thanks oh wise one.....nice take on the "bending moment." I guess you have a good point and examples to back it up. I just remember several machinists/engine builders and maybe a book and a magazine or 2 trying to say straight is right.....yeah yeah, I know reading car magazines is the devil!

 

I have to take exception to your conclusion, Brutus:

The bolts, as well as the studs are used in tension, not bending. In other words, all they do is clamp. Note that the bolts are not a tight fit in the holes, and the block area where the cap seats is recessed slightly, so the cap can't move side-to-side. You have to tap it into place. If it moved more than a few thou laterally you'd probably wipe out the bearings. With the (vertical) studs tight, you can easily slip the bolts into their threads by hand. No side loads at all.

Also note that the bolt head seats flat on an angled surface of the cap. There is no bending of the bolt unless the machining of the cap or block is bad.

IMO, the 20 degree splay angle used on Bowtie blocks was chosen to get the outer bolts into the meatiest part of the block between the lowest area of two adjacent cylinders. I can't see a stronger place to put it, at least on the 24502503, the CNC version of the 10051184 Bowtie block I just examined.

 

After assessing a few diagrams and thinking it over in my head about how the loads are actually dispersed, I'd have to concur. Thanks for the resolution. P.S.-I'm forwarding this to the editor of Hot Rod...I believe that was the magazine insisting straight is best.

 

Had to LOL. Unfortunately some of the opinions expressed in some of the car mags don't have too much basis in fact.

An exception is stuff by Marlan Davis. He's usually quite well researched and right on (unless the editor changes a few key words).

In some blocks straight might be just as good. It's the reasons for why something is done that get folks confused. Hey, the block doesn't know or care why the builder put in straight or splayed (love that word!) bolts/studs; it just does its best with what it has. Maybe it's too bad magazines writers aren't that real.

To be fair, one well known magazine Tech guy (not Marlan) is an aquaintance. We've had some talks on the phone and over some beers. He's very knowledgable about a lot of things, but he does have his own ideas on some things which don't always prove to be true. He's paid to write to get readers to buy the mag, but not necessarily to be the expert on everything. I respect him a lot for what he does, and read about everything he ever writes. He's cool.

Hey nobody knows everything from A to Z. (I've said I'm only up to Q or so!). Much of the agreement on this forum is about how things work, but much of the disagreement is about why, as it should be. Unfortunately, some of the more knowledgable folks may be too shy to speak out.

You know the old question: "How do you recognize an extroverted theorist?" Answer: "He looks at your shoes when he's talking with you." Apologies to anyone who this offends. Feel free to insert "engineer" "scientist" or "codewriter" for "theorist".

End of off-topic ramble. I still prefer splayed.