[Mean Green]

I have a crack in my AI (not AI2) block. It is cracked at the outer splayed bolt on the #4 main.

I have 2 questions.

What will it take to repair the block?

Is it possible run it as is for another month or two?

I was just about to ship this engine out to get freshened. But now I'm waiting on parts for my other engine, so I was going to use this engine in the meantime.

Thanks.

[mgarblik]

Aaahhhh, the beauty of aluminum. Any professional welder who welds aluminum on a regular basis can weld that up good as new. Not a big deal. Needs to be machined flat for the cap and I would absolutely use studs in those outer bolt locations. Iron is another story.

[73 TRANSAM]

I think he meant IA1 block. I could be wrong but it looks like a cast iron lock. Did u use a stud or bolts on the outer? How much HP were u making? Thanks.

[Half-Inch Stud]

Motor mount details?

[mgarblik]

Originally Posted by 73 TRANSAM

I think he meant IA1 block. I could be wrong but it looks like a cast iron lock. Did u use a stud or bolts on the outer? How much HP were u making? Thanks.

You may be right about that being an Indian Adventures Iron Block. I can't tell from the pics. I thought he said Al meaning aluminum but not the IA II version. Well if it's iron it can still be fixed by an experienced welder. Would need some pre-heat and a silicon bronze filler rod. That's how I would fix it.

[Dragncar]

I think its in a really bad spot. Even under good circumstances welding cast iron involves risk. It will always be a weak spot. Its in a major threaded hole.
Indy Cylinder Head. Give them a call . I know of repairs they have done where they heat up the iron in a big oven and bring it out glowing and a guy gas welds the repair by hand and put back in the oven. And it looks like it never happened. Even then, will your machine work all need redone ?
Might be cheaper to get a new block and worth the piece of mind.
Sorry, no easy way out.

[Mean Green]

My bad, yeah, it's an IA cast iron block.

[Mean Green]

Bolts on the outers. 850 hp.

Solid motor mounts. I just updated the car to mid/motor plates.

[Sirrotica]

Mean Green, a couple questions, if you don't mind, is that #3 main web, and were you using the earlier style 2 bolt mount? Also is that the left/drivers side where the break is?

Lots of people on this board will tell you that solid mounts won't hurt a block, just trying to determine if your crack is in the critical area.

Over the years there have been plenty of cracked block pictures posted on PY, that cracked in the center, (#3) bulkhead on the drivers side using solid mounts (usually the earlier style 2 bolt style). It's been documented both on factory, and aftermarket blocks.

From studying the 455 design mount system, revised in 1970, I'm under the impression that Pontiac engineers were concerned about block integrity with the new longer stroke high torque 455. If you compare a pre 1970 factory block, to the 1970, and later blocks there was a major re-design and strengthening ribs added in the area of the mounts, and with the re-design straddled both the #2 and #3 bulkheads spreading the load over 2 bulkheads, instead of just the #3 bulkhead.

I just re read your first post, it says does #4, sorry about the confusion, your's may have zero to do with solid mounts. If I would have looked closer, I would have seen it was the thrust bearing in the background.

[mgarblik]

I would repair it and run it with studs in the six locations. Indy Cylinder Head does great work but they were sold in the last 6-8 months. So people with talent may be gone to improve the bottom line. Also, there should be some good iron welders in CA. Hopefully, someone will chime in. It's not in a great spot, I agree, but way better than a crack through an oil hole or from an inner stud location to the center. The center straight studs take the vast majority of the load. I think it can be repaired by a shop that does this type of work . If your worried the crack extends down into the hole, there may be a Time-Cert that will screw into the 1/2-13 hole and reduce that fastener to 7/16". That would be an adequate size for the outer stud in that location. I don't think you would want a heli-coil or a 1/2" Time Cert in that location. Not enough material there. That's what caused the crack in the first place. The IA II solid aluminum blocks have 7/16" fasteners in the outer locations for that reason.

[janderson]

Agree on the studs on outer splayed fasteners.
I did a sketch of my cap(s) dimension, angularity of the bolt hole, thread engagement in the block and allowance for washer and nut.
Faxed it to ARP, they had studs in stock that would work.
Not expensive, only 6 of each (studs, washers, nuts).

[mgarblik]

Did a little checking for you on inserts for that hole. Looks like solid thinwall inserts that would screw into the existing 1/2-13 hole would be either 3/8-16 or 3/8 24. If you were using high grade ARP studs, that may be OK. Another option would be a step stud, 3/8 in the block and 7/16 through the cap. Using a 7/16" insert would take a 9/16-12 taped hole. you could direct tap that size in the block but it would be very thin when done. I don't like that option. Of course you could just weld up the crack, install a 1/2" stud and not worry about it. You could mag or dye penetrant the area to see if it's cracked to begin with. My guess is the crack stops in the bolt hole wall.

[61-63]

Two of you have mentioned Indy Head Service. I had a bad experience with them several years ago and would not recommend taking them anything to cast iron weld. I had a pair of SD 127 heads that had problems and needed a couple of the stud bosses repaired and took them to Indy Head on the way to Norwalk and asked them to do it for me. Several months later I get the heads shipped back to me and they had brazed them instead of cast iron welding them like I asked. There was something else I had asked them to do to the heads and they had not done it at all. They never called me they just failed to do part of the job and what they did do was not what I had asked for. I ended up taking those heads to Jim Robertson and he and I came up with another fix which involved having a custom set of shaft rockers made for them, which is covered in another thread on this site. The $$ I paid Indy Head was a complete waste. Just saying.

[steve25]

That crack looks like it started off from deep in that bolt hole, like the main stud was installed wrong and bottomed out, of if you where running bolts then maybe that hole was not tapped deep enough?

Either way I would not trust that block to handle more then 450 hp at this point.

[Half-Inch Stud]

Photo-study looks like the crack pattern forms a wedge piece. Machineshop might cut it out, radius it up, (i had a Factory 428 4-Bolt Block with a Casting Void right there of same size), no cracking.

Photos look less concerning every time i re-look. A wedge piece that takes fairly low loads repaired or left out.

or you leave it alone and;
Mid-Plate, rubber mounts, front plate, and you likely have a solution.

Crazy idea: wonder if that Outer Bolt hole &Cap can be machined to be a Splayed bolt?

[73 TRANSAM]

HIS, I'm sure its a splayed cap. Maybe just use 2 bolt on that #3 main? Cheapest?Good luck.

[GTOGEORGE]

I wouldnt use it, too many things can go wrong that would cost you a lot of money. JMO!


GTO George

[J.C.you]

Looks like crack goes into bolt hole? I would weld to cap joining surface, then leave the splayed bolts out on that main.

[Mark G]

Fix it use it take to someone who knows his ch#t...

[mgarblik]

If your really scared of that block, PM me. I may be interested in buying it. I am not the least bit scared of that little crack. Need a small bore , though for a customer project.