BBC head bolt hole near engine mount boss -blocked off by casting ???

caribbean · Aug 22, 2008

I have a "HI PER PASS" 2 bolt main 454 block that I am working on

In using the tap to clear all the head bolt holes, I found a hole on the exhaust side directly above one of the top engine mount bosses to have a piece of casting related to the mount boss protruding into the bolt hole

The threads are blocked off partially on one side near the end of the threads by what is a piece of casting that forms the mount boss -

so in tightening up that bolt - unless it goes to a precise depth - the bolt is likely to butt into the casting and give a false torque reading or worse off - be damaged

any one has any experience with this and what is to be done in this case

BillK · Aug 23, 2008

tk,
I know what you are talking about, but have never had a problem with it. The head bolts dont go that far down.

swcash · Aug 23, 2008

If you check your head bolts against a head, you can see that the head bolts only thread into the block less than 1" and the motor mount boss is further away is it not?
Squido

caribbean · Aug 23, 2008

well glad to hear I am not dealing with a bad core here -

I guess because most of the other holes the tap could go right through and nearly fall into the block - this one caused me some concern

it certainly looks like "less than an inch" depth for sure -will check depth as suggested

thanks

forcd ind · Aug 23, 2008

be reallllllllllllllll careful chasing threads, dont put much force trying to turn the tap deep down
a buddy broke a tap off down in one of the holes-i was able to burn it out with a tourch w/o any damage(bolt still torqed) i suspect the tap caught on a piece of cast iron protruding in

BBC head bolt hole near engine mount boss -blocked off by casting ???

caribbean

BillK

swcash

caribbean

forcd ind

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