of the 8mm fastener. Drills do not drill to size. They always drill oversize. The machining job is not impossible, but it would require the use of a smaller drill and then a reamer to bring the finished hole to specification poor to cutting the thread. This dimensional problem is why I chose to use a thread-forming tap instead of a thread-cutting tap when I did my main cap side bolt upgrade to John M's 10mm side bolts. Thread-forming taps use larger hole sizes to create the same finished thread dimensions because they literally form the material to the tap. You ought to consider the benefits of the rolled thread solution also if you intend to go from an 8mm fastener to a 9mm or, better yet, a 10mm fastener.

If your Teksid has the 1999/2000/2001 WAP style main caps, your main caps can easily accommodate the 10mm side bolt and realize a significant step up in strength.

Decades ago, we used to fill supercharged blocks to make them stronger. The only thing it did was make our wallets lighter. The blocks did not last any longer. I don't think they do today, either. You do lose your cooling system, however.
'
Main bearing failures (getting 'eaten up') are oiling failures, not block flex failures. Fix the oiling system. Don't wast time and money filling blocks.

I would suggest you look into the Wiseco BoostLine rods.

Bicycle part Material property Tool Auto part Font


Don't let the Wiseco name mislead you about these rods. In terms of bang for the buck and ultimate strength, I believe they own the high ground in both categories. They are flat-out impressive. I saw a Modmotor that pushed all five mains out of the block with the mains still attached to the crank. The Boostline rods were undamaged and went into the new engine without the need for any service! This is what the failed block looked like;

Wood Motor vehicle Machine Gas Auto part


And the rods (and pistons) were good as new ...
 
#19 ·
Thank you Ed for the response.

The Teksid block I have is from a 96 Mark 8 so the only upgrade I have for side bolts are the 9mm. I have a large collection of taps so I'll see if I have a 7.9mm. I'm not sure I understand the "rolled thread" solution? So don't use the 7.9mm?
Those rods look nice, I'll have to look into those!

Any time you go up only a single metric bolt size, i.e. 8 mm to 9mm, you face a challenge with major and minor diameter metrics between the two fasteners and recommended tap drills for the respective threads, Russ. Lets compare a Class 6g M8 x 1.25 fastener with a Class 6g M9 x 1.25 fastener.

M8 Fastener

Major Diameter ...... 7.972 mm - max, 7.760 mm - min
Minor Diameter ...... 6.619 mm - max, 6.272 mm - min
Recommended Tap Drill size 6.9 mm

M9 Fastener

Major Diameter ...... 8.972 mm - max, 8.760 mm - min
Minor Diameter ...... 7.619 mm - max, 7.272 mm - min
Recommended Tap Drill size 7.9 mm

The tap drill size for the 9 mm bolt is within 0.01 mm (0.0004") of the major diameter (7.972mm) of the 8mm fastener. Drills do not drill to size they always drill oversize The machining job is not impossible but it would require the use of a smaller drill and then a reamer to bring the finished hole to specification poor to cutting the thread. This dimensional problem is why I chose to use a thread forming tap instead of a thread cutting tap when I did my main cap side bolt upgrade to John M's 10mm side bolts. Thread forming taps use larger hole sizes to create the same finished thread dimensions because they literally form the material to the tap. You ought to consider the benefits of the rolled thread solution also if you intend to go from an 8mm fastener to a 9mm fastener.

If your Teksid has the 1999/2000/2001 WAP style main caps your main caps can accommodate the 10mm side bolt and realize a significant step up in strength.

Decades ago we used to fill supercharged blocks to make them stronger. The only thing it did was make our wallets lighter. The blocks did not last any longer. I don't think they do today either. You do loose your cooling system however.
'
Main bearing failures (getting 'eaten up') are oiling failures not block flex failures. Fix the oiling system don't wast time and money filling blocks.

I would suggest you look into the Wiseco BoostLine rods.

View attachment 169445

Don't let the Wiseco name mislead you about these rods. In terms of bang for the buck and ultimate strength I believe they own the high ground in both categories. They are flat out impressive. I saw a Modmotor push all five mains out of the block with the mains still attached to the crank. The Boostline rods were undamaged and went into the new engine without need for any service! This is what the failed block looked like;

View attachment 169443

And the rods (and pistons) were good as new ...

Ed
 
#22 ·
I like to use McMaster-Carr for most of my tooling, Russ. That said, if you are familiar with cutting tools you can find some amazing pricing on eBay for infrequent-use tooling — which pretty much describes how we use this type of tool.

In a production environment, I would always opt for name-brand tooling both for service life and quality. For our use, which closely approximates a one-time use, the eBay tooling alternatives can save you a significant amount of money and still produce good finished quality (in this case) threading. To be fair, you can also find new, name-brand, cutting tools on eBay also at very attractive pricing, so don't think of eBay as just a source of low-priced, potentially low-quality tooling.

McMaster will consistently provide commercial class, high-quality cutting tool choices, but you will also pay for those choices and quality.
 
#23 ·
Thanks Ed. It appears that size is hard to find. The side bolts are listed as M9. Having a hard time locating a closed forming tap for a 9mm let alone the size 7.9. I even went to McMaster's website and they don't list it either.

I like to use McMaster-Carr for most of my tooling, Russ. That said if you are familiar with cutting tools you can find some amazing pricing on eBay for infrequent use tooling - which pretty much describes how we use this type of tool.

In a production environment I would always opt for the name brand tooling both for service life and quality. For our use, which closely approximates a one time use, the eBay tooling alternatives can save you a significant amount of money and still produce good finished quality (in this case) threading. To be fair you can also find new, name brand, cutting tools on eBay also at very attractive pricing so don't think of eBay as just a source of low priced potentially low quality tooling.

McMaster will consistently provide commercial class, high quality cutting tool choices but you will also pay for those choices and quality.

Ed
 
#24 ·
The 9mm thread size is a non-standard metric size, Russ. It is not that it is unavailable but it is very difficult to find. It is going to take a fair bit of Google work to turn one up. That said I would give a call to the folks at Advanced Manufacturing (the guys in the link above) as a good starting point. If they do not offer one they probably know who does.
 
#26 ·
Appreciate your enthusiasm, Jan, but we want to be factual here.

The Manley rod is actually not an A-Beam rod. The industry and Manley refer to it as an I-Beam rod, and it is an excellent rod.

The rods are not made out of tool steel. The actual material that Manley makes the rod from, according to Manley, is either 4340 or 300M, and their catalog does not indicate when the different alloys are used or which products they are used in. The catalog does imply the lighter-weight versions of their I-Beam rods use 4340 steel, and the heavier-weight versions of the rods use 300M steel.

300M steel is a modified AISI 4340 steel with silicon, vanadium, and slightly more carbon and molybdenum than standard AISI 4340. 300M has a very good combination of strength and toughness when heat treated to the 280,000 to 305,000 psi tensile strength range. For components that are subject to cyclic loading and unloading, like connecting rods, the fatigue strength and ductility of 300M can significantly extend the service life of the parts. It is a through-hardening alloy and is frequently referred to as a super steel.

The most common applications for 300M steel in the performance industry aftermarket are axles, transmission input shafts, select transmission internals, billet crankshafts, and connecting rods. In the nonperformance space, applications that you will find it used in are typically highly stressed components such as aircraft landing gear, high-strength fasteners, and airframe components. It is definitely not a tool steel, and it is engineered for purposes and applications other than and different from tool steels.
 
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