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400 Motor help

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145 views 11 replies 8 participants last post by  geeteeohguy  
#1 ·
I have a 1970 GT with a 400 WT code motor bolted to a 4 speed.
The car originally came with a WS code engine which is long gone.
The problem I have is that there is water coming out of the drivers side exhaust when it comes to temp. Thought, Hoped, it was the head but we replaced them and still have the same issue.
So, it must be a cracked block.
I need to source another block or buy a remanufactured engine.
Its just a street car.
any tips and advice would be appreciated.
Thanks in advance, Lee
 
#5 ·
Places like Butler have blocks they sell with their builds, unless you are looking for a running engine.

You didnt see any AF in the bores when you replaced the head?

you may have a crack in the bore but you could likely sleeve that bore unless this is due to being over bored too much already
 
#6 ·
If the swapped engine in Mass doesn't work out and you want block only, I would suggest this:

May be on the wrong coast but, if you don't mind the truck freight from Cali, Frank's Pontiac parts in CA.
They usually have a good selection of Poncho blocks.
I've had no issues with parts I've ordered from them.


Magnafluxed and cleaned.
You can talk to a real person and order via phone.
Good luck.
 
#7 ·
Wait until teardown and inspection. Could be a cracked cylinder wall and a shop can easily sleeve that cylinder for a few hundred dollars and it will be as good as new. The block currently in my street car was sleeved in 1985 and that engine has been through hell as a race engine and now in lighter duty on the street. The sleeve can be bored to exact size needed and the piston reused if it hasn't been damaged.
 
#8 ·
I saw Franks website and they could be an option. The car is still running and at a restoration shop getting ready for paint. They wanted to keep it running so its not dead weight in the shop.
I am hopping to get one running and then do a quick swap. Has anybody heard of MABBCO?
They have long blocks for $3,500 or S&J Engines? They also have long block 400s.
I would love to use Butlers' but they are selling a rebuild kit for 15K. Good lord how much would would a complete rebuild be.
 
#9 ·
that seems awfully cheap. Would talk to them about what they replace and their machining.

The build have I just got done with was not as much as butler (many parts came from Butler like rotating assy) but wasn't that far off either... you have a 400 (vs my 65 389) so piston options are cheaper.

len williams machine is another one and I think some guys on this forum build engines for people.

if you want to buy a running one put a want to buy add in the classified section, there are also some FB pontiac engine groups , may find one someone rebuilt for a decent price.

Cheapest is to take it to a local machinist if you can find one. Do you know if it was over heated ?