Pantera24, Tinkerboater and I bore notched my 454 (+ .060" for 468cid) and it was rather easy. If you take the head gasket and lay it over the bore, you now have a great template for bore notching. The gasket will be the same as the combustion chamber....including the path of the valves. Lay a gasket on your block, see how much steel is "in the way" of air flow. If you take some of this material out, angled toward the valve, you in effect straighten the flow of air. This is more important on the exhaust side.....you want to get all the charge out of the chamber on each stroke.

Hey Kaama, I went to Jim V's websight as you suggested and checked out the bore notching. It is hard to see, but I get the idea. Question would be, I also have a 509ci 4.500" bore. Do you think that bore notching this motor will give it any noticable gain for the expense. Also, is this something that my machine shop here in Cincy willbe faimliar with, or is this less common of a procedure?? Motor is most likely coming out in a few weeks for head wrok and dyno time, this would be the time to bore notch. thanks.

Allan4, When dealing with a 4.500" bore, your pretty much at the point to where the bore is large enough that bore notching is no longer necessary. I have 4.500" bores on my engines as well and they have been bore notched only a HAIR! Maybe 1/16" of metal has been removed. However, as I have previously stated, it will make a much bigger difference on a 454 which is about 30hp/tq of difference on the bore of a 454 bore of 4.250". Whereas on a 502 bore which is 4.470" or a 509 bore which is 4.500", it will NOT make that much difference because bores are much larger and no longer has an adverse effect of valve shrouding.

Pantera24-650HP, find a thread where "JimV" has made a post and click on the word "PROFILE" a page will pop up and then click on his homepage address. When his homepage pops up click on the word "Tech Tips" and a picture will pop up with some details underneath. You have to look hard for the bore notching process. Go take a peek!

I was wondering about the effect of a bore job and ran it on Dyno2000 software. I think I saw about a 3 HP gain.

JimV, did actual back to back dyno tests with just bore notching alone on Earhart's dyno and found it to be worth about 30hp/tq across the entire RPM range! At least that's what he told me and besides, you can do it yourself, takes maybe 1.5-2hrs to do it and only requires a die grinder, air compressor, and some other very inexpensive tools. You can't really lose unless you REALLY BOTCH IT UP!

Wow, that bore notching looks like a piece of cake, with a little patience and attention to detail. Other than the die grinder and some emery cloth, what else is needed? I'll need to do this with piston in place, so other than obvious issues of cleanliness, are there any suggestions to do a better job? Waterfoul, what kind of result did you feel you got from the job? How much negative impact would stock exhaust have on the effort?

BT

bt, you'll need some blue scribing ink, a scribe and you'll need to use the same exact head gaskets as you plan to use when figuring where how far to grind so that you do NOT go beyond the edge of the gasket. Obviously, you do NOT want to go any lower than the highest point of travel of the top ring groove of the piston within the cylinder bore.

Kaama, I have a pretty good carbon ring on the top of the cylinder, so I'll stay .060 or so above that for safety. Got my 1027 gaskets today, so scribing is good. Thanks for the help. Any more 30hp (free) tips are welcome!!

BT/Dave

I'm not sure what kind of gains I got from notching. I changed a LOT of other things at the same time. I did it at the recomendation of KAAMA, Crazyhorse, Tinkerboater, JimV, and a host of others with more knowledge than I have!!!

If you do it with the pistons in, stuff some paper towel in the bore to catch the shavings. And do each bore with the piston at the bottom of the stroke.

Mike

I'm with you waterfoul. I was thinking cleaning the cylinders with laquer thinner, then duct tape all around. I have all winter so wtf. Keeps me away from mamas jobs!!

Thanks for the help,

BT