[Fot] Main brg strap

[tr4racing at googlemail.com]

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 <mailto: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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