Ken Troutman, owner of KT Engine Development, says that if you are choosing among stock cylinder heads and aren't allowed to use the Vortec, it is still hard to go wrong with Chevrolet's famous "double hump" head. It is so named-and easy to identify-because of the double-hump casting mark on the end of the head.
Some classes or tracks require you to run stock heads and don't allow Chevy's Vortec head. If that's the case, the best thing you can do is go with the double-hump head. This cylinder head is about as good as a Bow Tie Late Model Stock head because the chambers are so tight and the ports offer decent flow. They also have a good, thick deck so you can cut them down a bit. For a stock cast-iron head, they are hard to beat.
If you have to go hunting in the junkyard, a set of double-hump cylinder heads isn't hard to identify. They are cast with an identifier on the end of the heads that resembles a camel's humps. Just make sure they aren't cracked between the two center exhaust ports.
Ken TroutmanKT Engine Development
As we reach higher rpm levels, I believe there must be some type of harmonic issue with these motors, especially with the bigger strokes. Although we haven't identified the problem, we know that the damper cannot handle it. As a result, we break a lot of oil pump pickup tubes.
We have tried to do away with the OEM small-block oil pump and pickup tube, and we have stepped it up to M77 big-block pumps and even high-volume pumps accompanied by Kevco or Champ Pans pickup tubes. The bigger pickup tube's bracketry holds the oil pickup box right next to the oil pump, which helps. It is a bigger, beefier pump, which structurally is a bit stronger. I think there is less of an opportunity for this oil pump to cavitate, too.
So we have stepped up our program from a small-block oil pump to a big-block pump with a 3?4-inch pickup tube. The high-volume pump doesn't burn too much horsepower. Plus, since the motors are open, we are able to make enough horsepower so that losing a half-dozen horses doesn't really matter. The most important thing is to keep the bearings lubed and keep the pickup tube from breaking off so that you can race again next week.
Kent DavenportJR Motorsports
Many companies, such as Jeff's Performance and JR Motorsports, offer entire rotating assembly kits that include everything from the crank to the pistons and can save you a considerable amount of money versus purchasing everything individually. Hill says you can even purchase kits that have the rings already pre-gapped. All you have to do is assemble the parts into your block. Photo courtesy of JR Motorsports
The aftermarket has become aggressive with the pricing of performance cranks and pistons. You can do a lot better with your money by buying a complete rotating assembly in a kit. This way, you know that everything is already matched up to work together.
We now offer a basic economy kit that includes a new crank, rods, pistons, rings, and bearings. It's everything you need for the bottom end of the engine. Our kit costs around $449, so you can save a lot of money versus buying everything individually. The crank is cast steel, the rods are I-beam 4130 steel, and the pistons are hypereutectic. The entire rotating assembly comes already balanced, and the rings are already file fit, so everything is ready to be assembled. All you need is the block and the oil pan.
We don't recommend a cast piston, but we've had really good luck the last few years using hypereutectic pistons, which will save you a lot of money over forged pistons. There is no power difference between a forged and a hypereutectic piston, just the strength. They work very well unless you drop a valve, which will shatter the piston. So you have to keep on top of your valves and springs. Many people have two seasons on the kits we've been selling.
Jeff HillJeff's Performance
The ignition and carburetor are rarely part of the claim, so it's safe to invest your money in these components. Jeff Hill of Jeff's Performance says he recommends a racing HEI distributor like this one from Davis Unified Ignition (Performance Distributors) because it produces a hot spark and is dependable and simple to install.
If you are limited to stock components, anything you can do to lighten things up and reduce friction will help a lot. Grinding the stock 2.1-inch rod journal on the crank will reduce bearing speed and also cut friction. You can turn it down to 2.0 inches and use connecting rods from a 283 Chevy engine. The 283 was a popular engine from the mid-'50s on up, so it isn't hard to find.
Also, if you are sticking to stock parts, try to find a harmonic balancer from a Chevy 307. You can find 307's in Novas, Chevelles, and a lot of different pickup trucks between 1967 and 1973. The balancer from a 307 is about 4 pounds lighter than the stock balancer for a 350, and that will make a big difference in power hanging off the nose of the crank.
Ken TroutmanKT Engine Development
Checking your valvesprings will keep your engine running and help you avoid expensive failures. Since the rpm speeds have gone up, this is even more important. Get an on-head spring checker and start logging your spring rates. It's best to use your checker to log all the spring rates when the engine is brand-new, and then use the same spring checker every time. Different checkers may give you different readings, but you'll have consistency as long as you use the same checker.
Pull the valve covers and check your spring rates every couple of weeks. This way, you are more likely to detect a spring losing pressure before you have bigger problems. If a spring gets weak, the motor is going to run flat because it can't close the valve and keep it closed. If it gets worse a valve will hit the piston top, and the valve will break. That's when things get expensive.
We normally run springs that rate at 140 on the seat and 350 open. Running 1.6:1 rockers and an aggressive cam lobe is even harder on the springs, and you really have to stay on top of them. Anytime you see 10 pounds of drop, be aware that the spring is about to give up. When you see 20 pounds, go ahead and get it out of there.
Kent DavenportJR Motorsports