'74 Sleekcraft Rebel restoration

[archbuilder]

Re: Stripping paint

Re: Stripping paint

Cool, looking forward to your progress!

 

[Last Mohican]

Re: Stripping paint

Re: Stripping paint

The lock-N-Stich repair is complete and went very well. I will post an update to the lock and stitch sometime tomorrow. There is another issue though.

http://www.youtube.com/watch?v=bv20MtEHDEQ

 

[archbuilder]

Re: Stripping paint

Re: Stripping paint

Man that sucks! sorry to hear that, was it freeze damage or a weak spot in the casting?

 

[Last Mohican]

Re: Stripping paint

Re: Stripping paint

Weak casting. According to the casting numbers, the block I have is known for this issue. This crack is no where near the other one and there is no water in that part of the block.

 

[archbuilder]

Re: Stripping paint

Re: Stripping paint

I didn't think it was close to a water jacket.....how did you come across the damage?

 

[proshadetree]

Re: Stripping paint

Re: Stripping paint

Dang man you cant lose for winning. Stop strike that and reverse. I am sorry man. i hope you can find a mill or a service block you can use. What year block had this issue? I have a 71 455 I just dropped into a tempest that I hope is not effected.

 

[Last Mohican]

Re: Stripping paint

Re: Stripping paint

Dang man you cant lose for winning. Stop strike that and reverse. I am sorry man. i hope you can find a mill or a service block you can use. What year block had this issue? I have a 71 455 I just dropped into a tempest that I hope is not effected.

I hear ya. Not sure about the 455. My motor is a 400. I think you are safe though if your block is a 71.

From a post at hotrodders.com
"In the middle of the '75 model year, Pontiac started casting 400 blocks with thinner main webbing. I have seen a couple of these blocks, that were built for performance, crack in the main webbing. The blocks to avoid have casting #500557 or 568557. All prior blocks are good."

And another From 78ta.com
"The 500557 400 blocks are weaker and are known to crack at the dowels that locate the main caps, but there a few brave souls over at PY who have stroked them- go for it if you feel lucky.

My block is the 500557 casting.

 

[Last Mohican]

Re: Stripping paint

Re: Stripping paint

I didn't think it was close to a water jacket.....how did you come across the damage?

Just dumb luck. I had the stitching repair done. I was really excited. It looked great. Then moved on to the oil pan leak that was the original reason for pulling the motor. It was shear dumb luck that I noticed that crack. I had looked the bottom end over pretty well while cleaning up the oil pan gasket surface. I sat back in my chair to decide my next move and with the block at eye level I noticed a small gap between the center main cap and the block. I was all down hill from there.

 

[Last Mohican]

Re: Stripping paint

Re: Stripping paint

So here is the final on the Lock-N-Stitch repair. I have no doubt this is a permanent repair. I would have total confidence doing this type of repair again. You can bet if I ever need do it again, I will inspect the project completely first. LOL.

Basically I finish putting the pins in. Ground them down. Hit it with a zip disk to level it out. Hit it with a needle scaller to texture it. Painted it. If the light hits it just right like in the pics you can see where the repair was done. To the naked eye it is less noticeable. I am confident with a little more care with the grinder and scaller this repair could be completely undetectable once painted.

 

[archbuilder]

Re: Stripping paint

Re: Stripping paint

Is the Pontiac 400 a small block like the Chevy? I was thinking it was a cousin to the Chevy or is it actually a big block? Are you going to look for another 400 or change platforms?

 

[Last Mohican]

Re: Stripping paint

Re: Stripping paint

Is the Pontiac 400 a small block like the Chevy? I was thinking it was a cousin to the Chevy or is it actually a big block? Are you going to look for another 400 or change platforms?

All Pontiac blocks from 326 to 455 are the same external dimensions. There really is no big or small block. The larger displacement motors have larger crank journals. I have a lot of good parts in my rotating assembly. Forged pistons, Super duty rods, all balanced. For the moment the plan is to go back with another 400. You can bet your *** it won't be the 500557 casting though. As I get the motor disassembled, if I find other issues, I may change platforms. I always said if it ever blew up I'd switch over to GM's LSX platform. I expected the Pontiac's demise to be much more spectacular though. I should be able to pick up a good block off of craigslist for under $100. Then it's off to the machine shop for the expensive part.

 

[Last Mohican]

Re: Stripping paint

Re: Stripping paint

The rotating assembly looks to be in good shape. I have no idea how this thing stayed together. The damage to the block was worse than what I originally saw It has two mains that were cracked all the way through and one that had started to crack but was not all the way through yet. I pulled the two pieces out of the block by hand once the crank was out. The hunt is on for a bare block.

(Clickable thumbs)

 

[archbuilder]

Re: Stripping paint

Re: Stripping paint

I guess the good thing is you found it before it took itself apart! I doubt you would have many salvageable parts if that had happened.

 

[Last Mohican]

Re: Stripping paint

Re: Stripping paint

Just got home with my new std bore 67 year model 9786133 casting. It's a little dirty and rusty but I think the lifter bores will be fine and the cylinders will bore out .030 no problem. I gave $150 for it. If I can't make it work because of an issue with the block he will either give me another block or give me my money back. All of the Pontiac guru's agree this casting is equal too if not the best stock casting to build.

 

[archbuilder]

Re: Stripping paint

Re: Stripping paint

Cool, looking forward to hearing it running this summer!

 

[proshadetree]

Re: Stripping paint

Re: Stripping paint

Rock out man. Poncho stuff is getting hard to find. Great score.

 

[Last Mohican]

Re: Stripping paint

Re: Stripping paint

More bad news. Crank has a crack. Machinist said the crack is so small if it was his he would run it. Waiting for him to check my pistons and rods before I make a decision on what to do next.

 

[archbuilder]

Re: Stripping paint

Re: Stripping paint

That sucks....keep us posted!

 

[proshadetree]

Re: Stripping paint

Re: Stripping paint

Dang the luck. Has the person that you got the block from got a crank? I dang sure would not trust a crack in a rotating assembly. Wish you luck man.

 

[Last Mohican]

Re: Stripping paint

Re: Stripping paint

No crank from the same place as the block. Pontiac 400 cranks are not that hard to find. Its the $250 balance job after I find one that kinda hurts. Still waiting to hear if my pistons and rods are in good shape. That will be the final decision maker. If they are in good shape, I'll be looking for a crank. If not, I'm going to have some Poncho parts to sale.