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About 6 weeks ago we had the Rawhide my son drives down getting a new clutch installed,so he was driving my beloved blue Super Mutt and it decided to start knocking. Been swamped so haven't had time to tear it down as of yet,but we are thinking a broken piston. Up till now the old Cummins had performed well for me,but it is nearing 3 million miles on this block andwho knows how many overhauls,so I'm thinking its time for a change.After being in the little Super Pup for nearly a year now,I've really been enjoying the better fuel economy and the just plain unprecedented Mack stamina of the E6-350 as compared to the 400 Cummins. So should I rebuild the current engine,find another Cummins and replace it or repower with a Mack ? Money is not the issue,because I have none,so I'll be going to the bank no matter what I do. I know I'll have to change a lot of stuff to go to a Mack engine,but I have donor trucks,so that isn't an issue either. It's not going to get the miles it used to as I will be alternating between the 2 Superliners,that's one factor . Just fishing for opinions or advice from anyone that's done a Cummins to Mack swap.

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I just installed a mechanical E 7 in my truck and a little timing and fuel work a 400 cummins will work its self hard to stay with this. Cant say about the fuel burn but seems like the 350 E 6 so far.I timed it like it should be at 9 degrees and it was a fuel pig but I have it at 18 degrees now and its all I can do to push the pro to 800.

glenn akers

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I understand your problem first hand. Being that is a cummins I would look for an N14 it would be a bolt in and 84superdog knows the wiring. We've talked about maybe doing that for my E9 replacement, I think the E7 would be cool, but if you have a E6 and all the small parts then that's what I'd do. Good luck.

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After considering the Mack engine is shorter so the trans moves forward, driveshaft lengthened, new shifter hole, changes in air and fuel plumbing, changing the front mount may get into changing the cross member and spring hangers, the N14 may be your best option.

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having had both N-14 and E7's I would rather have the E7 N-14 has a better jake that's the only thing it would have over a tuned up manual E7

Your right about the jakes.Mine works better if you open both doors and hold them all the way open.

glenn akers

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My thinking is this,if it was Mack to Mack swap,no brainer,BUT being as the truck is set-up for a Cummins personally I think that is the best option,not so much to change over,and my Dad always had good luck with Cummins engines,especially the 400. Sure, in a perfect world we'd run all Mack engines,but I would not be ashamed at all to run a good "Hummin' Cummins" in a Mack.....just my .02 Mark

Mack Truck literate. Computer illiterate.

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Sorry to jack your thread but I had no clue your Superliner had a Cummins. Thought it had a 350! Sorry to hear she went.

Yep,the big blue one is a RW633 and has a Big Cam IV Cummins.#107 of 170 RW633's built The white and blue '88 has a E6-350.

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Sorry to hear about the engine troubles, I think I would have to stick with the big cam, I like the N14 idea and obviously I'm all for Mack engines. However the 855 Cummins is a solid engine, and you can in frame that engine cheaper than an E7. I wouldn't worry about the block unless it didn't meet specs, if the counterbores can be cut smooth and the crank and cam are good ID in frame it with Cummins parts and three reman heads. While your at it you can swap your injectors out for a set of CARB approved 9 hole injectors, the 48state injectors are 7 hole if I remember right and the better atomization helps power and economy. I don't know if they are still doin it but Cummins used to in frame big cam engines for like $8500 with reman heads, water pump and oil pump, and it was all Cummins parts not PAI.

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Sorry to hear about the engine troubles, I think I would have to stick with the big cam, I like the N14 idea and obviously I'm all for Mack engines. However the 855 Cummins is a solid engine, and you can in frame that engine cheaper than an E7. I wouldn't worry about the block unless it didn't meet specs, if the counterbores can be cut smooth and the crank and cam are good ID in frame it with Cummins parts and three reman heads. While your at it you can swap your injectors out for a set of CARB approved 9 hole injectors, the 48state injectors are 7 hole if I remember right and the better atomization helps power and economy. I don't know if they are still doin it but Cummins used to in frame big cam engines for like $8500 with reman heads, water pump and oil pump, and it was all Cummins parts not PAI.

You can inframe a Big Cam cheaper than an e7? Wow have times changed. Anyone else remember how cheap it was to infame a e6 back when Mack was Mack?

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You can inframe a Big Cam cheaper than an e7? Wow have times changed. Anyone else remember how cheap it was to infame a e6 back when Mack was Mack?

I sure do.Broke a head bolt on the 676 in my '76 R model, scored a piston,Mack dealer in framed it for $2200.That woulda been in '87.

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can get a reman from Drew at housby for around $5000. I have about $7000 in my e6-300 inframe last month. that is with all new valves and reworked heads.

not to change the subject,but I heard Drew was retiring and Housby was closing up it's used parts yard.

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that will suck! but it doesn't surprise me. he has been taking alot of time off. wouldn't be surprised if housby loses Mack to Gatr. they never have any trucks parts, and the service is starting to go down hill. The guys are geeat to work with, but the upper management seems to only care about the big contracts like Caseys and the VOCON auctions. the only way you can buy a used truck is at auction.

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I'm afraid GATR is going to end up with H & L Mack here at home . The owners health ain't the greatest,and GATR really been making deals on new parts.They are running a delivery truck down this way almost everyday. Wife said they've stopped here a few times,but I've always been gone.

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They way I see it is, if you need the truck back on the road ASAP, I'd inframe it, or swap in another Cummins. But if you have the time, I'd do the Mack swap. The E6 is one of the best motors ever made. Plus, like you said, the better fuel economy as well. I guess it all comes down to how bad you need it and what you want...

Being in the process of getting your CDL's is like sitting on death row...

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I live in Saint Cloud where GATR started. When the new owner bought it things got more expensive. We used to get a lot service work done there but the attitude of the whole place changed. Then he and Nuss were in a Volvo pissing match so he bought the Mack dealer in Iowa to sell Macks up here. Poor guy got busted a few months ago trying to buy a hooker......damn cops.

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