Question on Ford 3.4" '363' Crankshaft

[n2omike]

Several years ago, I started piecing together my 363. There were limited internally balanced 'over the counter' cranks available, and I got the 4340 Scat. It is a 28 oz-in crank, but I had lighter weight Oliver rods and light Mahle pistons. I noticed on a lot of cranks, that from the side, you could see daylight through the rod throws... so I took a drill to mine, and cheating to the outside a bit, drilled I believe a 3/4" hole through them. I didn't hit any oil holes, and all seems good. My machinist thought it wasn't a bad idea to drill the holes. He still needed to install a few pieces of Mallory, but it all neutral balanced out just fine.

Here's my question... With the Dart Sportsman block, Oliver rods and Mahle pistons, is the crank the weak link? Did I weaken it? The engine will see around 7500 rpm every time it comes out of the garage... and at the track will likely get hit with the same 200 hp nitrous plate that was on the 306. Total power on the bottle, close to 800.

Is the crank a weak link? What all is available now? I'm just getting ready to start putting it together, and want to make sure there aren't any issues before I get started... so figured I'd run it past you guys!

Thanks!

[Flatheadpopup]

Hey Mike, I'm not sure if drilling the crank weakened it or not--someone much more experienced than me would have to answer that. When I had my 363 built we used a RPM brand crank (I believe that Lunati and several others also sell this crank). Anyways, it is forged and meant for neutral balance so no heavy metal was needed. If you decide to swap cranks out it would be worth a look.

[Racer71]

I had a Bryant 3.43 billet that had the throws drilled like that. Mine was a 366” and routinely turned 9700 no issues. Not so sure on the scat piece though

[Walter R. Malik]

Several years ago, I started piecing together my 363. There were limited internally balanced 'over the counter' cranks available, and I got the 4340 Scat. It is a 28 oz-in crank, but I had lighter weight Oliver rods and light Mahle pistons. I noticed on a lot of cranks, that from the side, you could see daylight through the rod throws... so I took a drill to mine, and cheating to the outside a bit, drilled I believe a 3/4" hole through them. I didn't hit any oil holes, and all seems good. My machinist thought it wasn't a bad idea to drill the holes. He still needed to install a few pieces of Mallory, but it all neutral balanced out just fine.

Here's my question... With the Dart Sportsman block, Oliver rods and Mahle pistons, is the crank the weak link? Did I weaken it? The engine will see around 7500 rpm every time it comes out of the garage... and at the track will likely get hit with the same 200 hp nitrous plate that was on the 306. Total power on the bottle, close to 800.

Is the crank a weak link? What all is available now? I'm just getting ready to start putting it together, and want to make sure there aren't any issues before I get started... so figured I'd run it past you guys!

Thanks!

As long as the throw surfaces and fillets are at least .250" thick everywhere; you should have no strength issues.

[n2omike]

As long as the throw surfaces and fillets are at least .250" thick everywhere; you should have no strength issues.

Thanks Guys! I hope it's 0.250" thick everywhere. No way to really tell. lol
Was looking at the packing slips, and I bought most of this stuff 10 years ago! About the only choices at the time were Eagle and Scat... unless you went with something that was mega bucks. The Scat was the preferred part at the time. The rods are Oliver Ultralights. They're lighter than the standard 'lightweights', but still have top quality 7/16" bolts and the Mahle flat tops are their 4032 units, which should be fine for a small shot of nitrous. I'll study the oiling holes, and see if I can see any weak/thin points. If no problems are evident, I guess it's in she goes.

This will be my first time with an aluminum flywheel... so the lightweight rotating assembly along with the lighter flywheel will be a new experience! Hopefully, the car works as well as it did with the old combo... else, another steel flywheel might get called into action.