575sci 502 to 540
12-06-2012, 07:04 PM
#11
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Depending on how the pistons and crank counterweight are cut, they may or may not clear the crank counterweights with a stock (6.135) length rod. Usually, they won't clear, so you need to go to a 6.385 or 6.535 rod with a 4.25" crank. You would also have a less than desirable rod angle(1.44) with a 6.135 rod and 4.25 crank. If you use the longer rod, then you will have to change the pistons because the compression height will not be correct. Most would use a 6.385 rod with the 4.25" crank.
Eddie
Eddie
something to consider also. If your $hit's in good shape, and its power you seek, freshen it up, install some good headgaskets, a superchiller, a hyd roller cam, and up the boost a bit. If that doesnt sound like enough, sell those 256 blowers and bolt on some whipples, or 8-71s. You'll find more power there than just going up 35-40CI, for around the same money. Because at 540CI, your blowers will be smaller than they are now.
Last edited by MILD THUNDER; 12-06-2012 at 07:07 PM.
12-06-2012, 07:04 PM
#12
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My Potter built 540 is the short deck block .030 over with the 4.25 crank and 6.385 rod, this is what most do so you are starting out with a fresh bore, the right pistons, and is a totally fresh short block.
12-06-2012, 08:07 PM
#13
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12-06-2012, 08:29 PM
#14
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12-06-2012, 09:41 PM
#15
+1.
something to consider also. If your $hit's in good shape, and its power you seek, freshen it up, install some good headgaskets, a superchiller, a hyd roller cam, and up the boost a bit. If that doesnt sound like enough, sell those 256 blowers and bolt on some whipples, or 8-71s. You'll find more power there than just going up 35-40CI, for around the same money. Because at 540CI, your blowers will be smaller than they are now.
something to consider also. If your $hit's in good shape, and its power you seek, freshen it up, install some good headgaskets, a superchiller, a hyd roller cam, and up the boost a bit. If that doesnt sound like enough, sell those 256 blowers and bolt on some whipples, or 8-71s. You'll find more power there than just going up 35-40CI, for around the same money. Because at 540CI, your blowers will be smaller than they are now.
Last edited by JRider; 12-07-2012 at 05:45 AM.
12-07-2012, 11:36 AM
#17
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I failed to inform that I already have upgraded the blower to an 871 littlefield and a whipple low pro cooler. The motor is out right now and my gears are turning. Maybe it is time to just upgrade the cam to a hyd roller...going to have everything inspected and make some decisions. Wouldn't mind going to some aluminum heads either.
12-08-2012, 07:05 AM
#19
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Just a thought - if your 502 is running sell the long block and start over from scratch.
What's left of your old engine if you replace the crank, rods, pistons & heads?
What's left of your old engine if you replace the crank, rods, pistons & heads?
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Marc
www.mercruiserparts.com
www.go-fast.com
www.bammarine.com
www.cyborgtransmissions.com
It's not alive -www.BoatStuffExpress.com - temporarily retired
12-08-2012, 08:35 AM
#20
The biggest decision I have to make is heads. I cannot go with raised exhaust port heads due to my hatch clearance with the etops. That limits my selection of heads. I considered going with the edelbrock marine heads due to cost and hatch clearance...OR I could have Valako port my stockers on the exhaust side. Any input in this catagory would be helpful. After choosing heads the cam is next.
