Jaison Posted March 19, 2020 Share Posted March 19, 2020 Can I add a Jake Brake to this old girl she’s has a E-7 350hp engine in her! And if so what would I need to do? Quote Link to comment https://www.bigmacktrucks.com/topic/61549-1993-mack-688s-e-7-350hp/ Share on other sites More sharing options...
brettj3876 Posted March 31, 2020 Share Posted March 31, 2020 You should be able to. Call up your mack dealer give em your vin they should tell you. One of the other guys on here can prob tell ya Quote Link to comment https://www.bigmacktrucks.com/topic/61549-1993-mack-688s-e-7-350hp/#findComment-447385 Share on other sites More sharing options...
Joey Mack Posted May 21, 2020 Share Posted May 21, 2020 Hello, I have done a few of these.. It's been a while.. The Jake heads should be a 680 series.. There are spacers that go under the valve covers. The wiring comes off the aux relay in the dash and goes to the switch that you will install in the center dash panel, then to the clutch switch, and then to a micro switch on the injection pump at the throttle lever.. the late 70 models i drove, required me to hold the clutch pedal gently, or flip the dash switch off to stop engine braking while waiting at the red light. There are a lot smart people here, that can fill in the rest of the blanks..... The system is a combo, of simple electrical, and a hydraulic system that the engine provides through the jake heads.. youre rocker shafts have plugs located at the #2 and #5 oil galleries that come up through block. they will be removed and 2 little check valves will be installed there, to feed the jake heads. also, the jake reset screw lash is based on the turbo you have. Some were set to .060" and .080" based on the turbo and H.P. Text me: at 704-785-1738.. I have the engine books and will try to answer questions... Jojo. 2 Quote Link to comment https://www.bigmacktrucks.com/topic/61549-1993-mack-688s-e-7-350hp/#findComment-451646 Share on other sites More sharing options...
Joey Mack Posted May 21, 2020 Share Posted May 21, 2020 As far as going to the dealer..... You may find that they don't know or don't care... I"m currently building a 1960 -ish E-6 2V.. and a TRD-72 transmission, and the 2 dealerships her, don't care... I found info ...Here.... Good luck..:) 1 Quote Link to comment https://www.bigmacktrucks.com/topic/61549-1993-mack-688s-e-7-350hp/#findComment-451648 Share on other sites More sharing options...
Joey Mack Posted May 21, 2020 Share Posted May 21, 2020 I forgot to tell you about replacing the exh. rockers too.. text me if you need to.. Jojo Quote Link to comment https://www.bigmacktrucks.com/topic/61549-1993-mack-688s-e-7-350hp/#findComment-451700 Share on other sites More sharing options...
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