Jump to content
HybridZ

Stupid question: is a 406 SB or BB?


Guest Anonymous

Recommended Posts

Guest Anonymous

I feel stupid asking, I could have a deal lined up with a seller for a Zcar including a 406 and a turbo 350 tranny, need to do my homework. Thanks!!

 

Steven hail.gif

Link to comment
Share on other sites

400 Small Block bored .060 over.....

 

but sometimes it's a stroker crank....depends on who built it.

But a .060" over 400 is pretty hairy....Those are already 4.125", which is pushing the block....

if it's not a stroker have it COMPLETELY checked out...

JMO

AL :D

Link to comment
Share on other sites

Yes, a "406" is a Chevy 400, bored 0.030" over. On a 400, anything more than 0.030" is risky due to the inherent siamesed-cylinder construction.

The bore of a 400 is 4.126". The overbore takes it to 4.156"

Do the math with me....radius is 2.078", squared is 4.3181, times pi equals 13.5656 sq.in. for the area of one cylinder. Multiply by the 3.75" stroke equals 50.871 cu.in. for one cylinder X 8 cyl. = 406.97 CID. So, it's actually a "407" "She's like heaven, my 407".

But no, over the years, it's become known as a 406. Mucho torque, for sure. I have one in my hybrid Z, and am glad I went this route.

--JohnG

Link to comment
Share on other sites

Guest Anonymous

Chevy did make a 402 big block, but 30 over I'm not sure what the would make it. More than likely in modern circles the 406 is indeed the 400 that has been poked out .030 .

 

Regards,

 

Lone

Link to comment
Share on other sites

$2K for that? That's a terrible deal! E-mail me that guy's phone number. I want to ball him out personally! :mad:

 

Seriously, if everything is in pretty good shape it sounds like a bargan to me. With that combination you ought to win every burn-out contest you enter. :D

Link to comment
Share on other sites

there are ways around the thin cylender walls believe it or not on a 400. not too many consider this to be a safe alternative but my machinist has never had one come back on him. grout fill p to the water pump holes on the bottom end and on the head surface tap the existing holes and plug then with an flush fit allen head plug. after that go through and drill a hole in each hole about a quarter of an inch in diameter and your all set. my motor was done this way and has over 15,000 miles on it and hasn't given me the first problem with heating and i live in the deep south were it's hot almost all year. plus if you want to spray it or boost it your safe. i would recomend a good high compasity oil cooler though. by doing these things your good to go with about as much as you want to throw at it.

 

oh yea i'd also recommend getting a 2bolt block and having 4 bolt splayed caps installed.

Link to comment
Share on other sites

.030 over 400 Small Block = 406 ci of torque!

Find out what was done during the rebuild, (ie installing 5.7" rods to replace the short 5.565" stock 400 rods)

 

If it's a fresh rebuild .030 shouldn't be an issue, but if it needs to be "freshend up" don't assume you have a good canidate to bore out.

 

.030 over is the limit for some 400's while others can go to .040 over and a select few can go to .060 over.

Link to comment
Share on other sites

Guest Anonymous

just got off the phone with the guy, he said its a 400 that has been bored .030 over, and the 240z has been stored for 10yrs along with his 58 vette and 70 1/2 camaro z. He has shorty headers, electric fan, mallory dist, aluminum 4 bbl mani, and heads. the whole shebang including car, engine, tranny and parts he wants 2k for. sound like a good deal?

Link to comment
Share on other sites

Guest Anonymous

Jared...It is not a good idea to bore over .030 and to make anything substantial out of a 350 is to stroke it with a 400 crank and over 400 ci should be with a 400 block. Dsomer bought the JTR kit and I asked him to consider your needs first for the tranny mount. I really do not need the tranny mount exhaust allowances for a car with side pipes.If you do not want the tranny mount I am still intrested in it for a second project. Apparently the JTR tranny mount is not that ugly and should solve the drive shaft angle problems.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...