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Engine Swap advice for '66 Bluebird??? Jesse 9-23-03  
I recently bought a 1966 Bluebird School Bus that was converted into a motor home buy the prior owner a few years ago.

Up until about a week ago, the bus still had its original engine which was an unusually rare, large and impressive GMC 478 cc, 7.8 liter V6 gasoline powered rear engine that GMC only made between 1964-66. This was the biggest v6 gas engine that GMC EVER made!

Well, unfortunately, the engine is on its way out as the cooling system has been having some serious problems which then led to even more serious problems and well, I now either have to rebuild the original engine, though so far I can't even find pistons for it (parts for it are very rare) or replace it with a rebuilt engine.

Anyway, the old engine currently lacks the strength that the bus wants and needs, and so I was thinking about replacing the old engine with a rebuilt diesel engine that would be a good fit for the transmission and bus chassis/engine mounts.

Is there anyone out there who can give me advice regarding this situation? Is there anyone out there who is familiar with this particular rear-engined 1966 Blue bird school bus model or who is familiar with this 1966 478cc V6 GMC engine that can tell me which DIESEL engine make and model and year would make the best candidate for installation into this particular model when looking for the best AND LONGEST LASTING bang for the buck?

Bluebird told me that this bodytype, make and model bus also was made available with a diesel option, and that for that option they offered a cummins210 or a CAT 225. Which rebuilt diesel engine make and model would make a good candidate for an engine swap for a chassis and transmission made for either of these engines?

Thank you so much for taking the time to read my post!

Sincerely grateful,

Re: Engine Swap advice for '66 Bluebird??? Gene 4-9-10  
I also have a 66. Any photos ?
Re: Engine Swap advice for '66 Bluebird??? Rick 9-25-03  
The GMC V-6 was around for a few years in various displacements from the mid sixties to around 1972. I would check into a conversion to the GM big block gas truck engines. I drove an older GMC that had been retro fitted with a GM 366 V8 that replaced a 351? V6 and it ran great and looked like it was almost a bolt in. I think the bolt pattern on the bell housing was the same and the motor mounts were adaptable. Many of these chassis served both GMC and Chevy so the holes for the motor mounts should be present. The 427 medium truck engine would be the closest in power to what you have. A 502 V8 is also available. Most of the newer ones come with TBI FI and seem to much more responsive than the old 2bbl carbs were. Make sure you get a "truck" engine for the most service life. If you go with diesel you may have to change out your rear axle ratio to achieve highway speeds and keep the RPMs within specs not to mention modifications to the fuel system. The noise level tends to be high on the front engine flat fronts. That said the diesel does get better fuel mileage and will last longer. Most gas BB Chevys in school bus service seem to last to about 150k.
Best of luck and let us know how it works out.
Re: Engine Swap advice for '66 Bluebird??? Mark O. 9-25-03  
You didn't mention if your bus is a rear engine or front engine bus. You also didn't mention what sort of use you will doing with your RV. Both can make a big difference in your choices.

The big block GM V-6 engines were a complete family of engines, from the little 305 used in GMC pick-ups through the 351, 401, and the 478. All were gas hogs, low on power, bad for running unbalanced, and death on things like intake manifolds and carbs. They were also the platform upon which GM built the Toro-flow/Turbium diesel which later evolved into the 350 diesel and later the 6.2L diesel.

The easiest swap would be to change out the V-6 for a GM big block truck engine. The 366 would be very similar in power and torque as any of the V-6's. The 427 would be a step up.

The Cat 3208 will fit and the swap wouldn't be that difficult. The only problem is the cost will be much greater and the noise level will be considerably higher. Another couple of diesel choices would be the DD 2-cycle 6V-53 or the DD 4-cycle 8.2L. Stay away from the Cummins 555.

If your bus is a front engine, you can just about forget normal conversations or listening to tunes while you going down the road if you choose to go with the Cat. If your bus is a rear engine, you can just about forget normal conversations or listening to tunes while you are going down the road if you choose the 6V-53.

Unless you are going to be driving in excess of 10K miles every year for the next 20 years I would seriously think about staying with gas power. The big block gas engines are not that thirsty, about 3-6 MPG. The Cat is going to get about 5-8 MPG. You can travel a lot of miles for the $$$ more it is going to cost to swap in the diesels.

Good luck and happy trails.

Mark O.
Re: need manual 8.2L coolant sys. donald stevanus 10-9-03  
I have a strange water pump inlet from surge tank problem, not like any i've seen, must be a hybred. i would like veiw systems. non-turbo
Re: Engine Swap advice for '66 Bluebird??? Craig Jones 7-12-10  
I have a 66 bluebird pusher. Was wondering if you had any pics of yours.. Ill share mine.. It has the 7.8l v6.

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