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Hello fellow Enthusiasts; It appears that reinforcing the Cleveland block with "Hard Block" is an added benefit. I would appreciate anyone's input with their experiences with Hard Block, and as to the level the block should be filled for everyday street driving. I have read on various forums...."Up to the bottom of the water pump holes"...Is this correct?....also, the best "filling/pouring" method....Thanks to "All"!.......Mark
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Moroso makes a specific block filler that comes with instructions.
Others I know have used furnace cement. You're supposed to do
the fill before any machine work is done on a block with clean
water jackets. There can be a lot of casting flash left in the
water jackets and scale can build up so you need to flush the water
jackets. One shop I know uses a place called American Metal Cleaning
to clean the block and they come back spotless. Others recommend
muriatic acid. You're referring to
what is called a half fill. On a V8, you do one deck at a time with
the deck level. Mix up the fill per the instructions and have a
torque plate or head ready to torque into place after the fill.
You do one side and let set for several days, then level the other
deck and repeat. Have a helper on hand to vibrate (air hammer dialed
down) the block to aid with the pour settling. Wait a month before
sending the block out for machining (filler cures like concrete).
Contact your piston manufacturer to see what clearances they recommend
with a filled block. Water temperatures with a half fill are usually
not a problem as the combustion heat is mainly at the top of the block.
However, oil temperature can increase so monitor it and add a
thermostatically controlled oil cooler if necessary.

Dan Jones
I have done this method of stabilizing a block for many years 1/2 full. I cannot say I recommend this on the street, as I have never even attempted to use a motor filled 1/2 way with block filler on the street. As previously pointed out it has always been used in drag racing where stabilization and consistency was always the concern ... havent given much thought to why or how this would be applied to a street application.

Researching the product seems to indicate only an "Upside". If the Cleveland cylinder walls are notoriously thin & prone to cylinder wall distortion, by reinforcing the block by filling them, increases the rigidity & concentric dimensions of the cylinder walls especially in a stroked motor where cylinder wall pressure is increased, I can only see benefits....I just need to find out.....How much to fill?!.....Mark
I think that the main use has been high horsepower engines. You will sacrifice some cooling capacity as I understand it. Once the block has been filled with cementitious grout, the block or cylinder walls can't be repaired in the event of a cracked cylinder. It's popular among the Aussies and among drag racers, but would be unnecessary if the long-promised aftermarket Cleveland blocks are finally made available.

Promises, Promises....Reminds of of the Christmas I was "Promised" a pony!!!...does a bottle of Elmers Glue qualify?!....I would think that a "Fortified Block" is less inclined to cracking than an non fortified block, & since the cost of a used Cleveland block is "LESS" than the cost to repair a cracked block, I am going to "Fortify" mine!.....Mark

The original purpose of grouting was to reduce cylinder wall flex in drag race engines, which improves ring seal and makes more horsepower. There is no doubt that grouting accomplishes this. The original purpose of grouting was never to prevent cylinder wall cracking.

Grouting has not caught on in road racing or dirt track circles to my knowlege.

Some guys who have run grout on the street say they'll never do it again. Others who are currently running it say "no problem". The guys running it on the street all advise to fill to the bottom of the water pump discharge holes. They also all advise to make sure the cooling system is in top shape, and most advise to use an oil cooler. The oil temps WILL run hotter.

Nobody running it on the street ever mentions making more horsepower (which is the purpose of grouting). Of course, nobody mentions cracking cylinder walls with a grouted street block, but how can they prove the block would have cracked without grouting? So the jury is still out, and will always be out, in regards to the benefit of grouting a street motor. Its a religious thing, a matter of faith, you're either a believer or you're not.

My opinion:

The owner of an average "street performance" Cleveland does not need to worry about cylinder wall cracking ... if the motor has been assembled with the usual precaution and precision. I purchased my first Cleveland powered vehicle in 1976, and have never been without one since. I've never cracked a cylinder.

Those who are serious about avoiding cylinder wall cracking can do 4 things:
(1) Use the stock stroke crank for the best rod length to stroke ratio possible
(2) Index the cyliner bores during boring
(3) Use pistons with floating pins
(4) Use fully round skirt endurance racing pistons

To think it is possible to pour similar strength inexpensively from a bottle and avoid the cost of this machine work and the cost of these parts is dreaming. Supplementing these things with grout would seem reasonable however, that's how the guys who originally thought of using grout used it, as a supplement to all the other machine work and parts. They were in search of every possible last horsepower.

However if I were building a powerful street or road racing motor, and felt the 4 steps I mentioned earlier weren't enough, I'd use a NASCAR block for additional strength. I wouldn't grout. In my opinion its a drag racer trick. One thing I have learned over the decades, drag racers get away with a lot of stuff you can't get away with in other types of motorsports.

Grouting tips:

If you're going to grout use Embecco 885 or the suff Moroso sells. You'll need two bottles of the Moroso stuff.

Grout before you have the block machined because things are going to be moved & distorted by the grout.

Grout one side at a time and let one side set-up (harden) before you grout the other side.

Grout needs to cure for 28 days to be completely cured. In a week it is only cured about 50%.

Level the block front to back, and level each deck side to side before filling.

Torque the main caps in place before grouting.

Bolt a head with a gasket on each bank immediately after pouring, and leave them there while they are curing.

Last edited by George P
Hello George; As always appreciate your thoughts, input, sound reasoning. I believe especially in when it comes to engines in the old addage, "A chain is only as strong as it's weakest link", therefore I would never cut corners on "1" aspect of building a motor with the opinion that, "Another part will make up the difference". If by grouting my Cleveland I can add strength & by helping the cylinder wall retain concentric dimension, thus adding to better piston ring sealing & reduced wear, which should equate to additional horsepower albeit marginal ( I'll still take it)...I can only see an "Up Side"...let the "Grouting" begin!!....Mark
If the grout is Portland cement based, and I think it is, it will have all of the drawbacks.
Esentially, if it is pushing on the block enough to cause the iron to distort, who is to say that hasn't caused the iron to fail at those points?
Portland cement bonds well to iron or steel. It does have the tendency to be corrosive at those points though.
Portland cement will also develop expansion cracks, like you see in a sidewalk.
All things considered, I consider it a temporary measure, and the time ticking on each block will vary.
If you are looking for a super trick block, buy a new race block. It has all the correct considerations built into it and is not governed by some kind of Italian stone masons voodoo.
Last edited by panteradoug
> "What level to fill to?" for a daily street driver? the "bottom of
> water pump holes"?....correct?...

Yes. BTW, many new and some old engines had shallow water jackets.
My little Buick 215's were shallow water jackets.

> Nobody running it on the street ever mentions making more horsepower (which
> is the purpose of grouting).

The purpose of grouting is to stabilize the bottom end of the block
so the cylinders are less likely to split. That typically occurs if
the engine is turned to high RPM or has a bunch of core shift or has
been bored too far. A typical 2 bolt main Cleveland block will cap
walk before splitting a cylinder.

Dan Jones
One more possible comment: if your block has significant core shift in the cylinder bores, you won't cure it by half-filling it with grout. Best to have it (ultra)sonic tested before grouting. I hear that you can sometimes tell if there's significant core shift by the location of the lifter bores relative to the casting.

For the money invested in grout fill and any other downside it may have, I would rather get an aftermarket 9.2" deck Windsor block, TFS cleveland heads, and a TFS "clevor" intake... In the realm of street-driven engines, the new Ford Racing Boss 351 block with cross-drilled water coolant passages would be my first choice...

Last edited by coreyprice
Correct me if I’m wrong, but my understanding is “Block filler” was designed & intended for Drag racing use only.
Specifically for Methanol, (Alcohol) burning engines.
Adds rigidity & stiffness to the block.
Drag racing engines do not need much in the way of cooling when running Methanol as this fuel runs so cold & gives anti-detonation benefits, thus higher compressions can be run.
Drag racing engines also only run for several seconds or at the very most a few minutes & require much less cooling.

A street engine has cylinder cooling passages for good reason.
Pantera’s have never been the best for staying cool, the last thing I’d be doing was making the situation worse.

> For the money invested in grout fill

Grout fill is very cheap compared to a race block. Some people like to
build as cheaply as possible so that when something fails, less expensive
parts get damaged. Others like to build with the best components available
to lessen their chance of failure but when something does go wrong more
expensive parts gets damaged. You pay your money and you take your chances.

> would rather get an aftermarket 9.2" deck Windsor block, TFS cleveland heads,
> and a TFS "clevor" intake...

The TFS Clevor intake is for a 9.5" deck block, not 9.2" deck.

> In the realm of street-driven engines, the new Ford Racing Boss 351 block
> with cross-drilled water coolant passages would be my first choice...

Despite the name, the Ford Racing Boss 351 is a Windsor block, not a

> Correct me if I m wrong, but my understanding is "Block filler was
> designed & intended for Drag racing use only. Specifically for Methanol,
> (Alcohol) burning engines.

The guys running full fills run on methanol. The street guys run a half
height fill.

> A street engine has cylinder cooling passages for good reason.

Combustion heat is primarily retained in the combustion chamber.
You'll find many modern V8s have shortened water jackets as do
some older V8s. Half filling the bottom of the block doesn't seem
to impact coolant temperature to any great degree. However, oil
temperatures tend to go up so an oil cooler would be worth considering.

Dan Jones

I like the Boss block, and yes, it is a Windsor. Yes, it costs $1800 and needs some machine work.

I thought that TFS offered their intakes in both deck heights, but you are right, they only offer the Clevor intake in a 9.5" deck height.

I still would rather use a race block for really high horsepower engines, if possible instead of grout fill. One other possible solution would be to sleeve the block, but that isn't cheap...
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