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10-01-2015, 08:50 AM | #1 |
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Gm performance 305 block
Does anyone know why the GM performance 305 block (10243878) has 10mm bell housing and motor mount threads instead of the standard 3/8 16? Is there anything else dimensionally odd about the block? With priority main oiling and .260" thick cylinder walls, it sure seems like an improvement over your "fathers 305" block... Thanks, Patrick.
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10-06-2015, 08:36 AM | #2 |
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Re: Gm performance 305 block
I am not sure as to why they would do that, unless it's just there weird way of introducing something metric to the block or maybe it was just a freak thing they did without realizing it. those things have happened,lol but if your looking for a great 305 replacement thats all standard threads check out the this. Dart#301-31151411 it's a beefy 305..
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10-06-2015, 11:41 AM | #3 |
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Re: Gm performance 305 block
I don't think the Dart 305 block is on the approved list. I would get a clarification before you invest.
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10-06-2015, 12:31 PM | #4 |
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Re: Gm performance 305 block
The 305's came out when GM was going to change everything to the Metric system....but never really did.
The stock 305 bore is an odd number and I believe it may have been a metric dimension.... Most other GM engines were based on std. fractional sizes.... Only other odd one I can think of is a 396 bore.....4.093 ? Metric 200 transmissions were used with the 305's..... In the mid to late 1970's GM started using metric body bolts in some cars.....It was a pain to have to buy metric tools back then when everything else was std....
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Rich Biebel S/C 1479 Stock 147R |
10-06-2015, 12:56 PM | #5 | |
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Re: Gm performance 305 block
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10-06-2015, 01:16 PM | #6 |
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Re: Gm performance 305 block
Thanks for the feedback guys. They do list the dart block as an approved replacement. Why they didn't go with the SHP platform instead of the Little M I'm not sure; but it seems overkill for a 400 HP engine. I suppose if you're building a super stock engine that's a good thing. It's also about 70 LBS heaver than a stock block. I've been down the salvage yard block path only to be the proud owner of two cracked blocks. I thought maybe this block might be a little better than what came in the production vehicles. I guess the only way to find out is to buy one and try.
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10-06-2015, 06:37 PM | #7 |
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Re: Gm performance 305 block
Yes, i was not stating it for stock or super stock replacement. just saying it has more beef to the material. but I would recommend getting the NHRA approved list to be sure. and there are many blocks by World and Dart that are legal replacements.
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