Tech Tips

49cc Cylinder Heads – What Pistons to use?

Tech Tips

Dart’s Iron Eagle Platinum small block cylinder heads with 49cc combustion chambers are very popular among oval track racers competing in classes that require flat top pistons, but what pistons to use?

The small chambers produce high compression ratios, but they require a different piston than conventional 64cc or 72cc chamber heads as a result of a combination of machining changes that reduce the chamber volume.

The valves are closer to the deck in 49cc Iron Eagle heads and their location relative to the cylinder bore centerline is different than 64cc/72cc heads. Consequently the valve pockets in many pistons are not in the right locations. However, Mahle has found that their 21 degree flat top piston is a perfect fit for 49cc Dart heads – the pocket locations and depth work very well for those using this cylinder head. Pistons from other manufacturers that offer 21 degree flat top styles should also work in this application, but it is best to always check piston-to-valve clearance before final assembly.

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