I decided to try this out n my daily driver. It is a 1995 Chevrolet K1500 4x4.

I like this truck for a number of reasons. Its paid for, parts are cheap, its dependable, it looks good, its fairly comfortable to drive and it has ample capacity to drag anything around I may need. What I do not like is the milage, averages around 13.5 mpg between city and highway. The best I have ever gotten has been 17.5 mpg on the highway on only 2 tankfuls in the 35,000 miles I have put on it since I owned it. So what better vehicle to try this on!

Plus with 164,000 miles on it, those valve seals are probably leaking a bit anyway.

To start with I needed to see where I am at, that way I can detail what kind of improvements became
from this head modification. I already know my milage from logging it over the last 35,000 miles. Also why not compare the power and torque out put of the engine. To do that I went into Philly Dyno Works and ran it on their DynoJet inertia dyno. Below shows the graphical results of the before and after modification. There are 2 runs from before and 2 runs from after. The before is the stock engine just as it left the factory 11 years and 164,000 miles ago. The after runs are with the head modification detailed below. The truck has an automatic governor that cuts the engine out when you hit 100 mph, so in 3rd gear with the torque converter off, that was as far as I could take the graph. Redline is 5000 rpm for the engine, but 100 mph came a bit sooner.

Now to find a set of heads! I located a set of heads on ebay that looked like they would work as they were similar to the casting number I thought I had on the engine. Later, I found out, these were in fact the same casting number as was on the truck (14102193) so that was even better! Now to figure out what I had and what I wanted to do.

Here are the finished results of the heads, painted and ready to go. To check everything I did a mock up on an 1987 chevy block I had. I found out I had to shave the intake to get it to fit. To simulate the head gaskets there are 2 layers of file folders squished in between the heads and block. You can see how the grooves look from the inside in the one picture.

Now for the real work! Time to disassemble the engine down to the short block! The hardest part was getting the power streering pump out. The pulley was pressed on, and that had to be pulled off with a puller so I could get at the bolts to get the pump off the bracket. It had to come off the bracket because it blocked a single bolt that held the bracket to the head. What a pain! Other than that I took my time and made sure I did not do anything detrimental. Also a good shop vacuum works great for sucking all the crud that will inevitably fall into the cylinder bores when you pop the old heads off.

Here is putting it all back together! I gave up about 2 am Sunday morning and got some sleep. Started fresh at 9 am and worked through the day. Then at 8 pm, the most exciting moment! Time to fire it up and see if I put everything back together right or not! Did I put that distributor back in right? Were all those plug wires in the right spot? Did I adjust those rocker arms correctly? Would there be any unfortuate oil or coolant leaks? Yikes... I almost thought of just leaving it as it looked pretty good without starting it... but I didnt... Turned the key and it fired right up! VROOM! SUCCESS!

Well that chronicles the groovy heads thus far. The valves seem to have seated and the idle is very smooth, down to 550 rpm in gear and it stays very smooth. The second dyno run confirms botht he power and torque increase. Initially there was a slight, but noticible knock right off idle under light to moderate load. I could get it to do it by holding the brake in gear and reving it up to 1100 rpm in the driveway. Step on the gas more and it would go away as you rev past 1500 rpm. I ran about 1/3 cup of water through each bore on the throttle body to try and steam clean off the tops of the pistons and then just put some miles on it. After a week or so, it seems to have disappeared. Either there was excess buildup (from the last 164,000 miles) on the pistons that were getting in the way of the squish area, or the ECU has learned to shift the timing as to control the knock at these points. Either way, it looks like we are in the clear and time to see road milage and performace.