[67drake]

I was just reading through old threads on this site. Someone wanted to put a 400 into their ‘63, and was asking questions. A member said that in order to do that, most people put a 326 crank in their 400 because it’s the only way to get the rope shaft flange to bolt to the crankshaft.
Is this true?
I have the 400 out of my ‘63 automatic transmission LeMans at the moment. I’ve always had a slight vibration that I assumed was from the funky drive train, but if someone swapped the crankshaft and threw everything out of balance, then I would have to address that now.
Thanks

[tom s]

As I remember if running the factory auto trans you need a 63 326 crank or have your 400 crank drilled and tapped for the rope shaft.I dont remember if the stick shift could just use the stock crank.As I remember there is a splined shaft that goes thru the clutch disk and that shaft bolts to the rope shaft.Been awhile.Tom

[67drake]

Thanks Tom.
My gut feeling is that this was done as fast and cheap as possible, so I’d put money on this is not the original crank for this engine.
Looks like my “cam swap” is going full rebuild. I’ll have to verify by trying to ID my crankshaft.
If so, not a total loss, as I can then have a clean slate and build this engine the way I want. Trying to lower the compression ratio as it is right now.

[gavin]

The 336 crankshaft is 1/4”longer and a different balance to the 400ci crank. So you can easily put a 336 crank in the 400 but you need to rebalance the complete assembly as the pistons will be the incorrect weight for the crank. The alternative is the 400 crank drilled with a 1/4” spacer to make up the correct length and also to correct the crank recess size. I will put pics of my set up using the 400 crank. Note the welded on balance pads. Most likely yours Is a unbalanced 336 crank. I only just saw this post so the answer is a bit remiss.

[67drake]

I couldn’t look at a crank and tell one from another really. My machinist has my crank right now to polish it, just dropped it off Sunday. He said it looks like a 400 crank to him. ???
This is a picture I posted from a couple months ago.

[gavin]

Looks like a 400 or late 389 crank with a spacer sleeve to take it down to the 63 centre size. Either way the flex plate needs to have been balanced to the 400 or 389 crank. I took a stock 400/late 389 flex plate with 63 plate down to the balance shop and they match balanced the 63 to 400 plate. My adapter makes up for the 1/4” shorter crank but there may be enough spine for it not to be a problem but it might be a pain in the arse if it chews the end off. Yes the 336 cranks are 1/4” longer.

[gavin]

Actually forgot to add you must use 63 sump or modify late sump so as not to foul the starter. A mini starter may work.

[elefantrider]

I believe I remember hearing the blocks too are a different length. '63 Tempest V8 block is unique.