avco diesel conversion

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avco diesel conversion

Unread post by gon2sea » Fri Apr 10, 2015 12:36 pm

this might be of help or some inspiration to those who might be considering a diesel conversion.\n here is a link to a picasa web album covering my avco / cummins conversion.\n\nhttps://picasaweb.google.com/104905260722286217761/AVCOMotorhome

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Re: avco diesel conversion

Unread post by 77Travco » Sat Apr 11, 2015 9:39 am

Sweet...\nWhat chassis does your Avco have? I am guessing a M500? The 6 lug wheels are throwing me off.

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Re: avco diesel conversion

Unread post by gon2sea » Sat Apr 11, 2015 7:14 pm

hi, its a M600 chassi, i was surprised to see front and rear sway bars and how beefy the frame was compared to the newer Spartan chassi that was under the donor gulfstream 32 motorhorhome i bought for the conversion. the original AVCO had six lug, 19.5 bud wheels and so did the gulfstream. the avco had a 4.88 rear rockwell and the gulfstream to my surprise had a dana 80 with disc in the rear. right now i have 3.73 in the rear and will go to 3.31 soon as it is the lowest availlable for the dana 80, that will bring my cruise up to about 62 mph at 2200 rpm, very comfortable rpm for the cummins.\neric

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Re: avco diesel conversion

Unread post by Acesneights » Sat Apr 11, 2015 8:24 pm

That was a VERY good post. It will come to a point where we can no longer obtain parts for the M500 and your axle conversion is just the ticket. What did you use for a master cyl ? Are you running hydro boost or hydra vac ?\nAs much info as possible on the axle conversion. You look very skilled.
1977 Travco 270 Elite\n1974 Travco 220 Parts unit

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Re: avco diesel conversion

Unread post by gon2sea » Sun Apr 12, 2015 1:18 pm

i am using the stock hydroboost and am happy with it so far....im taking a trip into the mountains towing a car in a few days so i will get a better feel after that. If i feel like i need more power i can go with a hyromax it gives about 3X more braking power. the beauty of the transmission i have right now is that it has a retarder rated at 350 hp on it, havent played with that yet...\nthe axle conversion took some work, the original donor motorhome was diesel pusher, strangely all "spartan chassi" did was flip the axle backwards... so i simply flipped it back in its intended position, it meant re-welding the spring perches, changing the brake lines and bleeders so the bleeder could be on top, adding brackets for the sway bars and changing the yoke on the driveshaft to match the newer style ujoint on the newer dana 80.\nthe dana 80 is probably the best axle if welding is involved, the tubes are actual steel pipe pressed into the diferential housing, some other manufacturers use cast tubes and press them in, welding on cast can be tricky and the welds can be brittle, so the dana 80 makes it easy for anyone with little welding skills to get a good weld. \nright now with the 3.73 rear ratio im at 57 mph at 2200 rpm, when i drop it to 3.31 it will give me about 65 at 2200, that is the lowest ratio availlable for the dana 80, my other option is to go with an Allison 1000 series with overdrive 5 or 6 speed, that also means buying a stand alone controller.. when all said and done its a $ 2500 to 3000 deal... im not sure its worth it, i did a conversion years ago with a allison md 3060 and absolutely loved that transmission took me forever to wire it in and solder tons of wires to the factory computer and sensors.. but a 3060 is way overkill for this..

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Re: avco diesel conversion

Unread post by Half-a-Grand-lodge » Tue Jun 14, 2016 10:16 am

amazing photo gallery, thanks for sharing ... I have a dumb question ... why have the exhaust come out curb-side rather than street side?

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Re: avco diesel conversion

Unread post by gon2sea » Sat Aug 06, 2016 5:42 pm

Hi, its been a long time since i have posted anything, since then i have upgraded my transmission from an older allison 643 four speed ( non overdrive ) to an allison 2400 five speed, the 2400 is built on the same case / housing as the allison 1000 five speed and six speed. the 2400 does have a parking pawl like the 1000 series in chevy trucks. \nThis is a 2004 five speed, internally all allison 1000 series from 2000 on are six speeds, but were not used as 6 speeds untill 2006, prior to that a five speed valve body and five speed TCM prevented the use of sixth gear. that can be modified but that is a separate subject...\nso, now, with my 3.73 rear axle and fifth gear ( .75 ratio ) i can cruise at 70 mph at 1800 rpm, fourth gear is 1.1 and gives me the same speeds as my old 4 speed. now, great gearing for U.S highways, however when traveling on mountain roads or traveling down baja most of the time i find 5th gear a bit too tall. \ni am in the process of rebuilding a separate dana 80 out of another motorhome and installing 4.10 gears, that should give me about 1900 rpm at 65, i hope that will work out good and in most cases allow me to stay in 5th most of the time even when i slow down to 50 or so...\nregarding the last post and question.. the exhaust comes off the manifold / turbo on the passenger side and i get less fumes dumping it off the side instead of under/ behind motorhome...\nalso i now have added an exhaust brake as well..., upgraded to a carrier 45,000 btu bus a/c with roof condenser, huge improvements when its 100 outside...

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Re: avco diesel conversion

Unread post by Acesneights » Sun Aug 07, 2016 7:52 pm

Great stuff :D
1977 Travco 270 Elite\n1974 Travco 220 Parts unit

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Re: avco diesel conversion

Unread post by gon2sea » Mon Aug 08, 2016 7:13 pm

avco 080.JPG
here are a few updated pictures, new corean counters, larger refrigerator, bigger and deeper sink, i now have two new coleman 9000 btu mach 8 cub a/c's, a single one will run on the honda eu2000
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Re: avco diesel conversion

Unread post by gon2sea » Mon Aug 08, 2016 7:32 pm

as of now i get 12 mpg, carry 140 gallons water, 90 gallons diesel, next step is to convert to 4WD... because of the engine and intercooler etc.. i could no longer use the dash a/c, it was only a 15,000 btu anyways, cutting the overhead dash storage area worked good. the Carrier, bus 45,000 btu a/c works great.
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