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What If…502 to 540

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#22 ·
I am always willing to learn but when I hear 540 I instantly think tall deck 540 cube BLOCK
Not some stroker setup and boring ritual to get 540 out of it.
And no one answered my question of if you have to grind the block to get the crank to fit without slamming into the sides or not.
Seems all you guys are just jumping on CFM's bandwagon after he said yes you can.
Ill admit when I am wrong and I was wrong on this.
But like I mentioned before when I hear 540 I think of the HP500 Bulldog 540 cid "bow tie???" block not a 502 worked over and massaged with new crank.
Think it would be easier to just buy a 540 or merlin block to get those cubes than to start piecing together stuff if you have to buy it all new, a short block might be more cost effective for an individual to obtain.
Maybe I am wrong on that one as well.
 
#23 · (Edited)
My 540 fit the quarter over crank into a stock block with no grinding - not even close. The rods are longer and the pistons have a half inch higher wrist pin height to keep the same rod angle. It is done every day. I'm not sure what you mean by a 540 cube block. The cubes are determined by what stroke crank and bore you put in it. A chevy Tall deck block was still a 366 or a 454, it just had long rods,tall pistons and thick cylinder walls for durability. It was us (hp modifying types) that chose to put a quarter or half stroke crank in it and bore it out to make it a 540 or a 572 combo.

If memory serves me, the merc 540 and 572 stuff was tall deck and used more stroke and less bore than our common combos. I don't think the general public was privey to the small bore blocks that merc was using. I'm sure they did it for lengevity and exclusive parts prices. ;)

As to the price, it is far cheaper to buy a standard block and the stoker parts to get a 540 than to buy a aftermarket tall deck or merc short block - that is why it is done all the time. Down side is that you have less piston height and it is not as reliable in the long haul, like in a tall deck (truck) application. Don't get too hungup on a particular block being a particular displacement. Blocks have particular clearances and wall thicknesses enabling a range of displacements. :)
 
#24 ·
Sorry it took so long to get back to Jayl13,

My block is a Gen V and there was no grinding needed at all. A few of us in the DC area Potomac and Chesapeake have taken late model standard deck 502s to 540s with no problem. If using a crank for a Gen IV (most after market are) you do need a seal adapter. Other than that no problem. If I were to buy a tall deck I damn sure would be building a 572 or 598 and not a 540. I understand that on a tall deck you will have better rod angles, but if you already have a standard deck I would go for it.
 
#25 · (Edited)
Another reson to stick with short deck block (if you already have 1) is that you may run into alignment problems with exhaust when you switch depending on exhaust system. I replaced blown-up tall deck with standard deck and had to get my "s" pipes cut and rewelded to match.

Mark
 
#26 · (Edited)
The bore and stroke on the "late model" Mercury HP500 540 Bulldog are 4.44" X 4.375".
As you can see the bore and stroke is quite different from the short deck 540's some of us are running
(4.5: X 4.25").
They also use an 800 cfm carb and a comp ratio of (8.6:1). 470 HPat the propshaft.
 
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