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R-3 Mopar block repair

General engine tech -- Drag Racing to Circle Track

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DavidDean
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R-3 Mopar block repair

Post by DavidDean » Fri Feb 07, 2020 5:52 pm

I'm beginning to try to repair my R-3 SB Mopar. A few years ago it broke # 3 & 4 rods. They struck the block knocking 2 small holes, one in each side 1/8"-3/16" in diameter. It also put 2 hairline cracks through the 4 outer main bolt holes at position 2 & 3 main bulk head. The cracks didn't go into the water jacket area. I'm not a fan of cast iron welding. I've been able to use Belezone to do what I consider a good repair in the bulk head area. It would be extremely difficult to use a standard lock & stitch to repair the cracks due to their position. I'm planning on using the Lock & Stitch main & head thread repair insert kit. They seem confidant the process would work. Should I try to drill a small hole at the ends of the cracks ? I'll be using main studs. If everything works out the engine should make about 900-950 N/A.
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Geoff2
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Re: R-3 Mopar block repair

Post by Geoff2 » Sat Feb 08, 2020 3:45 am

With so many cracks, I think it would become a boat anchor looooong before it gets to 900hp......

mag2555
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Re: R-3 Mopar block repair

Post by mag2555 » Sat Feb 08, 2020 6:48 am

For sure, don't chance it holding up!

DavidDean
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Re: R-3 Mopar block repair

Post by DavidDean » Sat Feb 08, 2020 5:29 pm

Thanks for the replies. I've built another motor using a Ritter block and its worked well so far. I was trying to save this block due to replacement costs. Upon further examination Only 2 outer main bolt holes have cracks its a 4 bolt main block. I too still have little faith.

mag2555
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Re: R-3 Mopar block repair

Post by mag2555 » Sun Feb 09, 2020 6:57 am

If your going to take the chance on running , then yes each end of both cracks need to be drilled out.

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