Mile High Perf Dyno Tune 340

This week I finally got my 340 dyno tuned by Mile High Performance in Englewood, CO. Totally satisfied with the work they did. The engine is a +0.020 1969 340 block with Sealed Power hyper-eutectic pistons at a measured 9.8:1 CR. Heads are mildly ported X heads with the factory cut undercut cleaned to the port, and port matching only. The engine has a MP 284-484 cam and Edelbrock Perf RPM manifold with blocked cross-over passages. The car has TTi headers and 3:55 gears with a 727.

I am now running a 440 AVS carb, but originally ran the 340 AVS. Prior to the tuning session, I tried to get the car running at 5800 feet with poor success. At Brandimere, it ran a 16 flat at 87. Quite poor for this combo. It pulled to 6500 rpm, but was really flat and lacked power most of the way up.

The before dyno run showed 241 HP at 5500 and 320 lb-ft torque at 3500-4500, falling off after that. Peak HP was 290 at 5300 with a sharp decline to 241 after that. I will try to attach the dyno chart later.

Jay at Mile High worked on the car for two days which include fixing a bad batter cable, dead batter and broken (literally) water pump due to a bad fan balance. The after tune HP was 335 at 55000 and good power to 6200, and a remarkable 360 lb-ft of torque from 3400-4500 and some decline up to 6200 where he stopped the pull.

Before, the carb had a very bad off idle stumble and the idle mixture was not responsive. After Jay drilled the cluster metering hole slightly, the carb was responsive to idle mixture and the stumble was gone.

I recommend Mile High Perf (aka The Carburator Shop) in Englewood very highly. First class work.

Regards,
Bob