Porting 101

The "J" heads that our 360 has are the same basic heads as the highly sought after "X" heads, with the exception of a 1.88 intake valve instead of a 2.02. Even with its fairly good airflow capabilities for an engine of this nature, a little port work consisting of gasket matching and removing some of the "pinch" at the pushrod location was about all we were going to do. To save a little money, I did the basic porting myself. Then the heads were given to Jerry Wilt at Wilt Engine Services in Lakeland, Florida. We had Jerry shave .020 inch from the deck surface. Any more than that and the possibility of intake alignment becomes an issue. We also needed the new valvesprings installed and the guides machined for new positive locking seals. The reason the guides needed machining was the stock valvesprings are a single spring and the Lunati springs for the new cam are a triple spring. Room needed to be made for the smaller inner diameter of the spring and the positive locking seals as apposed to the stock umbrella-type seals. Also, since we are using "seasoned" valves, a three-angle valve job wouldn't hurt either. We also got new retainers for the springs and then had Jerry assemble the whole mess.

Piecing The Puzzle Together

With all the pieces back at the shop, it was time to put it all back together. We first installed the Lunati cam and degreed it in according to the cam card. Next, we used Fel-Pro head gaskets (PN 1008) with a crush thickness of .039 between the block and the heads. The pistons are around .080 in the hole, and in hindsight, the MP Gaskets (PN P4120094) may have been a better choice. The MP gaskets have a crush thickness of .024-.028. That would have bumped the compression just slightly higher and helped the quench a little. With the heads bolted back on using the stock head bolts, the intake--a Weiand X-CELerator single-plane PN 7545--was gasket matched and installed. The X-CELerator is a good intake for the 1,500-7,000 rpm range, and the square-bore mounting flange meant we wouldn't need an adapter plate to mount the carb.

Was It Worth It?

After the engine was reassembled and put back in the car, it was time for some dyno thrashing. We spent the day at Norris Motorsports in Ocoee, Florida, on Mike's Dynojet chassis dyno. With some simple tuning, we had to settle for 292 hp. There is definitely more horsepower in the engine, and I think our cam choice may have something to do with these numbers. Not that the Lunati cam is the issue. On the contrary, our choice of a 235 duration at .050 is the factor; another time where the advise of the cam manufacturer should have been asked. On the plus side, when we upgrade to a better set of heads, this cam will be more at home. With our J heads sporting a 1.88-inch intake valve, there is definitely a bottleneck hampering the flow. We surmised this by the peak horsepower coming in at around 5,000 rpm. Our first pass gave us baseline numbers of 242.3 hp at 5,000 rpm, and the torque numbers were 284.1 lb-ft at 3,000. With some simple tuning, we increased those numbers to 251 hp at 5,000 rpm and 291 lb-ft of torque at 3,600. That's an increase of 9 hp and 7 lb-ft of torque. Minimal maybe, but when you factor in that the factory rated this engine at 255 hp at the flywheel, we increased the numbers at the rearend to mimic the factory flywheel numbers. If you factor in the parasitic loses through the tranny, the Gear Vendors unit, and the rearend, we did improve our little 360. We wanted to hit the spray while on the dyno, but I forgot to bring the guide that let me know what jets to install for each horsepower shot of nitrous. So, in the interest of not installing the wrong jets and melting down a piston, (or having a loud "ka-boom" come from under the hood), we left the 75hp jets in and gave it the old winder-up-and-try-it blast. This time, the junkyard engine responded with 292 hp at 4,900 rpm, and 367 lb-ft of torque at 3,300. Sure, the numbers may be a little soft, but keep in mind that the bottom-end of this engine is 30+ years old, and a beating is a beating. It handled it nicely. Next, maybe we should try a good set of heads, and let this seasoned veteran breathe a little better. Sounds like a plan to us.

Hensley Racing Enterprises
Weiand (a division of Holley)
Bowling Green
Lunati (A Division of Holley)
Wilson Manifolds
4700 NE 11th Ave.
Ft. Lauderdale
FL  33334
Magnum HP
Wilt Engine Services
Norris Motorsports