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Do the 4 valves run better than the 2 valves?


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Curious to hear from guys who've driven both the old 2 valve Macks and the 4 valve Macks. I'm talking mostly about multi-speed higher horsepower engines. Was there any real noticeable differences. I had a guy telling me that the old 2 valves would smoke 4 valves when the fuel was jacked up...

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Fun is what they fine you for!

My name is Bob Buckman sir,. . . and I hate truckers.

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I've been told by a couple guys that had 350 2v they would walk a 425 cat back them. I like the 350 2v, it has a good crack to it.

A buddy of mine bought an '84 MH last year with a 350 2-valve... IMHO Mack's best ever engine. I also worked with the previous owner and this truck could run with any CAT or Cummins... We used to enjoy aggravating those LARGE cars with our little Macks.

Gregg

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I think they went to a chassis mount CAC in '82, and the 4 valve came in '84-'85. I had an '87 R model with a blown up motor so I dropped in a 2 valve 350 from an '82 model. I sold the truck but I still borrow it from time to time from my friend, and it will straight up SMOKE my 4 valve. I think it's got the peppiest throttle of any truck I've driven. The MH I got from Mr. Harbison seems to be running a close second.

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Jake

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Those later 2V 350's seem to be really uncommon. Were they chassis mount charge coolers?

My 82 Cruiseliner was chassis mounted charge cooler but I seen what I was told to be a 350 with the engine mounted tip turbine. The 82 350 2 valve had a 10 speed roadranger and other than maybe a 2 stroke joke with an Allision tranny id say that Mack was the quickest truck off the line id ever driven. It would s@#t & git!!!

Remember if it's got a hood it's no good!

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I dunno about 2 valve verses 4 valve I got my injector pump done up 7 or 8 years ago a bloke in western Melbourne ( he is yank cant remember his name ) did the job and as I recall he set the injector pump to the injectors he believed that was the correct way to have it done or at least thats the way I remember it

what a difference and the bark when pulling hard up a hill its like a gun shot going off (well maybe not quite) but you get my drift and pull my god it was like a different truck

what does all of this have to do with 2 or 4 valve not a lot but I feel a lot of what makes these trucks go hard is how good the bloke is at setting the pump not the amount of valves the size of the turbo the exhaust ect

no good spending bucket loads of cash if the basics arent right just some thoughts

Paul

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The first antique truck I bought about 4 years ago was a 84 MH613 w/ 350 2v and T2090. I also drove both Ford 9000 and Int 9200 with 425 Cats at work, and I'm sorry but there was no comparison. The 350 2v was very peppy, and I always felt guilty when I chowed down on it because with dual pipes it blew so much smoke you couldn't see the cars behind you! It was one way to make them back off! The Cats were just plain awesome. They had so much torque in the Fords(3406'Bs) they had problems with drivers ringing off the driveshafts and trans output shafts. The 9200's were computer controlled and you didn't get full power until top gear. The mack did put out a lot of power for the size of the engine though.

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I'm with dieseldriver, there is no way a 350 mack competes with a true 3406b setup at 425hp. Maybe you were running with 3406a which commonly in error is called a 425. We have had numerous macks with 300 and 350's and pound for pound they are one of best ever. With a 6 speed I definately don't agree, maybe a 12 speed you could hang in there.

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The original 3406DIT was 325hp and 3406DITA was 350hp or 380hp. Spent many a day "pulling the throttle" on those engines at the Testicular Center. The DITA used a water to air charge air cooler. It was years later when CAT went to air to air (ATAAC CAT).

Better torque on the CAT is mainly attributed to the larger displacement.

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Ken

PRR Country and Charter member of the "Mack Pack"

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I was wondering about the difference between the 2v and 4v also. On paper, the 4v has more torqure. I even bought a worn out 4v with the intent on rebuilding it at a later stage. But the difference in real world performance would be hardly noticeable.

The fact some guys are comparing them to a cat just tells you how great these little engines are.

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