Predator 212 First Mods, in the Order That Works

The 212 is cheap enough that people buy parts in whatever order the forum thread listed them. That wastes money in a specific, predictable way: the governor delete gets bought first, and then the engine revs to 7,000 with a cam that stopped making power at 4,700. Here is the order the dyno sheets support, and what each step is worth.

0. Break it in and take the throttle-stop screw out

Thirty minutes of break-in at varying load, then the small screw on the throttle linkage that keeps the stock engine from opening the throttle all the way. It costs nothing and it is what Red Beard's Garage's stock baseline was run with: 6.74 hp at 4,400 on a Hemi with the screw out. With the screw in, most of these engines never see full throttle. The governor stays in the engine for this step — you are only removing the stop.

1. The Stage 1 kit: filter, jet, header with muffler

This is the whole first move and it goes on together, because each part needs the others. The pod filter flows more air than the stock foam element; the jet feeds that air; the header with its muffler gets it out. On the same engine, same dyno, same day: 6.74 → 9.11 hp, 8.40 → 10.94 lb-ft. That is a 35% gain from the cheapest kit sold for this engine, with the stock cam and the governor still in place.

Buy the kit with the muffler. See step 3.

2. Jet it for where you live

The kit comes with one jet and the seller's guess at your altitude. A 212 that is right at sea level is rich at 5,000 feet and lean the other way. The jetting page on this site walks through it by elevation; the short version is that a lean engine makes less power and runs hot, and a rich one fouls plugs and makes less power. Half a jet size is a real difference on a carb this small.

3. Keep the muffler on

The Stage 1 header was tested both ways. With its muffler: 9.11 hp. Open: 8.70. The open pipe lost 3.65%. A small single wants a tuned length, and the muffler on the kit header is part of that length. If you want it louder, you are paying horsepower for the noise.

4. Now stop and read the sheet

At this point you have about 9 horsepower and the engine peaks at 4,700 rpm. Everything from here costs real money and requires opening the engine: a rod, then a cam and springs, then a carb that can feed the cam. The reason the governor delete is not on this list yet is that Red Beard's ran that exact experiment — Stage 1 kit, governor out, billet flywheel, 18-lb springs, stock cam — and got 8.90 hp, one lb-ft less than the governed engine. The engine revved to 7,200 and had nothing to do there. The rod guide covers what the governor and the stock rod each protect you from.

5. Rod, then cam and springs, then carb

In that order, because the rod is what lets you rev, the cam is what gives you something to rev for, and the carb is what the cam needs once it is in. The cam and springs guide covers picking one; the carb page runs the number for the stock carb against a 22mm and a VM22 on your build. Every one of those parts is in the simulator with its published specs, so the right move is to build your engine as it sits, then add one dropdown at a time and watch which one moves the number.

What not to buy first

A billet flywheel by itself. An open header. A bigger carb on a stock cam. A "Stage 3" cam on stock springs. Each of these is a real part that belongs on the right engine, and each is a waste on a stock-cam, governed 212. The calculator will show you the same thing: change only that part and the horsepower line barely moves, or moves the wrong way.

Sources: Red Beard's Garage — Road to Horsepower Ep. 1 (tQjitfEMDxM) and Ep. 2 (vaL4-d5Fz70), inertia dyno, corrected to 29.92" / 60°F.

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