Check out my car and talk to me about 318/340 swap

moparmat2000 said
Now that I am done at work today and have time to reply, heres for all you smart guys on here talking about running 360 heads on a teener. That performance gain is all in your mind. Heres 3 models for you to look at. Standard bore 318, stock rod ratio, pistons TDC .080" in the hole, and I will give it 5cc valve reliefs from a quickee rebuild. .038" compressed height felpro permatorque headgasket with a 4.03" diameter. Real common autopart store stuff. And the 72CC 360 heads. The first model shows 7.46-1 compression with them 72cc 360 heads on a stock 318 with stock pistons. Hardly an effing hot rod

Second model I changed nothing on the equation but stuck 60cc heads on it. CR jumps to 8.34-1. Better yes, but about a stock 318 running on rat piss.

The 3rd and final model I changed the heads to 62cc, and put the piston at near zero deck height with 5cc valve reliefs. This is typical of the KB167, and some decking. That shows 9.66-1 compression. A nice pump gas hot 318.

In closing are ya gonna get there with a low compression 318 short block and 360 heads. Hardly. You may get closer with zero deck flat tops and them 360 heads, but not on a stock low compression 318 your not. The numbers dont lie

LOL, I don't play with "computer" power. Your problem is: 1 not all 318's are the same; 2 Your cc are off, have you cc'd the heads you are talking about? I used Justin's numbers 68 cc for 675 casting number 318 heads, I trust his are right. Virgin stock closed chamber 273 heads measure about 65 cc, so not sure where you find 60 cc 318 heads. I personally have cc'd J heads, virgin untouched stock, and the largest chamber measures about 73cc. The example I gave was a J head milled 020 cc'd to about 69 cc. That leaves 1 cc larger chamber that a stock 318 chamber. Why mill heads? Because after time and thermal cycles they are not flat anymore. My machine shop charges one price up to .020, so that is what I do. So, your big compression difference is nonexistent. If you read my post the first time. The rest is what combination you use to make it work. There are more ways to mess that up than I care to think about, let alone gears and torque convertors. Airflow is what makes power, I use the best heads I can. No matter what size engine I am building.