Thread: Filled Blocks

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Hey southerner

I am a northener, and I run my SBC, partially filled, on the street. I use Moroso block filler and have had no problems with it. I fill my block 2.5 inches to 3.50 inches from the surface of the block deck. The alternative would be buying an aftermarket block. Block filling is old school and mainly for the cheap and the poor. For those who have the money, a better bet would be a block from Dart or World Engines.

I can not see any problem with a partially filled block other than perhaps the oil not being cooled due to the fact that it is being insulated from the water jackets. Therefore I decided to install crankcase cooling lines which feed into a cooler which is housed within the right hand tank of my radiator, at the cool end.

However, in my opinion, a far more greater danger of over heating the engine is that of not compensating for a design flaw by GMC in the cooling system as it pertains to the flow passage ways of the engine. You see, as the cooled water comes out of the rad, it runs through the water pump, then into the front of the engine, and then,.......it immediately exits to the thermostat housing and back to the rad.

If ever you have an engine that bits the cylinders due to over heating, (seizes) it will be one of the four most rearward pistons. This is largely due to the coolant not passing by the back half of the engine. I would guess that if one could measure the temperature of a high performance engine under load, that the front cylinders might easily be 40 degrees cooler than the rear four. If such is the case, one can easily see why performance might have issues as well.

Edelbrock realized the cooling design flaw, and on most of their intakes, you have the ability of directing the water past the rear pistons, then returning externally over top of the intake via heater hoses and fittings, back to the thermostat housing. Obviously they do not want to go too far, so they leave the two forward most water jackets wide open as well.

What I do in all cases to compensate for this, is I block off the two front passages, then drill a 1/4 inch hole into the material to allow for vapors and a small amount of water to trickle out of the front two ports of the heads. You can block off the passage ways with tough gasket material. However, what I prefer to do is weld in an aluminum block, then deck the surface just enough to get rid of any warpage, then drill a small hole, about a quarter of an inch in diameter in the center of the passageway.

[QUOTE]Originally posted by TyphoonZR
[B]Hey southerner

I am a northener, and I run my SBC, partially filled, on the street. I use Moroso block filler and have had no problems with it. I fill my block 2.5 inches to 3.50 inches from the surface of the block deck. The alternative would be buying an aftermarket block. Block filling is old school and mainly for the cheap and the poor. For those who have the money, a better bet would be a block from Dart or World Engines.

I can not see any problem with a partially filled block other than perhaps the oil not being cooled due to the fact that it is being insulated from the water jackets. Therefore I decided to install crankcase cooling lines which feed into a cooler which is housed within the right hand tank of my radiator, at the cool end.

However, in my opinion, a far more greater danger of over heating the engine is that of not compensating for a design flaw by GMC in the cooling system as it pertains to the flow passage ways of the engine. You see, as the cooled water comes out of the rad, it runs through the water pump, then into the front of the engine, and then,.......it immediately exits to the thermostat housing and back to the rad.

GOOD
And you have no problems with it. Interesting what you say about the water circulation problem. The rear pairs of cylinders can run up to 40 degrees C hotter, hmmm now I wonder, thinking it through, most SBC's kick a leg out of bed on the rear pairs of cylinders. With those cylinders running hotter and being prone to detonation it would make a lot of sense.

Heres what I do on some of my cast iron blocks, those round water passages on the top of the block, I tap em with a 3/4 BSP tap and screw iin a 3/4 plug then trim it down with an angle grinder to just above deck height. Then the blocks sent off to get decked. When the block comes back I drill a 4mm hole in the first plug then 6 mm in the second and then 8mm in the third. This seems to work quite well

Originally posted by southerner
Heres what I do on some of my cast iron blocks, those round water passages on the top of the block, I tap em with a 3/4 BSP tap and screw iin a 3/4 plug then trim it down with an angle grinder to just above deck height. Then the blocks sent off to get decked. When the block comes back I drill a 4mm hole in the first plug then 6 mm in the second and then 8mm in the third. This seems to work quite well.

I am well aware of this art work, however I have also seen where this causes the cylinders to crack due to the added side pressure. It is supposed to add strength, but in the end, I maintain that the strength is really needed in the bottom end, not at the top end, the deck.

What you are trying to do with filling the block , is add strength to the bottom end, so as to avoid vibration and harmonics which will cause the crank added friction and loss of power, not to mention cap walk.

Whereas the cooling situation which I addressed earlier, needs to be taken into consideration even in mild performance motors, it is a flaw. What I tried to convey is really in essence, a two fold rectification. One of strength to the bottom end, and the other, an inherent cooling problem.

Now, having said that, by filling the block, the cooling problem becomes more pronounced. Add to that, the engine oil cooling needs to be modified. So really, we have three problems. Make that four,..... with pre-detonation happening due to the rear cylinders over heating.

Oh by the way, I did not say 40 degrees C., I merely said 40 degrees, and I should have added, F. Sorry for that omission. I am guessing that you thought I inferred Celsius because of my statement, “I am a northerner”, when in fact I convert my language to the style of the southeners.

So, if the engine temperature reads 180 F., the rear cylinders are probably 220. So if the engine temp reads 200, oh boy!

Originally posted by southerner
Heard of a product called Hard Blok from race engineering in California

Yes I have. The best stuff I’ve used is Devcon-liquid steel B. I think it’s popular for plugging bowling balls for re-drilling. It’s a machinable molding material that supposedly doesn’t expand or shrink. It’s expensive and heavy. Admittedly, our experience with using this on the street is limited, although in the “old days” we did use it extensively in our racecars. Our street experience was in a friends tow truck that had a stroked small block. A little over zealous grinding found water in a few places in the crank case and block filler was deemed to be the best cure for the problem. Initially it worked fine, but after 3months it started leaking and the radiator showed a 15% flow restriction (according to our local radiator shop) over the same time period. Hard block is a lot cheaper than the Devcon and perhaps using that in a passenger block car block may make more sense than buying a purpose built block, I don’t know, a guy would just have to cost it out. I do believe, however, that over the long haul that any of the stuff will cause problems.