Torque plate when machining open-deck blocks?

It's not required but it's best. Never heard otherwise.

 

I've built or had built a LOT of racing engines, specifically Alfa Romeo and Tadek Marek-designed Aston Martin engines, and I would not consider boring or even finish honing liners without a torque plate.

Built with water jets now, it's easy to fab one.

 

Even lowly chevy guys building hi perf motors use torque plates on blocks since I was a child 100 years ago. If you do a search there is an interesting thread on a lambo head being done by a pro on Fchat discussing sealing problems post head rebuild. Last few posts on that subject discussed using torque plates on heads too. That was a new one for me to hear although I heard that the really high race motor guys did that kind of thing on head but not the streetcar crowd. Never did see what actually happened to that street motor by the way. It is all about precision and application. I think a 350 chevy block can make 200hp to 1000hp maybe more. On the low end of power generation mismatched pistons and hand crosshatched cylinders work fine. On the high HP end you have to do all the things we know work to make power that will stay together. That's why you are hearing it both ways.

 

Actually on an open deck the liners are so poorly supported I think distortion issues would be worse making the benefits of torque plates greater. May be wrong but it makes sense as an intellectual exercise. Also on a Ferrari the liners are crushed against a stop about 3/8 of an inch below the crown. An Alfa or Maser with an open deck they are crushed against a stop at or near the bottom of the travel of the rings. Seems to me they benefit more from torque plates.

 

Any engine benefits from torque plate honing. I built my own plates for Ferrari engines...I don't buy into Ferrari's idea of "drop in" liners. If I'm building a complete engine, I'm gonna do everything possible to make sure it's as good as it can get. I've honed some Honda engines with open decks and they flex all over the place without plates. For the little extra that it usually costs to have the block plate honed vs. not, why even risk poor ring seal by not paying the difference?
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Here is my argument. First off I have to state I do not have an engineering degree, but ive had my fingers inside engines since I was about 7 years old. And I have read a great deal.

First, I see the Ferrari engine as being very plastic. Each times its heated and cooled it moves, and changes stress areas. It shrinks in some places and grows in others. Gaskets swell and contract.

Secondly, you can look at the liners and visually see the wear areas. They appear to wear very evenly. People have put over 100K on the bottom end, and for a small bore engine that spins up like it does, thats saying a lot.

The last argument I have comes from Ferrari themselves. 308 liners are machine finished outside the engine in a fixture. The OWM specifically tells you to have them reground that way. Now someone argued once that thats all fine and good, but Ferrari wouldnt do it on a race engine. I would argue that they did.

In the 60's when Ferrari was just about broke they ran the P3 project. It came out in the 0846 thread that the car ran various races with varying displacement engines, but that the engine numbers were the same. It appears Ferrari was so broke they were swapping sleeves back and forth to make different displacement engines, and to maximise theyre available parts, which was not much. I believe that between the handful of cars there were barely a dozen engines, they just didnt have the jing to produce more.

My personal belief is that while cold, you could in fact get laser sharp bore centers with a deck plate. But I also believe that after its been run a few times and the liners move around, it wont matter anymore. But I dont believe there is any way in hell to prove it one way or another. If it makes sense to you, and you have the tool, by all means use it. But I wouldnt lose any sleep over it if you dont.

 

Interestingly, DINOS require the plates to be used on the heads WHILE DOING THE VALVE JOB, lest the seats leak when installed.
Obviously, you use them on the block as well....

Typically-and I've been doing this a long , long, time-I will use a Kwik-Way FB to bore the liner to within .002".
After the deck has been squared and trued to the perpendicular of the crank centerline and the rod pin,
I'll squre the liner's hole and the mounting shoulders for the liner-equalizing the depth of insertion, then install the liners,{this procedure usually will require some REALLY expensive VMC CNC machine}
and into The Brerco it goes to get the deck grinding to yield a .09mm protrusion height.

Install your plates-both sides-and finish hone in a Sunnen CV-616/J...
tolerances within .00015" are acceptable, you can do only 2 holes per bank, per session, as heat will affect the sizing as well.
Did I mention that you must also torque up the mains as well... prior to the deck plates? This is also when you may wish to ensure a proper alignment of the crankshaft's "galley" for the mains....if out, again, another Berco....


When completed, make a chart...undo the plates for pre-build cleaning, and see what sort of differences you see!!!!!
That will be the end of the story/discussion about the merits of deck plates for Ferraris right then and there.

For those curious...running 195 degree water through the block, WHILE honing, has proved to yield NO MEASURABLE differnece/results!
Room temperature-oddly-has as a great an effect on results as does relative humidity-we measuired...nothing quite like impirical data.

If you are not using a pair of deck plates, then you are not machining the block-you might as well be using a "dingle berry hone"-the rings will "oil can", fatigue, and not seat properly, to say nothing of wearing prematurely and unevenly. In short, it was a waste in time and money to say nothing of the effort involved which is prodigious.

 

Wow! I am amazed that just the heat of honing would make a difference here. Honing seems to be a fairly benign process but obviously not.

 

I think all of the answers are reasonable and plausible. Perhaps I can help clarify when a torque plate is helpful and when it's not necessary. In my experience, a torque plate is essential if the cylinder bores are to be honed insitu and any real amount of material is to be removed. Why? Because the tooling used for removing ten thousands or twenty thousands just works better and produces a better finish if the cylinder liners are very securely located. Even slight lateral movement can produce an inferior finished surface which increases ring wear and increases blow by. Now, for a new set of liners being installed which have previously been properly bored/honed (concentric and along the bore axis itself) on the bench a torque plate probably isn't necessary because you're not going to be removing any meaningful amount of material...perhaps just a light finish hone with a stone.

What seems to be equally important is getting the deck height consistent across all of the liners and the block - now, that's not easy to do for engines with separate liners if you have to remove any real amount of material. You obviously can't use a torque plate for that machining procedure. I've seen more head gasket failures from this than any poorly done cylinder boring/honing procedure. To be precise, it's not the head gasket that fails, it's doing its job quite nicely, it's the failure of the deck to be completely flat that's the problem!

 

I'm SOOOOOO confused!

When I did my QV, I pulled the liners and sent them out for re-nikasiled and refinished, put them back in. The rings seated and it had 0% leak down (gap-less ring). The factory assembly method worked just fine.....I don't see any reason in the world why I would want to make my life harder then it has to be by trying to finish the liners in place with torque plates. How much better than 0% leak down is it going to get with the extra work?

 

I certainly have nothing against "attention to detail" but most of this is "gilding the lily".

 

When i was machining race blocks for nascar, can-am, sprint etc. We bolted water pumps, and anything we could that was on the motor to replicate static deflection and then cycled coolant through the system as we honed. Its like loading your rods before you final size. Details and tolerance stacking are what wins and loses races. A motor is dynamic, everything is changing so why even bother you ask? If it didn't matter it wouldn't be done. And you knew it right away when you blew a motor on a dyno. In your street car.....makes no real difference.........For street and enthusiasts open deck motors, it was just far more convenient to use to keep the liners in place while honing. I finished honing by hand.......only used the CV616 for rough........i don't know what they have out now.......haven't machined in 25 years.

 

No worries......i used to do liners by hand on the Rod Machine........it's just faster and easier to do in the block.......you can knock them out faster that way.

extra (good) work = reliability = HP

You can get 0% in a high ring load motor running running 3 rings with marginally distorted walls..........

Then with extra work you can accomplish the same with 2 ring low tension motors.........and the pistons literally slide in place......with little friction coefficient....... again that was many many years ago for me........probably lot has changed.

 

not all of them check out a LT5

 

So this improves the consistency in the cross hatching pattern side to side, top / down?

 

Yes and no. For a simple finish hone (where you're typically just using a stone or something similar to get a surface which is compatible with bedding in new rings) a torque plate is not necessary - you're not putting any significant side loading on the liner. For a honing in which you're actually removing material (going to an oversize piston for example) ie. boring, then it makes a heck of a difference - you want a torque plate in place if you're honing that cylinder while in the block. If you don't have a torque plate (they're not that tough to fab up) then you'll want to remove the liners and hone them in an appropriate honing machine.

 

Which is specifically what the OWM prescribes. Actually it specifies replacing them with new, but that if your going to grind them, to remove them from the block and do so in a fixture.

My problem with using a torque plate on the Ferrari is that it adds an unknown. The engines wear pretty evenly the way they came, and we have no long term evidence to support torque plate honing [with a Ferrari].

 

When ever possible I always will use a torque plate during boring and honing. Most of the engines I am rebuilding are sport bike engines some are closed deck and some open deck. The distortions caused by the clamping loads vary from engine design as well as casting variations. If you really want to see a difference get a dial bore gauge with a 0.0001" dial indicator and go and map out the cylinder. When you do this check more than the top center and bottom X and Y method. Then take the head and torque with the head gasket you are going to use on that engine. Now using the dial bore gauge remap the cylinder from the bottom of the block a second time. The difference between an unclamped bore and a clamped one can be quite different. The biggest amount of distortion are found in engines that have studs running from the cases through the cylinder and up to the head. The longer the stroke the more distortion you can see.

 

No it hasnt changed. The late model 4.6 mustang engines I build are such a treat. Super low tension rings and pistons that slide in like butter. They make big HP with small displacements. When I build my nephews stock car SBC I cringe when I need a piston mallet to move the piston down the cylinder to install the rod cap. Low friction low weight and great sealing, that will always be the way.

I agree do them in a fixture and forget it on an older ferrari application. The boxer engines in particular suffer from liners that move around in service. Why fret about straight cylinder sleeves that flop around in the block? I imagine the 308 is similar.

 

IIRC the Maserati C114 has liners that are designed to move around/rotate in the cylinders.

Ciao,
George