2900 RPM to 2300 RPM @ 60 MPH

This is the RPM drop I will experience. Well my modification may not exactly fit in with the stock crowd but gotta change or I will not be driving the car much more. My 52 Buick Super Estate Wagon has Dyna Flow, straight eight and 3.90 rear end gears. I bought a 71 Chev 1/2 ton pick up rear end today with 3.08 rear end gears and trailing arms. I am going to put a nailhead engine in, a switch pitch turbo 400 and the Chev rear end. The lower gear numerically rear end will make higher speed driving more attainable and with the V8, air conditioning will also be possible. I rebuilt the transmission last winter, I am starting to assemble the nailhead and I finally found a good rear end. I pulled the cover, the ring and pinion and side gears looked good. I plan to replace all the bearings and seals and call it good. So I can get rid of the leaking Dyna Flow and enclosed drive shaft. I have new cracks forming in my straight eight exhaust manifold and I have used my last spare. I have one last long trip in my Buick to San Diego in September, I hope the exhaust manifold lasts, or it could be a loud trip. My only unknown is the steering gear. I have factory power steering and the gear is so big a V8 will not fit with it in there. The lower A arms are so long that a conventional rack and pinion will not work because of bump steer. A conventional steering gear might also be to big. Has anyone had experience with electric steering? I am planning on having my Buick back on the road next year. My intentions are for this modification to look like it came from the factory.
up grade powertrain

On the surface it sounds like a very do-able project, is a brake up date in the work just thinking about wheel stud/lugnut spaceing
there might be more questions someone out here might have completed this swap and could share, My first nailhead swap was in 1964 a364 into a 56 belair,I learned something new every day
Good Luck, Bob
Yes better brakes are in the plans, disks up front. I plan to use the hydro boost type. I plan on putting the hydro boost unit in the same area as the master cylinder is. There are several suppliers that have disk brake conversions for stock 52 Buick spindles. I plan on using a power steering pump that will also support the power brakes. Leaving the master cylinder where it is eliminates the need to redesign brake pedal linkage and I do not want to hang a big ugly vacuum booster on the fire wall.

I am going to stay with the 5 X 5 wheel bolt pattern and have not decided on studs or lug nut. I have a good friend who is a good machinist. With him available my only limitations is my imagination and pocket book!

I am planning on a larger (taller) radiator with a fan shroud. Using a large mechanical clutch fan and an electric puller fan hidden inside the fan shroud for those really hot days, idling through town with the AC on.
I got way off course with family and house projects but I am seeing a light in the tunnel again and I can get back to work. My goal at the beginning of this swap is to not cut up my car so if after I am gone and someone wants to put it back to stock it will just be a bolt in. So my big problem with putting the 425 in the 52 frame is the factory power steering is much to large. I experimented with some modern power steering gears and they also will not fit. So I started looking at rack and pinion steering. I have been a heavy equipment mechanic all my life and I always lean to the side of larger and stronger is better. My car weighs 5,000 lb. empty so I could not consider a rack designed for a little car weighing 3,000 lb. being safe to use. I came up with a rack and pinion on a Chevrolet Trailblazer could work as the vehicle is pretty heavy. It also is a rear steer meaning the rack and pinion are behind the cross member. I am satisfied with the factory designed front suspension as the car is not affected by ruts in the road. I have previously installed a larger sway bar and tube shocks. It drove real well.

I have studied a lot about bump steer and Ackerman angle and I think I have that understood. As the Trailblazer lower A arms are only 12 inches long and the Buicks are 20 1/2 inches long that presents a big bump steer problem. I am using a "travel bar" to cure that problem. I can explain that system later.

The mounting holes for the straight eight engine supports can be used to mount the rack and pinion support brackets and also the front motor mounts.

I hope to be able to use hydro boost type of power brake system if there is enough room other wise I will use a remote mount hydro vac. I intend to use all the factory brake linkage and keep the master cylinder near the frame. I like the look of the firewall not cluttered with a hydro vac and master cylinder.

There will be lots of room between the engine and radiator and I am trying to get the widest tallest radiator possible in there. I expect the fan shroud to be deep enough to mount a large electric puller fan next to the radiator (probably manually operated) and a clutch fan on the end of the water pump. My goal is no heating problems with the AC on idling on a 100 degree day.

Since 1953 was the first year for V-8s, most people will not even miss the straight eight. Another goal is for the installation to look factory 1952.
As the Trailblazer lower A arms are only 12 inches long and the Buicks are 20 1/2 inches long that presents a big bump steer problem. I am using a "travel bar" to cure that problem.

is there a reason you're not having a metal fabrication / machine shop lengthen the Trailblazer arms?

i mean, i can understand if you don't want to trust your own welding on a steering component. but that's still pretty straight forward and should be well within the capabilities of any decent welder.
Hi Bob, I will try to answer your question. The rack and pinion designed for the Trailblazer, has a swivel at each end of the rack. It swivels right there because that is also where the A arm swivels, thus eliminating bump steer. Those swivels are about 38 inches apart. Those pivot points on the A arms on my Buick are about 6 inches apart. Thus a Trailblazer rack and pinion would not work. But if you weld up those swivels and eliminate them then you can attach a bar from one end to the other and it will extend one way and contract the other when the steering wheel is turned. So then I can use a 21- 1/2 inch connecting bar from the shortened steering arm to the place on the traveler bar that aligns with the A arm pivot point. Thus it should work after I figure out how to mont the rack and pinion. I sat everything into position tonight and there was room for the steering input arm and the rack clears the oil pan by about 5 inches. There will not be any exhaust problems with the factory manifolds I found. I will talk about those later. Gong to watch Oregon State in the baseball college World Series, I think they are going to lose, they are already down one game, best two out of three.
Wow Oregon State won the College World series. I removed the old steering gear mount and master cylinder mount today. Decided to fabricate motor mounts and transmission mount so I can set engine and transmission in to determine the ride height. Then I will know what height to mount rack and pinion sow they will be the same level as the steering arms during normal operation to counteract bump steer. I am going to fabricate plates to mount to the engine and then mount the motor mounts to them. Since I have to relocate the mounts a little I am using Chev 454 motor mounts because they are cheaper, readily available and the lower portion of them will be easy to fabricate. The transmission mount should be quite easy and straight forward. I am going to start taking some pictures so it will be easier to follow what I am doing.
I have not started taking pictures because nothing is firm yet. I have motor mounts in place as well as the rear transmission mount and the 425 is sitting in the car. I am now starting to place the rear end in place. I cleaned up the trailing arms on the Chev rear end. Just a quick measurement shows they are to wide where they are to mount into the X frame by about 3 1/2 inches so I have to relocate them inboard on the axle. They will be right next to the coil spring mounts but I think they will work. I am now figuring out haw to fabricate a mount to attach the front of the trailing arms to the X frame. I am also considering a double cardan cv joint at the output on the turbo 400, then I will be able to mount the rear end input shaft at the same angle as the transmission about 6 degrees. When mounting a rear end using a four bar or leaf springs you should plan on about a 2 degree axle wrap at highway speed but I am using a train arm suspension which is less prone to axle wrap so I am planing on 1 degree movement. So with a double cordon joint you set it up for the drive shaft to go straight into rear end. The engine-transmission is at 6 degrees because I can not get the engine down anymore because the fan will come in contact with the front cross member and the factory shock absorbers, the top or the transmission is nearly touching the floor. I checked my drive shaft angle and I would be in about the 4 degree angle for a u joint and I am not comfortable in that area for longevity. Three is much better. A double cardan splits the six in half, three degrees. The double cardans are are usually used on a two piece drive shaft the extends in the middle, my turbo 400 is set up for a sliding yoke output shaft, will a flanged sleeve for a double cardan work on the output shaft for a turbo 400 (the sliding action)? The cardan joint is much heavier than a conventional u joint. So I have some home work a head of me.
Well I am back almost a year later, after my mom died we discovered there was a reverse mortgage on her house that I did not know about. Took a while to get that straightened out. I bought the house back from the government spent the winter fixing it up and we just sold it. Now I can get back to the Buick. I ordered a 40 inch piece of 15/16 chrome shaft that will work with my rack and pinion. I give in and the mounts that I fabricated for the rack and pinion are going to be welded to the frame of the car, they can always be cut off. The steering arms are to long, so I am going to cut a section out and weld them up shorter. I have always been impressed with how sharp the car turned so I am going to check that before I fabricate new steering arms. Just waiting for the chrome shaft to get here.