[Fot] Main brg strap

[Bob Kramer]

Agreed.  Mine was a TR3 block and they had less meat than the later blocks,
thus more susceptible to the cracking. The crack was only found when it got
bigger, multiple head gaskets later. This was in 1997, before I knew any
better.  A healthy TR4 block was the permanent solution.

Bob Kramer


On Tue, Jan 14, 2020 at 3:08 PM Chris Marx via Fot <fot at autox.team.net>
wrote:

> If the block is cracking from head stud to water jacket, it is normally
> caused by tightening the head studs in the block.
>
> To avoid cracks, run the studs in by hand, without any tool. That is
> enough.
>
> Tighten them will split the block.
>
>
>
> The torque of the head nuts are at the limit of what the block can take,
> that’s why the split in the thread hole zone when the studs are wrenched in.
>
>
>
> Cheers
>
> Chris
>
>
>
>
>
> *Von:* Fot <fot-bounces at autox.team.net> *Im Auftrag von *fubog1 via Fot
> *Gesendet:* Dienstag, 14. Januar 2020 22:00
> *An:* fot at autox.team.net
> *Betreff:* Re: [Fot] Main brg strap
>
>
>
> That crack is pretty common with these, a Timesert or similar is the
> correct repair.
>
> Re the center main cap strap, in my experience, these are engines are good
> up to 6.5kish, if it has a good crank & all is within spec and well
> balanced, and the loads are within reasonable limits.
>
> Beyond that the bending loads increase with RPM, due to the recip weight
> heavily loading that center main, and it gets overloaded.
>
> Once the cap deforms and/or fastener stretches, ie it's not round anymore
> and not supporting the bearings, the bad stuff starts to happen.
>
> You can tell if it getting overloaded, measure the center journal very
> carefully, we're into tenths now, and note where the wear is, it's normally
> even all around the journal.
>
> When the load gets too heavy the wear will be mostly on the crankpin side
> of the journal; it will be very obvious.
>
> At that point a center strap will help for sure but the loads will still
> be there unless weight is reduced.
>
> This is why I try to focus on torque vs high RPM HP with these engines.
>
>
>
> Glen
>
>
>
>
>
> On Mon, Jan 13, 2020 at 10:43 PM Nick Black via Fot <fot at autox.team.net>
> wrote:
>
> Well it’s finally time to build a new motor... the crack at the rear head
> bolt just won’t stop leakin anymore...so...
> I’ve found the Chevy front strap to use on the center main, but what are
> you using for main bolts/studs for the additional length?
> How about a complete set of fasteners for the mains? Does ARP make
> anything?
>
> Motoring on in NORCAL
> Nick
>
> Sent from the wilds of NorCal
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