4905 6V92 & V730 Reman w/Pix

[chris4905]

It's been 3 months of work.  Almost every night after working the regular daytime job and almost every weekend.  But it's almost done.

Took out the cracked block 8V71 and also the Spicer 4 speed.  Got the engine and trans from NIMCO.

The engine and transmission are in.  I have had the engine running, couple small oil leaks that I'm trying to stop, but the engine oil pressure gauge shows 25psi at idle, engine sounds good, no problems discovered yet.  Have moved the coach forward and reverse about 25 feet each way, so at least the tranny is working that much.

Got a used Stone Bennet Air Shifter, had to make up my own controller.  I am now installing the SB air shifter on the transmission and drivers area.  Once that's in close to doing a test drive.

Took out the oil bath air filter and replaced it with a new Donaldson air filter.  Got that mounted and tonight started to connect the air filter to the turbo.

Took out the old muffler from the dog house area.  It was almost falling apart.  We were getting exhaust dust in the bedroom the past few years, I figured it was just a non-air-tight area and the fumes were working their way up from the engine compartment.  Actually, one of the two exhaust manifold tubes, where they connect to the muffler, had sheared off the majority of the exhaust wasn't going to the muffler, it was being dumped into the dog house area.  Gonna put in a Donaldson muffler above the engine area.

Lots of re-work due to the V92 of course being a different size engine, and different configuration, than the V71.  Had to rework and weld the cradle to match the V92, lots of water, air, fuel, and oil lines had to be redone and re-routed.  Had to even make up completely new radiator to engine coolant connections.

Lots of work, but it's downhill now, keeping my fingers crossed for no major problems.

I have included a picture.

Chris Christensen
1974 GMC 4905 with 8V71 & 4 Speed Spicer 6V92 w/V730
Eagle, ID (I know....what's a guy in Eagle doing with a GMC ?!?!)

[niles500]

WOW! Nice job!

[TomC]

Very nice job-just have to make a big ol shroud for the fan.  I can't really tell, but it looks like you used PVC piping on the lower hose of the engine.  If so, I'd highly recommend you not use PVC since the vibration of the engine will probably cause it to crack.  A simple solution would be to take the PVC that is already the right shape and size over to a muffler shop and have them duplicate it in the steel pipe used for exhaust.  Then you can also paint it that pretty blue like the rest of the engine.  The PVC will work for awhile, but why wait for it to crack when it will be relatively easy to do it now!  Good Luck, TomC

[AKThom]

Very nice!!!

[chris4905]

Thanks everyone for the kind comments.

TomC............your right (as usual) on both counts:

I have to have a sheet metal shroud made for the radiator fan.  The V92 is shorter than the V71, hence the extra room.

It is PVC pipe.  It is connected on both end with silicone hoses, but I agree, it will not last for long.  I intend to remove it this winter and have a radiator shop use it as a pattern for the finished product.

I can't begin to list all the fellow busnuts who gave guidance, encouragement, tips, shared pictures and email files, the list would be extensive and I don't want to name names because I would for sure leave off a few names and I don't want to slight anyone.

You all know who you are, and I can't begin to thank you all for your continuing help and encouragement !!!

Chris

[Dreamscape]

Chris,

Very nice work. You have done a remarkable job on your daunting task. Keep us posted on further work, we just like to drool.

Paul

[FloridaCliff]

Chris,

Fantastic Job!   

Its nice to see your repower coming to completion.

Cliff

[JackConrad]

Chris,
   Beautiful simply BEAUTIFUL!!  But, do you really think that painting the DD blue instead of green will stop the oil leaks? LOL  Jack

[tekebird]

you may want to reconsider the PVC Radiator Pipes.

That stuff was not designed for the vibration it will recieve nor is the glue used to join them.

Blue? Thats Blasphame

[Utahclaimjumper]

Ford blue should be nowhere neer a Detroit,anyway, for what its worth when my friend and I installed a 6V92TA in his 4107A we machined an aluminium spacer to move the fan over to the rad shroud.>>>Dan

[Sojourner]

Great work on your project....a soup up sport bus.

Like what TomC quoted about PCV & fan shroud. I would suggest to OEM fan location by adding 1.5" cold roll steel (with matching key ways) shaft extension with constant flex coupling in between fan's shaft & engine's fan hub. Need only one self-align pillow block ball bearing with locking collar plus a safety stop collar with two set screw to keep fan from moving to radiator while driving. Fabricate a bearing support near fan for pillow block bearing using 1/4" thick "wide angle" iron with a diagonal brace and bolt it onto frame so you can remove to servicing in the area. This arrangement allows more air flow freedom before engine and larger opening at below.

On the other hand by adding shroud's extension to move it to where your fan is now will be more prone to cause noise & vibration to cause possible crack in sheet metal panel. Plus harder to access behind shroud's tunnel.
You might want to update the shroud's design by using contoured design fiber-glass from class 8 truck if its size is right. It will increase air flow some.

Here a link on all about shroud opening design...I believe you find it interesting:
http://www.multi-wing.com/grafik/technical/IVTarticle2004.pdf

The closer tip clearance the quieter and greater flow..

Bottom-line is that some new models of class 8 trucks are designing shroud to be mount on engine to achieve closer tip clearance. However in your case is to have shroud mounted with pillow block bearing mounting frame to keep it in control.

FWIW

Sojourn for Christ, Jerry

[Brian Diehl]

Chris, The repower is looking great.  I'm glad you have been able to do a successful "drive" test!  I know the feeling you had when it actually worked!  Keep up the good work and do the best you can to build a trouble free installation.  Well worth the time and effort.  I also know what you mean about full time job and then coming home to the work.  It will come to an end and then it will take you a while to figure out what to do with yourself!

[TomC]

With the increased cooling needs with the 2007 engines with catalyst and particulate trap, we started by increasing the radiators from 1350sq/in to 1625sq/in and have the mounting of the shroud on the radiator mounted directly to the engine.  This did two things, one it kept the engine-radiator-shroud-fan as one moving all the same so the gap between the fan and the shroud is only big enough to slip the serpentine belt through.  Second, during assembly, it allows the fan/engine/transmission be installed as a complete unit-much like what cars have been doing for years.  We are so sure of the none movement, the shroud is made of venturi aluminum.  While the engineers weren't sure of the cooling at first, we've found that the engines are actually running within the temp range closer then with the old system.  Good Luck, TomC

[JohnEd]

Tom,

Interseting post.  Reminded me I have had a long standing question.  You mentioned that the sq inches of a radiator went up due to added heat loading.  How can you correlate sq inches to hp as in needed to cool.  I know that the rad core can be of many different rows and then there is the serpentoine or dimpled aspect.  How can you define this in terms of what is needed for a given horsepower.  If this is muddled...I apologize.

I read the Wing site data and they talk about % of airflow increase.  Makes sense that more airflow would net better cooling.  Also, colder air would net better cooling.  Etc.  So, do we tell the radiator guy how much air we can blow or does he spec the rad and tell the fan guy what size pullies he needs to use?  I am trying to get a grip on this topic and it seems too slipery.

Thanks and I am hoping for you now familiar stellar response.

John

[TomC]

John- Freightliner uses aluminum radiators with only two rows of cores.  The coolant tubes are large- about an inch deep and maybe about 1/8" wide.  It has been determined that with the aluminum fins being very fine and dense, the addition of a third row would not help-most likely hinder with decreased air flow.  Hence with the same core used with all engines, the engineers have a base line on what exactly the radiator can reject with heat.
As compared to the many other designes available in our buses.  For instance, MCI with their twin radiators, on my transit one large radiator.  My radiator is about 1100 sq in.  I had a 5 row straight fin core and had it replaced with a 6 row serpentine fin core that will make for a true 20% increase in cooling.  While I've had to add misters for heat control, I only have problems on long pulls on days over 90 degrees.  Since most of my driving is in non 90 degree weather, I'm not to worried about it.  I pulled a 8 mile 6% grade going up to Mammoth Lakes when it was 102 out.  I slowed down into first at about 32mph (still passing some other RV's) and stopped halfway up for a breather.  It took only 5 minutes for the temp to come down, so I knew the radiator was working well.  Besides, I have no choice in the matter-no more room for anything bigger.  Besides, I'm officially done with my drive train-am satisfied with the performance, and don't want to spend anymore on it (except of course of failure).  Good Luck, TomC