I need some help here. I am new to this site and computer skills are very lacking. We'll see how this turns out. I have a very nice 67 Buick special. It is stock with a 300 in it. No dress up parts available that I have found. Yesterday I purchased a 73 455 motor,no miles on rebuild,heard it run and will pick up next week. What can I expect on this swap. Will I need special motor mounts. Everything else seems pretty close to what I have. Would appreciate any advice. Once I get this computer thing going I'll have my wife help me post some pictures. gb
swap Well, it is more complex than it seems. You will need frame mounting pads from a 67 gs 400. motor mount pads from a 67 gs 400. transmission crossmember from a 67 gs 400. drive shaft fabricated. 12 bolt posi diff. air bags inside the rear springs [ air lift ] heavy duty shocks all the way around. GS front springs. a heavy duty 4 core radiator with a fan shroud. a 7 blade fan. headers or exhaust manifolds from a 67 gs 400. complete exhaust pipes and 2 mufflers, hangers ect. after mkt rear axels to handle the torque. larger[ wider ] tires and wheels. Rear sump oil pan. Move the battery to the rt rear of the trunk. the car WILL be hard to handle without the suspension mods. it will get sideways on full accelleration and will have a tendency to swap ends. Wheel hop will be severe. breakage will be severe unless you make provisions for the massive torque. Without the hd cooling system it will run hot real quick. put a chain on the left side of the frame to the engine to keep from peeling the left side motor mount out. when you get it running, drive for a while to get a feel for it before getting on it. it will definitly be a beast. have fun building it and racing it but always consider that you are holding a wolf by the ears that will bite if it gets the chance. I raised the body up off the frame 2'' with spacers. this gives a lot more room under there to work with. I put a 430 punched to 442 in a 64 skylark with a turbo 400 and 4.11 posi. These recomendations are based on that experience and in fact are what I had to do in that swap. :Brow: p
Welcome Welcome aboard EB. I understand the frustration of not having too many dress up items for the 300. Most you can do is get a set of Offy valve covers and headers from Poston . Unfortunately they won't have any in stock until next year. Everything else you have to adapt something to fit. I have done several of the swaps you are looking at doing. I currently have two in the works now. The swap is fairly simple if you want to keep the cost down but there are several items to be aware of. As mentioned above you will need the motor mounts. You can buy the frame brackets from TA Performance along with the motor mounts. If you use the original 67 GS 400 brackets you will need to find a set of 67 GS 400 mounts to make the swap easier. I have used the 68 GS 400 mounts with modifications on the original frame brackets. Please note the frame brackets are a pain to mount with the lower control arms in place. You didn't say if you have AC,power steering, or power brakes. I am also assuming the 455 engine comes complete with a carb and exhaust manifolds. If you don't have AC and you are keeping the engine stock( rebuilt not Hot Rodded) than this is fairly simple. You can drop the motor in utilizing the 2 speed trans. You will need to upgrade the Radiator to a 3 core and get an exhaust system if using manifolds. The fan, fan shroud, and upper radiator hose can be reused. You will need the correct pulleys for a big block and the correct A-body power steering brackets for a Big Block. These are a little tough to come by but they are out there. In particular you will need the two steel plates (the ones that mount to the pump) the aluminium mount is the same. I have seen somewhere on this site recently that someone is going to be reproducing these brackets. This here will get you going. If you have AC you will need to change a few things. You will need a 4 core radiator. This will require the top radiator mounting plate to be changed. The one in your Special will only support a 3 core. These are found in 67 GS 400 and 340-4 w/AC cars. I have used the aluminum AC brackets off the 300/340 but you will need the upper mounting plate for a Big Block. If using the stock 73 intake manifold, I think you will need to use the heater by-pass valve off the small block. The 67 GS 400 manifold required a heater by-pass valve with smaller threads. Aftermarket manifolds, I believe use the larger threads also. Tranny changes to a 350 are a bolt in. To change to a 400 trans you will need to move the crossmember to the rear most holes and shorten the drive shaft. Upgrade the fuel line from the tank to the pump to the larger GS 400 size. I don't know the size off the top of my head. I would upgrade the springs and sway bar to better the ride and restore ride height. This is just a tiny reference. I am sure others you have done these can assist you also. Changes to HEI and headers all present their own set of challenges. Good Luck Clyde
Thank you Clyde for the much needed information. With just the motor mount information I'll be able to get started on the right track. Picking up motor tomorrow and am getting excited about this project. Have had the car for almost five years and and suddenly got this wild hair. Been trying to find a Buick motor for about 6 mo. and came across this one. Hope it works out. Thank you Doc for your very animated info. Do not intend to go quite that radical (yet) but did get a few good chuckles out of your input. I'm sure I'll have more questions once I get started. Have a fairly knowledgable friend helping so wish me luck. Will let you know how it's going. Thanks gb
Have either of you any experience with putting an AOD transmission behind a 455 with this kind of swap?
Thanks for the link. I don't have the money for a AOD either, but I am trading a bunch of left-over Chevelle parts to a mechanic/buddy in exchange for a built AOD.
