Bore Notching
 

I will be be bore notching a +.030 over 454.

Do I notch to match the cyl. head combustion chamber?

Thanks

Scribe the head gasket chamber. Stay away ring depth.

Bore notching is said to be worth about 30hp or so on a 454-468cid engine and is a simple/easy free HP job---just so you know and be aware that your compression ratio will drop some when bore notching the cylinders though. Have fun.

DONT SCREW UP THE BLOCK BY MAKING THE VALVE RELIEF NOTCH CUT TOO DEEP DOWN length of THE BORE.

.........otherwise the top piston ring will not seal....!!!!

3/16" into the bore and gasket as template is ample, all you're trying to do is unshroud the intake valve

I agree,...and I should also add that the "30hp gain" is something that was told to me by someone years ago from some back to back dyno testing that was said to have been done here locally so, not exactly sure how true or accurate the "30hp" claim is, but logic would say there should at least be some HP/TQ benefit from the un-shrouding the valves. Whether it is worth 30hp or not I do not know as I have nothing to back up that quote.

The GM factory did it on their 454 blocks...although it appeared to be kind of a crude machining type of fly-cut process, they must have still thought they had a good enough of a reason to make it worth doing.

Also consider whether the block was decked. If somebody shaved 020 to zero deck the pistons the rings are up that much higher. I would assemble and check where rings actually top out before notching...

The block has been decked .020 making the piston to deck zero. I will be using layout dye and making templates to keep each notch the same. I plan to stay .100/.125 from the top ring. The compression ratio calculators say I should be right around 10 / 1 so lowering it a bit will be just fine with me.

Thank you for the advice.

How is your valve shrouding situation within the combustion chamber itself? What heads are you using?

I will be using AFR 305 heads once they get to me.

can you tell us more about this build.

Here is a pick of my 454 bore notch. When Valako did this to my blocks he said he saw 25-30hp on back to back dyno runs. I believe they pulled the heads off on the dyno, bore notched the engine, and then made more dyno pulls. This was a built 454 and I believe it was running 2.30" valves.
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+1 an Jim Valako. Jim can compete on price and his BBC heads will flow more and make more power than the AFR 305 heads. Also, the AFR exhaust ports are something less than great. As you are also in MI, it is worth a phone call.

Just curious how much power will these heads make? and what's wrong with the AFR exhaust port?

Ive seen a few engine builders and cylinder head specialists state that, the published flow numbers on the AFRs, do not live up to their claims. .

As far as JimV, he used to be the go to guy here on oso years back for cylinder head work. http://www.valakoraceheads.com/

He had alot of happy customers right here on oso. He probably doesnt post much any more because of threads like this one below.

http://www.offshoreonly.com/forums/g...s-540-sci.html

My build is not looking for the absolute max hp. It was supposed to be a low dollar re-fresh of a 25yr old engine. It has grown exponentially.

1988 Mag 454 bored .030
Wiseco pistons +21cc domes
K1 rods
AFR 305 cyl. heads 114 cc chambers
Scorpion rockers 1.7
Victor Jr manifold
Holley 850 carb
Gil manifolds w/ Hardin aluminum risers wet
Morel roller lifters
Cam TBD Bob Madura will be consulted

Rookie Thanks for the pic. It is worth a thousand words.

Thanks

I'm not going to ruin the OP's thread I'll start another thread on this.

Sounds like a nice build

that's why I said 3/16" of an inch is ample... there will be no ring interference regardless of "0" decking the block

Did the bore notching today.
Big thanks to Rookie for the pics.
Did not make a template. Used the head gasket, layout dye, a sharpie and a drum sander to notch the bores.

On my way back together.

No problem, I'm glad I could help.