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<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>Since most of you like to play the “death with pistons” game
keep in mind one additional factor as you are building your engines. Over the
years I have found crankshafts which were reground and the throws were not very
precisely indexed. When a crank is setup on the grinding machine for grinding
rod journals it is set and reset by the number of “throws”… on a 4 cylinder
engine the grinder has to be indexed twice and on the 6 cylinder, 3 times. If
the grinder, either the person or the machine is not perfectly accurate you
will see variations of TDC for the throws! I have seen these deviations be as
much as .006” when a good grinder will hold dimensions within .001”. <o:p></o:p></span></p>
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color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>So, if you are running close squishes…. Measure TDC on #1 and #2
on the four cylinder and #1, #2 and #3 on the 6 motors….. this way to can make
sure your throws and TDC’s are spot on.<o:p></o:p></span></p>
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<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>Steve Yott<o:p></o:p></span></p>
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color:#1F497D'><o:p> </o:p></span></p>
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<p class=MsoNormal><b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span></b><span
style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'> John Styduhar
[mailto:johnstydo@gmail.com] <br>
<b>Sent:</b> Thursday, May 26, 2016 4:32 PM<br>
<b>To:</b> Gregmogdoc@surfnetusa.com<br>
<b>Cc:</b> Charly Mitchel; Steve Yott; Jim Gray; Triumph 'Friends of Triumph<br>
<b>Subject:</b> Re: [Fot] TR6 Piston / Head Clearance<o:p></o:p></span></p>
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<p class=MsoNormal>My forged pistons are .006" in the hole at TDC and I
use a .030" thick solid copper head gasket and stock crank at 6200 rpm.
When removing the head, the piston tops are clean in the squish area and it
looks like a slight indentation at the ledge of the combustion chamber,
probably from piston rock when the engine is cold. <o:p></o:p></p>
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<p class=MsoNormal>On Thu, May 26, 2016 at 3:23 PM, <a
href="mailto:Gregmogdoc@surfnetusa.com">Gregmogdoc@surfnetusa.com</a> <<a
href="mailto:Gregmogdoc@surfnetusa.com" target="_blank">Gregmogdoc@surfnetusa.com</a>>
wrote:<o:p></o:p></p>
<p class=MsoNormal style='margin-bottom:12.0pt'>IN our experience with TR-4,
and English Ford Kent<br>
racing engines the safe clearance between the head<br>
and the piston crown is .035". A TR-4 with billet<br>
rods will just "touch" the head at 6800 rpm with<br>
.026" clearance. It will "hit" the head hard enough<br>
to make an imprint in the piston crown at .029"<br>
I would say that the TR-6 crank probably flexes more<br>
than a TR-4 does at high rpm. You would like to have<br>
a little safety margin, I would think. I would not<br>
run less than .035", maybe even a couple more if the<br>
engine is going to run over 6,000 rpm.<br>
<br>
<br>
Greg Solow<br>
The Engine Room<br>
Sports Car Specialists<br>
Santa Cruz, CA 95060<br>
831 429-1800<br>
<br>
<br>
<br>
------- Original Message -------<br>
From : Charly[mailto:<a href="mailto:charly@mitchelplumbing.com">charly@mitchelplumbing.com</a>]<br>
Sent : 5/25/2016 6:52:35 PM<br>
To : <a href="mailto:tr4@wi.rr.com">tr4@wi.rr.com</a>; <a
href="mailto:toodamnfunky@comcast.net">toodamnfunky@comcast.net</a><br>
Cc : <a href="mailto:fot@autox.team.net">fot@autox.team.net</a><br>
Subject : RE: Re: [Fot] TR6 Piston / Head Clearance<br>
<br>
I tried b u idling a TR6 motor with a pop-up on the<br>
piston on c e. Instead of having the pistons cut<br>
down to zero clearance I left them about .005" high.<br>
It eventually bent the rod and broken it. The<br>
pistons had an imprint of the combustion chamber on<br>
them. I learned that at 6000 rpm's, there is<br>
enough deflection in the crank to let them hit the head.<br>
I believe most head gaskets are .0035" aren't they?<br>
Charly Mitchel<br>
TR6 #44<br>
<br>
On Wed 25/05/16 11:31 AM , <a href="mailto:toodamnfunky@comcast.net">toodamnfunky@comcast.net</a>
sent:<br>
> The rattling is likely piston slap on cold forged<br>
pistons. Did it go<br>
> away when it warmed up and came back on the next<br>
cold start ?jim<br>
><br>
> -------------------------<br>
> FROM: "Steve Yott"<br>
> TO: "Robert Lang" , "FOT List"<br>
> SENT: Wednesday, May 25, 2016 11:27:27 AM<br>
> SUBJECT: Re: [Fot] TR6 Piston / Head Clearance<br>
> I doubt that your .030 squish would cause the<br>
rattling as you<br>
> describe. The deflection caused by the crank, rod<br>
and piston in order<br>
> to hit the head at .030 would be way up in the<br>
rpm’s like 8000!<br>
> Did the rattling go away after all the parts warmed<br>
up and oil was<br>
> well disbursed or is it still rattling? My first<br>
guess would be<br>
> either the engine was not pre-oiled or you have<br>
loose piston pin<br>
> bushings…. Were the rods rebuilt with new bushings<br>
fitted to about<br>
> .0003?<br>
> Steve Yott<br>
> FROM: Fot [ mailto:<a href="mailto:fot-bounces@autox.team.net">fot-bounces@autox.team.net</a>
] ON<br>
BEHALF OF Robert<br>
> Lang<br>
> SENT: Wednesday, May 25, 2016 11:29 AM<br>
> TO: FOT List<br>
> SUBJECT: Re: [Fot] TR6 Piston / Head Clearance<br>
> Hi,<br>
> Where I was going with the query was this: I had a<br>
late block<br>
> "decked" with the intent of making the deck flat.<br>
The machinist took<br>
> of .032 to accomplish the goal. With a head gasket<br>
installed and the<br>
> head torqued, the clearance in the squish area is .030.<br>
><br>
> I had initially wanted only about .025 removed, but<br>
we had to shave<br>
> an extra .007 to get rid of the fire ring cuts.<br>
><br>
> On initial startup, the motor sounded like it might<br>
be "rattling" and<br>
> I'm trying to figure out why.<br>
><br>
> When I used a stethescope on the block, everything<br>
sounds okay - no<br>
> rapping and the valve train sounds "normal" and<br>
there were no weird<br>
> sounds coming from the crank.<br>
><br>
> I guess where I'm going with this is: if piston /<br>
head clearance is<br>
> too tight, I'll see some sort of indication on the<br>
piston, right?<br>
><br>
> TIA for any sage advice.<br>
><br>
> This is my first experience "decking" a block. I'd<br>
like to get it<br>
> right, I don't have the resources to start a new<br>
block from scratch.<br>
><br>
> Regards,<br>
><br>
> Bob Lang<br>
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