Em6-275L

[Lmackattack]

If i recall right the 300 was a maxidyne and had more tq than the 350 but a 350 had more hp and if geared right would out pull a 300. My thoughts are a 300 is a better off road low rpm lugging engine and a 350 was better narrow power band engine suited to on road duty.

[rsb502]

If i recall right the 300 was a maxidyne and had more tq than the 350 but a 350 had more hp and if geared right would out pull a 300. My thoughts are a 300 is a better off road low rpm lugging engine and a 350 was better narrow power band engine suited to on road duty.

A 300+ was a bad mutha, I ran both mechanical 300 and 350's and I always thought the 350 pulled better, after the swap to V-MAC I ran all 350,400,427 and 460's. I always liked the way a Mechanical 350 ran especially an E7 they seemed to have an endless supply of torque, the heavier the load the more low end grunt the truck seemed to have, I had a 93 CH with the VMAC 1 400 (bosch electronic pump) it ran the same loaded or empty, you had to get it on a pretty good hill or really load it down to notice any real difference in power, of course I run em to about 1600 and shift I dont know if I ever had that truck over 1700 that was about72 and fast enough for me pulling a dump trailer at 80,000. I have had to learn to drive a Mack over the years, I ran the piss out of em when I started and tried to get em as high in the rpm as I could just wasting fuel and killing the trucks, I was too young and smarter than the old guys that told me I would haul just as much letting the truck do the work. I think after I really figured it out and got used to a Mack I rarely even look at a tach I give it about half pedal and when torque peaks I shift it so Im probably only running 1200-1400 in low then maybe up to 1600 in high range, that is the greatest thing I have learned from all the older guys I have watched over the years, let the truck do the work let it tell you when to shift and if you cant feel it you better just get out of it, you have to feel a truck to drive it right.

[oilburner]

If i recall right the 300 was a maxidyne and had more tq than the 350 but a 350 had more hp and if geared right would out pull a 300. My thoughts are a 300 is a better off road low rpm lugging engine and a 350 was better narrow power band engine suited to on road duty.

The 300 i drove pulled real good, it was a 80 model and had a air shift 6 speed, and it pulled good everwhere in the rpm, but when you pulled it down to about 1400 it was like that was as low as it would pull down, it would go there and hold 1400 very good, and for a truck that just had a 6 speed in it would do about 72 2100 and i ran it there alot, the truck was proberly the best pulling truck i have drove but i do rember the pryrometer was somthing you had to keep a eye on it would heat up on a long pull and you could downshift it and get the rpms up aroud 1900 and it would cool back off again, if it wasn't for that i thank it would pull hills in high gear loaded, you guys may thank i am blowin smoke, and that old 300 blowed alot of it, but to me mack quit makeing good engine when the 4 valves came out. I have drove alot of the mack E6 and E7 and eveytime it just dissapoints me when i thank about that old 300. I have drove 350, 400, 427, and 454 and none of them would pull with it, and the guy i drove it for still uses it and as far as i know all he has done to it was have the jake heads rebuilt and a new turbo, i guess emission are what holds the newer engine back but to me nothing like the old non-electric engines The 300 i drove was a tipturbine, you could rush it though the gears empty but if you done it loaded, it would heat up and smoke bad, the owner said the fuel was turned up on it but i thank it might of had a little more timing than factory, it was a triaxle log truck and we usaly gross 70,000. Edited October 5, 2012 by oilburner

[pmolitor]

Thats how my 300+ pulls. I can run with the guys with 425hp up till 45mph. I think if it had a 12 speed I would have no problem running with them. I have a spare 300+.... I wonder if it would fit in the CH?

[oilburner]

Thats how my 300+ pulls. I can run with the guys with 425hp up till 45mph. I think if it had a 12 speed I would have no problem running with them. I have a spare 300+.... I wonder if it would fit in the CH?

I never drove a 12 speed put i did drive a 10 speed that had 2 sticks, it would have been alright if it was airshift, i didn't drive it longe enough to get to like it. I still like the old 300, i drove a 2 vavle 350 with a air to air that done good to but to tell the truth i could tell the differnce in the two put it did have a 15 speed fuller and between gears the ratio were very close it didn,t heat up as bad on the hills. I thank the 15 speed is a good set up with the old mack engine, but they did not have the low hole like the old 6 speed put they were better out on the highway.

[oilburner]

I never drove a 12 speed put i did drive a 10 speed that had 2 sticks, it would have been alright if it was airshift, i didn't drive it longe enough to get to like it. I still like the old 300, i drove a 2 vavle 350 with a air to air that done good to but to tell the truth i could tell the differnce in the two put it did have a 15 speed fuller and between gears the ratio were very close it didn,t heat up as bad on the hills. I thank the 15 speed is a good set up with the old mack engine, but they did not have the low hole like the old 6 speed put they were better out on the highway.

that old 350 had the best engine break i ever seen on a mack to, it was a dynatard, we had to work on it onced because one head quit and i thought it was the craziest looking thing, it had a pluger in the rocker arm and the oil presure pushed it out and caused the push rod to keep presure on the vavles, but the owner told me they were harder on cam shafts than a jake, he had already put one in it, but it held back pretty good.

[rsb502]

that old 350 had the best engine break i ever seen on a mack to, it was a dynatard, we had to work on it onced because one head quit and i thought it was the craziest looking thing, it had a pluger in the rocker arm and the oil presure pushed it out and caused the push rod to keep presure on the vavles, but the owner told me they were harder on cam shafts than a jake, he had already put one in it, but it held back pretty good.

The best engine brake on a Mack in my book is the Powerleash on the Aset engines, but I havent driven an MP8 or MP10 so they may be better. The old E-7 and Etech brakes worked good with thick cold oil but started to slack off after the oil thinned out, we put a high volume oil pump in an Etech 350 and that sucker had some great braking power after that. I know the dynatard in an E9 works best cold with thick oil it fades after it gets hot too, but the engine pulls so damn hard I just dont care. I like HP!

[m5040]

I had my 84 EM6275 changed to a 300 by a old time Mack mechanic, he said he put "bridges" on the main bearing caps.