NailHead Alternator Brackets
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This page is all about alternator brackets for Buick "Nailhead" engines, specifically the 364, 401, and 425 cid engines. If you're working on a Buick Nailhead engine and you're following my pages on Alternator conversions for older GM's and  "Push Gas To Start" with an Alternator, this page is for you. This page is targeted to the folks out there who want to convert their NailHead engine to an alternator and need to figure out the brackets. It is based on my experience with a 1958 364 cid NailHead engine originally equipped with a generator mounted on the passenger's side of the engine and no AC, along with information gleaned from other folks I have talked to who are knowledgeable about NailHeads in general. This page contains a decent amount of information about the various brackets used on NailHead engines in general, so you may find this page useful even if you are not doing an alternator conversion.

The usual disclaimers apply here - use at your own risk, this is all provided as an FYI, don't do anything too stupid, use common sense, and if you mangle or otherwise damage yourself, someone else, or your car - I didn't tell you to do it and it's not my fault. Work smart and keep yourself and your car around and working properly for future enjoyment.


Donor Brackets and Background Details

The key detail here is that the 401 and 425 engines produced from 1963 through the final Nailheads in 1966 were all factory equipped with alternators. These are the donor engines for the brackets you will need. There are two brackets on a non-AC engine, an upper and a lower. The lower bracket primarily bolts to front outboard head bolts on the passengers side head, along with a separate bracket the connects to the engine down near the top front of the passengers side engine mount. The lower bracket provides the support for the weight of the alternator as well as a pivot point for it to rotate on for adjusting the belt tension. The upper bracket (the long arc shaped bracket with the slot in it for adjusting the alternator belt tension) mounts to the upper bolt on the passengers side of the water crossover and hangs out over the top of the alternator. It bears considerable weight, and must be well-braced to prevent movement, fatigue-related cracking, and/or failure of the bracket. The upper bracket provides no support and only serves to hold the alternator in the right position to provide tension on the belt - as such it is only under a moderate compressive force and is not prone to fail.

Since the 364/401/425 share the same heads, the later-model brackets will work just fine where they bolt to the head. The spacing to the pulley groves was also unchanged, so this should line up just fine as well. The spacing and distances between the water manifold bolt and the alternator mounting points also did not change (since the heads are the same), so this bracket should also work untouched. The only difference that is important is that the 401/425 and the 364 engines have a different deck height (a longer bore) - this makes the length from the alternator bracket and the third mounting point near the motor mount different between the 401/425 engines  and the 364 engines. This is the only area where modification that may be needed to use these brackets on an earlier engine.

The way the generator and alternator brackets mount to the head is slightly different, but very important to get right. They both use the two front outboard head bolts on the passengers side, but with different bolts. The generator bracket bolts are the same length as all of the other head bolts used on the engine, but they have what appears to be a 2"-3" long stud coming up out of the center of the bolt head. (This stud is a permanent part of the head bolt and cannot be removed.) The alternator brackets simply use longer head bolts in those two positions. This is important because the generator bracket sits about 1/2" higher off the head than the alternator bracket - the exact thickness of the bolt heads. If you do not use the right bolts, the mount will sit just a touch too high, stuff may not align right (particularly the upper alternator bracket), and the mount may not be able to be installed and/or properly tightened down. The moral of this story is to use the right head bolts in those two positions!

Also, the single bolt used to mount the upper bracket for the generator to the top bolt of the water crossover is the same basic style as the generator style head bolts - there is a stud coming out of the head that the bracket mounts to. I am as of yet unsure how the upper alternator bracket mounts, but again, the moral of this is to use whatever style the donor car used to originally mount the brackets you are using.

If at all possible, pirate the relevant bolts from the donor car when you grab the brackets. Even if they're nasty, rusty, and grungy - you can learn a lot of important details from having them to compare against and they may very well clean up enough to be usable. The special "bolts with studs out of the top" are not being reproduced anywhere that I know of, and they make servicing stuff a breeze because you can remove the brackets without unbolting the actual part (water crossover or cylinder head) and that's a very nice "feature" to have. I really don't like the idea of completely removing two of the head bolts to remove the generator bracket and not unbolting the rest of the head - the chances of warping or cracking the head are a bit high for my tastes.


A Word About Air Conditioning

Why does air conditioning matter to an alternator bracket? On the NailHead engines, the alternator and AC compressor are both mounted on the passengers side of the engine. They typically share a common bracket with the AC compressor being mounted directly over top of the alternator. They also typically have a shared dual belt arrangement where two belts go over both the AC and AC compressor side by side and only the alternator is adjustable to take up the belt slack. All of this matters to the brackets, so if you have AC and want to swap to an alternator - just know that it will probably matter quite a lot on a NailHead. Even though my car is not presently equipped with AC, I do plan on adding it at a later date, so I have done my research with that goal in mind and I have tried to put that information into the relevant places on this page.

The good news is that if you already have a 401 or 425 engine, the swap is a simple-bolt-on using factory brackets - see the section below on the 401 and 425 Engine Brackets.

The bad news is that if you are not already running a 401 or 425 engine, having AC considerably complicates the swap to an alternator - if you want to keep your AC. In short, there is no simple way that I know of to get a factory alternator and AC bracket from a 401 or 425 engine to work on an earlier engine. Since the 401 and 425 engines were the only NailHeads ever produced with an alternator, this limits your choices to custom brackets of some kind. Even if you attempt to hack up a later model bracket set for your needs, it's still very involved and is definitely not a bolt-on. As crazy as it sounds, in some cases, it may be more realistic to simply install a 401 or 425 engine and enjoy the extra cubic inches along with the alternator conversion. I say this because custom making brackets is way beyond most folks, while getting an engine rebuilt and swapping it into place is much more do-able for the average home mechanic. Granted, it might not be cheaper, but I just wanted to point out the relative complexity involved based on my research. In my case, I've decided to do a simple alternator swap now and focus on custom brackets for the AC swap later. Basically, I'm avoiding the problem for now and hoping that before I'm ready to add AC that I have an epiphany about how to do this with factory brackets, someone in the aftermarket starts selling brackets for this, or my metalworking skills advance to the point where I can build my own brackets.


401 and 425 Engine Brackets

This is the easiest case to handle and it's a direct bolt-on. The 401 was introduced in 1959 and was produced relatively unchanged until the NailHead's demise in 1966. The 425 was introduced in 1963, was only ever produced with an alternator attached to it, and shares external block dimensions with the 401. This means that all brackets interchange as complete sets, and often as individual pieces as well. Because of this, any 1963-1966 401 or 425 alternator or alternator and AC bracket set is a direct bolt-on to a 1959-1962 401 engine originally equipped with a generator. Track down a bracket set from your favorite source (friend, wrecking yard, eBay, etc.) that meets your needs (alternator only or alternator and AC), and have at it.

If your car has AC or you you want to add AC, that you get a bracket set from a donor car that had AC on it. It's really that simple. Note that if you are adding AC, you will want to grab the 3 groove water pump and crankshaft pulleys from the donor car for use on your conversion, and you will probably also want to grab the 2-groove alternator and AC compressor pulleys - just grab the entire alternator and AC compressor and cores for later use. They're also handy for mockup for the wiring and adding/running the AC hoses if you're swapping AC onto your car.

Once you find and bolt up the brackets, you should now be able to install your alternator, and your AC if desired, put the belt on, and snug everything up. Check your belt alignment to be sure all is well, and tighten down the alternator belt so it will all work when the engine fires up. Consult my pages on Alternator conversions for older GM's and  "Push Gas To Start" with an Alternator for electrical and wiring details to complete your swap.


364 Engine Brackets

This is the swap I am doing, and the original focus of this article. Everything works except for that pesky support brace that goes from the outer edge of the lower alternator bracket to the engine mount area and serves to support and stabilize the outer edge of the bracket. Fortunately, this supporting bracket is made from flat metal stock (about 3/16" thick plate steel) and is relatively small. This is important because you will need to build a custom supporting bracket to replace the original 401/425 one and get it to fit on your 364. Following are instructions on how to do this at home with simple tools.

  •  First, bolt the main part of the lower alternator bracket onto the engine and snug up the bolts.
  •  Then get a piece of heavy cardboard and cut out a triangular shaped piece of it to fit roughly in the space you need the new metal piece to be. It will go between the outer edge of the lower alternator bracket and the mounting point just above the top front of the passengers side engine mount. Right now it's more important to get the lower portion of this cardboard template exactly right than the upper portion as you can mark the upper portion of the metal brace for the final trimming once it's roughly cut and held in place. Pay careful attention to the location and size of the lower mounting hole that will go onto this custom brace.
  •  Once your template is roughly in shape, use this cardboard to mark out the size and shape on a piece of 3/16" thick plate steel.
  •  Drill the lower mounting hole in your piece of plate steel first, then make the rough cuts around it. For a piece this small, a hacksaw and some careful work with a file will do fine. Be sure to leave the upper area a bit wide and tall to allow for final trimming.
  •  Bolt your newly rough-cut metal brace onto the lower mount and line up the upper edge. Use the main bracket to trace out the final cut lines and the final locations to drill the two upper mounting holes.
  •  Remove the rough-cut brace from the engine and use your markings to do your final drilling and cutting to size.
  •  Check your progress against the main bracket piece already on the engine to be sure it's right.
  •  Once it is done, file any sharp edges down for safety and then paint it your favorite color so it doesn't rust.
  •  Install it onto the engine and to the main bracket and snug down the bolts.

If all went well, you should now be able to install your alternator onto the lower bracket and support bracket assembly, then install the upper bracket, put the belt on, and snug everything up. Check your belt alignment to be sure all is well, and tighten down the alternator belt so it will all work when the engine fires up. Consult my pages on Alternator conversions for older GM's and  "Push Gas To Start" with an Alternator for electrical and wiring details to complete your swap.


322 and 264 engines

Some of the details above on the 364 engines may apply to the earlier 322 and 264 engines, but I have no idea how much because those engines share very few parts with the later engines - and thus some or all of the information about the 364 engines might not apply. However, based on what I do know about NailHead engines, I believe that the simple alternator-only bracket swap advice from the 364 engines will apply largely as-is. The AC bracket situation is also likely to still require you to go with custom brackets.

If you know it does work or you know what does not work, please let me know and provide pictures, details, etc. so I can update this page - any information I get back will be combined into this page. When I originally wrote this page, I floated some questions about this to people who might know; but I never heard back from them with details. 


Custom Brackets

I have and continue to contemplate making custom brackets for this swap. It's not an easy idea, but it would be more flexible and allow for more custom control of things. I'd like to move the alternator, power steering pump, and (if equipped) AC compressor so they mount down below the level of the valve covers. The beauty of a fully dressed up NailHead engine should not be hidden under brackets and compressors, but doing so within the tight confines of this engine compartment will be a tough task. While researching this, I've seen some ideas for using a modern remote reservoir power steering pump and custom brackets to mount it low on the drivers side, but I'm still searching out these ideas and seeing how to turn them into a reality.

If you did this, one neat idea would be to shuffle the pieces around a bit for better packaging overall. The most interesting idea would be to move the alternator to the drivers side - the battery and starter are there already, so the wiring would be simpler. The power steering pump would stay on the drivers side because the steering box is already there as well. You could then use a double-pulley arrangement on the alternator and power steering pump to ensure easy adjustability and no belt slippage on the power steering pump. The power steering pump itself is very, very small and can be mounted almost anywhere. The alternator is also relatively small and could be mounted just outboard of the engine down near the frame. On the passenger's side, the AC compressor would have to be tucked in underneath the exhaust, and fitment between the frame, exhaust, and motor mount could be tricky because the A6 style compressor is so long. The AC box and condenser fittings are already on the passengers side, but the hoses could be re-routed along or even inside the frame rail to keep it super sanitary looking. If all this could be done, it would be a huge win for making the engine look nicer from the top and would also help keep the proper hoses and wiring on the same side of the motor and make things simpler. The remote reservoir for the power steering pump could even be done as one of the "beehive" style containers for more of the that "period perfect" finned look.



I've added some pictures of various brackets to help folks out with visualizing things - there is also descriptive text in some of the pictures to help with the visualization process.

364 Lower Generator Bracket (circa 1958) Can be used for a hack-up-the-bracket style conversion to an alternator or as a simple template to fabricate your own bracket from scratch. The problem is that the generator mounting tabs go in front of and behind the mounting pieces on the bracket, but the alternator is designed to mount between the tabs. If you do this and try to use a spacer behind the alternator, then the alternator pulley does not line up with the water pump and crankshaft pulleys - the alternator would be spaced back to far the same thickness as the metal on the bracket. To make this work, the front section would need to be moved one metal width forward with some creative metal fabrication and if you can do that, you should be able to fabricate your own custom bracket out of a few pieces of 3/16" plate steel. This bracket is typical of the generator brackets that were used and is primarily useful for getting ideas about how to make such a simple custom bracket.

NailHeadBracket-364LowerGenerator1.jpg (232936 bytes) NailHeadBracket-364LowerGenerator2.jpg (233653 bytes) NailHeadBracket-364LowerGenerator3.jpg (238906 bytes) NailHeadBracket-364LowerGenerator4.jpg (131349 bytes)


401 and 425 Alternator Bracket (circa 1963-1964) Small and simple. There is also a flat steel brace (not shown) that extends from the two side bolts down to the motor mount area, very similar to the 1958 generator bracket. These are a good choice for swapping an alternator onto a 364, but they require different head bolts. Note the thickness of the bracket around the two main mounting holes - about 1/2" thick. This is much too thick to use with the original "stud coming out of the top of the bolt" head bolts on the 364 and will require using the correct head bolts for this era engine. I believe the correct head bolts are longer for these positions, but I have not yet confirmed that. You will need to make a custom flat metal support brace if you want to use this on a 364 - the deck height changed for the 401/425, and thus the length of that bracket changed.

NailHeadBracket-401And425Alternator1.jpg (582533 bytes) NailHeadBracket-401And425Alternator2.jpg (522360 bytes) NailHeadBracket-401And425Alternator3.jpg (563034 bytes)


401 and 425 Alternator and AC Bracket (circa 1963-4) Huge and ugly, but it works. Note that the alternator mounts "upside down" and that the alternator and AC have a double belt running around both of them, and adjusting the alternator adjusts the belts for both of them. Note that this bracket set mounts to the heads, block, water pump, and intake manifold and thus it spans the areas that changed in dimension between the 401/425 and 364 engines. That makes this bracket set unsuitable for a swap back to a 364, but it will work on a 1959-1963 401 engine. Note that the extra belt for the AC requires a triple groove pulley at the crank and at the water pump - this will use the front two grooves with the rear groove being available for the power steering pump.

NailHeadBracket-401And425AlternatorAndAC1.jpg (62613 bytes) NailHeadBracket-401And425AlternatorAndAC2.jpg (68166 bytes) NailHeadBracket-401And425AlternatorAndAC3.jpg (74582 bytes) NailHeadBracket-401And425AlternatorAndAC4.jpg (58841 bytes) NailHeadBracket-401And425AlternatorAndAC5.jpg (80637 bytes) NailHeadBracket-401And425AlternatorAndAC6.jpg (57110 bytes) NailHeadBracket-401And425AlternatorAndAC7.jpg (67590 bytes) NailHeadBracket-401And425AlternatorAndAC8.jpg (41418 bytes) NailHeadBracket-401And425AlternatorAndAC9.jpg (66118 bytes)



Other Helpful Pages

There are some related pages with details about brackets and such on Ray Elkins' site. (NOTE: Ray's site has been down for quite some time - if someone has archives of these pages, please let me know and I'll host them myself.)

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Page last updated 12/27/2011 10:23:21 AM