Don Terrill’s Speed-Talk

The skirt profiles on many pistons are getting better so they can run tighter at the guage point. Not just "cam and taper" anymore, it's....like a curve. If you only ever measure pistons at the gauge point then your not seeing the full picture and what's going on. So....I'd add .001", but I don't th...

176+38=214 not 222 Perhaps you added 4 instead of subtracting it. Getting closer tho! Don't sweat it, this IS tricky. I can make it sound simple but, that's just because I"m naturally good at it, AND lots of practice Oh I see, am I right in saying I would use subtraction if the IVO ATDC? and additi...

Hard to say who wrote that and specifically about what. On the one hand I believe it, but then again if it was specific to that engine might be doubtful. It was probably already known long before, or should have been. Ford was using that same kind of design, on probably less sturdy blocks, and I've ...

176+38=214
not 222
Perhaps you added 4 instead of subtracting it.
Getting closer tho!

Don't sweat it, this IS tricky. I can make it sound simple but,
that's just because I"m naturally good at it, AND lots of practice

spec sheet has Duration specified at 0.35mm (.014") and 1.25mm (.049")
You guessed it first. I had not read your reply. Thought of it all of a sudden this morning.

I think he is not adding the lash from his indicator reading.

If the engine is set at .010 lash, then the indicator should be "zeroed" at .010", not 0

Bill
1.25mm is .0492
Close enough to .050

if the pistons were .001 off spec or more I'm pretty sure I could tell that measuring through the coating.
In most cases the coating adds .0004-.001 to the total skirt size.

it surely DOES distort the main housings....some amount. Most V8, you might notice there is not that much metal holding the two sides together, and most of that is at the front and back ends. enough to cause a problem? probbly no. If you tightened the bolts in the worst possible way it might be sign...

I think it is possible, it's no april fools joke.
but while your at it.... I'd like to see a vid of installation using only wooden tools.


There are many engines that do not have any timing marks. It's weird, but not so bad once you get accustomed to it.

Duration at .35mm lift
You measure 234
it's supposed to measure 266 according to card

That's way off. Not even in the ballpark.

What do you get checking at 1.25mm lift? Checking at .050 has become the standard worldwide. not sure why you checked at .35, not a big deal, but NEXT time.

No I can't elaborate. "What is the duration measure" should be a simple quesion You are elaborating and making this so extra complicated by adding extra information I don't need to know. Lets make it even simpler. You degreed the cam, what were the results? Not six less than some other number, just ...

I have used micrometers with ball points or small tips to do this, but I don't feel it is very accurate, the surface is usually rather rough and the contact pressure is too high with the small tips. So.....IMO if you buy good pistons there will be a spec sheet that says the skirt size, it is accurat...

Duration and installed centerline can be calculated from your two .050 points. if you have a open and close point at .050 lift, you can find the 'center' of that, what crank angle is halfway between each, and this is the centerline angle. This can be adjusted. the total duration is all in the cam gr...

The long term durability of wood is very poor.
At least use aluminum