Hardblock Question

[njk53]

What would happen if anything if Hardblock was poured into the engine after the block has been bored and honed? When Hardblock sets up can it distort the cylinder walls? I am not sure if the material expands or contracts when it cures.

[SSGT Mustang]

Originally Posted by njk53

What would happen if anything if Hardblock was poured into the engine after the block has been bored and honed? When Hardblock sets up can it distort the cylinder walls? I am not sure if the material expands or contracts when it cures.

I've always been told by various engine builders that you Hardblock before honing because the cylinders will go out of round. Also, you should install a torque plate or head while it sets up.

[SSDiv6]

Originally Posted by SSGT Mustang

I've always been told by various engine builders that you Hardblock before honing because the cylinders will go out of round. Also, you should install a torque plate or head while it sets up.

Correct. In lieu of Hardblock, I prefer Embecco 885 structural resin.

[MAURICE BLENDHEIM]

We HardBlok before any machine work, and install cylinder head as it's setting up. There has been occasions where we have filled engines that have already been machined with no problems (finish hone with torque plate). HardBlok is designed specifically and has the same expansion and contraction rates as cast iron. I've used other compounds that lose adhesion between the casting walls. This allows coolant to form rust and it puts pressure on cylinder walls as it grows to the point of eliminating clearance in areas of the bores. Had a case (in the 80's) where the cam tunnel became distorted and tore up the cam and bearings. We have been using HardBlok near 30 years with no problems. With a buddy helping, a soupy mix, a funnel, a series of coat hanger tools and a decent size dead blow hammer striking the block to assist on levelling the compound through out and a level engine stand (deck up) your set. Chase head bolt threads in block before you start. Have your cylinder head, gasket and bolts ready to install. Allow 24-36 hours per side with head in place for best setup results. Hope this helps…MB.

[SSDiv6]

Not trying to get in to an argument, nevertheless, I can't see how can Hard Blok have the same thermal expansion as gray cast iron.

The expansion rates of aggregates and gray cast iron are very different. Also, Hard Blok does not contain cast iron in its composition.

Although dangerous to use, Methylene Chloride will dissolve Hard Blok.

Below is another past discussion on the subject:

http://classracer.com/classforum/showthread.php?t=14045

[randy wilson]

We've had this discussion before at least 2 times. My thoughts, for what it's worth is I would never fill a block. And I've filled 5 or 6 before. I never gave it much thought until a very experienced engine builder showed me after my first teardown how much chatter the honing stones had. Well, I told him the next time it would settle down and hone smoothly. Wrong! It was worse. So we did an identical 283 block with just deck plugs, and no chatter after 4 rebuilds. Just my experience. I would not fill any block. Get an aftermarket block, or get a good stock block and use deck plugs, and no filler. Bowtie or after market preferred.