Topic: Piston to valve clearance-do I need to check this? Opinions...?

[Jerry E.]

I am building an 836 motor(1975 FO), using the Wiseco (10.25 comp. ratio) pistons, which say they are relieved for high lift cams. I am using the 125-00 (smallest lift) Megacycle cam, and the head has been milled .010   Do I need to clay the piston's for valve clearance, since I am using a small lift cam? Has anyone any experience with this setup, regarding valve clearance?  The piston's have reliefs cut in them, factory. If I do clay them, do I need to install the rings on the piston's, since will need to assemble cylanders/piston's/head w/clay, then dissassemble/ reassemble during final assembly of the motor. Would hate to break a ring. Do I need to torqe everything tight to spec, and buy more gaskets for final assembly? 

[MCRider]

How can one answer this? There is only one answer, yes, you should clay the pistons.

Now that the formalities are out of the way,  , you should be fine. Just be sure to turn the engine thru a few turns to be sure you don't have contact, before actually lighting it up.

Yes, that comes from experience with Powroll pistons, ACtion4s, and ARIAS 888cc pistons (10.x to 1) with small lift cams.  No WiseCo though.  Dirty little secret its a step that is often skipped. (I refer you back to the first line).

If you do do it, no you don't have to have the rings on, and that will obviously save some time and effort. Don't crush the head gasket, but allow some room in your clay as if you had. I've heard 10 to 20 thou for the amount of crush of the head cheeze.

OCICBW

[754]

 Good engine building practice, says check everything... Leaving things to chance,  even if it is "supposed to fit"..is a road littered with broken parts, extra costs, low hour used gaskets, etc, etc..

[Jerry E.]

That's kinda what I thought. Was hoping some wise old timer would say,"save the effort, no problem." New better, I guess, but had to ask.

[MRieck]

From experience you will have no problems with that combo. The Wiseco 750/915 reliefs are so large and deep you can mill .030 off the head and deck the cylinder at least .010 AND use a .400 lift cam and still have plenty of room. On the hand......I check everything. I can teach a chimp to assembe an engine but it takes a craftsmen to build an engine.

[MCRider]

Uuummmm bananas  Yum   

[MRieck]

Uuummmm bananas  Yum   

Hey, hey hey MC.....you are a bit higher on the evolution ladder than that.

[MCRider]

Uuummmm bananas  Yum   

Hey, hey hey MC.....you are a bit higher on the evolution ladder than that.

Not much, ask my wife.   

[Jerry E.]

Alright, now you talked me into doing it, for sure. lol  Just for the experience of doing it, and piece of mind. My hotrod motor has heads milled.030, with a .576 lift cam in it, but I don't think I clayed that engine. It's been a few years tho, maybe I just forget. Either way, I lucked out with that build, I guess, since I've flogged that motor quite a few times over the years with no problems. Thanks for the input.

[754]

 There is a way the RC eng  guys Checked externally..
Put an. Indikatoren, on the valve collar, get to full lift..ZERO Indikator.  . Now place big screwdriver on rocker framework ( cam bearing holder), and lift the rocker pädagogische till valve stops..note indicates reading..
 Only good on 750s

[bwaller]

You having a stroke Frank? 

[scottly]

TRW 836 piston, with a low lift cam. Notice the "clearance" the valve pounded into the piston near the bottom of the pic. Luckily, no serious damage was done.

[MCRider]

TRW 836 piston, with a low lift cam. Notice the "clearance" the valve pounded into the piston near the bottom of the pic. Luckily, no serious damage was done.

I did that one time with some Yosh 750 HC pistons (750cc) and a high lift cam. The fact that it started and ran, and ran very well makes me wonder if damage like that (assuming your motor was still running too) is a result of valve float from over revving, and not so much an assembly clearance issue. IDK

I never reassembled my engine. Had taken it apart for other reasons. Like a bent rod.   

[scottly]

My motor had definitely been over-revved, but was still running well when I tore it apart and found the evidence of the valves hitting the pistons. I don't believe valve float would have made such deep dents, but it is a possibility. Big Jay did mention that the TRW pistons required added clearance on the exhaust side....

[MCRider]

My motor had definitely been over-revved, but was still running well when I tore it apart and found the evidence of the valves hitting the pistons. I don't believe valve float would have made such deep dents, but it is a possibility. Big Jay did mention that the TRW pistons required added clearance on the exhaust side....

Ah.

[754]

 Geez, I finally got a modern device.. BlackBerry tablet playbook..
 The oddocorrect drives me freaking bananas, if you don't proof what you know you typed, it looks retarded....not to mention when the language choice button gets accidently hit..