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Author Topic: A TIMED 8V71 AND 4 SPEED  (Read 2443 times)
4106-123
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« on: April 10, 2008, 07:41:21 AM »

I PURHASED A 8V71 THAT WAS JUST REbuilt with a v730 the engine is A timed. i was going to replace the 4speed package with the auto package but im having second thoughts with the fuel prices being so high. so im thinking about just taking the rebuilt A timed 8v71 and replacing the engine thats in the coach now. can anyone tell me what to expect with the A timed engine and 4speed mpg and performance? also the a timed engine has a jake brake how is that set up with a four speed? thanks
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TomC
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« Reply #1 on: April 10, 2008, 08:15:24 AM »

To give you an accurate answer, we need to also know what injector size and color tags your running.  An A timed with 55 or 60's will work well with the manual.  With 65's you'll most likely have some smoking.  Don Fairchild can better answer that though.
With the 4 speeds on the coaches, no matter what timing you have, if you go to either the 65 or 70 injector, that creates what Detroit called a high performance engine, which has its' maximum torque at 1600rpm (and really should not be run lower than that either).  The 55 injectors were called economy, and the 60's were combination, both having the torque created at 1200rpm-perfect for the 4 speed manuals.  If you want maximum fuel economy, then stick with the 55's, which in my opinion will be enough for your 06.  Personally, I would put in the V730 since it is such a joy to drive-I have one in mine.  Good Luck, TomC
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Tom & Donna Christman. '77 AMGeneral 10240B; 8V-71TATAIC V730.
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« Reply #2 on: April 10, 2008, 08:34:01 AM »

its got the 65 injectors
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makemineatwostroke
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« Reply #3 on: April 10, 2008, 09:03:55 AM »

4106 your in the 265 hp range and you are not going to save that much fuel by changing it around now just go with what you have
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TomC
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« Reply #4 on: April 10, 2008, 09:13:02 AM »

I can tell you from direct experience, that while the 65 injectors will give you the best performance, you'll be far from the best economy.  65 injectors will get you 300hp and 800lb/ft torque.  The 265hp that MMATS is talking about is the peak horsepower rating for 55 injectors or 253hp net horsepower-that will be your maximum economy.  The bus companies used 55 injectors since you could run all day with your foot on the floor and never hurt the engine-even lugging it.  What is your present engine have for injectors?  If you're satisfied with the performance just stay with that.  Good Luck, TomC
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Tom & Donna Christman. '77 AMGeneral 10240B; 8V-71TATAIC V730.
makemineatwostroke
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« Reply #5 on: April 10, 2008, 09:35:58 AM »

your right TomC got my injectors mixed up with 65 and and a timing he should be 300 to 304 hp sorry
« Last Edit: April 10, 2008, 09:41:00 AM by makemineatwostroke » Logged
Utahclaimjumper
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« Reply #6 on: April 10, 2008, 03:41:24 PM »

Mines "A" timed with N65 Brown tags, VS2-8 and NO smoke. N70s will smoke.>>>Dan
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Utahclaimjumper 
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« Reply #7 on: April 10, 2008, 04:07:55 PM »

I inherited N70 injectors from the PO. I live in the mountains and I find it takes careful throttle work to keep it from smoking. I do not know if I have an ďA timedĒ engine though. I have gotten from 6mpg to 8mpg depending on many factors: Flat or hills, towing or not, and how bad I want to get home. Where I live and take my bus I donít have a choice, V730 is the must have bomb!
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L. Christley - W3EYE Amateur Extra
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« Reply #8 on: April 10, 2008, 08:33:33 PM »

When I first got my bus, I had the 55 injectors changed to N65 brown tag, but it was standard timed.  So in the mountains, above 4,000 ft got smoke-pretty serious smoke up at 7,000ft at Flagstaff, Az.  This is why I turbo'd it.  Actually, I should have retarded the cams and replaced the cylinder liners with shorter intake ports, but didn't want to spend the money.  Probably could see another mile to the gallon, but it now runs like a you know what ape, and it doesn't smoke even at 8,000ft after a little bit of smoke at first acceleration. Good Luck, TomC
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Tom & Donna Christman. '77 AMGeneral 10240B; 8V-71TATAIC V730.
Don Fairchild
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« Reply #9 on: April 11, 2008, 08:56:06 AM »

I don't know what injectors you have but set the valves at .014 the Jake's at .057 and turn the rpm up to 2500. You can control the smoke with your right foot, or left if you drive that way. Get a tac and run around 1700 rpm on the flats. In the hills run it up to 2300-2350 rpm and don't lug it and watch the tell pipe and temp.

Drive it and enjoy what you have. MPG will very by driving style.

Hope that helps
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Don Fairchild
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« Reply #10 on: April 11, 2008, 09:05:53 AM »

one other thing if i still has the oil bath filter get rid of it and go with a Donaldson with the  paper element.
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« Reply #11 on: April 11, 2008, 03:47:00 PM »

Don,
What does going to the paper filter give us? I thought the oil bath was just harder to maintain.
Fred
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Fred Thomson
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« Reply #12 on: April 11, 2008, 05:48:31 PM »

Fredward, most of the paper filters are less restrictive and more free flowing than oil bath, I converted my 06 to paper useing filters that I buy from Wall-mart for less than 10 bucks apiece.>>>Dan
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Utahclaimjumper 
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« Reply #13 on: April 11, 2008, 07:42:40 PM »

There isn't a truck or bus made today still using oil bath air cleaners.  The quality and flow rate of paper elements, and the ease at which they are serviced is the main reason that everyone uses paper elements. Plus, very few know how to properly service the oil bath type.  Good Luck TomC
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Tom & Donna Christman. '77 AMGeneral 10240B; 8V-71TATAIC V730.
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« Reply #14 on: April 11, 2008, 08:12:55 PM »

Ok I'm 'tupid. What is A timed? Embarrassed

I know I could look it up, but it's more fun asking and reading all the replies.  Wink

Paul
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Sam 4106
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« Reply #15 on: April 13, 2008, 08:29:54 AM »

Hi Utahclaimjumper,
Did you use the original four canisters when you switched to paper air filters? I switched our 4106 to paper filters using the original canisters. The last time I  paid $33.02 each for the filters from the auto parts store. The filters I use are Hastings AF 193. Would you please share the filter number with me for the ones you get from Walmart?
Thanks, Sam 4106
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« Reply #16 on: April 13, 2008, 10:44:50 AM »

Sam,

This is a post of what my 4106 has and how it was done. There are several different ways to do it. Mine was done by the PO.

http://www.busconversions.com/bbs/index.php?topic=788.0

Laryn
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L. Christley - W3EYE Amateur Extra
Blue Ridge Mountains, S.W. Virginia
Itís the education gained, and the ability to apply, and share, what we learn.
Have fun, be great, that way you have Great Fun!
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