Nailhead Engine Swaps
Created By: Russ Martin at NailHeadBuick.com
I get many questions weekly on engine swaps so I thought I would list some info on the subject. The most common question is how do you install a 57-66 364-401-425 in a 53-56 Buick.. If you look at the 53-56 264-322 and the 57-66 364-401-425 they look very similar but the fact is there are very few interchangeable parts in the two engine series. The motor mounts, the bell housings and even the exhaust manifolds do not interchange so it is no bolt in swap. We make front mount adapters and recommend going with a later trans and open drive rear end. There are exhaust manifolds from different year 57-62 Buicks than will clear the 53-56 frame and steering. You can fab up a 4 bar setup, but do so before the torque tube has been removed to save time. An easier way is look in our Drive line parts section for a Torque Tube Eliminator Kit.
If you have a 57-61 Buick with a 364 a 59-63 401or 63 425 is a bolt in with the correct flexplate. You can't bolt a 64-66 401-425 to a 57-63 Dynaflow trans because the 64-66 crankshaft center is too small for the Dynaflow convertor. You can however bolt a 57-63 engine to a 64-66 ST400 trans and is explained in the trans swap section.
Swapping Nailheads in Other Cars and Trucks
The biggest problems with swapping Nailheads in other cars is the starter wanting to share space with the steering box! but thank God we now have mini high torque units that are half the size and weight of the Delco units. U-Joints for the steering and Vega type steering box are other items that have helped a whole lot. Some cars will need a center sump pan and some will need a rear sump. The centersump came on 62-66 401-425's and give more ground clearance so I favor them when they can be used like pre 35 Fords or others, the 35 and later Ford cars and 35-41 Trucks need a rear sump pan as does many vintage cars. Most trucks on the other hand have loads of room down there especially when they were already made for a V8. Another interference point we have had problems with is the distributor, it hangs out to the rear more than most other engines. When building early fenderless rods we like to stretch the frame a few inches between the firewall and radiator, the car looks and rides better with the extra wheel base. The C-4 on the 264-322 and the ST400 on the 364-401-425 give the most room inside in the floor area. They engines have more torque than you Chevy and Ford engine so strong mounts are a MUST and save the weak 8" ford rear ends for small blocks, bolt a 465 Foot pound Buick motor in front of an 8" and it will look like Mike Tyson (no teeth.) The first time you drop the hammer!
Building a 65-66 GS Clone
The 364-401-425 can be bolted into the 64-72 A body GM chassis by using the special 65-66 GS Skylark parts. You will need a rear sump pan, a special rear sump pickup, the 6 piece engine mount setup and a 65-66 GS radiator and sometimes a different radiator support and 65-66 GS exhaust manifolds or headers. If you use the ST400 the trans mount we need to moved back about 4". There are other things like modifying the wiring harness and moving the battery box but nothing that difficult