Picked up a 63 buick 401 nailhead ,got it running ,good running motor I might add , had a manual flywheel here I thought was 63 401 . Bolts on fine ,correct size for the crank indexing ,lined up hole in crank and flywheel ,all is correct . Have a vibration at around 2500 rpm . I am starting to think the flywheel is for a 364 nailhead . Balancing is different for a 364 and a 401 from what I have read. Can the flywheel be rebalanced to 401 specs ?? And who would rebalance it ??
Any good machine shop should be able to balance it...I would have the pressure plate and flywheel both balanced...
It most likely is a 364 flywheel, which differs from the 401/425 one. To balance it correctly, the machine shop would need the crankshaft and damper, or the correct balance specs. May be cheaper to buy a new one.
The currency exchange and shipping to Canada will likely get it balanced here and take the wife out for a nice dinner. LOL
I just sold a fresh 401 and a 364 flywheel and clutch. One of the best engine builders I know, told me the correct way to do it, is to tear the engine down and internally balance the rotating assembly to match the flywheel.
Talk to Bendtsens as they can supply brand new flywheels for the 63 401 Buicks. I've bought one for my engine plus the required spigot bush. Their supplier would know what the balance situation is, there is a fair amount of out-of-balance built into the flywheel and also the flexplate as I have both. Not cheap but you've gotta pay if you wanna play LOL. And I had to pay in US $$ then pay shipping to Australia. But it is an after-market part which does work, and that's the important thing.
I have 4 motors to get up and going , this was the the second , runs strong good oil pressure and compression . Also have a running 425 but has a bit of blow by and still in the car . Have a 65 and a 66 401s that I haven't had running yet .Just want 1 good one for my 33 chev 3 window . Already have a manual flywheel for a 401-425 ..
^^^^ Only two vendors carry the flexplate for the 64-66 motors, which come from the same supplier, in which their latest production run had all the offsets stamped backwards. Ask me how I know...
So just to follow up ,I took a 1965 flexplate to the machine shop and had the indexing hole opened up from 2.456 to 2.900 and bolted it on the 63 engine . Engine runs smooth ,had to use the 65 starter as well . Some other nailhead guys told me that there is a 1 oz difference in the 364 flywheel and if I bolt on a 1 oz weight over top of the existing weight that it will work too ?? Not going to try it ,as I will likely just sell the 364 flywheel .
A '64 Buick 401 (AT) I bought years ago vibrated hard when it came off idle. Turned out the flex plate was bolted up wrong
IIRC, the 322" Buick V8 was used in some '55-'56 GMC and Chevy medium trucks and buses. Many nailhead flywheels have been salvaged from these. jack vines
Gotta watch them flywheels with the little hole in the flywheel and crank line up . Have seen a few with them not ..
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