Getting a “head” of the curve, Part 2
Hi everyone and welcome back! Man, has this last month flown by! Things at Roeder Performance Machine, my business, have been insanely busy lately. Trying to find time to work on my own projects has been a job in itself but for you the loyal reader I found a way! Of course, losing four stinking days to a winter ice storm that took out all the power for four days didn’t help anything! Iowa winters, you gotta love it, or move. Now onto the meat and taters of the article.
Last month I introduced you to the Racing Head Service 200cc aluminum cylinder heads I am using on the new 347 stroker for Project Muscrate. With a little basic “gasket matching” and smoothing out the “knobblies” in the port and pocket area I was able to see a peak of 290 cfm and a pretty nice flow curve along with it. My plan is to not get into any fancy porting that the average hot rodder may not be able to handle. I want to demonstrate what is relatively easily attainable for anyone with the basic hand tools and a little skill and patience.
Since the last installment I have tried a couple things that normally show some gains in flow and are pretty simple to do. The first thing I did was to lay out the head gasket pattern on the combustion face of the head by using some bluing die, a head gasket, and a scribe. I wanted to see how much “shrouding” of the valves there was by the walls of the combustion chamber. To do this you simply brush on the die, lay the gasket on the head making sure to line up the head bolt holes and dowel holes for reference, and scribe the gasket circumference onto the head. Then the basic idea is to carefully grind away any material that is inside of the scribe marks and around the vicinity of the valves.
Absolutely do not grind too much and cross over your scribe marks! If you grind too much and go over the line you may have just gotten rid of the surface the gasket uses to seal in the compression. That is bad. Fortunately for most people these heads did not have much of a shrouding problem so there wasn’t much to grind away, and unfortunately for me there also wasn’t much of a gain. But, it all adds up.