Used 406 small block

kornball426

Royal Smart Person
May 29, 2009
1,457
83
Philadelphia, PA.
So I already bought it so it's kind of too late, but I need some opinions. So I bought this 406 Chevy small block, it has splayed 4 bolt billet main caps, eagle forged crank and H beam rods, mahle forged pistons, Brodix IK200 aluminum heads, harland sharp 1.6:1 roller rockers Brodix SP1 single plane intake manifold, holley 850 DP carb, and an unknown but supposedly pretty gnarly cam matching the intake and heads. Supposedly it's 10.5:1 compression and only had about 2,000 street driven miles on it before the car it was in (C3 Corvette) was crashed and totalled a couple years ago and the seller decided not to fix the car, pulled the drivetrain and it has been in his garage since.

So questions, it has a basic looking internal balance style harmonic balancer, so does that mean I can I use any typical SBC flexplate? Or do I need a weighted one for a 400. I am 99% sure it's internally balanced those forged 400 cranks usually are and the neutral balance harmonic balancer sort of backs that up. It was in front of a manual so I need a flexplate.

How much power do you think that setup makes, I'm guessing around 500... Should I swap for a milder cam and dual plane intake for a more streetable engine?

Also this i really don't know, I think it's a 6 inch rod build... Do they live relatively long? Those ring support things that protrude into the wrist pin hole makes me a little nervous, but a ton of guys are running strokers like that, so it must be fine... I personally would have built it with 5.7 inch rods to keep solid ring lands all around the piston, but you can't always get what you want.

Final question, will it run fine with an OEM stock HEI distributor or should I get an MSD or Mallory/Accel or whatever? It comes with everything but the distributor and flexplate.

I pulled the valve covers and oil pan and it looks brand new inside. Fingers crossed the seller is honest and he really did destroy the car it was in, and didn't pull the engine because it's hurt.
 

kornball426

Royal Smart Person
Thread starter
May 29, 2009
1,457
83
Philadelphia, PA.
so the balancer is perfectly round?no weird shape to it?
Yes as far as I could tell the balancer on the front was perfectly round, no heavy external balance weight.

However the crank flange where the flywheel/flexplate bolts is not round, however I think that's just typical of a two piece rear main seal flange. I haven't seen an old style SBC crank in a a few years, but IIRC it's normal for it not to be round lol.
 

kornball426

Royal Smart Person
Thread starter
May 29, 2009
1,457
83
Philadelphia, PA.
So, it doesn't come with the flexplate?
If it's internally balanced, you need a neutral damper and flexplate.
Yeah that's what I thought... I tend to overthink things. I need to confirm 100% it's internally balanced, it should be and I'm like 98% sure it is though.

Think it would be a bad idea to yank the HEI distributor and flexplate off the 305 currently in the car, or should I step up to a heavy duty flexplate and hi performance distributor? This is without a doubt the hottest small block I've ever had without even having driven it.
 

kornball426

Royal Smart Person
Thread starter
May 29, 2009
1,457
83
Philadelphia, PA.
So, why not ask the seller? Unless he's big on internally balanced engines, he should let it go.
Because like I said it was in a C3 Vette with a manual trans, so it had a flywheel not a flexplate. I didn't mention he sold the transmission and all those parts separately to someone else. Although being a manual even if he had those parts they would be of no use to me since I am going to run an automatic.

He said he pulled the distributor to put in his dad's Corvette with a 327 in it since he just had the engine sitting on a cradle and needed a distributor.
 

Tc77

Apprentice
Sep 19, 2018
70
33
Depending on cam you are going to need a brass gear on the dizzy.
 

kornball426

Royal Smart Person
Thread starter
May 29, 2009
1,457
83
Philadelphia, PA.
It's out of the car. Check the bearings. Why wouldn't you?
Had 12 point heads on the bottom end studs which I didn't anticipate and it was about an hour away so I didn't want to make a return trip. Although that is a good idea. The oil that was in it was dirty but there was no visible sign of metal particles in the oil so I'm keeping my fingers crossed the bearings are fine. It all looks very clean and new inside.
 

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