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Author Topic: Advice--NewBe 4107 8V71/V730 swap  (Read 1064 times)
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« on: January 05, 2007, 04:16:04 PM »

I am new here and could use some advice from the incredible experience here!
I have a 4107-078 , which needs a motor and transmission
 <------ Smiley
And a "donor bus” Grumman Flx 8V-71/v730
 The label in the bus, 1980 Grumman Flxible
                              Bus                                               Mdl# 53102-8-1
                  Eng# 8VA402035                                    Mdl# 8V-71  7087  4523
                Trans# V-730   13371                                axle ratio 4 5/9 : 1 ?
   - - - -   -- -   - -- -  - -
The trans. # plate reads...                                                   Model#? 23013542
                                                                                             ??  80J27
I have the manuals for 4107 and the v730 conversion ligature (I’m not sure if it is complete, no wiring for 4107?)
And I will get the Grumman manuals If can use them.
1. Before I pull the donor motor and make the FlXiblex a "n0n-runner"...Will this motor/trans. Swap work?  Electronic control??
    If it is DDEC what does this mean for a swap?  I have the whole Grumman. It runs and starts great. I think I want the air throttle and shifter?
2. Do I really have to cut/relocate a bolt in the cradle support bracket? Any reports of long term (RV) failures in the modified bulkhead? If properly reinforced?

3. Is there a big enough advantage/difference in the brakes or axle/rear to change it as well? (But not with the Flx’s transit 4 5/9 : 1 ?? rear gear)

Thanks for all the Great Information you all have here..
Happy Friday

Hero Member
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« Reply #1 on: January 05, 2007, 04:21:30 PM »

I have basically the same setup in my transit conversion.  The rear end is probably a 4 5/8 (usually was in fractions) which converts to 4.625.  This is the ratio I have and will give you 65 mph at 2100-which is alright to run all day.  Although, it be better down around 1800 which is 55mph.

If the doner is a DDEC, then take ALL engine and transmission wiring from the Flx including the gas pedal and shifter.  If it is mechanical, then by all means go with the air pedal-I have it and love the light pressure needed.  Good Luck, TomC

Tom & Donna Christman. '77 AMGeneral 10240B; 8V-71TATAIC V730.
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« Reply #2 on: January 06, 2007, 10:29:41 AM »

 Here is a site you might lok at he used the engine and transmission from a 1981 Grumman-Flex.  http://home.att.net/~kirbybus1/
I also used a engine from a 1980 Grumman-Flex. You have to use the engine cradle from your GM. You have to cut the cradle and relocate the RH cradle to firewall mount to clear the V730. There is a lot of wiring and lines that can be eliminated. The fan drive was different on mine then the GM no angle drive and about 7" shorter. I used a 4.33 rear end ratio which gives me a top speed of about 73mph. A 4.125 will give you abvout 78mph top speed. The data plate on my donor bus also stated 4 5/9 for it's rear end ratio. I have many pictures of this project.  I can send some of areas that might help.
We both installed these into GM 4104's. There are differences but the end results is  basically the same
Craig C
4104 8V71TA/V730
Craigc at hughes dot net

Craig C
4104 8V71TA/V730
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Posts: 40

« Reply #3 on: January 06, 2007, 01:57:51 PM »

Hey Oregon,   send me your phone number.  I have done this engine swap using a 6V92ta.   Frank  in Idaho
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