Boring a 5.0 +.060

[50FoxBodyGT]

Hey guys,
How do feel about boring a 5.0 to +.060? Has anyone had any good/bad experiences doing this? Is it just too much or will I be okay?

 

[BlownFiveLiter]

I'm pretty sure you'd really be pushing it on a factory block. The figure I've always heard for a stock block is .030 over, .040 being the absolute max before needing to have it sleeved or having to pick up a new block.

 

[85ragtop]

I don't know about the 302. My 351 is .060 over. No probs so far.

 

[50FoxBodyGT]

I think the 351 might have thicker walls, though. Not sure on that. What's the issue with over-boring? Is it that the engine will run hot or am I going to bust a rod or something through the cylinder wall?

 

[R2D2]

If your chosen machinist doesnt have the ability to sonic check the block and tell you the numbers then run away. Some will take, most wont. Unless your .040 now there is no advantage to taking it from 4.0-4.030 bore to 4.060. Yes the issue is the thrust side of the cylinder.

 

[Woodrow]

I have a .070 motor that I run with no issues. I wouldnt advise it on the street though.

 

[Shakin66]

I have bored two 302's to 60o/s and both ran hot....I swore i'd never do it again the second time.

 

[bentley429]

I'm pretty sure you'd really be pushing it on a factory block. The figure I've always heard for a stock block is .030 over, .040 being the absolute max before needing to have it sleeved or having to pick up a new block.

Exactly, 308 is the biggest I'd go on a stock 302.

 

[dastang2]

i have done it with no problems. yes it runs hotter at around 260-290 on a stock 3 core truck radiator but an aluminum radiator and electric fan would help a lot. i still have the pistons from it since the bearings didn't last.(because i didn't get the block allign honed

 

[Phatt_daddy]

the stock engine in my '87 was .060 and I had no problems w/ electric fan and stock rad.....until I killed the compression rings. Finally got around to puling the pistons out and 6 out of 8 the top ring fell off into 4 pieces