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Discussion Starter #1
What is the difference between a mercruiser 502 and a GM 502 (if any)

Anything that makes these ill suited to a Turbo engine?

Would the bowtie heads from my 454 bolt right onto the 502?
 

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502

It all depends on the year from what i have been told the older MK IV 502 blocks are a bit different than the gen6 502 GN7 gave me some schooling on this the other day he will be by to clear it all up for you.
 

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What is the difference between a mercruiser 502 and a GM 502 (if any)

Anything that makes these ill suited to a Turbo engine?

Would the bowtie heads from my 454 bolt right onto the 502?
It all depends on the year from what i have been told the older MK IV 502 blocks are a bit different than the gen6 502 GN7 gave me some schooling on this the other day he will be by to clear it all up for you.
There is a MK IV 502? I know there are MK IV Bowtie blocks that can be built as 502s, but I am not aware of production MK IV blocks that have siamese bores and will go 4.47 bore.

As for the Bowtie heads on a Gen motor. It depends. If its a Gen 6 block yes they will work. If its a Gen 5 and the heads are LATE bowtie produced after the Gen engines were introduced, they will work. If they are early Bowtie and a Gen 5, I wouldn't recommend it.



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odd, you would think it would be the other way around :)

So, if I were going to look for a 502 short block in a GM or Mercruiser...what should I be looking for?

Weighing this against stroking the 468 to 496.
Not really. GM woke up the fact that some heads were a problem on the GEN deals and put a fix in. It did require much. You can hardly tell the difference in the decks by looking at them side by side. The early heads did work on some GEN 5s,. I know at least 2 people running stocl iron MK IV heads on GEN 5's with no problems. All depends on the core shift and EXACTELY where the water jacket opening fall.
The easiest way to spot a Gen 6 is by the 6 bolt timing cover verses the 10 bolt MK IV and Gen 5. Also, most GEN 6 timing covers are plastic with a few being alum, and the even rarer stamped steel units. But they all have 6 bolts. the block can be drilled and tapped for the older style 10 bolt cover. Some performance GEN 6s have a fuel pump boss. None of the GEN 5 do.



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Discussion Starter #8
Not really. GM woke up the fact that some heads were a problem on the GEN deals and put a fix in. It did require much. You can hardly tell the difference in the decks by looking at them side by side. The early heads did work on some GEN 5s,. I know at least 2 people running stocl iron MK IV heads on GEN 5's with no problems. All depends on the core shift and EXACTELY where the water jacket opening fall.
The easiest way to spot a Gen 6 is by the 6 bolt timing cover verses the 10 bolt MK IV and Gen 5. Also, most GEN 6 timing covers are plastic with a few being alum, and the even rarer stamped steel units. But they all have 6 bolts. the block can be drilled and tapped for the older style 10 bolt cover. Some performance GEN 6s have a fuel pump boss. None of the GEN 5 do.
nothing like making it easy :)
 

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What is the difference between a mercruiser 502 and a GM 502 (if any)

Anything that makes these ill suited to a Turbo engine?

Would the bowtie heads from my 454 bolt right onto the 502?
If you are up in MA, get a hold of Carl Hinkson at CNC Block in Windham ME. Huge Dart dealer and can prep a block for you.
 

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Discussion Starter #12
x2...it's a great block...
I am sure it it, but at twice the price...

Looking at the specs of a Gen 6 502, It seems like I could throw 12-15lbs of boost at it with basically stock internals and call it a day and can be picked up for a couple thousand...re-ring it, clean it up, and put my bowtie heads on it and it is something I could get past the wife :)
 

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Discussion Starter #13
not that I have to say it in this forum...

but please feel free to let me know where I am wrong here :)

For instance, I saw this on-line today:
Fully built 509 . Compression is 180 across the board except in 2 cylinders they were 140s.

$1500...Change the heads...sell them...re-ring it, and I would be ahead of the game?
 
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