Favorite piston to valve checking methods?

[Cs19]

Which way do you like to check it?

[pw_Tony]

No head gasket, and with cold clay. Cut the clay in half and use some dial calipers to measure the thinnest part. The 100% accurate, but with 10 thou I would say

[Daytona100]

Full throttle at the bouy line!!!!!!!!!!!! Best place to check um!!!!!!!!:D

[Cs19]

Been reading about it tonight on the comp and crane sites, Im seeing alot about checking numerous points BTDC and ATDC by doing valve drops with light checking springs or with a spring pressure checking tool and your actual valve springs.

[steelcomp]

Best way is with a dial indicator on the retainer. I just rotate the engine untill I get the minimum clearance, regradless of where it is...what I mean is, I don't bother with degrees. It's irrelevant. You'll either have enough at the closest point, or you won't. Don't forget to check side clearance to the pocket in the piston, either.
Thought you already did this?

[Cs19]

Best way is with a dial indicator on the retainer. I just rotate the engine untill I get the minimum clearance, regradless of where it is...what I mean is, I don't bother with degrees. It's irrelevant. You'll either have enough at the closest point, or you won't. Don't forget to check side clearance to the pocket in the piston, either.
Thought you already did this?
Have not done it. Im in the middle of mocking things up. so far so good.
how do you determine when things are the closest?

[pw_Tony]

I make my cheesy valve springs out of a coat hanger or something. Turn the motor over until you have full cam lift. With a dial indicator on the retainer, or the valve stem you can push down the valve slowly and read how far it goes down on the dial indicator. Of course with cam timing things can be different.
Or just sticking some clay in the valve notches on the piston and turning it over with full valve springs. And then pull the head back off and cut the clay in half and measure how thick it is with a dial caliper and that's your clearance.

[YeLLowBoaT]

quater and some bubble gum... :D

[HONDOG]

Simplest way I have found is to figure out how much clearance you need, put that amout of feeler gauge under the rocker and rotate the motor(slowly and carefully by hand). If it doesn't hit you have enough.

[thatguy]

I use the light checking springs, set lash, and rotate crank SLOWLY. When piston approaches top of cyl., on the exauhst / Int. overlap stroke, I push down on the rocker tips while turning until I find the minimum clearance point. Once I see where that point is I go over it again in very small increments for a "fine" measurement. A little dye or marker on the piston is helpful, as stated above, often it is not the depth but the edge of a valve that is touching the pocket. Especially on canted valve engines like BBC.
A little massaging on the pocket can unshroud the valves in many cases without actually flycutting.
I do it without the head gasket, that is the insurance policy in my book.
Tommy
Note: It is not advisable to assume that the minimum clearance will be at Max. valve lift. It is often closest during overlap.
My .02

[wsuwrhr]

Been reading about it tonight on the comp and crane sites, Im seeing alot about checking numerous points BTDC and ATDC by doing valve drops with light checking springs or with a spring pressure checking tool and your actual valve springs.
I have always used the checking spring and a dial indicator

[Terminal Velocity]

I use the light checking springs, set lash, and rotate crank SLOWLY. When piston approaches top of cyl., on the exauhst / Int. overlap stroke, I push down on the rocker tips while turning until I find the minimum clearance point. Once I see where that point is I go over it again in very small increments for a "fine" measurement. A little dye or marker on the piston is helpful, as stated above, often it is not the depth but the edge of a valve that is touching the pocket. Especially on canted valve engines like BBC.
A little massaging on the pocket can unshroud the valves in many cases without actually flycutting.
I do it without the head gasket, that is the insurance policy in my book.
Tommy
Note: It is not advisable to assume that the minimum clearance will be at Max. valve lift. It is often closest during overlap.
My .02
I did as stated above, no gasket, set valve lash because valve lash can change the duration of the cam and when valve opening/closing events happen. On my engine (other one than the dam clearance problem and it's still Brian's fault:D ).
I found true TDC set up my degree wheel and started turning the motor over when i got to the point of approximately .100 clear i began checking every 5 degrees of crank rotation here's what i came up with...
Exhaust Clear Intake
25deg BTDC .090 3deg BTDC .095
20 .050 0 TDC .076
15 .019 5deg ATDC .057
10 .005 (shiat) 10 .052
5 .009 (dam) 15 .065
0 TDC .030 (hmmm) 20 .095
5 ATDC .067
Obviously your results may very, this is with a 286deg duration solid cam around 650 lift. By doing this without the head gasket you'll get actual clearance and then add the compressed thickness of the gasket to get your final v/p clearance. For me to add a gasket thick enough to get at least .080 on the exhaust i'd loose about .5 in compression and with the players in the super stocks i can't afford to loose that!
Since i can't "modify" pistons because of my race rules i talked to the cam manufacturer explained what was going on and he said well, you can advance or retard the cam O say 8-10 degrees but your pretty well fawked on what power you'll have or i can sell you a cam with less duration and pick up the clearance by closing the valve sooner ...4 days and $300 later my new cam showed up.:D
from 286deg to 274 deg duration he figured i'd pick up .030ish add that to the .010+- i have currently a .041 gasket and i'm in the .080 range. Of course when i check it now i'll probably end up with freaking .150.:D
Did i mention this is all Brian's fault?;)

[wsuwrhr]

Best way is with a dial indicator on the retainer. I just rotate the engine untill I get the minimum clearance, regradless of where it is...what I mean is, I don't bother with degrees. It's irrelevant. You'll either have enough at the closest point, or you won't. Don't forget to check side clearance to the pocket in the piston, either.
Thought you already did this?
Yep.

[wsuwrhr]

I believe you did.
I am just glad someone else in this world encounters the same problems I do.
Brian
On my engine (other one than the dam clearance problem and it's still Brian's fault:D ).
Did i mention this is all Brian's fault?;)

[Terminal Velocity]

I believe you did.
I am just glad someone else in this world encounters the same problems I do.
Brian
:D :D :D believe me, i've had more than my share of "issues" lately. And it all doesn't pertain to engines. Funny thing is, 10 years ago it was clay and plastigauge motors ran for seasons...Now i get all this fancy measuring crap and all hell breaks loose...literally!
PS delivering the block in about an hour for my little main clearace problem.:rolleyes:

[wsuwrhr]

Funny thing is, 10 years ago it was clay and plastigauge motors ran for seasons...Now i get all this fancy measuring crap and all hell breaks loose...literally!
now that is funny.

[thatguy]

Brian, you sure get blamed for alot of problems!!:D :D
T.Velocity,
Can you get a visual on where the contact is made on the piston? Shiny spot or a little dye? I don't know your class rules, but if it is contacting just an edge does your class allow any piston de-burring? .650 is getting you close normally though (depending obviously on piston choice). I've had 0 clearance on smaller lift cams so those numbers sound right to me. Actually, they sound somewhat forgiving. Is (was) that cam installed straight up? It almost sounds a little advanced now the way the piston is departing from the valves so rapidly ater TDC.
Then again, I have been accused of only being an "assembler"!:D ;) :D
Tommy

[wsuwrhr]

I have broad shoulders.
I am not scared.
Brian, you sure get blamed for alot of problems!!:D :D
Tommy

[Terminal Velocity]

Brian, you sure get blamed for alot of problems!!:D :D
T.Velocity,
Can you get a visual on where the contact is made on the piston? Shiny spot or a little dye? I don't know your class rules, but if it is contacting just an edge does your class allow any piston de-burring? .650 is getting you close normally though (depending obviously on piston choice). I've had 0 clearance on smaller lift cams so those numbers sound right to me. Actually, they sound somewhat forgiving. Is (was) that cam installed straight up? It almost sounds a little advanced now the way the piston is departing from the valves so rapidly ater TDC.
Then again, I have been accused of only being an "assembler"!:D ;) :D
Tommy
The valve vs piston is canted a little (different angle couple degrees +-maybe) the pistons are spec JE/SRP with APBA embossed on the top, per rules One piston must remain totally untouched. we used to be able to run TRW and/or Speed Pro's. I'm thinking where i may have also FUBAR'd myself is i started and made sure i whittled down the heads to the absolute minimum cc's allowed by the rules as well as made dam sure i had 0 deck...i'd give a whole lot of sack to have those thousandth's back!!! My head guy figures he can pick me up a little also with sucking the valve into the seat without hurting the flow...to a point.
The cam was indeed straight up per the cam card, checked that 4 different times over 2 days thinking i had to have done something wrong, which is usually the case. Beats the hell out of me.
Another little piece of funny...the v/p clearance issue is at my dad's house in Salt Lake. The main clearance problem is here in Vegas, it's a biatch to try and get 2 engines together in 2 different states you know!

[Terminal Velocity]

I have broad shoulders.
I am not scared.
Brian is actually a great guy, he helps a lot of people out here on the boards. I'm just blaming him because i read his clearance issues thread 2 days before i started mocking up my engine and thought "that poor guy, that would really suck to have to go through all that crap"...guess what i found out it does suck. At least he was able to do it with a bearing change i get to go back to the machinest, wait, re-wash the dam block.:mad:

[wsuwrhr]

Laughs
At least you didnt get pummeled from multiple fronts because you asked for help.
Sheesh,.,..
Brian is actually a great guy, he helps a lot of people out here on the boards. I'm just blaming him because i read his clearance issues thread 2 days before i started mocking up my engine and thought "that poor guy, that would really suck to have to go through all that crap"...guess what i found out it does suck. At least he was able to do it with a bearing change i get to go back to the machinest, wait, re-wash the dam block.:mad:

[thatguy]

Yeah, they are tricky to build over the phone. Or the internet for that matter.
Sinking valves can lead to major expenses later, as I am sure you know. Replacing seats sucks. Expensive and if your guy isn't double sharp it can lead to "catastrophic engine failure". A term I do not like! Personally I would not go that route to any degree. Thats too bad about the surfacing of the heads. In a class legal deal you always want to be on the edge, but other factors come in to play. As you are well aware of at this point.
Good luck and hopefully it will work out, it always does. :)
Tommy

[Terminal Velocity]

Laughs
At least you didnt get pummeled from multiple fronts because you asked for help.
Sheesh,.,..
yea, i kinda tried to stay out of that one, actually i waited to post my problems until they got tired of causing crap and moved on, not to mention i just kinda piggy backed onto an existing thread:D

[steelcomp]

Have not done it. Im in the middle of mocking things up. so far so good.
how do you determine when things are the closest? I know that as the piston is approachintg TDC on the ex stroke, (or overlap), it and the ex valve are moving toward eachother, and I start checking. I'll rotate a few degrees, and check. Rotate, check. You'll start feeling the valve hit the piston, and the clearances will start to decrease. I just repeat that untill the clearances start increasing again, then go back, and do it a few more times untill I find where the clearance is min. It's a lot easier with checking springs since you can just depress the valve with a finger, but if your heads are assembled, you can use a spring checker. I use an old head gasket and tighten (Just tight, not torqued) the head bolts/studs around that cyl, (presumably no. one) and a few others across the head to make sure it's sitting flat. Install everything else as you would on that cyl, and lash to hot setting. I don't like the "do it without a head gasket" method. You need to know what the clearance is, not calculate what it might be. The min. clearance is going to be after max lift, and before TDC. I'm guessing you're loking for about .100-.120 on the ex, and .090-.100 on the intake.

[thatguy]

Steelcomp,
Yeah, on a class legal motor I would use the gasket. Get it right to the nats aas. But I do it without one for "everyday" engines for myself and customers. That way if I can get adequate clearance without the gasket I know we are good with it. Like I said, it's more of an insurance policy then a calculation. Other than that the way you describe is the exact way I do it. Simple, fast and accurate!:)
Tommy

[Fiat48]

Have not done it. Im in the middle of mocking things up. so far so good.
how do you determine when things are the closest?
Try checking 7 to 10 degrees before or after tdc on overlap. Usually the closest point. Let me know.
Method I use about the same as others. Mock up with head gasket, etc. Light test springs. Adjust to zero lash.
Insert .060 worth of feeler gauge between rocker and valve stem. Pry apart slightly. Turn motor over to overlap area.....you can feel piston pushing against valve....against feeler gauge....feel tightest point by rocking back and forth....then measure clearance with feeler gauges. Repeat on other valve. Add lash to number.
Also you can push open the exhaust valve and look into the cylinder....see your contact point of the Intake valve as a double check.
Gotten away with .070 on the intake and .100 on exhaust. But I think most guys want .100 & .125.
Rule of thumb....advancing cam tightens P/v on intake about .007 per degree....and therefore loosens exhaust that much. Retarding tightens exhaust.....loosens intake p/v clearance.

[blowngas]

Don't forget to check side clearance to the pocket in the piston, either.
I got into that deal one time----marked the piston with 11/32 transfer punch-----measured the valve diameter----added .015 to flycutter to make sure clearance was gona be there-----cut pistons, checked it and valve still hitting piston----just barely on one side of the pocket----problem was, when I punched the piston, it was down in the hole some, and didn't realize it, which changed where the valve center was----had to hand dress all pistons valve reliefs to give clearance----moral of story, check everything 5 times before ya committ!!!