Oldsmobile Engine Build - Milennium 403

We've written on these very pages about the untapped potential within the 403 Olds. We've also made a point to state how the one major weakness of this otherwise decent performance block has been their windowed main bearing webs, which don't have much strength to support big power. But big power is a relative term, and the lesser Olds may not be down for the count as badly as many people think. Certainly, there are new technologies that have changed the way we think about the 403 and we'd like to tell you about them.

Is 599 horsepower on pump gas enough power for you? We think so, and we feel this particular engine was worthy of documenting. Yes, the Jeg's Engine Masters Challenge is over, and yes, this engine did participate and it did not win. It was not even the highest-finishing Oldsmobile entry. However, it was, by far, the smoothest-running engine in the entire competition. It wanted to idle far below 1,000 rpm, and it was difficult to even tell it was running just by watching it during the Challenge dyno tests.

For these reasons, we wanted to show you this engine. We felt no other entry could have shown itself as a better, more honest street engine, and the fact it was based on the common 403 Olds was all the convincing we required. Dick Miller built one hell of a good street engine, and it's one we'd love to have under the hood of our daily drivers. Check out the build, and know that plenty of smooth power in a truly usable rpm range is the result of these efforts. It's a cool build, and we're proud to share it.

In case you're wondering, the engine you see here--which is built to race strength standards despite being a pump gas bullet--will set you back about $13,000, depending on options. That price includes the forged steel crank and billet Oliver rods, but you can have the very same thing for the street (with identical horsepower output) for around $9,000. The street version of Dick Miller's 403 Olds uses a 350/403 cast-iron crank and forged Oliver rods. If that's too rich for your blood, Dick sells the parts separately, so you can build a 403 yourself as time and finances permit. If you're a true died-in-the-wool Olds fan, that's a bargain. We can't wait to see what Dick cooks up for next year's EMC!

GETTING DYNO READY
aPrior to the Jeg's Engine Masters Challenge competition, Dick only had two days to dyno-tune this engine (seen here at Southern Performance prior to the Challenge). Without testing a wide variety of parts, we must commend Dick on the performance of this particular engine. As we stated previously, it was by far the smoothest running mill we tested. We can't wait to see how it does once it finds a home on the street.

As far as the rest of the combo goes, the carb was by The Carb Shop and was developed to produce a very linear fuel curve. The distributor was also by the Carb Shop, and was a DUI HEI unit with their unique adjustable knob. This locking knob (not seen in the photo) allowed for easy timing changes and is calibrated so a complete 360-degree turn is worth a total of 2-degrees of adjustment. It allowed Miller to fine-tune on the fly, compared to other competitors who had to go through much more labor to fine-tune their timing and waste precious time. He also ran a Mezeire electric water pump, Melling oil pump, and Total Seal Gapless rings. You can clearly see the BHJ neutral-balanced damper for less rotating weight.