Looking for general info on a swap. I have a 76 Buick Custom (Century) wagon. I am looking to replace the stock 350 with an Olds 455 with 400 th. Need to know if this is a direct bolt in. The 455 is out of a 70 88. Excellent motor and trans.I am aware that I will need to change out the alternator and items such as this but both vehicles are approx same size including the engine compartments.

wow, talk about a non-standard swap, we're so used to hearing people talk about swapping in chervies we just might let you get away with this w/o giving you too much crap. ;)

you've got the olds engine mounts, right? you could've used the buick trans but i'm sure that the one that's already on the back of the olds is easier to deal with.

I am aware that I will need to change out the alternator
you will? why is that? i can see needing a different accessory bracket but i think all of the belt driven stuff (excepting the water pump of course) like power steering pump, AC and alternator were standard GM equipment.

was there a change from 2 wire to 3 wire between 70 and 76 or something?

Yes, actually there was a change. From a voltage regulator to an internal regulator. The wagon has an internal so I will be changing out the alternator. If the mounts match than all should work. I am just not sure if they are that is the reason for my inquiry.

oh yeah, forgot about the regulator thing.

anyway, I take it then that the swap is an easy one so long as I have the olds motor mounts?. As for the existing tranny, it is a 350TH and is no good. I would rather keep a 400 on an engine that size. After over 30 years of building motors I have never swapped only replaced what came out except my 66 442 which I replaced a bad 400 for a Hurst Olds 455. My 76 Cutlass was an easy swap if you want to call it that. I replaced the stock 350 with a 455 that I built to over 550 hp.
This thought is different so reason why I am asking about it to be sure it will not entail a great deal of extra work.

i've never done such a thing so i couldn't tell you for sure but as long as you've got all of your belt driven accessories on the olds motor / tranny combo and don't have to try to transfer stuff from the buick i think it should be pretty straightforward.

after all, that wagon frame was shared with olds, pontiac and chevy wasn't it? and THEY all put big blocks in their versions of the wagon.

i suppose it's possible that the crossmember is actually drilled in different locations depending on the make but i've never heard of such a thing.

a review of the engines shows they are actually the same size front to rear. The TH400 cross member is not the same used for the th350 but since I have the entire 70 olds car I have the cross member, the exhaust etc. Appears the only problem will be the mounts. Chevy Malibu wagons for 76 looked identical ie: size but being chevy's small "block" is trully a small block compared to Pontiac, Olds and Buick the mounts would definetly be different. So far looks like the olds mounts will. will let you know when we do the swap.

Should be no problem, GM used a Buick 350 in my '79 Bonneville wagon. Are you sure the original motor is actually a Buick? Remember, Buick, Olds,& Pontiac all had 350's and they all could be replaced with the 455's. By the way, I replaced the Bonniville's 350 Buick with a '74 Caddy 472. (I had the Caddy on hand when I blew up the Buick so don't jump on me!)

it is an actual Buick 350 in an actual 76 Buick Custom wagon. This is a totally stock fully option and loaded station wagon. I only am curious as to whether I can swap out the 350 and put an Olds 455 in it's place. The Olds 455 is from 1970 out of a full size Olds 88. It will work if mounts are correct and frames are correct. 79 Bonneville in no way is related to 76 Buick. In 1978 all GM cars were reduced in size. The no longer used the platform that was available til 1977 therefore any change from motors in 1976 to a GM model year in 1978 to current would not be a direct bolt in. I build Olds motors and am very knowledgeable regarding the difference in Pontiac, Buick and Olds. IE: Distributor locations on Olds not same as Pontiac and Buick. Oil Fill tube on Olds is only one of it kind. No oil filling in valve cover etc. As for the "Buick" 350 in your 79 Bonneville wagon. I think if you research further you will discover that GM had no Buick 350 v8's available in 1979. In 1978 and 1979 they pulled chevy 305 and 350's off the rack and installed them. GM in it's infinite wisdon neglected in designing the small platform to consider that Pontiac, Buick and Olds did not have "true" small block motors when you actually measured the outside dimensions. When they were done with the platform they discovered this so elected to install Chevy 350's which are "true" small block motors thus they fit. They were sued for this by numerouse Pontiac, Buick and Olds buyers once discovered that there cars were not "True" due to wrong motors. In 80 Olds introduced it's own small block that would fit. It was the 307. Same wide spread design with oil fill tube traditional to Olds motors but designed to fit in the small platform. In 78 and 79 the only true motors for the Buick, Pontiac and Olds line were their own V6's. If you look at that motor take a measurement and you may find that it is not a spread from outside valve cover to valve cover of approx 23 inches. inside head to head should be approx 14 to 15 inches on the Buick, Pontiac and Olds true 350's.

One more note, I am the second owner of a 1978 Olds Cutlass. Totally stock and purchased 4 years ago with only 106,000. It came from the factory with a stock chevy 305 4bbl. This info is documented and my Buick nor any of my original Olds 350's would never bolt directly into this car. Could one be swapped, yes but there would need to be manuevering and some adjustments not worth the hassle.If you check you parts store for parts, they may have different #'s when you ask for them and reference Pontiac but if you tell them it is a chevy, the odds are you will see the same identical part. Just different #.

JR/Bob K. Well we got the 455 pulled. I will be pressure cleaning and de-greasing than repaint. It will be painted stock Olds gold with the black brackets. I did not realize that it has the heat riser set up on it. Cross under exhaust may be a problem. My 350 does not have hear riser. If a problem with mounting will have to eliminate the cross under exhaust and manufacture a seperate driver side exahust from the maifold. I also, though remembered the alternator changes from 70 to 76 (no longer needing the voltage regulator) forgot that there was also a distributor issue. 455 has stock points and condensor with vacumn advance. The 76 has the stock electronic. I want to keep the stock 70 points unit so now I will have to figure out the wiring. Oh well, just something else to deal with when swapping.

Well the swap is not going anywhere near as easy as first appeared. The 70 455 mounts cannot be used based on position and design. They are not even close in resembling the Olds mounts from 76 as on my Cutlass. I picked up a set for mid 70's Olds which at this point appears will work. I will have to eliminate the eshaust manifolds and cross over system as this prevents the motor from dropping down into the cradle where the mounts need to be. A friend is fabricating the bast plate for the mounts. Next I will have to order headers and will need to look at manual choke or a new carb due to heat riser no longer will be on the engine. I would not recomend this swap to anyone. As an Old's person I will be the first person to tell you that headers on a 455 is one of the most difficult hook up's there is.
Anyway between that and ordering a new exhaust system It will be a few more weeks before this is considered finished.

The size of the car from the large earlier models in the 70's to the smaller sizes in the late 70's did not change the motor mounts for the cars...you can stick a 1970 350 right in a 305 equipped mid size 1980 monte carlo if you want. If you werent saying that you couldnt, then sorry to bother you lol

of course I meant a chevy 350 smile.gif

I am glad that you cleared that up since Chevy is not a BOP and will not bolt up the same. The overall size of Chevy 350 is smaller than BOP 350's. The 455 out of the 70 Delta bolts directly into the frame not on a base or frame mount. We are trying to use the base mount on the 76 but it sits fairly high compared to the way the 455 with 76 motor mounts would sit as in my 76 Cutlass. Not to mention that we are not sure of angle though the frames are same there is no guarantee that the angle of the base/frame mount will comply with the motor mount correctly. If not than we will just cut these down to fit the proper angle. The other thing to keep in mind is that 78 on to 81 used chevy motors that were referred to as Buick, Olds and Pontiac but were nothing more then true Chevy 305's and 350's. These were not in fact BOP motor's. 76 did not come with Chevy 350 but an actual Buick division 350 ci.

well we finally got the beast in. All that was needed was the mid 70's Olds 455 motor mounts. These are not the same as the ones that came on the 70 Olds 455. The 76 Century stock wagon frame mounts were compatible and once we allowed for headers it actually dropped in fairly easily. So in the future I will now know that the Buick mounts will accept Olds motor mounts so long as the years are compatible. Motor looks good in there. Today we have the cross member to put back. Tighten down the motor and finish up bolting the headers. Once that is done, start connecting up vacumn lines and electrical.