Step 1: Understand what you have, what you want to do, and what you have to work with

This is the part where you need to be honest with yourself. If you’ve never raced before, are borrowing your dads buddy’s sled, and are struggling to make your truck payment – racing in open mod probably isn’t the best place for you. There’s nothing wrong with crawling before you walk. Stock class is a great place to start. You will have great competition and will learn a ton without spending the farm. After you have figured out what level of racing is right for you – the next recommendation is to read the rules. You will be far better off building a sled for a class rather than trying to fit a sled into a class. We have seen it many times – a guy builds his dream sled and doesn’t have a class to race in or has to race against much bigger engines. You have to know where the target is before pulling the trigger. Now you’re ready to start turning some wrenches. It’s time to tear it down and make sure everything is solid. These are vintage sleds – who knows where that thing has been and what neglect it’s had over the last thirty years. Pull the crank and send it to a professional to have it rebuilt and gone through (we may know somebody).  Put in new piston’s, rings and gaskets. Vintage ignitions tend to have intermittent issues, which can turn a sane man insane. It’s a good idea to have a lot of spares to trouble shoot with, or if possible retrofit something new (we recommend MSD). Replace all of your chassis bearings and make sure everything is straight – easy performance. Then there’s your clutches, two of the most critical components of the package. Clutches that don’t have slop, move freely and are consistent are key to winning races. We recommend starting with new clutches – Polaris primary’s and Cat secondarys being our favorite combination. Now that you you know what level you are going to race at, what class you are going to race in and what your equipment is, it’s time to burn some gas.

Step 2: Dyno Testing

At this point you should be sitting with a fresh engine, a working ignition, a clean or new set of carbs, a set of pipes that you have some confidence in and an engine that starts and idles. It’s now time to find a shop with a good dyno setup (or give us a call). We do not recommend going onto ebay and finding a good deal on a dyno to run yourself. Unless you have a lot of time on your hands or a buddy that works for a dyno company, you will most likely spend a lot of time and effort getting a lot of questionable numbers or breaking your engine. A good shop will have a lot of history with their dyno that they can show you. They will utilize a fuel flow meter and a weather station, some sort of exhaust system and dead weight test before every dyno session. A shop that knows how to use their dyno will be a big help. Now that you have found a good dyno shop it’s time to start running. (Make sure to bring your tach. This is a great opportunity to make sure your tach is correct.) Get it strapped down and make a few pulls, adjusting jets between pulls to get your fuel flow numbers where you want them. We like to start rich and work our way down until we get around the 0.6 pounds per horsepower-hour brake specific fuel flow number range. This is a general rule of thumb, your engine will tell you what it likes based on how well it responds to the fueling change or if it starts to detonate. We then like to make sure we get two back to back runs that are within a couple horsepower of each other. If everything looks like you expected then you can pull the engine off. If not, it’s time to start tweaking pipes, ignition and carbs to get the most out of your engine package. After you have rung every last horsepower out of that monster on the dyno, you should walk away with the following info: 1) Engine rpm that the engine makes its most power (clutching target). It’s also good to know at what rpm on both sides of the peak that the engine looses 10 percent of its power at. This will define how big your clutching window is. 2) That your tach is accurate. If not, what sort of rpm offset do you need to consider in order to make it accurate. 3) Your baseline jetting. You should have your air density gauge present while testing – or get a temperature and pressure off of the dyno’s weather station. This will allow you to jet at the races based on air density changes relative to when you dyno tested. This will save you time and gain you consistancy. 4) The power of your engine. Don’t forget about the fun stuff!

Step 3: Initial Setup and Documentation

At this point you should have a sled sitting there ready to run. Now it’s time to take an initial swag at setup and write everything down that’s in the sled. First, go to our “downloads” page and print off a copy of the “sledspec” document. Start with the engine. You should have the ignition timing and base jetting figured out from dyno testing. Run through the rest of the items in the engine section of the sheet, filling in everything you can. When you get to the track, let your air density gauge sit in the shade for 10 minutes. Change your jetting based on the density difference with the dyno numbers. Second, move to your clutches. Whether you are running a stock sled or a mod sled, consistant clutch settings are key to winning. First, make sure your alignment and offset are correct. Next, set your belt to sheeve clearence. We like to run it nice and tight, around 0.025″ clearance. After that you will need to load the clutch. If this is the first time you have had the sled out you will need to take a guess at what to put in it. For the average 440 mod sled with Polaris primary and Secondary clutches we like to start with 40 gram weights, Polaris blue primary spring, 36 degree helix and Polaris long blue secondary spring in the 3rd hole . Testing will lead you to what the sled likes after that. Third, you will need to put gears in it and setup the suspension. Our general rule of thumb for gearing is to gear it for speeds 10% over what we expect the sled to run. Obviously at this point you don’t know what that is, but take a swag at it and see how it goes. As far as suspension setup goes, they are all unique. We recommend staring at it for a while trying to envision how it works. Then take a wild guess at how you think it should be setup and then dial it in while testing. With those basic steps you should be able to make it down the test track. The most important advise we can give is to write everything down before testing then again after testing. It is sometimes amazing how you can spend a day trying different things and end up really close to where you started.

Step 4:Test, Document, Test, Document, . . .

This is where it all starts coming together, testing. First, and probably most difficult, is to find a good location that doesn’t violate any laws. You are on your own on this one, we have a hard enough time finding places for ourselves to test. Second, stock the trailer. The basic tuning parts that you will need are, a variety of main and pilot jets above and below what’s in your sled, 5-6 helixs, a 2-3 secondary springs, a 2-3 primary spings, a variety of weights, and a few combinations of gears (and chains to match). Make sure you have the tools necessary to pull and work on clutches and enough race fuel to get through the day. Finally, we recommend bringing a spare belt or two along. This is a great opportunity to break in a couple belts, so you have them ready for the races. Now you’re at the test location, it’s time to get the timers out. It doesn’t matter if it’s ovals or drags, to get the most out of limited test time you need some sort of equipment to put numbers to your changes. Some people like to use a radar gun, some like on board data aquisition. We prefer timers with 60foot and 500foot times. Warm-up your sled and bring it to the line just like you would at the race. Try to keep your cool, keep the sled going straight and watch the tach. When you get back to the trailer write down your times, check your plugs and make suspension and clutching adjustments as necessary. I won’t go into a lot of detail here on clutching advise, I’ll write it up and put it on the “download” page – keep checking.