I've often seen the term "bored over .somethingorother" thrown around when talking about engine builds. I understand the concept (essentially making the cylinders wider) but what I'm curious about is - what else needs to be changed when you bore out a motor like that? Seems to me the pistons wouldn't seal properly anymore but besides those, what do you need?
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boring out a block
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- 1990 Ford LTD Crown Victoria P72 - the street boat - 5.0 liter EFI - Ported HO intake/TB, 90 TC shroud/overflow, Aero airbox/zip tube, Cobra camshaft, 19lb injectors, dual exhaust w/ Magnaflows, Cat/Smog & AC delete, 3G alternator, MOOG chassis parts & KYB cop shocks, 215/70r/15s on 95-97 Merc rims
- 2007 Ford Escape XLT - soccer mom lifted station wagon - 3.0 Duratec, auto, rear converter delete w/ Magnaflow dual exhaust
- 2008 Mercury Grand Marquis Ultimate Edition - Daily driver - 4.6 2 valve Mod motor, 4R75E, 2.73s. Bone stockTags: None
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Originally posted by 1990LTD View PostI've often seen the term "bored over .somethingorother" thrown around when talking about engine builds. I understand the concept (essentially making the cylinders wider) but what I'm curious about is - what else needs to be changed when you bore out a motor like that? Seems to me the pistons wouldn't seal properly anymore but besides those, what do you need?
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the head gaskets usually aren't a concern unless you're going way oversize. Modern blocks don't really support much over .030 or .040 safely, so thats not much of a concern. As long as the firing ring in the gasket is bigger than the hole in the block, its fine. Generally speaking, boring an engine out does not give you enough extra displacement to be significant. A .030 over 302 motor is a 306. 4 cubic inches in the grand scheme of things is nothing. Most of the time, the block is bored out because the cylinders are no longer round and straight, or they are worn beyond spec so the rings won't seal properly.86 Lincoln Town Car (Galactica).
5.0 HO, CompCams XE258,Scorpion 1.72 roller rockers, 3.55 K code rear, tow package, BHPerformance ported E7 heads, Tmoss Explorer intake, 65mm throttle body, Hedman 1 5/8" headers, 2.5" dual exhaust, ASP underdrive pulley
91 Lincoln Mark VII LSC grandpa spec white and cranberry
1984 Lincoln Continental TurboDiesel - rolls coal
Originally posted by phayzer5
I drive a Lincoln. I can't be bothered to shift like the peasants and rabble rousers
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ahh, makes sense. So it would only really be done as a repair on one of these motors?sigpic
- 1990 Ford LTD Crown Victoria P72 - the street boat - 5.0 liter EFI - Ported HO intake/TB, 90 TC shroud/overflow, Aero airbox/zip tube, Cobra camshaft, 19lb injectors, dual exhaust w/ Magnaflows, Cat/Smog & AC delete, 3G alternator, MOOG chassis parts & KYB cop shocks, 215/70r/15s on 95-97 Merc rims
- 2007 Ford Escape XLT - soccer mom lifted station wagon - 3.0 Duratec, auto, rear converter delete w/ Magnaflow dual exhaust
- 2008 Mercury Grand Marquis Ultimate Edition - Daily driver - 4.6 2 valve Mod motor, 4R75E, 2.73s. Bone stock
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or to build up a performance engine using a "seasoned" block.
Only two things are infinite, the universe and human stupidity, and I'm not sure about the former. -- Albert Einstein
rides: 93 Crown Vic LX (The Red Velvet Cake), 2000 Crown Vic base model (Sandy), 2003 Expedition (the vacation beast)
Originally posted by gadget73... and it should all work like magic and unicorns and stuff.Originally posted by dmccaigOverhead, some poor bastards are flying in airplanes.
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also on some motors, boring the cylinders gets the walls further away from the valves, which helps them flow a little better.http://secondhandracing.com/Home.aspx
http://secondhandradio.com/
R.I.P. Jason P Harrill 6-12-06
http://www.grandmarq.net/vb/showthread.php?t=5634
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Alot of times going too far with the bore leads to issues with cooling, in engines with thin wall castings.
Some people have bored the 283 Chevy an 1/8" (makes a 4" bore) with success. My Dad did one in the late 60s, and it had issues with overheating at low engine speed.**2012 Ford Mustang Boss 302: 5.0/ 6 spd/ 3.73s, 20K Cruiser
**2006 MGM,"Ultimate": 4.6/ 2.73/ Dark Tint, Magnaflows, 19s, 115K Daily Driver
**2012 Harley Davidson Wide Glide (FXDWG):103/ Cobra Speedsters/ Cosmetics, 9K Poseur HD Rider
**1976 Ford F-150 4WD: 360, 4 spd, 3.50s, factory A/C, 4" lift, Bilsteins, US Indy Mags, 35s Truck Duties
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Originally posted by P72Ford View PostAlot of times going too far with the bore leads to issues with cooling, in engines with thin wall castings.
Some people have bored the 283 Chevy an 1/8" (makes a 4" bore) with success. My Dad did one in the late 60s, and it had issues with overheating at low engine speed.
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old 302 blocks, like pre-72 and the Mexican blocks are supposed to have the thickest walls. You can sonic check a block to find out how much material is there so a safe over-bore can be worked out but generally speaking, the less oversize you can make the hole the better your chances of not having stupid problems.86 Lincoln Town Car (Galactica).
5.0 HO, CompCams XE258,Scorpion 1.72 roller rockers, 3.55 K code rear, tow package, BHPerformance ported E7 heads, Tmoss Explorer intake, 65mm throttle body, Hedman 1 5/8" headers, 2.5" dual exhaust, ASP underdrive pulley
91 Lincoln Mark VII LSC grandpa spec white and cranberry
1984 Lincoln Continental TurboDiesel - rolls coal
Originally posted by phayzer5
I drive a Lincoln. I can't be bothered to shift like the peasants and rabble rousers
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so not all blocks are identical in size? or does thickest in this context mean higher grade/content of metal?sigpic
- 1990 Ford LTD Crown Victoria P72 - the street boat - 5.0 liter EFI - Ported HO intake/TB, 90 TC shroud/overflow, Aero airbox/zip tube, Cobra camshaft, 19lb injectors, dual exhaust w/ Magnaflows, Cat/Smog & AC delete, 3G alternator, MOOG chassis parts & KYB cop shocks, 215/70r/15s on 95-97 Merc rims
- 2007 Ford Escape XLT - soccer mom lifted station wagon - 3.0 Duratec, auto, rear converter delete w/ Magnaflow dual exhaust
- 2008 Mercury Grand Marquis Ultimate Edition - Daily driver - 4.6 2 valve Mod motor, 4R75E, 2.73s. Bone stock
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thicker in this context just means there is more material between the water jacket and the inside of the cylinder, so basically there is more you can cut out of the block before you run into problems. The more material there, the stronger the block is as well. Thinner blocks are lighter, but they are not as strong, and will not support as much of an oversize bore. they're cheaper to make too.86 Lincoln Town Car (Galactica).
5.0 HO, CompCams XE258,Scorpion 1.72 roller rockers, 3.55 K code rear, tow package, BHPerformance ported E7 heads, Tmoss Explorer intake, 65mm throttle body, Hedman 1 5/8" headers, 2.5" dual exhaust, ASP underdrive pulley
91 Lincoln Mark VII LSC grandpa spec white and cranberry
1984 Lincoln Continental TurboDiesel - rolls coal
Originally posted by phayzer5
I drive a Lincoln. I can't be bothered to shift like the peasants and rabble rousers
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thanks.
how about parts that need changing when stroking the motor out? i would imagine heads, pistons, rod, cranksigpic
- 1990 Ford LTD Crown Victoria P72 - the street boat - 5.0 liter EFI - Ported HO intake/TB, 90 TC shroud/overflow, Aero airbox/zip tube, Cobra camshaft, 19lb injectors, dual exhaust w/ Magnaflows, Cat/Smog & AC delete, 3G alternator, MOOG chassis parts & KYB cop shocks, 215/70r/15s on 95-97 Merc rims
- 2007 Ford Escape XLT - soccer mom lifted station wagon - 3.0 Duratec, auto, rear converter delete w/ Magnaflow dual exhaust
- 2008 Mercury Grand Marquis Ultimate Edition - Daily driver - 4.6 2 valve Mod motor, 4R75E, 2.73s. Bone stock
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stroker kit usually involves rods, a crank, and maybe different pistons. There is also sometimes internal clearancing depending on the stroke and the engine. You don't have to change the heads, but if you're spending the bucks on a stroker kit, it would be moronic to bolt crappy stock heads on top.86 Lincoln Town Car (Galactica).
5.0 HO, CompCams XE258,Scorpion 1.72 roller rockers, 3.55 K code rear, tow package, BHPerformance ported E7 heads, Tmoss Explorer intake, 65mm throttle body, Hedman 1 5/8" headers, 2.5" dual exhaust, ASP underdrive pulley
91 Lincoln Mark VII LSC grandpa spec white and cranberry
1984 Lincoln Continental TurboDiesel - rolls coal
Originally posted by phayzer5
I drive a Lincoln. I can't be bothered to shift like the peasants and rabble rousers
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so the stroke doesn't dictate I put certain heads on?
I remember being given a very vague explanation of a 383 stroker...the guy said it was a 350 with 400 heads?sigpic
- 1990 Ford LTD Crown Victoria P72 - the street boat - 5.0 liter EFI - Ported HO intake/TB, 90 TC shroud/overflow, Aero airbox/zip tube, Cobra camshaft, 19lb injectors, dual exhaust w/ Magnaflows, Cat/Smog & AC delete, 3G alternator, MOOG chassis parts & KYB cop shocks, 215/70r/15s on 95-97 Merc rims
- 2007 Ford Escape XLT - soccer mom lifted station wagon - 3.0 Duratec, auto, rear converter delete w/ Magnaflow dual exhaust
- 2008 Mercury Grand Marquis Ultimate Edition - Daily driver - 4.6 2 valve Mod motor, 4R75E, 2.73s. Bone stock
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