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4 Valve Or 2 Valve?


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:( Don't know what to do. I've been looking for a used E6-350 4vh engine for my truck at a reasonable price and had no luck. Found two 300's to choose from, a 1990 E6-300 4vh for $3,000 no core and a 84 EM6-300R for $2,500 no core. I'm thinking seriously about buying the 90 E6 4vh engine, but the guy with the EM6 says the 4vh engines had camshaft problems but slightly more power. What are the pros and cons of each, and should I wait and try to find a 350? Thanks in advance, Kevin
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Are you useing a 5 speed or a 9 or 10 speed, i dont know wheter the M is for maxidyne or not , you can use 9,10,13 behind the maxidyne, but the E6 might be made for a multi speed, dont know about useing a 5 speed , it might not be good lugging the engine down that low with a 5 speed.

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  • 2 weeks later...

The EM6300R is a reduced RPM fleet engine. It should work well with the 15 speed as the torque curve is relatively short. I am running one in my 71 R600 with a RTOO9513 with a 3:73 single rear and it pulls good from 1200 to 1600 RPMs but the torque falls off rapidly after about 1700. I think they were governed at 1800 from the factory.

1971 Mack R600 Toterhome "Superdawg"

living the life of leisure pulling

1999 NuWa Snowbird 34+2 SE102 "Dawghouse"

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I thing the low RPM engines are governed at 1800RPM

Im not a fan of the low RPM engine as the power band is to short. this also makes the gearing diffrent and you will need to make 100% shure that your trans and rear end ratio are not going to make the truck slower than a pete.

most of the low rpm engines I have seen had 5.?? rears and 9 speeds giving the truck about 70 MPH at 1800 RPM.

Standard EM6 300HP Mack engines are fairly easy to find

350s somewhat easy

E7s seam to be difficult

E9s seen them but always have issues to be fixed

I myself would like to find a 315,300+ tip turbine and use a 9 speed

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The EM6 in my Mack came from a 1983 R686ST with a fuller 9 speed and 3:65 Mack rears. Seemed to have plenty of low end power and would tote the log loader on it around 75MPH.

I agree that the power band is a little short, but when all you are pulling is a 16K Snowbird 5er it really doesn't matter.

1971 Mack R600 Toterhome "Superdawg"

living the life of leisure pulling

1999 NuWa Snowbird 34+2 SE102 "Dawghouse"

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The EM6 in my Mack came from a 1983 R686ST with a fuller 9 speed and 3:65 Mack rears. Seemed to have plenty of low end power and would tote the log loader on it around 75MPH.

I agree that the power band is a little short, but when all you are pulling is a 16K Snowbird 5er it really doesn't matter.

that sounds about right. Even the new computer mack engines dont have the balls like they should. you feel the power come on strong and then it falls off... I hate that! Just imagine what a 2100 or 2300 RPM engine could do with a 9 speed and 3.65s out on the big road!! im not a fan of speeding but the lower rpms at hwy speed would be nice. thats the only thing I dislike about the 5/6 speeds.

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If you use an airshift 6 speed out of around 1988 it is overdrive, a freind of mine bought an 88 at an aution for $ 1800., 4 valve head 300, 6 speed ,5.55 rears, i drove it home for him , would run 65 mph @ 1800 , you could lug it down 1050, i turned the rpm up to 2200, it might run 75 mph now Ron

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