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Old 09-13-2012, 04:06 PM   #1
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5.0 question

i have a 5.0L that i want to bore out i heard you can bore these engines up to a 429 can someone help whats the max i can bore out the engine? will greatlly appreciate your help
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Old 09-13-2012, 04:13 PM   #2
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Safest you can go is probably 347 but no more than that and a stock block can only handle about 500 hp
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Old 09-13-2012, 04:21 PM   #3
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Quote:
Originally Posted by 1987mustanglx50
i have a 5.0L that i want to bore out i heard you can bore these engines up to a 429 can someone help whats the max i can bore out the engine? will greatlly appreciate your help
You're thinking of the 351. Foxtrot is right, a 302 is limited to a 347
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Old 09-13-2012, 04:45 PM   #4
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Quote:
Originally Posted by Foxtrot
Safest you can go is probably 347 but no more than that and a stock block can only handle about 500 hp
Cool thanks really do appreciate it

---------- Post added at 02:45 PM ---------- Previous post was at 02:45 PM ----------

Quote:
Originally Posted by 93slowstang

You're thinking of the 351. Foxtrot is right, a 302 is limited to a 347
Cool thanks really do appreciate it
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Old 09-14-2012, 01:24 AM   #5
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Re: 5.0 question

The maximum you should bore any factory 5.0/5.8 block is .030". That being said, people can and do bore them as far as .060", but that severely weakens the block and can lead to overheating and reliability issues. It all depends on how much core shift the block has from when it was cast. You can eyeball check for core shift by observing if the side freeze plug holes are drilled into the center of the casting hump or off to the side a bit. The closer they are to being centered the less core shift the black has experienced.


Also, when building a high HP 5.0/5.8 it is a good idea to run main stud and valley girdles to help strengthen the block. You can also have the side freeze plug holes tapped to accept cast iron screw in plugs. While this will negate the use of these holes for freeze plug protection it does provide a good increase in block strength.
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Old 09-14-2012, 01:58 AM   #6
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Mine is a stroker bored .040 over bringing the CID to 349. I've never had any issues and it makes over 600 hp. I have main stud and valley girdles. But the main thig you should check before going farther is how much metal is in the block. The Mexican made blocks are known to generally have more metal then the US blocks. Have the block sonic tested to be sure that it will take a .040 or .060 bore. Any more then .040 an you will probably have cooling issues. And if u want a .050 bore you have to have JE or someone custom forge you a set of pistons. Off the shelf they only come .040 or .060
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Old 09-14-2012, 03:17 AM   #7
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Re: 5.0 question

Quote:
Originally Posted by Blown347 View Post
Mine is a stroker bored .040 over bringing the CID to 349. I've never had any issues and it makes over 600 hp. I have main stud and valley girdles. But the main thig you should check before going farther is how much metal is in the block. The Mexican made blocks are known to generally have more metal then the US blocks. Have the block sonic tested to be sure that it will take a .040 or .060 bore. Any more then .040 an you will probably have cooling issues. And if u want a .050 bore you have to have JE or someone custom forge you a set of pistons. Off the shelf they only come .040 or .060
I'm glad to hear that, because I'm shooting for 600+ myself.
Be careful and don't get to complacent about it holding up. If you run it very hard it will break eventually. That much power in the thin wall casting block is just a time bomb waiting to go off.


I did a lot of research some time ago on the Mexican 302 blocks. What I found was that they are only slightly better than the stock 5.0 blocks at best. They were supposed to have a higher nickel content, but that was eventually disproved. What they do have are thicker main bearing caps (just like the 289 HIPO) and sometimes, not always slightly thicker webbing in the block. I found that most of the things I had heard about them over the years was just not true and that I would be much better off getting a Boss 302 or Boss 351 block, because they will hold up to 1500 HP if built right.
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Old 09-14-2012, 11:49 AM   #8
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Quote:
Originally Posted by Trojan Horse

I'm glad to hear that, because I'm shooting for 600+ myself.
Be careful and don't get to complacent about it holding up. If you run it very hard it will break eventually. That much power in the thin wall casting block is just a time bomb waiting to go off.

I did a lot of research some time ago on the Mexican 302 blocks. What I found was that they are only slightly better than the stock 5.0 blocks at best. They were supposed to have a higher nickel content, but that was eventually disproved. What they do have are thicker main bearing caps (just like the 289 HIPO) and sometimes, not always slightly thicker webbing in the block. I found that most of the things I had heard about them over the years was just not true and that I would be much better off getting a Boss 302 or Boss 351 block, because they will hold up to 1500 HP if built right.
Oh definitely a boss or a dart block is the way to go in the line of a safe build. I'm sure my block will give out eventually, but I also only rev my motor to 6500, and a stroker can rev to about 7300. I'm kind of cheating the system a little, but she hasn't failed me yet haha
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Old 09-14-2012, 05:17 PM   #9
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My block is bore (.60 over) i bought from late-model restoration and with my HCI and exhaust I'm still using stock radiator and fan and I have no cooling issues at all. Temp gauge doesn't go past 190 degrees
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Old 09-14-2012, 05:40 PM   #10
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Originally Posted by WhiteCobra94
My block is bore (.60 over) i bought from late-model restoration and with my HCI and exhaust I'm still using stock radiator and fan and I have no cooling issues at all. Temp gauge doesn't go past 190 degrees
Sometimes it works great and other times it don't. Hopefully since they are selling them as fresh, the proper tests were done on them. But glad its working out for you.
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