I recently purchased a NOS 428 SCJ block still in the factory crate to replace the 390 in my 67 FB Mustang.(Not many left these days)
Unfortunately the sonic tests showed thin cylinder walls on #s 5, 7 & 8 at 90 degrees to the thrust face of the bore. The measurements are .085/.090/ .095 / " respectively. There appears to have been some minor core shift on the left bank during casting.
I have heard that Drag racers used to brace the cylinder walls using some type of cement or epoxy.
Does anyone know of this technique &/or the material used for bracing or any other way to strengthen the cylinder walls?
Any help would be appreciated, I don't want to have to scrap this block.
The intention is to build a 455 cid stroker producing around 530 HP so I need to be sure of the cylinder wall strength

......is what they call this engine filler. It's some sort of hardening non shrinking cement that you pour into your water jackets while the block is flipped on the stand.
Your cooling will dramatically suffer and your engine won't be streetable anymore. I have no experience w. hard block, so someone else might give you more on this.
BTW. The MEL 430 cid 300 HP 10,1 : 1 compr. engine rec. 0,170" min. cilynder wall thickness in its' shop manual. Sorry to hear your NOS block suffers from core shift.
Good luck

Thanks for the info. Have checked it out & it looks like it is just what is needed. The bonus is that because I only need to stabilize the bores at 90 degrees to the thrust face we will be able to use a much smaller amount than recomended thus negating the over heating issues & making the engine Stretable.
If this works I will post the results for any others with a similar problem.
The Engineer building my motor has worked for Ford Special Vehicles and on F1 engines, so if he can't make it work then probably no-one can
regards
David

what is the composition of hardblock, and how long will it last? Also, if it is a "cementitious mix", what keeps particles from getting loose and being deposited "elsewhere" in the cooling system?

(hey Theo, how ya doing guy, got any more car show pics?)

Mr. P

....Hi P,
I didn't know you're back from I##k;...He He just kidding
I got all these pics from the street races and car shows, but I'm mostly too busy and too exhausted to get them stuffed into web-albums late at night. I'm currently working on a web photo album that shows my musical gear (guit. and amps). Things go slowly since school keeps me busy 10 hours a day. That will go on for a year and in the end I'll hopefully be able to do fantastic things on screen, sound & video. The weird thing is that I need to buy me a HP MAC which I hate and can't afford right now.
I think the hard block is a solution that's only good for hopeless cases. Like you I don't trust stuff like that.
It got quite here. Probably the summer season.....
Good to see you around

From the reseach I have done it is hard to tell exactly what the composition of Hardblok really is. However if it is a true cement it will probably outlast the block itself.
Once it sets nothing will come loose, the iron filler will be locked into the cement matrix much like the pigment in paint when it drys.
Unlike paint cement sets by a chemical reaction making it very stable and long lived. The main concern is whether the manufacturer had got the co-efficient of expansion right to match that of the block

regards

David

I had a "1/2 fill" done on it just for cylinder strength. The motor is pushing 540-550 hp now so I was starting to get worried. Also, my last motor developed a cracked cylinder wall so I am gun shy. I think the last motor was bored way too far though.

Anyhoo, my machinist assured me the motor would cool okay with Hard Blok. He actually tried to talk me into getting a "full fill". I chickened out and went with just the half fill. Well, I broke in the motor yesterday. It is in the car and the car was in my friends garage. It was probably 80-82F outside. With the motor at various rpms from 700-2000 for 20 minutes it stayed cool the whole time. Max temp was 175F

So far I am liking the Hard Blok. Have to see how the car drives around town, but I don't foresee any problems. Sitting in a garage is like sitting in traffic, plus a new motor tends to run hotter anyway.

Paul

Good to hear about your success. I'M very curious about how the hard block works out in traffic situations. It's not that I'm waiting to see that it will overheat; if it works out o.K. that would be new and sensationally great news. Keep us updated Paul

I have a 428CJ that's bored .060 (439CI) and makes 540 hp in my drag car (67 Mustang). I've use the standard big block radiator with no heating problems and no cyl problems for the last 4 years. Most of your heat is in the top of the motor (Heads and cumbustion chambers). If you hardfill the bock to the bottom of the water pump holes, it shouldn't cause overheating problems. Also, make sure not to get air pockets. I would hardfill it before boring the cylinders.

67 428CJ Mustang Coupe Super Pro/Hot Rod Drag Car
67 289 Mustang Fastback
68 390/GT Mustang Fastback
92 F150 p/u TRK
2002 BMW 3.0i Z3 Roadster

HEY !
Thanks for that info. I have a 428 (390, .080 over) that is filled to the bottom of the pump inlet holes. It will be race only but I havent fired it up yet. I was worried about overheating, but your info, eases my mind a bit ,Thanx

Thanks to all who responded to my query.
After much research we have decided to do a 1 inch block fill using the Moroso block filler. The calculations show that it will give the needed strength without any overheating probs.
The reason for using the Moroso product is that it has better rheology, hence making it easier to pour & less chance of getting air pockets, otherwise Hardblok would have been the choice. When they are set the 2 products seem to be the same.
I will post the results after the motor is built & running

Regards

David