Mailbag: Can You Use Block Filler to Improve Engine Cooling and Bottom-End Strength?
(Image/LSX Magazine)
Q: I’m getting ready to build a 406 small-block to put into my Camaro.
My question is about the use of block filler. I’ve read that if you fill the block to the bottom of the freeze plug openings, that it will increase the cooling ability because this limits water flow to the oil pan area and increases flow to the head. I’ve also heard that the procedure strengthens the bottom end.
Is this all true? And can it be done to a street engine?
Is there a certain kind of block filler I should use? Are there any other considerations for using block filler? I’d appreciate any help you can offer.
A: The short answer to all of your questions is—yes.
Block filler can improve cooling and cylinder strength, and it can be used in a street engine successfully.
The type of filler you want to use is called “short fill,” which means that enough filler is used to partially fill the water jackets in the block.
A good engine block filler is called HardBlok. You can find the pre-measured short-fill container of HardBlok engine block filler here, which comes with the instructions you’ll need.
…
If you limit coolant to the oil pan area should you also add an external oil intercooler to compensate?
Unfortunately there’s no short answer here because of all the different variables at play (e.g. engine type, engine bay size, driving environment, etc.). There are plenty of folks who’ve done this to their street cars, but every vehicle has different factors to consider. If you’ve got a specific application in mind, you should call the Summit Racing tech team at 330-630-0240, they answer questions like yours all the time.
This can be done on a street engine, but it’s not a good idea. If block strength is a question – buy a better cylinder block like the Dart Sportsman block – its’ stronger and better in several ways. The problem with filling the water jackets is that it does not improve cooling – but instead has a serious effect on oil temperature. For a drag race engine, this can be a small advantage to get the oil up to temp quickly. But for a street engine – this could raise the oil temperature significantly. I can’t give you a specific answer as to how much – but enough that you would need a separate oil cooler. Frankly, the smart move is to just buy a better block and you have all the strength you will need. But block filler for a street engine is not a good idea
I am seeing many engine types using grout without any problems. Clevos, Windsors seem to be ok with it. Holden 6 and V8 race engines are using it with no problems either. And it does stiffen the bores. And you cannot buy better blocks for all of these. Oil temps are about the same, water temp stays the same. Though synthetic oil and proper coolant, never water.
Never used it myself but may next time I rebuild the anchor [Clevo] as they are bad at splitting bores, and striking water too @ 030! mine is 020.
Not for street use unless it is very strong,, and then NOT a street engine anyway.
You absolutely can buy better blocks for clevo’s and Windsor’s .
http://www.tmeyerinc.com/product/track-boss-cleveland-block/
I used it on the engine in my Hudson Tereplane, works great.