IMCA's claimer rules are so popular that many other series (such as the Southern Modified
You have to hand it to the IMCA-they really know how to get to the heart of a problem. Almost all sanctioning bodies claim they try to keep the costs in check for their racers, but rules mandating such "low-cost" options as smaller carburetors, steel valves, and heavy cranks are rarely effective.
The IMCA has a rule in its Modified and Stock Car classes that has been in effect for many years now, and while racers have different opinions of it, there is no denying that it has the intended effect of making racers keep a close eye on the checkbook. That rule is, of course, the IMCA's claimer rule, and the best part about it is its simplicity. Essentially, the IMCA lets you run just about anything you want, but anyone on the track who finished below you can claim your engine for $525 or the engine in their car. (Usually, the team getting claimed has the choice of which they want.)
The rule is so successful that many other sanctions use some version of it in their own rule books. Building any race engine for $525 is practically impossible, so the goal for the racer is to get the best engine possible for the least amount of money. When you do that, however, durability becomes an issue as engine builders try to find and use the least expensive components available. It becomes a tricky puzzle trying to balance cost, power, and durability, but for savvy racers, it can be done.
To get some ideas on what's currently going on with top claimer engine packages, we visited some of the top engine builders for these engines as well as IMCA's Vice President of Operations, Brett Root. We also spoke with Kent Davenport, machine shop manager of JR Motorsports; Jeff Hill, owner of Jeff's Performance; and Ken Troutman, owner of KT Engine Development. The following are general tips for this class of racing to help you spend your money smarter, race faster, and race longer without mechanical troubles. We didn't follow any specific rule book, assuming only a very low-cost claimer rule.
You may think of JR Motorsports as a mail-order racing warehouse, but the company also bui
Some guys in these classes are doing it economically, and some guys are spending what I think is way too much money. It all comes down to issues of convenience and time. If you don't have the time, you have to spend the money.
In general, what I've noticed is regardless of what they are spending, the racers who have very good maintenance programs are the ones having the most success. They are the ones making sure their valves are right, regularly changing the oil, cutting the oil filter open and checking it for debris-doing basic things to make sure their engines are taken care of. They make sure they have adequate fuel systems, a good water pump, that kind of stuff. Regardless of what they spend, those are the guys who seem to make it work. They run well and run consistently week after week without a lot of problems. I believe that is a big key-not whether you are running a particular connecting rod or whether you are running a forged piston instead of a cast one.
One of the few rules in these classes is that you must run a stock block. Original four-bo
You are required to run a stock block. When building a Chevrolet, I still prefer the blocks with the two-piece rear main seals. They are getting tougher to find, but you can still find them with two-bolt main caps.
The problem we run into with two-bolt main caps is racers spin the engines so high that the caps break. Everybody is big on rpm. It has to do with the four-link rear suspensions on the cars. Racers are using engine speed to keep the car up on the bars and keep it moving to get traction.
To eliminate cap breakage, we offer four-bolt caps that can easily fit onto a two-bolt block. It is fairly simple for any machine shop to make the block accept a four-bolt cap. You are going from a cast two-bolt main cap to a much stronger four-bolt billet piece. The caps cost a little bit, but the two-bolt blocks are usually a little cheaper, too. Overall, you may spend more money than if you found a block with four-bolt mains, but you are still getting a stronger piece this way.
Keep the timing down. Guys like to put a lot of timing in these motors, but that puts a lot of heat in the cylinders. They will definitely make more power with a lot of timing in them, but the engines won't last as long. If you can keep the timing down to around 34 degrees BTDC, or 36 degrees max, that helps a lot. It just helps keep the engine from detonating. And detonation is definitely going to hammer the top of that piston. You might not be able to win every race if you keep the timing down below 36 degrees, but you will be at every race without spending a lot of money.