Valve Clearance on Larger Camshaft and Flat Top Pistons

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DC 340 said:
Once you move ahead, I would definitely check valve to piston with checker springs/dial indicator to see where you are at (forget clay).



I always went by 0.080 minimum on intakes, 0.120 minimum on exhaust. I was always insane (7200 rpm plus) and I never hit an intake at real close to 0.080, but I did tap the piston carbon on one exhaust valve at 0.109 clearance. Just a data point to consider.
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I cut a set of pent roof hemi prostock pistons down to legal superstock height back when I switched to superstock , they bairly touched the heads at high rpm , Tom Hoover told me, (at a chrysler seminr, in OKC) , he gave) that is just right if it didnt cause any problems , just kept the carbon off the pistons where they touched ...ran for about 10yrs that way...
 
Newbomb Turk said:
BTW and FWIW, if 92b would continue to read the Godbold book, he’d learn about buckling loads and why pushrod flex isn’t the issue when checking this stuff.
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My post is a direct quote from his book. If you believe that information to be incorrect I'm curious, what part you disagree with?

When you say " checking this stuff" I'm guessing we are still talking about checking undeflected and deflected lift measured as outlined in his book and that we haven't moved on to another subject?
 
DC 340 said:
Checker springs and a dial indicator will give you the most accurate readings. The indicator will show you where the tightest stage is. Just a degree at a time until you find the inflection point. If you are close enough with valve to piston to be concerned, clay won't get you an accurate answer in my experience.
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not as fast as rolling the engine over all at once , with clay in the reliefs , takes too long checking it degree by degre for me ...
 
92b said:
My post is a direct quote from his book. If you believe that information to be incorrect I'm curious, what part you disagree with?

When you say " checking this stuff" I'm guessing we are still talking about checking undeflected and deflected lift measured as outlined in his book and that we haven't moved on to another subject?
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pushrod deflection IS a big deal with dragracers hunting every last bit of horse power and needing longivity...
 
92b said:
My post is a direct quote from his book. If you believe that information to be incorrect I'm curious, what part you disagree with?

When you say " checking this stuff" I'm guessing we are still talking about checking undeflected and deflected lift measured as outlined in his book and that we haven't moved on to another subject?
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And I quoted from the book.

The problem is you didn’t keep reading.

Godbold calls it BUCKLING LOAD. I call it plastic deformation.

If your theory was correct (and the way you read the book was correct) then the bend in the pushrods would remain when you stop turning the crank.

Sorry, it doesn’t stay bent or flexed or whatever you call it.

Also, the chart you posted doesn’t jive with your theory either.

I’ve asked you many times how YOU determine how much of the flex is the rocker and how much is in the rocker, but you do what trolls do. You post a chart or someone’ words.

You NEVER post what YOU do and HOW you do it.

You fucked up another thread and gave the OP bad advice.

Explain yourself or STFU.
 
Newbomb Turk said:
That is better suited to ordering pistons with the notch depth you need.
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The way I understand it is the OP is in the build phase, everything I posted gives him the tools to determine minimum clearance for any camshaft he is using depending on the head gasket used.
Helps when using a generic piston with standard reliefs, unless they are cut for .750 lift. Did I say that. lol :D
 
fishmens67 said:
The way I understand it is the OP is in the build phase, everything I posted gives him the tools to determine minimum clearance for any camshaft he is using depending on the head gasket used.
Helps when using a generic piston with standard reliefs, unless they are cut for .750 lift. Did I say that. lol :D
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Exactly. Check it with clay and you can see how close the valve is to the notch and other things.

I’m going to find the video (if I can) I mentioned above about the guy checking clearance by running the adjuster down on a loaded spring.

You might be surprised at the shop doing it.
 
famous bob said:
pistons down to legal superstock height back when I switched to superstock , they bairly touched the heads at high rpm , Tom Hoover told me, (at a chrysler seminr, in OKC) , he gave) that is just right if it didnt cause any problems , just kept the carbon off the pistons where they touched
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I heard that with valves too. lol
My generic minimum clearance on valves is .060" intake and .090 exhaust, generic means it depends I don't won't any more.
 
Newbomb Turk said:
If your theory was correct (and the way you read the book was correct) then the bend in the pushrods would remain when you stop turning the crank.
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It’s not my theory. It's a quote from his book. Tell me what you think my theory is and maybe I can figure this out. Somewhere there is a disconnect. The only person taking about permanently bending pushrods when checking valvetrain deflection by turning the motor over by hand is you.
 
92b said:
It’s not my theory. It's a quote from his book. Tell me what you think my theory is and maybe I can figure this out. Somewhere there is a disconnect. The only person taking about permanently bending pushrods when checking valvetrain deflection by turning the motor over by hand is you.
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I’ll ask one more time.

How do YOU determine if it’s the rocker flexing or the pushrod.

Use YOUR OWN WORDS big boy.
 
Newbomb Turk said:
I’ll ask one more time.

How do YOU determine if it’s the rocker flexing or the pushrod.

Use YOUR OWN WORDS big boy.
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Under what conditions? Are you talking about deflection when turning the motor over by hand against the spring I would would be using vs a checking spring? Also what did you think my theory was? I think if you answer that it will help figure out where the disconnect is.
 
92b said:
Under what conditions? Are you talking about deflection when turning the motor over by hand against the spring I would would be using vs a checking spring? Also what did you think my theory was? I think if you answer that it will help figure out where the disconnect is.
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You are the disconnect.

You equivocate like a pro.

The OP asked about checking p/v. Do you that with a running engine?

Try again. I hope the mods are watching your passive aggressive bullshit and you again are ******* up a thread and confusing people.

Answer the question or **** off.
 
Newbomb Turk said:
You are the disconnect.

You equivocate like a pro.

The OP asked about checking p/v. Do you that with a running engine?

Try again. I hope the mods are watching your passive aggressive bullshit and you again are ******* up a thread and confusing people.

Answer the question or **** off.
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I'll take that as "not a running engine". I wasn't sure since you have covered a lot of ground in this thread. I'll pop a couple of springs off a motor and set it up with pictures. Probably tomorrow nightish. Don't hold me to that time frame.
 
mopowers said:
How is that? Do checking springs add additional valve movement? I'm having a hard time picturing that in my head.
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The real spring takes all the slack out of the system. Checker springs can “hide” clearance in many places. How hard it pulls keepers into the retainers and any number of different “tolerances”. You check with the real spring, you know what you have. There are so many things that you can’t control or really know, why add any variables to them. If you are doing the job, you have the tools, why not use the real spring. I guess if you run hydr, but not a fan and won’t run anything hydr, but even then, do you KNOW your checking spring isn’t changing what you hydr is showing you?
 
DC 340 said:
So tell me, how do you get an accurate reading from clay? Do you jam a caliper depth gauge into it with a flashlight and eyeball the reading? Do you peel it off and hope you haven't changed it? Then measure it with a caliper hoping you haven't compressed it?
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taught to me by an 18 time national record holder : fill the valve relief full of clay , even w the top of the piston , roll the engine over in a complete /contiuous rotation , pull the head , take a razor blade ind slice the remaining clay in the pocket in half , "up and down" or vertically , it can be done perfectly if your careful , then measure with a depth gage of your choice , ACCURACY DEPENDS ON YOU ! ---------FAILPROOF!!
 
Maybe I'm wrong, but 0 decked with 050 gasket and flat tops is terrible "squish". Not gonna make much power. .050 waay too much. I wouldn't even begin to worry about valve clearance.
 
Ironmike said:
Maybe I'm wrong, but 0 decked with 050 gasket and flat tops is terrible "squish". Not gonna make much power. .050 waay too much. I wouldn't even begin to worry about valve clearance.
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True, under 0.040’’ is a good figure to aim at for squish / quench, provided PV clearances are ok. That’s assuming closed chamber heads, open chamber is another story.
 
Fish Bite said:
Head gasket of 0.050" is ideal for the desired dynamic compression with the the Trick Flow chambers and cam profile
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Assuming-6.6cc reliefs in the pistons, 4.180’’ gasket bore size & 60cc T.F chambers your SCR should be around 10.6:1. With a 0.039’’ gasket, 10.9:1.

You can bring your SCR down by polishing the CNC tool path marks off the chambers. Added bonus of some pre-ignition resistance. I did this on some Eddy CNC heads and gained just on 5cc’s. Did it by hand, started at 80grit IIRC, went through the grits up to 2000, then polished with a small die grinder and polish wheels. Came up beautifully. A head porter can do all this, of course.

The T.F chambers are smaller than the Eddy’s, but even if you gained 3cc’s with a 0.039’’ gasket you’d be back around 10.55:1 with a better quench / squish. Best of both worlds.
 
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