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Author
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Topic: Should I sleeve 351C block?
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Fastback68
Gearhead Posts: 3702
From: Sucat, Paranaque, Philippines
Registered: Jul 99
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posted 01-03-2005 06:32 AM
   
I've read a whole bunch about this, including from resident M&Mer Dan Jones on another site (Dan, you there?), and it seems reboring or sleeving a 351C is a decision that needs a lot of expertise - and even then can be a hit and miss affair.
I don't have a sonic tester available, or even a guage for measuring bore or taper accurately, but even if I did, I could barely make sense of the graphs I have in my rebuild manual.
Could someone give me an educated guess what to do?
The block has never been bored. Original pistons in good condition. But I can slip a .004 feeler guage down the side of the piston when it's positioned about two inches into the bore. And the gap in a piston ring slipped into the bore is definitely too big.
That tells me (I think) an overbore would probably need to be .004 over, which is a no-no with 351Cs.
In the US, it seems, the advice is always just to get a new block. That's not so easy here! So I was thinking of sleeving the whole thing - but I'm nervous it may crack a cylinder.
What to do? Oh yeah, the block has been hydrotested and got a clean slate.
Many thanks!
Simon
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clevelandstyle
Gearhead Posts: 1189
From: Connersville, IN
Registered: Jul 2001
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posted 01-03-2005 07:08 AM
You can go .030" over without creating to much problem. Just doin't go more than that without sonic checking. A lot of us are running .030" making good power. Unless you are building a max effort race engine with N2O, I wouldn't worry about it. Filling the block also helps.------------------
Ben
Grabber Green '70 Mach I 351C 4V
Robbin Egg Blue '79 Fairmont 408C 4V, best time to date is 10.50 best MPH 127
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Moneymaker
Administrator Posts: 26811
From: Lyons, IL, USA
Registered: May 99
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posted 01-03-2005 11:56 AM
What are you going to do with it Simon?
If you are not going to install a 14-71 blower or a 5000HP No2 set up, you can bore the block safely to .040 without sonic testing it.------------------
Alex Denysenko
Co-Administrator and Moderator NHRA/IHRA/SRA member and licensed Superstock driver
MCA member# 53321
NHRA and IHRA SS/LA & SS/MA National Record Holder '00,'01,'02,'03,& '04
First SS/MA in the TENS!
IHRA division 5 Superstock Champion
Fleet of FoMoCo products including 88 ASC McLaren Mustang #28 The Barry of BarrysGrrl Quote #1: "I never met a magazine mechanic I liked."
Quote #2: "Make sure brain is in gear before engaging mouth!"
Quote #3: "If you can't run with the big dogs, stay on the porch!"
www.moneymakerracing.com
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Fastback68
Gearhead Posts: 3702
From: Sucat, Paranaque, Philippines
Registered: Jul 99
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posted 01-03-2005 07:50 PM
Thanks guys! My plans for this engine are totally stock, but I AM planning to pop it in a Grande and sell it so I don't want it blowing up as it leaves the lot!
I read somewhere that for a street engine, filling the block is not a good idea. Something to do with cooling, maybe?
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clevelandstyle
Gearhead Posts: 1189
From: Connersville, IN
Registered: Jul 2001
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posted 01-03-2005 11:02 PM
If it's stock or even hot street, you got no problems. Don't even bother filling it.------------------
Ben
Grabber Green '70 Mach I 351C 4V
Robbin Egg Blue '79 Fairmont 408C 4V, best time to date is 10.50 best MPH 127
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Daniel Jones
Gearhead Posts: 872
From: St. Louis, MO
Registered: Aug 99
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posted 01-04-2005 03:27 PM
> I've read a whole bunch about this, including from resident M&Mer Dan Jones
> on another site (Dan, you there?), I'm here. > The block has never been bored. Original pistons in good condition. But I
> can slip a .004 feeler guage down the side of the piston when it's positioned
> about two inches into the bore. Wait a minute. Do you mean 4 thousandths (0.004") or 40 thousandths (0.040")?
Big difference. "40 over" pistons are 40 thousandths or 0.040" larger in
diameter. When you checked the clearance on the piston, you are referring to
a radius which is half the diameter so that implies you'd need 0.080" over
pistons. That seems very large for a block that's never been bored. Perhaps
there's a decimal point problem here. Does the block have a noticeable ridge
at the top? > That tells me (I think) an overbore would probably need to be .004 over,
> which is a no-no with 351Cs. Not necessarily. If you think about the difference between 0.030" and
0.040" it's only 0.010" total or only 0.005" on each side. That's maybe
the thickness of a credit card. Not much when you think about it. If
the block is good at 0.030", it should be okay at 0.040". Clevelands
can suffer from core shift, so a sonic test is worthwhile if available.
If not, take a careful look at the casting uniformity around the cylinder
holes. > Oh yeah, the block has been hydrotested and got a clean slate. Make sure you blow out any casting crud in the water jacket. Knock out
the core plugs and blast it with high pressure air, followed by a good
rinsing with water. I also poke and prod with a magnet. It's surprising
the amount of stuff that can come out. > I read somewhere that for a street engine, filling the block is not a good
> idea. Something to do with cooling, maybe? You can get a way with a 1/2 fill on the street with a decent cooling system.
All the heat is generated in the combustion chamber so the bottom does
relatively little cooling. Water temperatures are usually unaffected but
oil temperatures may rise so a good oil cooler is recommended (with large
input/output lines). For a standard rebuild like this, I wouldn't bother. Dan Jones
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Fastback68
Gearhead Posts: 3702
From: Sucat, Paranaque, Philippines
Registered: Jul 99
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posted 01-05-2005 06:12 AM
Thanks for stopping by Dan!
quote:
Wait a minute. Do you mean 4 thousandths (0.004") or 40 thousandths (0.040")? Big difference. "40 over" pistons are 40 thousandths or 0.040" larger in
diameter.
You got it! I was using the wrong feeler gauge!
quote:
When you checked the clearance on the piston, you are referring to
a radius which is half the diameter so that implies you'd need 0.080" over
pistons. That seems very large for a block that's never been bored.
Scratching my head here. I'm sure you're right, but I wasn't trying to tuck a feeler under both sides of the piston at the same time. If one side is snug against the bore and the feeler goes in the other side, there's no need to double the measurement, right? Maybe?
quote:
Does the block have a noticeable ridge at the top?
There is a ridge but nothing that I haven't seen on a bunch of OK blocks before. This is the first time I've got involved with a Cleveland so it's the first time I've actually tried to measure one of these things myself - after reading all the scare stories.
quote:
Clevelands can suffer from core shift, so a sonic test is worthwhile if available. If not, take a careful look at the casting uniformity around the cylinder
holes.
What exactly would I be looking for there?
quote:
Make sure you blow out any casting crud in the water jacket. Knock out
the core plugs and blast it with high pressure air, followed by a good
rinsing with water. I also poke and prod with a magnet. It's surprising the amount of stuff that can come out.
I did all that, except for the magnet part, so I sort of did something right 
I'm going to show the block to a pro tomorrow and I'm feeling a lot more optimistic! Especially since I learned I don't know how to use a feeler gauge! Even though I know we all talk about .040 overbores, I got it into my head that that didn't make sense. I mean, why would anyone add that zero on the end? Who needs forty thousandths when you can have four hundredths - .04? So I chose the .004 gauge instead.
I guess it's 'cos the pros have .045 overbores and the like?
Thanks again fellas! I ain't to proud to learn
Simon[This message has been edited by Fastback68 (edited 01-05-2005).]
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bbjay351
Gearhead Posts: 223
From: DeSoto, Mo Us
Registered: May 2004
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posted 01-05-2005 02:03 PM
I've got an .040" bore on my cleveland and it's still screaming up to 7600 rpms at the track..... I wouldn't be the least bit scared of it.
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