What are advantages to using Block filler!

Looking at using block filler on my 71' 351C in my Torino. I should get it back from the machiner next week and have heard some pros and cons to filling the block. I went .030 over on the block and running KB flat tops with stock rods with 9:5 compression for NOS.

Other notables...
Weiand Intake
Comp High Energy Cam
Heads have been refeshed with mild porting
650 Holley DP
125 shot in the arm

This won't be strictly race, but I don't want to compromise my cooling capabilities filling the block. I actually have heard more pros based on overall added strenght and dampening.

Please advise!


Torino -The forgotten classic!!!

Its supposed to stiffen the block "which I question when it comes to the 351c block because of how the water ports sit " And it is supposed to dampen vibration. I question if you need to use it in your application, My next 351c will be a full Hardblock alcohol monster and I wont even consider that fer another 5 years- You SHOULD have the rotating assembly balanced-

I used hard block in my 408c. It helped eliminate cap walk and is supposed to enhance ring seal by keeping the cylinders from distorting. I noticed a little bit of a cooling issue, but nothing major. It just runs a like 5-10 degrees warmer than it used to. But I think the pro greatly outweigh the cons.

I filled my 351W this winter, but I will be running alky so won't need as much coolant, if any.

Did your machinist tell you to fill the block before boring? As the fill hardens it will push on the cylinder walls and distort. My block was at .030 before the fill, had to take it to .040 after.

Also, depending on the filler used it will take some time to set up. I used the Moroso and I think it's Ok to bore after a week or so, but I let mine set up a full month before machining.

I don't think you're going to need it. 351C's tend to split the cylinders with high rpm, 550-600hp outputs. If you aren't pushing that, then don't worry about it.

Block filling makes the engine heat up more slowly... and cool down more slowly, as there is more solid mass. It WILL also significantly raise oil temperatures! If you run a filled block on the street, or anywhere else where it will be run for very long periods of time, you need an oil cooler, and you need to run good synthetic oil, as synthetic is much more tolerant of high temps.

I filled my current 302 block, and have done a write-up about the process. Do an advanced search under my user name for 'hardblok'. (search function in the blue bar above where you username is displayed)

Good Luck!