Body front end, Engine & Transmission removal? '77 Itasca C25C Class C

Started by johnnytugs1, December 12, 2009, 01:39 PM

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johnnytugs1

Just when I had some bennies squared away for the old girl the younger one needed it more. B U T, I don't give up the ship that easy, never say never, blah....blah....blah! Thanks frank, lefty, terry and exodus you are great ! I was considering cutting it out and maybe welding up some street sign to retro fit it but maybe i'll take a closer look at it and try the sledge. then i could always cut it out if it doesn't work. I'll let ya know how it goes when i get off in 10 days.
Thanks again,
JT
p.s. The engineer on my boat said this would work......any thoughts?
http://m.summitracing.com/parts/cee-4031

1977 itasca class "C"
under construction

Rickf1985

A solid mount kit. That would be so unbelievably noisy you would no longer want to drive it. Basically it would transmit all of the engine noise through the metal mount right into the frame and directly to the drivers compartment.

johnnytugs1

o0o0o0o0oh, thanks Rick!I never thought of that. That wouldn't make S.W.M.B.O. very happy.
JT
1977 itasca class "C"
under construction

Froggy1936

John That plate is a drag raceing only modification ! Not for street use . Your problem is trying to stuff 10 lb of sh-- into a 5 lb bag. Lots of luck .  Our bodys are not P30 design they are different And i dont think Chevrolet ever put the big block in one . But nothing is impossible , Though you may end up with a different throttle control (something from the handicapped applications)  Becase the room you need is takeing away the gas pedal area .Are you updateing from your 350 trans ?  Good Luck Frank
"The Journey is the REWARD !"
Member of 15 years. We will always remember you, Frank.

bluebird

The BB and SB engines frame mounts are in a different location. I've done the swap a few times, not in a MH but trucks and cars. Remove both frame mounts, bolt them to the engine, then let it down. Make sure the drive line, is lined up, then redrill your new holes.

johnnytugs1

Thanks Bluebird, I'll explore that option. Frank i'm using the trans that was with the 454 I believe its a 400 beefed up to pull 30k lbs. If i cut the dog house wall, from what I saw in regard to the gas pedal I was thinking maybe i could just move the pedal over but I didn't put to much thought in it yet. I just saw that some thing needed to be done unless I can do as bluebird mentioned and maybe get a longer drive shaft ( it's a 2 piece shaft but I saved the one from the 454 set-up). If I can do as bluebird mentioned, what else should I look out for or need to consider? Bluebird as the motor sits now there is approx 4" space on pass. side and none on the drivers, can i center the motor in that space or just not set the motor in as far (which may  bring about a problem with the oil pan)? This is really turning into a P.I.T.A.
Thank you,
JT
1977 itasca class "C"
under construction

bluebird

I would install the trans, then bolt the engine in, with the frame mount bolts removed. You have to be sure the drive line is with in certain specs. So if you just center the engine in the hole the back of the trans may be pointing to the left or right of the rear end. Can't do that, you will have terrible vibrations, and it will be very hard on the trans and u joints.

That coach only had a th350 trans? My old minni winni had a 400 turbo in it, so did my gmc gimmy. But they both had SB in them. If the coach did have a th350 in it before and you put a th400 in it the cross member will have to be moved too, unless some one already did some mods to put a th350 in it.

Would have been nice to know what the centerline was before you removed the old combo. You have a lot of measuring to do. I don't recall how much wider a BB is compared to a SB, but it's not a lot down at the mounts, maybe an inch or so. Remember you have to get the radiator back in too so don't move the engine forward at all.

Froggy1936

John The TH400 should not cause any sugnificant problems (that is what was behind my 350) There is a difference at the frt u joint non slip or slip but that can be addressed after its all bolted down . The engine problem is width at the valve covers. As you know how to overcome the motor mount problem . AS far as Moveine the rear Xmember there is enough room to slide it either way With my 4 speed i had to go back 3 in and was able to use holes that were already there And drilled a new trans mount to X member hole . As far as alignment of the drive shaft i used a laser beam flashlight a tape and good old eyeball left to right is very important height not so much The straighter the better When the made up my driveshaft i had them shorten just the frt section 3 in As the center bearing came out ok with the original rear section I had a problem with AC compressor and was looking at modifying dog house wich would have interferred with acc pedal . But i found a V6 compressor/ Power steering pump mount from a 2006 solved the problem Good luck Frank
"The Journey is the REWARD !"
Member of 15 years. We will always remember you, Frank.

TerryH

Something to consider is that ideally your drive train should follow a linear straight line from harmonic balancer to rear differential. Driveshaft universals will accommodate height differences and movement between tailshaft and differential, but linear movement will possibly and eventually destroy seals and bearings.
Not sure about your particular frame, but common practise on early 70's GMC truck frames was to punch holes for both SB and BB motor mounts and cross members (standard, automatic and 4x4 with transfer case) during frame fabrication.
Also a common problem for the frame during those years was steering box to frame mount causing a frame break. Would be worth checking as well.
I repeat, not sure about your particular frame.
Terry
It is not our abilities that show what we truly are - it is our choices.
Albus Dumbledore

Rickf1985

I am not real familiar with the cclass C motor homes but if they are on a cab and chassis then it most likely is set up for any motor an transmission combination that could have been used under a truck. The cab and chassis was used for everything from a mini dump truck to delivery vans to campers to you name it with every possible engine and transmission combination that GM made. The only difference would be the body that was on it would be the limiting factor on the engine size as you are finding out. Just as an aside, you may find all the holes are there to bolt in a front differential and make it four wheel drive. W%

bluebird

C class MH are built on a G chassis not a P chassis, completely different. I have never seen an older G chassis with a BB engine in it, not saying that GM didn't make some, but all of the ones I've seen were SBs. Largest engine I've seen in the older G chassis was a 400 SB, most were 350s.

Rickf1985

Agreed, the G's were all van chassis so they were all small blocks. That being said, fi you are spending money on it to stuff in a big block then spend the money on a 383 small block instead. The longer stroke will give a lot more torque than a stock 350 and if you go with a torque package from Edelbrock of one of those companies then you can have quite the motor for not real big dollars.

bluebird

I just looked it up on O'Riellys website. It appears they did put a 454 in a G30 in 1975, in a hi cube van. So it has to fit, doubt very much that they changed the front frame that much, so it may have the holes for the mounts already there.


It also said that the mounts are the same part number for the frame. If the holes are already in the cross member it should just bolt in. Man you're lucky!!


Looks like they used the 454 for 3 years 73/74/75.

pvoth1111

With a grinder a torch and a welder anything can fit....question is how serviceable will it be...why not just put in a nice modern fuel injected small block from a salvage yard???
We call our coach "Charlie Brown"

Rickf1985

I know on the Fords and I think on the Chevy's the engine is offset to the passengers side a little bit to give more room for the driver. The rear differential is also offset the same amount. I know a lot of guys that ran into vibration problems when they got van rears cheap and put them into pickups. They found out why they were cheap. What I am saying is that if you start measuring do not be surprised if you find the engine is offset. Measure the front pully of the engine in relation to the frame and then carry that difference on back if there is a difference.

bluebird

I agree.. Most vehicles are off set to the passenger side, some more than others. I believe my sons Firebird is 2.5 inchs. My buddy is building a 37 Chevy truck and put a 454 in it, centered. When I told him about the offset he didn't believe me till he measured the rearend. The Oldsmobile rear that he's using is 1  3/4 to the passenger side, he had to make some new mounts. 

johnnytugs1

Thanks guys, I'm getting ready to go home tomorrow, i will check these replies more in depth when i get squared away.
JT
1977 itasca class "C"
under construction

johnnytugs1

Well I've been home for 4 full days and haven't even had a chance to look at it. Cross your fingers for me!!!
Thanks,
JT
1977 itasca class "C"
under construction