Hi Guys. Im going back and forth on either a filled or dry block in my new comp coupe. My concerns/ questions are based on recycled info from the internet and books. My concerns: -Hot spots in a hollow block and heads. -Strength in the cylinder walls Some facts about the build: Late flathead Ford 4-1/4 stroke 3-5/16 piston 471 Blower Running on gasoline (I know alky is cooler maybe in the future) Steel heads This is obviously a compe***ion only car. Real world experience appreciated. If you run a filled block what product/ material did you use. Yes I have the blown flathead book. I humbly await your guidance. Thanks guys
I've never had a blown flathead engine, but all I've ever read about them includes the warnings about the crank support. Would filling the block even strengthen the mains in any way? You don't hear about cracking through cylinder walls or other weak block spots, just the main webs.
Since the exhaust ports snake through the water jackets and around the cylinders, it's hard to imagine any product you could stuff in there that wouldn't decompose and outgas in contact with them. I suppose you could pack it with steel shot or the like, but I'd probably just circulate some coolant through a can.
A friend of mine used to take his flathead race blocks to an aluminum foundry and have them poured mostly full. His dragster had a 180 crank, injected Nitro, ran in the 8's at nearly 160 !
I believe some use cement mix to fill a flathead. Read that in a couple of places but it still sounds weird. Ask Auliz from Finland.
My 296ci blown 8ba is grouted/semi filled but not heavily for street use. my engine builder explained he did it to eliminate core shift.
I'm not sure if it would help honestly. I have billet main caps to hopefully keep the crank one piece. Thanks for all the replies guys I appreciate it.
Rick Snell filled the engines for the Slider dragster with aluminum. It allowed him to cut the extra exhaust port in the top, and helped keep things together when the block started to come apart (The black strap in the front corner of the engine is holding that corner of the block together in this photo from 2010). Of course the Slider runs 50% to 60% nitro, and that has a completely different latent heat transfer profile than 100% gasoline. For a blown 100% gas motor, I would leave as much cylinder wall as possible (Flatheads have a ton of it to start with), run coolant, and focus on keeping the crank inside the oil pan with only 3 main bearings. I.E. Billet caps and Girdle.
Ive been reading about this product but alot of the info of course is from later model engines and only partially filled
Member @D_Lazaris has/had a fuel injected flathead called the "Antique Doll". But it doesn't look like he's been on here for the last year or so. He mentioned having the block filled with aluminum in his build thread. https://www.jalopyjournal.com/forum/threads/the-antique-doll-flathead-dragster.625706/ You might try PMing him to see if he can make any suggestions. In case you need any motivation . . .
Skot Ingram,Austin,Texas hot rodder runs some sort of “filled block” on alcohol. I sold him a French flathead block(I was the salesman for the French engines when they arrived in College Station,Tx around 1999-2000.) that I ported “right into the water jacket”——Skot replied,no problem, he was going to fill the block and use it and save it.French blocks are made of cast steel—-not cast iron and are 30 pounds heavier than a Henry block. Flatheads Forever!!
Same here TMK, did a 2.5" fill of Hard Block mixed with iron filings - been in there for years on a 290 cube blown street flathead. Did this mod along with all 3 caps being aftermarket billet steel with ARP studs. The fill was'nt so much for improving pan rail strength (hopefully it did) but for low cylinder stability/rigidity as from what I have found, the lower cyls are thinner than they are at the middle or top of the bore. Zero cooling or engine issues.
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