youngstown.bulldog80 Posted April 22, 2018 Share Posted April 22, 2018 For my own information... I read about someone’s 1971 R model described as having “a 673 Mack engine with turbocharger, 237 Hp, gold engine”.....Is the 673 a thermodyne? Doesn’t gold only apply to Maxidyne? Just looking for some clarification. Thanks. Quote Link to comment Share on other sites More sharing options...
Rob Posted April 22, 2018 Share Posted April 22, 2018 The "Thermodyne" and "Maxidyne" are both 673, (672 and change) in displacement in your example. The "Maxidyne" was a different tuning calibration to the injection pump to allow a flat but high torque rise at very low rpm to allow a five, or six speed transmission to keep shifting down. Gold paint was used to clarify the "Maxidyne" from the "Thermodyne" series. 1 Quote Plodding along with no job nor practical application for my existence, but still trying to fix what's broke. Link to comment Share on other sites More sharing options...
h67st Posted April 23, 2018 Share Posted April 23, 2018 I didn't realize the Maxidyne was 673...I thought they were 675. 1 Quote Link to comment Share on other sites More sharing options...
j hancock Posted April 23, 2018 Share Posted April 23, 2018 ENDT 675 was the engine stamping/identification for the 673 CID 237 HP Maxidyne and the engine code was 85. An R-685 truck would be powered by a 237 HP engine ENDT 675. 1 Quote JimIt doesn't cost anything to pay attention. Link to comment Share on other sites More sharing options...
youngstown.bulldog80 Posted April 23, 2018 Author Share Posted April 23, 2018 1 hour ago, Rob said: The "Thermodyne" and "Maxidyne" are both 673, (672 and change) in displacement in your example. The "Maxidyne" was a different tuning calibration to the injection pump to allow a flat but high torque rise at very low rpm to allow a five, or six speed transmission to keep shifting down. Gold paint was used to clarify the "Maxidyne" from the "Thermodyne" series. thanks for your reply...makes sense, the transmission in the truck mentioned above is a 5 speed. Quote Link to comment Share on other sites More sharing options...
youngstown.bulldog80 Posted April 23, 2018 Author Share Posted April 23, 2018 4 minutes ago, j hancock said: ENDT 675 was the engine stamping/identification for the 673 CID 237 HP Maxidyne and the engine code was 85. An R-685 truck would be powered by a 237 HP engine ENDT 675. sounds good, thank you...sometimes i get a little thrown off with the different names and all. Quote Link to comment Share on other sites More sharing options...
BillyT Posted April 25, 2018 Share Posted April 25, 2018 Youngstown Bulldog,do you remember JVMcnicholas and Toms Express? Quote Link to comment Share on other sites More sharing options...
youngstown.bulldog80 Posted April 25, 2018 Author Share Posted April 25, 2018 1 hour ago, BillyT said: Youngstown Bulldog,do you remember JVMcnicholas and Toms Express? Didn't McNicholas liquidate back in the early 80's having something to do with a wildcat strike?? Then the grandson of McNicholas started AIM Lease or something? I might be wrong. But I don't recall Tom's Express. Quote Link to comment Share on other sites More sharing options...
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