I check them allways but i dont hardly ever do stock rebuilds...remember that radial clearance is important too.

 

Duration?

Lift is not an issue, but duration is. The only time the piston is close to the valves is that split second as the piston is moving to the top of the exhaust stroke, chasing the exhaust valve as it is closing, and subsequently the intake beginning to open, chasing the piston down.

What is the duration of your camshaft?

 

Lift is not an issue, but duration is. The only time the piston is close to the valves is that split second as the piston is moving to the top of the exhaust stroke, chasing the exhaust valve as it is closing, and subsequently the intake beginning to open, chasing the piston down.

What is the duration of your camshaft?

WELL THIS CAM HAS THESE SPEC'S BUT MY QUESTION IS MORE ON THE GENERAL SIDE, SO IF DURATION IS THE CULPRIT AT WHAT DURATION IS IT TIME TO CHECK THE CLEARANCES
Adv duration 277/289
@.050 251/259
Lift .596/.600 w/lash
Lash .008/.012 (nice and quiet)
Lsa 110 Deg
ICL 104

 

I'm not real sure where the line is. Your cam grind definitely needs to have the valve to piston and all other typical valve train checks done.

Just guessin', I'd say around 225-230º@.050" is the middle of the gray stripe. Thing is, I can't remember the last time I had something like that. It's either much milder or much more radical.

 

No doubt you need to check...and record your clearances for example if you later on want to change your cam phasing and also to know where your 'safe' redline is...valvefloat is nasty stuff with super tigth combo.

 

GREAT IDEA WILL DO.

 

piston type ?

What type of piston are you using? Big block or small block?
Most dish types will clear easily. piston to deck clearance?

 

What type of piston are you using? Big block or small block?
Most dish types will clear easily. piston to deck clearance?

GM FORGED .100 DOMED
ZERO DECKED

 

My basic rule of thumb is you must check SBC above .500 and BBC above .600. This of course assumes stock valve angles etc. Not a hard and fast rule but a general guideline, Roller cams typically have less trouble with clearence than flat tappet due to severe ramps.

 

ideally, you would always check this on any engine. If you were building engines constantly, you would have learned which are necesary from experience but guessing, as the cam size gets bigger can always be a problem, therefore you always check it. Kind of like CNC's "always sonic test", if you don't check clearance you may be lucky many times but one time it may bite you.

 

ideally, you would always check this on any engine.

I CAN'T BELIEVE ALWAYS IS THE ANSWER.

 

OK I BELIEVE I HAVE TO CUT MY PISTON FOR CLEARANCE, I HAVE LOADED A PICTURE OF THE #1 CYLINDER I USED PLUMMERS PUDDY , I INSTALLED HEAD WITH GASKET AND SNUGGED IT DOWN WITH FEW BOLTS INSTALLED PUSH RODS AND ROCKERS VALVES HAVE CHECKING SPRINGS, I THEN ROTATED IT OVER SEVERAL TIMES AND HERE IS THE PICTURE OF WHAT I SAW AFTER REMOVING HEAD AND TAKING A PEAK.


I THEN PUT A DEGREE WHEEL ON THE CRANK,PUT THE HEAD ON,INSTALLED ROCKERS SETUP A DIAL INDICATOR ON THE INTAKE RETAINER, AND THEN STARTING AT TDC TURNED THE CRANK AND CHECKED THE CLEARANCE EVERY 10 DEGREES ON THE DEGREE WHEEL AT ONE POINT 10 DEGREES BEFORE OR AFTER, I FORGOT NOW, I MEASURED .010 CLEARANCE BETWEEN INTAKE VALVE AND PISTON.SO I QUESS NOW I HAVE TO CUT THE PISTONS FOR CLEARANCE IS THAT CORRECT? SHOULD I LOOK FOR A CLEARANCE OF ABOUT .080?TWO STEPS FORWARD 1 STEP BACK UNTIL I GET THERE.
I HAVE THE SHORT BLOCK ALL PUT TOGETHER.SHIT.

 

So how thick is the putty now?

Edit: Sorry, I missed that you said .010".

Are you using a solid lifter? If you are using a hydraulic lifter, hopefully your checking springs are very weak. Otherwise your hydraulic lifter may be collapsing and as a result you may be seeing more clearance than you have.

Also be careful that you have adequate clearance around the edge of the valve (looks ok in the photo, but the photo may also show that the putty is thinner on the left side than the right side (though this may be my interpretation of the photo, not reality). The other thing is that you should check that the current valve relief is machined parallel to the valve face.

How much clearance you need is subjective. .080" and .100" on the exhaust is a conservative number. I've done engines with as little as .055" intake and .075" on the exhaust, but you need to be very precise, and check every cylinder, both valves.

 

So how thick is the putty now?

I use wire solder - easier to to deal with & much easier to ck thickness. As you can see putty is difficult to measure precisely - .125 dia covers all situations. Use a couple of drops of "crazy glue" to hold it to top of piston, in eyebrows or wherever - cleans right off when finished.

 

I always do my piston to valve checking when doing my first mock up. no rings on pistons jut no1 and no6. this way I haven't assembled the whole thing and have to take it apart. depending on your cam choice you may be able to retard it a few degrees and gain some clearence , but it may not run as good as you want.

 

YES I KNOW NOW I GOT AHEAD OF MYSELF, I CHANGED MY THE BUILD IN MID STRIDE. I NOW HAVE TO JUST BITE THE BULLET AND TEAR IT BACK DOWN TO HAVE THE PISTONS CUT, HOPE THERE IS ENOUGH MEAT ON THE PISTONS.IF SOMEONE HAS A GOOD IDEA TO CUT THEM IN THE BLOCK LET ME KNOW, BUT I DON'T THINK THAT WOULD BE THE WAY TO GO.

 

There are really two steps that should be done on any engine. First is the depth of the valve relief in the piston, start by installing and properly degreeing the cam. I usually install one piston in each side but only check the second if the first is close or if the piston valve pockets need machined. Next install the head complete with correct head gasket, but with soft valve springs. I always use a used one that would be already compressed and don't actually torque the head just very snug with the bolts around the cylinder I'm checking. Next install push rods and rockers and set the valve lash. Set a dial indicator on the valve retainer. When you check the intake side begin checking it as the valve starts to open you will quickly find the closest spot by actually pushing the valve down till it hits the piston then while turning the engine find the closet point. release the valve back to the seat and zero the indicator and take a reading at your closest clearance point. The exhaust is checked the same except it will be closest while it is closing. The second check is the diameter of the valve relief. I set the engine up basically the same as before except with no valves in the head and with the piston at top dead center then insert a transfer punch down through the valve guide and very lightly just with my fingers dot the top of the piston. Remove the head and with a set of dividers set to half the diameter of your valve you can swing the valve pockets in your piston and understand how much clearance you have. As for as clearance goes, on a steel rod common forged piston at relative low rpm i would keep the Intake depth at a .080 minimum and .120 on the exhaust. On the diameter of the pocket I would keep a minimum of .050 per side not diameter. If you use lighter engine components such as aluminum rods,light weight pistons, titanium valves,retainers, etc you can tighten things up considerably closer but only should if you need. The method I described would be utilized after first checking with clay. If you obviously have more clearance than described then you don't need to do. I hope this helps.

 

I HAVE THIS PRINTED OUT THANKS.

 

Try this on engine piston fly cutter. I think it is easier to pull the engine down myself.


http://www.etsupply.com/edgetools/lindyfiles/adjpiston.html

 

I THOUGHT ABOUT IT, BUT NO, I,LL TEAR IT DOWN, IT WON'T TAKE THAT LONG. IM VERY PISSED AT MYSELF, I'M BETTER THAN THAT.

 

Cut that putty with a sharp knife, its alot easier to measure. Oh man, i'm glad that you checked the clearances!!

 

I CUT IT WITH A RAZOR, I MESSED AROUND WITH IT, IS WHY IT LOOKS SO.
ME TOO.

 

Great work. I think I would have just pulled it apart you have more patience than me.