D17 center main girdle
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Forum Name: Pulling Forum
Forum Description: Forum dedicated to Tractor and Garden Pulling
URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=206196
Printed Date: 17 Apr 2025 at 3:40pm
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Topic: D17 center main girdle
Posted By: 7080R62
Subject: D17 center main girdle
Date Posted: 06 Apr 2025 at 8:07pm
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I have a D17 block with broken center main cap. I remember a post a while back with a machined center main. Any help appreciated. It is 6in stroke also. Thanks
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Replies:
Posted By: DrAllis
Date Posted: 06 Apr 2025 at 8:45pm
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Over the last almost 40 years, I have probably built a dozen large W and G-226 engines. From the very first one I have always made a simple girdle for the OEM center main cap. I always faced off the bottom of the main cap ever so slightly for the brace to rest against. The brace was just a 3/4" thick by 1 1/2" wide flat of mild steel. These numbers are from memory, but the width can only be so wide. Thicker would be better. Two homemade thick walled spacers from an old piston pin and two longer grade 8 bolts. The parts were assembled so I could just slide a sheet of paper between the brace and the flat spot on the bottom of the cap. The main cap ears aren't usually exactly the same height, so your spacers are made for each specific location. This set-up also helps keep things going when the block splits down the middle at the top of the deck. You've got your ignition timing retarded somewhat ??
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Posted By: 7080R62
Date Posted: 06 Apr 2025 at 8:48pm
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Ok do you have any pictures of what you have made. And yes timing is retarded some.
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Posted By: DrAllis
Date Posted: 06 Apr 2025 at 8:54pm
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No pics. Longer grade 8 or 9 bolts. Two spacers. A plate of steel that I gave you the dimensions to. It's very simple and apparently works as I have never had a center main cap failure.
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Posted By: 7080R62
Date Posted: 06 Apr 2025 at 8:59pm
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Ok sounds good will see what I can do there after getting back from machine shop. I am having block and crank checked.
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Posted By: DrAllis
Date Posted: 06 Apr 2025 at 9:09pm
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I've gotten out my decades old engine notes. The brace is 3/4" x 1 1/2" as I said. It is approx 6 inches long and will hit the oil pump tube if too long on that side. Other side not important. G-226 bolts are Grade 8 or 9 and are 5/8 NC x 4 1/2" long. If you make the brace thicker, which you can, then you have to get longer bolts of the correct length to use all the threads the block has to offer without bottoming out.
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Posted By: 7080R62
Date Posted: 06 Apr 2025 at 9:37pm
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Ok yes i am following you on that. One other question is there a oil pan that you know of made for rods to clear or just make it to fit?
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Posted By: DrAllis
Date Posted: 06 Apr 2025 at 9:49pm
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No special oil pan that I know of. The last engine I built with 5.800" stroke had D-19 Buda rods and I said I'd never do another oil pan. I had to remove the pan rail braces, heat, bend and grind the pan and refit the braces to get the rods to clear. My pan looks like a bomb went off inside it. If you had custom rods made with offset caps, that would surely help.
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