Assistance needed for replacement of fuel filter on Nailhead 401


The 401 in my 1966 Wildcat is some kind of Frankengine.

My immediate concern is the fuel system:

Part of the AC has been removed as well as the return fuel gas line. There is no fuel filter. Instead, there is an inline plastic bowl (without filter inside) that rests against the engine--with signs of melting. See photo below. This is a receipt for catastrophe.

I need to replace this with a proper filter (initially, without AC until I figure out what has happened to the return line and whether it is fixable). But the chassis manual is a bit unclear as to where the filter should be located and how.

Would someone with a 401 post in a response a photo of their fuel filter assembly?

Where would you recommend I purchase the new fuel filter?

Any assistance with this matter would be very much appreciated!



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I think your car should have a return filter similar to some of the ones (two fittings on one end and one on the other) you find on ebay here:
1966 Buick Fuel Filter

If you look along your frame, perhaps you will find the return line blocked off.
In one picture it appears that the bracket for the filter may be there, though the filter is not in it. I believe mine is mounted of the water pump.
Thank you Bob. In due course, I may instal a filter with a return vapor when I have time to re-install the AC and return hose. For now I am just trying to find where it is supposed to be attached to the engine (bracket?) in order to instal ASAP a fuel filter.

The Chassis Manual does not have a schematic/figure for fuel line on the 401/425. It only has a figure for the 225, 300, 400 and Skylark Gran Sport (64-2 and 64-3).

This is the reason I would be thankful for a picture of an actual 401/425 fuel filter/line. That would also help me identify, in due course, where the fuel vapor return hose is located.
I finally found a photo online of a 1966 401 (the convertible version). It seems that the fuel filter is attached to the base of the cooling hose via a bracket.

Is that correct?

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Active Member
Looks like it is mounted to the ignition coil, on the smaller engines, and to the thermostat housing bolt on the 401. Is the bracket still there?

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Looks like it is mounted to the ignition coil, on the smaller engines, and to the thermostat housing bolt on the 401. Is the bracket still there?

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No, no bracket... So the top photo of the restored engine has the bracket in the right general location -- they just fixed the bracket back to the wrong thermostat housing bolt (front one instead of back one).

I now need to find a bracket. yet another piece I need to get (but to date have not found a supplier).

Anyone here with a spare bracket?


Active Member

Maybe Tom Telesco can help (Telriv)
Basically the location on the thermostat housing depends on the bracket you can find. has a couple. Thank you Larry for the suggestion. Much appreciated.
As Bob's posts above indicate, the '66 fuel filter mounts lower down, in between the fuel pump and the fan pulley. The bracket attaches to a double-threaded bolt for the water pump. The parts layout is shown on pg. 80-8 of the shop manual (see attached).

The fuel filter bracket for the '66 400-401-425 is GM part no 1376363. This is a one-year-only part. Different parts nos were used on earlier brackets that mounted on the thermostat housing: '63 used a 1355086. '64-65 used a 1364248.


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Of course, under section 80 for the oil tank. 👍 It will take me some time to understand the organization thinking of Buick engineers 😳

The location makes sense for the AC version in order to connect to the vapor return line. My bet: the factory location is an odd place to service and mechanics just moved the filter up for their convenience — but from a safety perspective..?

Thank you Todd!