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Author Topic: rebuilding the 871 or repower with cummings  (Read 3663 times)
la chiva
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« on: March 19, 2012, 05:46:07 PM »

hey guys
i'm thinking to rebuild my 871 in my 4107but for the price i started to think maybe
to repower with a cumming 8.3 anyone as done this?? the work involved what would be
the perfect match engine tranny any suggestion??
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lostagain
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« Reply #1 on: March 19, 2012, 06:53:18 PM »

Are you rebuilding it yourself for the price of the parts?

Are you having it done at a diesel shop for 20 to $30,000?

The cheapest is doing the overhaul yourself, and slide it back in.

Swapping for something different will involve a lot of fabricating motor mounts, intake and exhaust plumbing, looking for a suitable transmission, bell housing, etc, etc.

The strickly logical answer is: overhaul what you have. Or look for a bus that has the drivetrain that you'd rather have.

Now if your heart really tells you to go for a different engine, tranny, for more power, better fuel mileage, bragging rights, etc, then go for it, but it will take a lot of time and money.

JC 
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JC
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la chiva
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« Reply #2 on: March 19, 2012, 07:54:46 PM »

actually i am having the engine rebuilt by detroit the cost about 15,000
i think i can do the repowered with a cummins for a few thousand more
my friend as a old flexliner that is repower with a cummins on the same trip cost him
alf the price in fuel  and it's getting harder to find 2 stroke mechanic on the road
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luvrbus
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« Reply #3 on: March 19, 2012, 09:26:07 PM »

Your friend has a bus that is easy to do a repower the engine turns in the right direction buy the time you buy a ZF or Allision V730R transmission with all the parts and do the fab work and spacers 20 grand is on the low side
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« Reply #4 on: March 20, 2012, 03:38:54 AM »

Re-power with the Cummins Wink

BTW,  $30 to rebuild a 8v71?!?!?!  Are you kidding me? 
For that kind of money you can install an ISX or C15 with 600+ horses, and even the wheelie bars that you would need.
« Last Edit: March 20, 2012, 04:02:50 AM by morefire » Logged

David G
Toronto, Ontario
2009 Bluebird 40' Coach
Cummins ISX-675HP!!
la chiva
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« Reply #5 on: March 20, 2012, 05:38:56 AM »

i already have a alisson 730 on the bus
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la chiva
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« Reply #6 on: March 20, 2012, 05:42:03 AM »

and probably can get my hands on a 8.3 cummins with allisson 6 speed serie 3000
for about 6,7000 with almost no milleage
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buswarrior
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« Reply #7 on: March 20, 2012, 06:28:53 AM »

I think we're confused?

A 4107 has a V drive.

The engine rotates in what is described as a left hand direction, or backwards, from everything else. You can't just source any old engine to swap in, or you will have to drive it forwards in reverse gear, and not very fast, however, it will be a blast in the other direction!

The busnuts who have actually taken a project to that point are hard to find, and they don't talk much about it...

There is a reverserer available for the V730/V731 transmission to "turn around" a right turning engine, but you have to find one that isn't worn out from its transit duty. The later models of the RTS were available with right turning 4 stroke engines using this reverser ahead of the Allison V drive often with a hydraulic retarder too. Designated VR731R.
I've seen L10 Cummins and S50 Detroits in the back of RTS hooked to VR731R transmissions.

You won't be able to use any other type of transmission in a GM coach except a V drive.

Unless, you want to take on a conversion to a T drive set up, like the MCI/Prevost/Eagle/Setra/Van Hool/etc/everything new.

And that's a big, big job, that takes deep pockets, and/or a lot of sweat.

happy coaching!
buswarrior

edit: I should mention that ZF had a 4 speed auto in V drive configuration that I have seen hooked up to an L10 Cummins.
« Last Edit: March 20, 2012, 07:46:08 AM by buswarrior » Logged

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la chiva
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« Reply #8 on: March 20, 2012, 07:13:25 AM »

hey busswarior
this is exactly what i was thinking to convert to a t drive since the cost of rebuildind my 871
at detroit is about 15 000
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robertglines1
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« Reply #9 on: March 20, 2012, 07:31:49 AM »

15grand would total many buses of your vintage. Must be a lobor of love. Seams you could find a good runner with a 100,000 miles left in it for 3 grand. Just a thought. If you are in love with it and have deep pockets go for it. Just remember you will either have to make it longer or loose inside space and move drive train around to t-drive. Longer I would think by several feet and create a new frame system. I don't think the present engine mounting system will support the extra weight that far back of the axle. Just some observations. Need to talk to someone that has done it in your particular type of bus. Doesn't the roof structure actuall carry  most of the engine weight or do I have it confused with some other type of bus?  Bob
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la chiva
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« Reply #10 on: March 20, 2012, 07:35:45 AM »

also the reason i am here is to get as much intel as possible and the pros and cons
of a job like this. from all of you guys that been around these bus for years before i decide
what to do
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luvrbus
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« Reply #11 on: March 20, 2012, 07:48:58 AM »

That would be a job with nothing to weld into on 4107 the rivet,drill bit and bolt suppliers would love you lol buy another bus that one will wind up the scrap yard trying to do a T drive
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buswarrior
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« Reply #12 on: March 20, 2012, 07:54:59 AM »

I think the cost of paying someone to convert the coach to a T drive would fail the cost-benefit calculation by an exponential magnitude.

Best to figure that you'd neither get a penny of it back in re-sale, nor would you recoup much in operating efficiencies unless you drive it many thousands of miles a year, for many years.
In fact, I think it will make selling the coach harder, or impossible, as the "extreme modifications" will scare off the few potential purchasers of an old GM bus conversion.

That being said, if you have the money and want to spend it this way, there are folks on this and the other board who have lots of good advice as to how to go about designing the conversion to T drive.

Let the investigation continue!

happy coaching!
buswarrior





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« Reply #13 on: March 20, 2012, 08:37:45 AM »

I think we're confused?

A 4107 has a V drive.

The engine rotates in what is described as a left hand direction, or backwards, from everything else. You can't just source any old engine to swap in, or you will have to drive it forwards in reverse gear, and not very fast, however, it will be a blast in the other direction!

The busnuts who have actually taken a project to that point are hard to find, and they don't talk much about it...

There is a reverserer available for the V730/V731 transmission to "turn around" a right turning engine, but you have to find one that isn't worn out from its transit duty. The later models of the RTS were available with right turning 4 stroke engines using this reverser ahead of the Allison V drive often with a hydraulic retarder too. Designated VR731R.
I've seen L10 Cummins and S50 Detroits in the back of RTS hooked to VR731R transmissions.

You won't be able to use any other type of transmission in a GM coach except a V drive.

Unless, you want to take on a conversion to a T drive set up, like the MCI/Prevost/Eagle/Setra/Van Hool/etc/everything new.

And that's a big, big job, that takes deep pockets, and/or a lot of sweat.

happy coaching!
buswarrior

edit: I should mention that ZF had a 4 speed auto in V drive configuration that I have seen hooked up to an L10 Cummins.


I used to have a full sized, fully equipped shop, and a friend who had a fully equipped machine shop. We overhauled an antique genset engine in a boat. Poured the babbit bearings & turned the rings, sent them out & had them chromed. Changed truck engines. Lengthened & shortened frames. Electrified a truck for theft deterrent one time. Twin-turboed an 8V-92. Put a 1693 Cat in a Marmon. Put an Allison Aircraft engine on his sawmill. Built a set of headers for a 549 International...... Now, that thing did sound good!   Lots of crazy stuff.

The only reason I can see for doing what you describe is the challenge of doing it & the bragging rights of having done it, as others have already said.

If you do this, figure it's gonna cost twice what you think, it will take at least twice as long, and, if you are particular like me, you'll have to do at least three of them before you're happy with the results.

TOM
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bevans6
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« Reply #14 on: March 20, 2012, 08:50:13 AM »

Those buses were specifically designed to replace the engine in a day.  I would find another known good drive train out of a similar, newer GM, and stick it in.  Others have done so on this board, with great success.

Brian
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Don Fairchild
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« Reply #15 on: March 20, 2012, 09:23:49 AM »

it is your money but if it were me I would find an 8V71TA from transit or a 6V92TA also from a transit. The 8V will run circles around the 6V but you probabley don't care. You want millage so any turbo two stroke will be better than a naturaly asperated engine. I would seriously look at you friends set up. I have several friends the have S&S motor homes with the 8.3 and they don't get any where near the kind of milage. They also can't keep up in the hills, I have to pull over and wate for them quite often. I run an 8V92TA and get 8.4 mpg pulling my chevy 3500 crew cab 4X4.

Don
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la chiva
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« Reply #16 on: March 20, 2012, 08:38:46 PM »

guys don't get me wrong l love that old detroit the one in my 4107 is still running strong but it's pissing oil like crazy and could probably use some ajustment and i also have a 4905 with a spare engine it was park for 7 to 8 years i brought it home put some fuel and batteries she did about 3,4 turn and she went runs pretty good to but have no idee the can of shape it is.it's just that here in quebec the good two stroke mechanic are hard to find unless you go directly to detroit and then is $$$$$ the few shop i have tried if they touch it they all want to rebuild it.and i am planning full time in the bus so just trying to prevent breakdown on the road as much as i can

hey Don you talk about a 871ta or 692ta from a transit why? because they are LH turn
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« Reply #17 on: March 20, 2012, 10:10:38 PM »

Quote from: la chiva

hey Don you talk about a 871ta or 692ta from a transit why? because they are LH turn

yup
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« Reply #18 on: March 21, 2012, 05:22:20 AM »

Where in Quebec are you?

Brian
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la chiva
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« Reply #19 on: March 21, 2012, 06:18:58 AM »

hey Brian
i'm in Rigaud about 5 minutes from the ontario border
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bevans6
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« Reply #20 on: March 21, 2012, 06:22:33 AM »

I was thinking that if you were at the other end, near Gaspe or Rivier du Loup you might be able to find 2 stroke technicians at a commercial marina.  Did you talk to these guys?  http://www.wajaxpower.com/contact/dorval/  My local shop (Hamilton, Ontario) was a Harper Power, Detroit Diesel dealer, taken over by Wajax a year or two ago.  They have guys who know two strokes, but they are a commercial shop and priced to suit commercial operators - high!  That's why I do my work myself.  Learned a long time ago that I couldn't afford to do anything if I had to pay other people to do my work.

There is a bus yard on AR-30 south-west of the AR-15 interchange, there is a nice old Prevost in the yard that would have a 2 stroke in it.  Maybe they could help you.  

Brian
« Last Edit: March 21, 2012, 06:30:46 AM by bevans6 » Logged

1980 MCI MC-5C, 8V-71T from a M-110 self propelled howitzer
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la chiva
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« Reply #21 on: March 21, 2012, 01:56:44 PM »

thanks brian

i did talk to the guys in dorval  very expensive this is why i'm trying to find a independant
i do most everything myself to take out a engine tranny put another back in i have ne problem with that as a matter of fact i just pull the engine and tranny out of my 4905 today it's now sitting on a pallet.but before i do anything with my 4107 that i'm using i would like to have it check out by a pro. when it comes to tuning ang adjusthing this is out of my league maybe that
all it needs i just ad the bus for 1 years and i been travelling like this i dont really know the history of that engine i'm sure its not the original engine this one is red
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bevans6
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« Reply #22 on: March 21, 2012, 02:01:24 PM »

Check out the bus charter guys, call them up, ask for the service manager, ask him if he has any 2 stroke guys would like to run the rack on your bus for you on their day off...

Brian
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1980 MCI MC-5C, 8V-71T from a M-110 self propelled howitzer
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la chiva
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« Reply #23 on: March 21, 2012, 02:06:49 PM »

brian heyp that was my nexy plan there is one in ontario not far from me  LEDUC coach
my body drives for them he told me in the old days this company use to run buffalo
i'll go see them
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gus
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« Reply #24 on: March 22, 2012, 01:09:47 PM »

The 8V71 with V730 is the perfect engine setup for a 4107. I wouldn't trade mine even for a 4-stroke of any kind.

Nothing sounds as sweet in a bus as a 2-stroke DD!!

To do all you talk about it would be cheaper and much faster to just find another newer bus with what you want, probably a lot cheaper!
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PD4107-152
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« Reply #25 on: March 23, 2012, 10:58:04 PM »

La Chiva -

Lots of good comments here, let me add my loonie's worth:

Your 4107 doesn't have a frame, in the traditional sense.  The outer skin, bulkheads and floor make up the chassis.  The engine literally hangs off the roof and the rear bulkhead, as you found out when you pulled the powertrain out of the 4905.  Thus, fabricating T-drive frame rails would be a major undertaking which would literally mean taking apart the entire rear of the coach. 

I saw a 4104 in SoCA quite a few years ago that the fellow had put a 6V92TA/HT740 in a 4104 as a T-drive.  Whole rear of the coach was lengthened 24 - 30 inches, increasing the rear overhang by the same amount.  Also made the coach "look funny" - the proportions were slightly "off."

The reverser V730 is quite rare, as are the few 4-stroke V-drives mentioned by BW.  Just not that many ordered. . . especially since GMC got out of the bus building business.

Why not do some PM on the current engine to see where the oil's coming from?  It may as minor as loose bolts/fittings, etc. - wouldn't be the first time!  (There was just a post recently where a bolt had worked itself loose under the alternator, leaking oil everywhere!)  If the engine runs pretty strong, sometimes if it ain't broke, don't fix it!

These engines will often stop "using oil" once it's discovered that somebody put multi-weight into the crankcase, instead of straight 40wt, and it gets changed to the proper type.

And, as Gus posted, if you really want a 4-stroke, buy a newer, already converted coach - the market's in the toilet nowadays, so great deals can be found with a little searching.

FWIW & HTH. . .

 Wink

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RJ Long
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la chiva
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« Reply #26 on: March 24, 2012, 06:02:51 AM »

well guys
thanks to all of you for your advice and comments i finally found a 2 storke mechanic
not to far from me i'm having both my engine check next week just went to pickup my 4107
yesterday from storage didn't even need to charge the batteries first turn she went and purs like a cat
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« Reply #27 on: March 25, 2012, 08:17:12 AM »

Don Fairchild turbocharged my 8V-71.  We put in 7G75 injectors for 375hp and 1125lb/ft torque (compared to 300hp and 800lb/ft torque with 65 injectors and no turbo).  Turbocharging an 8V-71 REALLY wakes them up.  Yes there is more heat, and I have to slow down on hills in summer, but you have enough power at highway speeds to pass someone!  Keep with what you have.

Yes you can change your engine to a 4 stroke.  The engines that have been used with the V730 using a reverser gear are Detroit Series 40, 50, Cummins ISC, ISL, ISM.  As with any change over, it takes alot of engineering.  Even my turbocharging was an engineering feat since I added an air to air intercooler.  I ultimately had to upgrade (change) my muffler, air cleaner, radiator, and add an auxiliary transmission cooler with fan. I now have 15,000 miles on the turbocharging and the only thing I've had done is new injectors.  I didn't rebuild it to a turbo spec, hence my fuel mileage isn't as good as it could be (the turbocharging cylinder liners have shorter ports allowing a longer power stroke before the exhaust valves open up).  Rebuild your engine to a turbo spec and you'll be tickled pink.  My mileage is the same as when the bus was not turbo'd, but the performance is drastically different.  Good Luck, TomC
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« Reply #28 on: March 26, 2012, 08:13:02 AM »

That's a big chunk to bite off, even if you do all the work yourself assuming you can find all the parts you need.   Also what I know about late model Cummings engines,  personally I won't consider that conversion at all!!!   Hope this helps.   Busgeek.
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la chiva
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« Reply #29 on: April 09, 2012, 08:38:04 PM »

well guys

finally found a 2 stroke mecanic work for detroit and does work on the side
he went over the engine needed a rocker job worn out pretty bad so the timing was off
fix a few leaks cost about $2200 and said my engine will probably outlive me definetelly
much better then rebuilt or repower for the difference in price i can put fuel for a while
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« Reply #30 on: April 09, 2012, 10:13:52 PM »

Whats a rocker job?
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« Reply #31 on: April 10, 2012, 04:47:37 AM »

Rocker job AKA setting the valve rocker lash and timing the fuel injectors.  Just a different term for "running the rack".

Brian
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1980 MCI MC-5C, 8V-71T from a M-110 self propelled howitzer
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Vintage race cars -
1978 Lola T440 Formula Ford
1972 NTM MK-4 B/SR
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