anyone ever weld up cracks in the mains and have any luck with it?

anyone ever weld up cracks in the mains and have any luck with it?

ive been spraying 2 plate systems on the car. a69 gp street car 10 inch tire.I welded mine up and im curently putting it back together.the block is o-ringed filled steel 4-bolt caps scat 6.800 rods cast crank not a N crank 4.25 stroke.car runs 10's on motor 6.o's on the dope.any info would be great.

The mains in the block (bulkheads) or mains on the crank?
Crank? NEVER!!! It WILL break...
The block? Iffy. Welding cast iron is an art. In most places, a crap-shoot. "Spray" welding will fill the holes, but won't add any strength lost to the crack. Arc-welding (nickel rod, low energy) MAY work, but has been known to extend cracks ("spider webbing").
Best of luck. We would rather machine up another block to be safe, unless you simply have SO MUCH money in the block, it's worth the risk.

Welding cast iron is tuff to do. I would never weld up any block that has main webs cracked. If it is thru the oil galley it will never have the correct pressure. The block broke for a reason. Welding it will not make it stronger. Welding cast iron make it more brittle and will brake faster than the not welded area.

I often wonder what impact it would have to run the block regardless of the cracks. I have cracked a couple in the past, but only knew of the cracks after end of season tear downs. Car never slowed and never showed oil pressure variances. Who knows how long the were cracked.
Just wondering.

Erik

I agree.

For me......cracked mains = throw the block in the garbage. I will not try and repair a cracked block. I will very rarely even sleeve a block unless it is a rare restoration engine that is hard to replace. I just threw away a 66 corvette 425HP 427 4-bolt block because it was cracked up through a main web up towards the cam tunnel. I cost me $1900 to replace the block if that tells you anything.

Had a nice back-up 474 that went 9.55 in a 3100 pound car, 8.70's w/250 shot. While freshening, discovered crack in #2 and #4 main webbing. Made the decision to spend $1000 to get it "fixed". They ground material out of the cracks, heated the block up in a huge oven, brazed the cracks. Then machined the bottom of the block flat, bored the mains, bored and sleeved the cam bores.
Ran the motor last half of the season. Ran great, no oil pressure or performance issues (were running a titan pump).
Recently disassembled for inspection: #4 main web cracked up through lifter valley, #4 cam bearing spun - scored cam journal, #3 main bearing and crank journal scored, crank cracked at #3 main journal, #5 & 6 rod bearings wiped. Surprisingly, crank end play was only .010 and #4 thrust bearing looked pretty good, considering. Block AND crank are now both junk.
Was it worth the gamble? In hindsight, no. The block repair company routinely does these kinds of repairs, but those blocks probably aren't subject to this kind of abuse. One more weekend on the racetrack and we would have been picking up pieces.
Now I need a good block that can bore .060.

Shaggy, if you decide you need a block, I'm just right down the road from you in Orange. I've got a few that might work.

shaggy, this is john in austin with the fairmont. we were running steve's motor last year with the stock block and when we tore it down for inspection we found no problems. if you want to talk to me about block prep or if you need to find another block call me at 512-771-5257 and i'll hook you up. but please don't try to weld up the block and think it will hold with what you're running. it wont work.

the block has been cracked for awhile probly..i never lost oil presure.im guessing the motor makes 600HP because of the weight of the car and what it runs on motor.i've sprayed 275 bigshot plate off the line and added a 175 shot midway through 2nd gear on top of it for a total
of 450 im pretty sure it was the 275 out the gate that has cracked it and the weight of the car.thanks for the info.

That is why we built the IA II. Save the stock block for restoring a nice car. The time and money that you spend on building a stock block, you have spent over 2k to make a block that will take 700hp for a while, but in time it will not last. For the dollar per run IA II is the only way to go. Add the resale value of an IA II motor to this equation, and you have an even better return to the investment. We added more meat in the main webs of our IA II motor and remove all of the stress risers in inside the water jackets that were in the old IA motor. It is the things that you can't see that made our block the strongest and only after market block made.

ive got plans to build a new combo in september when i get my bonus.will go with the new IA-II block but trying to get buy for a couple months with my curent stuff.

Had a formerly reputably machine shop line bore a block and install four bolt mains.He made the thrust .023" too narrow.Had the block brazed up @ the best shop in town. Block split #4 web and was losing HP on the Dyno.Was making 588HP@5800 & 603 #s @ 4300.Then it was all downhill power wise.was losing a little oil pressure and each sucessive run was down 20 or so.pulled valve covers and saw metalflake. I would never braze or weld on a structural cast iron part again.

I suspect Rear and front engine plates will ELIMINATE cracked mains webs.

Do a Force-Balance Diagram on the Block with Factory engine mounts and see where all the distortion-inducing Force concentrates... http://forums.performanceyears.com/g...on_redface.gif

Cracked block is a cracked block and a cracked head is a cracked head.

If I was trying to save a RAV head or something, I'd try the stitch plugging stuff. Drill, tap, plug, grind and repeat...

I tried to torch weld a crack once. Drilled a hole at the end of the crack, ground a groove along the crack, heated up with the torch and started welding. Everything was going fine till I noticed a crack was chasing my welding.

All the effort of block fill, steel main caps, align honing mains, and you can still only max bore to 4.250. Then praying you don't find rust pinholes in 30 year old castings with .040 or less wall thickness to concrete in places.

Motor Plate better but not the cure.

Get an IAII.

-Rob

Repairing cracked parts (I.E. Iron Heads, Iron blocks) is for <span class="ev_code_RED">Very Rare</span> or #'s matching <span class="ev_code_RED">Very rare</span> collector items.

Maybe a dumb ? But does the IAII block come machine or do you have to have everything machined?
Thanks Tom

Hey Shay.....glad to see you are finally here!
Took you long enough! http://forums.performanceyears.com/g...on_biggrin.gif http://forums.performanceyears.com/g...on_biggrin.gif