Hardblock Question
 

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.

Re: Hardblock Question
 

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.

Re: Hardblock Question
 

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

Re: Hardblock Question
 

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.

Re: Hardblock Question
 

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

Re: Hardblock Question
 

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.

Re: Hardblock Question
 

I fill the blocks and let them sit at least a month with both heads and main caps torqued before boring, never an issue with honing, I use Halco machine grout.

Re: Hardblock Question
 

I had the same experience about cylinders going out of round, even after letting it dry for 30 days. .005 -.010 at the bottom of the bores. Car started smoking it was so bad!

Re: Hardblock Question
 

X2.Needs a month to cure correctly under stress of heads and mains torqued,also we put a 1/4 plastic tube in the water jacket to the drain plug ,after curing we pull the tube out and have draining access.Mostly use aftermarket blocks now.Bill C.

Re: Hardblock Question
 

I have never seen much of an issue with Hard Block. I did have a customer use one of the other brands and he had a heck of a time. Took a couple of freshen ups for that stuff to settle down :(
I am getting ready to fill a SB Mopar block, maybe I will do some measuring before and after and report back ?