Yep, Mavman's 408 is concreted, as is the 302 in the Stang. These are strictly race engines and help retain the bore concentric's and strengthen the whole block itself. Water flowing to the heads and intake only(and approx. 1inch of the upper block) will still cool enough for racing. Blocks that are to be bored to the max, benefit the most. There is a factor of added weight, but reliability and longevity, outweighs this. The block "must be filled" before being bored, the cylinders will be distorted a few thousandth's, when it dries. Did my 347 for next year too. The process of filling is a bit tricky but can be done by anyone who can turn a wrench, so to speak. If you would like details on the procedure, maybe Mavman will jump in and explain it for you. I think it is a great way to prolong the inevitable destruction, and many other advantages, of a full race engine.
i think hard blok claims can be used after machining of cyls is done, but dont know for a fact. obviously track only, you need either a killer cooling system or to run alcohol. most that i've seen are filled to the bottom of the water pump openings, or 1/2" below them. allows coolant around the heads and intake.
I did it to every Cleveland engine I've built. Couple of late model 302 roller blocks also. Works fine for race cars or limited street use cars with excellent cooling systems. Torque the mains, level the block front-rear and side-side. Fill to the bottom of the water pump opening. Use an air hammer with a blunt chisel to "tap" the block. This relieves any trapped air in the filler material. Once you're satisfied that all the air bubbles are out then install a cylinder head and torque it down. Go drink beer. Go to bed. Go to work the next day. Come home. Repeat process for other side of the block. Like I said...if it's a race car or limited use street car w/killer cooling system then I'd do it in a minute. The added block stability and ring seal are worth it.
Just for info, youngest son had a .060 302 to put in his Mustang drag car. Decided to fill the block on his own, leveled it on the stand and filled and purged air correctly. Looked great, installed a set of KB pistons on Eagle I beam rods. Lot's of drag when rotating but decided it was OK. Wrong, third pass on the engine and she began to seize up. Pulled it out and found some badly scored pistons, I honed on it for him to get the bore's round and straight again, another new set of KB's, and she runs 1.52 60's and 7.10 1/8th mile. That was two years ago and on a recent teardown to freshen it up, found no scoring and bearings were like new. What is amazing is the fact that the bore's were honed .007 clearance to get them rd. and straight. Not sure a decent set of light weight pistons could have withstood the 7 to 8000 rpm burnout's all day long. Fill and bore&hone, is my advice to doing it right. As an added note, I alway's tape half way up the water inlet hole's, and fill that much more. Does not seem to affect the cooling any, and IMO, gives a little extra strength, higher on the cylinders. Never did torque the main caps or use a head while drying because always had the block line honed and decked anyway. Does make me think it is a good idea though, for lot's of reasons. Never too old to learn new way's to improve performance.
very good info , in the future i want to build some sorta stroker , prolly 393 or 408 since my car is already set up for a windsor. ive been wondering about stuff like hard blok. Is pinky getting a 408 in the near future?
About filling...if/when you decide to do it: Level it front to back and level one bank (cylinders should be straight up & down and the deck should be level). You will fill one bank at a time. I do believe hard blok will probably work after it's been machined, but I don't trust it...I'd rather pour it first, let it set a week or so and then machine it. Ideally, you'd want to either bolt a head to the block during the set period or use a torque plate...but it isn't totally necessary and I have never done it. I have, however, torqued the mains down before pouring. I also like to have nice clean water jackets before pouring...which means vatting the block and/or acid treating it the water passages. Now, on the 351w block if you look closely at the water holes in the deck, the casting protrudes downward into the water jacket about an inch or so. If it wasn't for that you could easily fill it higher than normal. I used a piece of duct tape to tape half of the WP hole and fill to the halfway point, no more. As you're pouring, it's a good idea to use a hammer and smack the sides of the block and the inside of the valley to help settle the "concrete" and aid in removing air bubbles. I always like to mix the stuff pretty wet so it pours easily and air will displace more readily. On a 351w block, you'll need a little more than 1 1/2 buckets of hard block, IIRC. Either way, get 2 buckets of it. After doing both sides, itd probably also be a good idea to have the block line honed...but again, not totally necessary unless you're nitpicking and after every last 1/4 horsepower. For me, it was just a bracket engine....if it makes 5 hp less than everyone else, so what. It does what it's supposed to (zerox timelips) and that's all I care. If you're driving on the street...hardblok is NOT for you. Yes, it will overheat. Especially if you're making a long run down the freeway at extended periods of RPM...like...say with a C4 trans turning 3200 RPM for an hour. Also, even with an alcohol engine like mine, you have to watch oil temps....and this gets tricky with alky on a cool day...oil temps can climb and your water temp gauge will stay at 140 degrees. There is no water in the bottom half of the block to help cool the oil and concrete will tend to get hot & stay hot...and won't readily cool off even circulating coolant through the engine it takes FOREVER to cool a concreted block. The heads, intake may be less than 100 degrees but the bottom of the engine can still be 200+ easily...I like to use a little squirrel cage fan to blow air across the oil pan when I'm hotlapping in the final rounds. Helps cool the pan a little=more consistent ET. The Mustang...it's still on gas and in the summer heat, it can be challenging to keep the motor cool. After a run it can sometimes be over 210 and after driving back to the pits, sometimes 220 or more. Thats with a GOOD griffin radiator, aluminum heads & intake and electric water pump. Later rounds are even worse. But, it has been proven that ring seal is good and overall block rigidity seems to be better with hardblok in the jackets. You can literally hear the differenc when boring the block....a regular wet block will have a distinct ring whereas a concreted block will sound very solid.
