what block to choose?
09-03-2009, 03:10 PM
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what block to choose?
ok so i blew up my 502 whipple charged motor and the block is no good. I have two options and wanted to see what you guys think. I can get a standard 454 block or a 427 tall deck block for free. Both in new condition. My plan is to keep the whipple sidemount and stroke whichever motor, and get close to 500CI which was already in there. Trying to get some pros and cons. I really would like to use the 427 tall deck because it would be easier to stroke, but tell me what you guys think. Thanks
09-03-2009, 03:15 PM
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The 502 will be either gen 5 or 6, the 427 is likely mark 4 and the 454 could go either way. You will be suprised hoe little of the current parts from your 502 will not interchange. It might be cheaper to find a 502 that you have to pay for. There is a 502 block and crank on austin craigslist with some other parts with it for 1k. Cost about $250 to ship it anywhere in US.
09-03-2009, 04:55 PM
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GM didn't offer the 502 until the Gen V's were released in 1991. The 502 blocks came from GM with the 4.466 bore while still maintaining good cylinder wall thickness. I think they are siamese cylinders.
One other thing to note is that the Gen V and VI use a one piece rear main seal.
One other thing to note is that the Gen V and VI use a one piece rear main seal.
Last edited by DesertRage; 09-03-2009 at 05:05 PM.
09-03-2009, 05:19 PM
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Gm started producing the Gen V in 1991, but I think Merc. was a couple years behind. I've got two 465hp 502's sitting in my shop.... Mark IV. They're out of a 1991 Fountain. The earlier 502's were definitely Mark IV.
I think the 502 was available from Merc. starting in 1990.
I think the 502 was available from Merc. starting in 1990.
Last edited by cubicinches; 09-03-2009 at 05:25 PM.
09-03-2009, 08:21 PM
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What casting numbers for the older 502's. I can not seem to find any casting informantion for a 502 bowtie block, or the older 502's.
09-03-2009, 08:58 PM
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I did not know there was a mark4 502, I am guessing they are quite rare, So that makes his block most likely a gen5/6.
If you are not well versed in big blocks it is hard to understand that they change that much from generation to generation. Most poeple cut thier teeth on small blocks, until recently everthing was interchangable, not so with the BBC.
I assumed since he was planing on stroking the 454 or 427 that he would be getting another 2 piece rear main crank.
If you are not well versed in big blocks it is hard to understand that they change that much from generation to generation. Most poeple cut thier teeth on small blocks, until recently everthing was interchangable, not so with the BBC.
I assumed since he was planing on stroking the 454 or 427 that he would be getting another 2 piece rear main crank.
Last edited by tx911; 09-03-2009 at 09:00 PM.
09-03-2009, 09:09 PM
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I would be intersted to know the casting numbers on the mark 4 502 also. Looking at the list of BBC casting numbers the only one I see before 1991 larger than 454 was a 509 built in 70-71, it was aluminum block for canam racing. The list shows bowtie blocks and does not show any 502 prior to the gen5.
