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Author
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Topic: What are the odds? (shortblock help)
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88gt
Custom
Member # 579
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posted
 
 
If I get new heads and cam I am toying with the idea of putting in new rings and bearings in the stock shortblock, using the stock rods, pistons and crank. I don't think I have any major compression issues now, but I've got the typical 100k+ slow oil burning 5.0. What are the odds that I won't need to have the block machined or decked? The motor runs fine, so I'm not expecting to see anything troublesome down there when I tear it apart. Any educated guesses or experiences welcomed here. ![[patriot]](graemlins/patriot.gif)
Posts: 1482 | From: Santa Clara/Bay area | Registered: Nov 2001
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CustomFastbackCA
¯
Member # 1369
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posted
In my expert opinion, I say sell your car and buy a Honda Civic hatchback. ![[burnout]](graemlins/burnout.gif)
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www.CustomFastbackCA.com
1995 Dinan M3 Avus Blue Metallic
1967 GT Mustang Fastback (Eleanor)
Ask questions if you have'em, anyone who thinks they're too cool, know's it all, or doesn't want to look stupid has more problems than you.
Posts: 346 | From: Santa Clara | Registered: Jun 2002
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JohnCM
CAFords OG
Member # 1076
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posted
I'd say do it right the first time, And if you're gonna half ass it don't bother.
Posts: 3545 | From: Roseville | Registered: Mar 2002
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JohnB
Tech Moderator
Member # 969
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posted
Odds are you won't need any machine work. The highest wear item in the entire engine is the crank. Even if you had to machine it, that's cheaper than a new one.
While it is nice to have everything fresh and to exacting tolerances, you can do it on a tight budget-as long as the correct tolerances are there.
I've rebuilt numerous engines with just a ring/bearing kit. The biggest thing is to get everything clean and break out the micrometer. At the very least, get the rods re-sized.
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1965 Shelby Cobra
1993 Cobra
2012 F150 Raptor
2020 GT500
Posts: 6523 | From: Orlando FL/Redding CA | Registered: Mar 2002
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88gt
Custom
Member # 579
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posted
Thanks for the reply Jon. Have you actually done this yourself? Anyone else ever done this or know someone who has?
Posts: 1482 | From: Santa Clara/Bay area | Registered: Nov 2001
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93PONY
Mr. Valve Events
Member # 60
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posted
A leak-down before the heads are pulled will give a good idea of how well the shortblock is currently running. When you pull the heads you be able to see the wear in the bores. If there's much of a ridge at the top of the cylinder, chances are you'll need to get it bored/honed. I've pulled off heads on quite a few 5.0's & the worst I ever saw was on an oil burning stock 100K mile motor.....that had obviously been abused. Yet even then, the cylinder walls still showed the cross-hatching & the ridge was maybe a few thousanths. On a buddies 150K+ mile motor, there's hardly any wear at all. Still shows the cross-hatching.
Worst case is the cylinders are a little out-of-round & will leak a little more at BDC then a new block....but so what, it really doesn't effect performance. The valves are always open at BDC.
You may not even need new rings/bearings. But, if you do it, use some ARP rod bolts.
However, if you plan on boosting the motor, or taking a shot, I'd recomend better rings. The stock ones tend to lose tention with high cylinder pressures....especially if detonation is present.
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www.advancedenginedevelopment.com
SCT dealer
Dynotuning
(916)715-7569
Posts: 4265 | From: Fair Oaks, CA | Registered: Nov 2000
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88gt
Custom
Member # 579
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posted
Thanks Shaun. I figure since the motor has almost 110K on it, it wouldn't hurt to re-ring it. I dont see any true need as of now to do it (leakdown numbers will tell for sure), but it would be comforting to freshen it up, and at least make sure i'm not leaking any oil or losing compression through the rings. I'd be doing the work myself, the cost would be pretty cheap.
Posts: 1482 | From: Santa Clara/Bay area | Registered: Nov 2001
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JohnB
Tech Moderator
Member # 969
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posted
Yes, I've done freshen-up's on everything from 225 Slant 6's to 460 jetboat engines. Total number? Somewhere around 15.
Do a leakdown, or at the very least a comprsession test. If the numbers are close, tear it down and give it a good once over. If all checks out, get a decent ring and bearing kit, some rod bolts, and you're on your way-
[ February 13, 2003, 07:48 AM: Message edited by: JohnB ]
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1965 Shelby Cobra
1993 Cobra
2012 F150 Raptor
2020 GT500
Posts: 6523 | From: Orlando FL/Redding CA | Registered: Mar 2002
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93PONY
Mr. Valve Events
Member # 60
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posted
Shortblocks don't really burn oil.
The main cause of oil consumtion is valve guides/seals.
Throw on a new STD melling oil pump & ARP driveshaft while your at it. Cheap insurance.
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www.advancedenginedevelopment.com
SCT dealer
Dynotuning
(916)715-7569
Posts: 4265 | From: Fair Oaks, CA | Registered: Nov 2000
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