Getting ready to assemble my 496(non metric) this coming week and have been going back and fourth on wether to bore notch the block or not. Need opinions from those whom have actually done this.

Specs:

454 Gen V block w/ 4.310 bore
Forged pistons with 12cc dome
Dart pro 1 alum heads with 121cc combustion chambers 2.19 intake/ 1.88 exh

I've never notched a block, however, it doesn't seem too complicated, just need to be very careful not to cut into the upper rings area of travel. My local machinist wants about $350 to do this. To me that sounds a bit ridiculous. Thanks for your opinions!

That is ridiculous for an hour of labor. But do it and why so small intake valves on the good heads? I put 2.30"s in mine 4.320" bore.

These pro 1's came with the 2.19's and they flow quite well for my build, (600+hp) and on the advice of DART, decided going up in size wasn't worth the expense. If it's about 15hp or so I really could care less, and after in depth convos with tech and others who have built similar, it seems this is the consensus. That said, an hour or two grinding some proper notches for 30hp, seems like a no brainer. I appreciate the input!

Also, how much conpression is lost on average doing this? I would think its minimal if any.

That is ridiculous and the loss of compression is minimal.use your gasket and keep w/ .010" away when you scribe.

It is real easy on cylinders that have marks from the top ring - just stay at least 1/16 th above that line. Scribe the outline of the head gasket on the top of the block and stay off the line. I have done it on many blocks and for a few friends for free. It should take someone that has done it more than once less than an hour.
On a 454 it adds 25 HP.

Beau,

A relatively simple process, well worth the additional effort.

Here's a link to detailed instructions. You will need to use tools to invert page 2.

http://www.mediafire.com/view/rlk90l...re_Relieve.pdf

Bob

Dang Bob, my neck is getting sore. And I tried using my tools, but I can't see where my crescent wrench is going to help with this.

Good article, and very simple process for some free horsepower.

They come in handy to throw when you're pissed off in the garage...that's the best use for them.