Don Terrill’s Speed-Talk

Let's put some priorities in place.

Which is most important and in what order?
Bore roundness
Bore taper
Correct bore size
Surface finish
Consistent measuring temperature

How much deviation can be tolerated for each parameter?

Depends on the goals.......

David Redszus wrote: ↑Mon Apr 16, 2018 2:00 pm Let's put some priorities in place.

Which is most important and in what order?
Bore roundness
Bore taper
Correct bore size
Surface finish
Consistent measuring temperature

How much deviation can be tolerated for each parameter?

I don’t know the answer of order in every situation. I try my best with all and with the equipment I’m using.
I would put roundness and surface finish at the top.

I don’t make plate honing an up sell, I just do it as part of the job.

If I had to choose being .0003 off size OR having the best finish
I'll take .0003 off size.
I think "wave" is fairly important but not usually measured.

Taper is even less important, but how do you hone a tapered bore?
If it is tapered that means the hone isn't working right.
If the hone is working great then there won't be any taper.
So, maybe they are chasing a perfect bore for the wrong reason, but it doesn't really matter.

Aren't some engines deliberately 'reverse taper' honed to compensate for the top of the bore being warmer than the bottom at operating temperature? A 20° delta would cause about a 0.0006" diameter change in a 4" iron bore...

MadBill wrote: ↑Mon Apr 16, 2018 9:43 pm Aren't some engines deliberately 'reverse taper' honed to compensate for the top of the bore being warmer than the bottom at operating temperature? A 20° delta would cause about a 0.0006" diameter change in a 4" iron bore...

A lifetime ago when I did some aircraft engines it had a designed in taper for that very reason ..

I did a test once on a thin casting block .. used a plate on one bank and not the other ... arp studs torqued to higher then standard on plate and heads ...high output nos engine ... leak down never showed a difference ...ran hard for a few years ... when I tore the engine down the bores on the unplated side had different marks in the bore where the bolts had distorted the bore and rings wore the high spots down ....the plated side looked great .... so on light blocks it does help make a better bore but never saw any problems with not doing it ...

rustbucket79 wrote: ↑Sun Apr 15, 2018 11:31 pm

machinedave wrote: ↑Sun Apr 15, 2018 10:50 pm I have found that you can spend all day carefully honing a block to final size, come back 8 hours later and check it again. I use my IR temperature guage to confirm 69 degrees. Now come back the next day and it can shrink a few tenths even at the same temperatures.

I've experienced the same thing. The block is going to be in the hone for a few hours of cooling time before the final few sweeps, job (time) management is one of the many tasks of a competent machinists.

Yes very time consuming. I usually only have one torque plate so I can tie up a V8 block in my honing machine for 4 days with careful measuring and long cooldowns. I am probably being a little too careful but I like a perfect cylinder even if it's just an old stock Chevy plow truck.

I find a softer stone with a very light pressure allows me to get that last .0005" done even with a couple 10's larger in the center of the bore.
I always use a plateau finish for most of our builds so finer softer stones allow for the finer removal of small deviations in size very easy with out the need to let blocks cool more then a few hours.

I should mention when warmer weather comes I will put blocks in a cooling room with a large fan that way I can knock out several blocks to .0005" from finished size then force cool them and touch them up larte in the day. They still get checked the next morning and adjusted if needed but since I started using a large fan to cool down blocks it has taken the wait time out of the problem thus allowing us to get more done.It works well on 90% of blocks but any 5.9 cummins or similar diesel blocks because of their heavier designs needs overnight cool down before final finish is done.

cardo0 wrote: ↑Sun Apr 15, 2018 1:36 pm Well if you're that concerned about ring seal then look for a shop that can flow/circulate hot water near 200*F through the block while they plate hone it. Sky is the limit when chasing ring seal. But do you really need the expensive machine work? What is the motor used for? Just a street rod? Ya know very few production car motors are plate honed from the factory and the car will run fine w/o plate honing while saving you 200 bucks.

I read most the gains in plate honing are 1% or less and you need a very accurate calibrated dyno to see them. Not the $100/hr dyno most of us can afford. But the gains do add up. Plate hone, drilled pistons, zero gap rings, vacuum pump. Maybe gain 5% to 10% hp.

Good luck with your build and please share what you find.

Tried this hot honing years ago, way more to this than you would think, have you ever measured what a blocks bores are like after hot honing them when they are cold?

Assuming that we have accomplished the honing task list correctly, another problem remains.

Anyone who has studied honing with a plate knows that bore distortion can be caused by the head bolt
torque values and bolt depth.

Now consider what occurs when an engine is running under load. Combustion pressure tries to lift
the head off the block which produces he same effect as over-torqued head bolts.

Once again we have the issue of static vs dynamic values.

Once again we have the issue of static vs dynamic values.

Agree, torque plate, two-step, hot; the perfect cylinder honing job is akin to chasing one's tail. It's also akin to flow bench testing. The highest paid guy I knew always maintained it was a waste of time to perfect a port without the intake attached. He showed me before and afters which proved his point. It made him crazy he still couldn't really simulate a running engine. But then, as he said, a flowed head is still better than a production one.

It's all been achieved by small steps. Never mind power adders; we old guys still can't adjust to the ever-increasing NA outputs which have become routine checkbook garage builds today.

jack vines

Always wonder what happens when engine heats up,even only 140-150 deg watertemps,and we've all been letting the bores cool to finish them.......

^ good point - likely end up with additional piston to wall when at operating temp?

I don't think we are being paid enough to chase things this far.

I suppose chasing details to a certain degree is in our nature. Chasing details into oblivion however is unhealthy.

When you're honing a block the thinner sections of bore heat up more, so distortion is unequal.
When a motor is up to temp heat is more even.
So we let it cool more as a 'normalising' process so that there are no warmer sections, not because the bore will be the right size cooler.

Looking at the bores of an engine down for a freshen up tells the tale - plated bores have more even wear with less high/low spots, unplated bores often have witness's around the bolt hole areas.

So we can't see what the bore is doing in a running engine, but we can look at the results of the honing process after the fact & deduce how effective a process is.

If using a torque plate is a good thing then why do some shops rough bore to .003 or less from finished size and
expect the bores to be on size and round when they get the block back??

I had a fellow bring in a BBC block to get finish honed for a Mahle piston and ring set today and sent him away cause the block was rough bored to between .002 and .003 from his desired size. The block was to be 4.350" finished size and he did not leave much room even without the plate it never would get the bore smooth enough.

I should be clear here that the 1st shop was a local small guy with a deck mounted bar that charges $75 to rough bore a V8 block.And he did not bore the block deep enough to take that step out of the bottom so the stones don't hit it.He believes that you don't need at least .005" to hone out to make the bores nice and smooth.
He also charges an extra $50 to hand finish hone if he bores the block but he will not use a torque plate.

There is a couple other larger shops near me that only go .003" to hone out using a CK 10 machine but always seem to go larger and have rattlers when they are done.

FYI this fellow is watching this thread now that I sent him a link just to prove there are others in the trade that don't do it that way