I tried b u idling a TR6 motor with a pop-up on the piston on c e. Instead of
having the pistons cut
down to zero clearance I left them about .005" high. It eventually bent the rod
and broken it. The
pistons had an imprint of the combustion chamber on them. I learned that at
6000 rpm's, there is
enough deflection in the crank to let them hit the head.
I believe most head gaskets are .0035" aren't they?
Charly Mitchel
TR6 #44
On Wed 25/05/16 11:31 AM , toodamnfunky@comcast.net sent:
> The rattling is likely piston slap on cold forged pistons. Did it go
> away when it warmed up and came back on the next cold start ?jim
>
> -------------------------
> FROM: "Steve Yott"
> TO: "Robert Lang" , "FOT List"
> SENT: Wednesday, May 25, 2016 11:27:27 AM
> SUBJECT: Re: [Fot] TR6 Piston / Head Clearance
> I doubt that your .030 squish would cause the rattling as you
> describe. The deflection caused by the crank, rod and piston in order
> to hit the head at .030 would be way up in the rpmâ??s like 8000!
> Did the rattling go away after all the parts warmed up and oil was
> well disbursed or is it still rattling? My first guess would be
> either the engine was not pre-oiled or you have loose piston pin
> bushingsâ?¦. Were the rods rebuilt with new bushings fitted to about
> .0003?
> Steve Yott
> FROM: Fot [mailto:fot-bounces@autox.team.net] ON BEHALF OF Robert
> Lang
> SENT: Wednesday, May 25, 2016 11:29 AM
> TO: FOT List
> SUBJECT: Re: [Fot] TR6 Piston / Head Clearance
> Hi,
> Where I was going with the query was this: I had a late block
> "decked" with the intent of making the deck flat. The machinist took
> of .032 to accomplish the goal. With a head gasket installed and the
> head torqued, the clearance in the squish area is .030.
>
> I had initially wanted only about .025 removed, but we had to shave
> an extra .007 to get rid of the fire ring cuts.
>
> On initial startup, the motor sounded like it might be "rattling" and
> I'm trying to figure out why.
>
> When I used a stethescope on the block, everything sounds okay - no
> rapping and the valve train sounds "normal" and there were no weird
> sounds coming from the crank.
>
> I guess where I'm going with this is: if piston / head clearance is
> too tight, I'll see some sort of indication on the piston, right?
>
> TIA for any sage advice.
>
> This is my first experience "decking" a block. I'd like to get it
> right, I don't have the resources to start a new block from scratch.
>
> Regards,
>
> Bob Lang
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