Camshaft Piston to Valve clearances

TooManyToys · Apr 3, 2019

That's interesting. I've added this to the other two I have and included the piston data. The standard deviation of the pistons matches the standard deviation of the protrusion of that motor. Not that it would always correlate as the crank throw and rods are also a factor to the protrusion, but it may indicate the manufacturing tolerance.

Let's see if this image is readable.

Zeb · Apr 3, 2019

TooManyToys said:
That's interesting. I've added this to the other two I have and included the piston data. The standard deviation of the pistons matches the standard deviation of the protrusion of that motor. Not that it would always correlate as the crank throw and rods are also a factor to the protrusion, but it may indicate the manufacturing tolerance.

Let's see if this image is readable.

Readable.

I’m going to clean up the heads and measure valve recession in the next day or so. They are not stock heads. They’ve been ported, etc. From my preliminary measurements the valves are deep.
Depending what the valves measure, I’m not going to take any material off the top of the pistons and will check piston to valve clearance.
I’m doing some bowl work on the pistons and hope to not have to take any material off the top of the pistons as I’d like to keep compression closer to stock on this motor.

TooManyToys · Apr 3, 2019

When you remove material on the pistons do you do a rotating assembly re-balance?

Over the last weeks, I still haven't gone back to the motor and rechecked P-V with stock springs.

Zeb · Apr 3, 2019

TooManyToys said:
When you remove material on the pistons do you do a rotating assembly re-balance?

Over the last weeks, I still haven't gone back to the motor and rechecked P-V with stock springs.

Did one time. Spent $500 to find it was only a few grams out of balance.
Considering the rpm these motors turn most of the time, I see money spent on balancing as a waste.
On a high(er) rpm motor it’d make more sense, be more necessary, but most of the time I don’t see the need.

TooManyToys · Apr 3, 2019

I agree. I did the calc a few months ago for the ring on the top of the 6.0L piston, but never confirmed it.

Volume Piston Top per 0.001" Thickness 0.007903069 ci

Weight per 0.001" (g) 0.349542358 g

0.005" Removal 1.74771179 g

I've done my 289HiPo's but they will spin.

Zeb · Apr 3, 2019

TooManyToys said:
I agree. I did the calc a few months ago for the ring on the top of the 6.0L piston, but never confirmed it.

Volume Piston Top per 0.001" Thickness 0.007903069 ci

Weight per 0.001" (g) 0.349542358 g

0.005" Removal 1.74771179 g

I've done my 289HiPo's but they will spin.

The machinist is adamant that we balance the rotating assembly that’s going in the motor for my single cab.
It’s a bit different.....
Slightly modified standard bore Maxxforce 7 pistons in a 6.0 block, on modified 6.0 rods. :toast:

TooManyToys · Apr 3, 2019

Yeah, I would say so .....

TooManyToys · Apr 4, 2019

Gained about 0.005" P-V clearance by using the stock valve springs rather than the lightweight testing springs I was using to hold the valves. But damn it's hard to compress the stock springs. History proves correct, I should have learned.

Zeb · Apr 4, 2019

TooManyToys said:
Gained about 0.005" P-V clearance by using the stock valve springs rather than the lightweight testing springs I was using to hold the valves. But it's hard to compress the stock springs. History proves correct, I should have learned.

So still a little too close to run a Motorcraft gasket. Felpro gasket would give you enough clearance.
I’ve run a few sets of Felpro’s with no issues. If you oring the heads, make sure to keep the wire protrusion at 0.008”-0.010”�. I had a friend try 0.013”-0.015” on Felpro’s and the wire cut the gasket.

TooManyToys · Apr 4, 2019

Agreed, I already have the FelPro's. The Motorcraft did a remarkable job considering the deck surfaces, but that issue has been eliminated. I quoted the wrong number now that I looked at what I wrote down last night, gained 0.007", but still need the Felpro.

I'm not doing the o-rings even though when asked it's what I recommend. I like to see how the stock situation does with the variables of surface cleaning are removed.

Zeb · Apr 4, 2019

TooManyToys said:
Agreed, I already have the FelPro's. The Motorcraft did a remarkable job considering the deck surfaces, but that issue has been eliminated. I quoted the wrong number now that I looked at what I wrote down last night, gained 0.007", but still need the Felpro.

I'm not doing the o-rings even though when asked it's what I recommend. I like to see how the stock situation does with the variables of surface cleaning are removed.

Orings are insurance.
On a close to stock setup proper deck and head prep, and properly torqued studs are sufficient.
I beat the daylights out of my old 4 door on studs that were put in one at a time and it went 5 years snd 50,000 miles before they failed. Dynoed nearly 800 hp on its hottest setup, and the majority of that time was in the low 700hp range.