1wonton Posted January 10, 2023 Share Posted January 10, 2023 Have the 673 C engine (five speed transmission) in my B 61; Is this engine similar to the Maxidyne and/or will it handle low rpms like the Maxi? Quote Link to comment https://www.bigmacktrucks.com/topic/71017-673-c-engine/ Share on other sites More sharing options...
terry Posted January 10, 2023 Share Posted January 10, 2023 19 minutes ago, 1wonton said: Have the 673 C engine (five speed transmission) in my B 61; Is this engine similar to the Maxidyne and/or will it handle low rpms like the Maxi? Is it a straight 5 spd, i believe that engine should be hooked to a triplex, quad series transmission. terry Quote Link to comment https://www.bigmacktrucks.com/topic/71017-673-c-engine/#findComment-520794 Share on other sites More sharing options...
Freightrain Posted January 10, 2023 Share Posted January 10, 2023 The C engine is rated at 250hp, but it is a thermodyne and will need more then 5 spds. Under a load it will really struggle to recover speed at 1100 rpm when you shift. It needs to be around 1500-1600 rpm. On a hill it will really hurt it. I was really hunting for one of these motors to replace my old P motor for many years. The 237 showed up and I went that way instead. It has its own issues with being ahead of a Triplex(single countershaft transmission). You can't lug it down to 1100 as it will try to spit the gears out. So I drive it more like a thermodyne. 1 Quote Larry 1959 B61 Liv'n Large...................... Charter member of the "MACK PACK" Link to comment https://www.bigmacktrucks.com/topic/71017-673-c-engine/#findComment-520810 Share on other sites More sharing options...
theakerstwo Posted January 10, 2023 Share Posted January 10, 2023 The model on the 250 HP should be ENDT 673C and it was never in a B model from the factory.If that engine is a 673C it would not have a turbo. Quote glenn akers Link to comment https://www.bigmacktrucks.com/topic/71017-673-c-engine/#findComment-520821 Share on other sites More sharing options...
1wonton Posted January 10, 2023 Author Share Posted January 10, 2023 It is not the original 673. It is the EDNT 673C, 250 hp Turbo, mated to a five speed trans. Seems to have lots of torque at 1100-1200, never really lugged it down to stall. Just wondering how it compared with the Maxi from anyone's experience. Quote Link to comment https://www.bigmacktrucks.com/topic/71017-673-c-engine/#findComment-520838 Share on other sites More sharing options...
theakerstwo Posted January 11, 2023 Share Posted January 11, 2023 It should have a ten speed or more trans.It is not a maxi.Like the pump is set now it dont have the low end torque for a five speed. Quote glenn akers Link to comment https://www.bigmacktrucks.com/topic/71017-673-c-engine/#findComment-520852 Share on other sites More sharing options...
1wonton Posted January 13, 2023 Author Share Posted January 13, 2023 Any comments about pulling a loaded trailer with the 673C, five speed tranny and 3.7 rear axle? Quote Link to comment https://www.bigmacktrucks.com/topic/71017-673-c-engine/#findComment-521047 Share on other sites More sharing options...
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