I need help figuring out which motor I have?

[1966kustomkat]

I recently purchased a 1966 Buick Wildcat 4 door Hardtop (no post) Kustom. This thing is badass, By Kustom I mean shaved door handles, air-ride airbag supsension. House of Kolor paint with old school paint scheme with scallops and glitter paint, white wall Coker tires and Moon Discs.

Anyways, I dont know which engine is in there. The guy I bought the car from was clueless. He knew as much about Buick's as I do (which isnt too much). I have done some research like check the head casting numbers to see which engine they should be on like the 401, 425, 455 etc. and compared other numbers on the engine block and have found that nothing matches. I thought perhaps it was a 401 but recently I needed to replace the alternator and purchased an alternator that is called for on a 401 and found the bolt pattern on the alternator wasnt the same as that on the block. I subsequently removed the housing from my old alternator and swapped it out with the new one.

Is there any other way I can tell which motor is in my car? I dont think it is the 455. It is definately a big block. Which would eliminate the 300 - 340 or would it? Any help from anyone would be appreciated.

Thanks.

[Bob]

The nailhead series of engines were quite small, that is a big reason they were popular with hotroders.

Here is some info which should help...
http://www.buicks.net/shop/engine_ident.html

[bob k. mando]

the 401 and 425 were the only Nailheads available in 66. the 455 / 430 / 400's and the 300 / 340's are definitely NOT Nailhead engines.

the 400 / 430 weren't available until 67, the 455 not until 1970. these are all known as the 'Big Block Buicks'.

the 300 and 340 were both available in 66 but the 300 has a shorter deck height than a 340 (they had to raise the deck to accommodate the 340's longer stroke) and would be unlikely to be mistaken for a 'big block'. both of these engines, as well as the 215 and 350 are known as 'Small Block Buicks'.

so, assuming you have the OEM engine in the car your choices are 401, 425, 300 or 340.

if the distributor is at the front of the engine you have a small block buick (340 or 300) with 4 bolts securing each valve cover. if the distributor is next to the firewall / at the back of the engine you have a Nailhead (401 or 425) with 2 bolts securing each valve cover.

if you're # of valve cover bolts doesn't tally with the above paragraph try this thread:
http://www.teambuick.com/forums/showthread.php?t=9402

[fueler191]

my moneys on it bein a 425^^ can you read the back of the block at all? i cant remember if you can read what size it is with the tranny on or not...

[buick72racer]

are the valve covers angled on the engine or are they horizontal
is the dist in front or back, is the thermostat housing horizontal
or is it vertical on the front of the intake manifold