Jamming in a big block?

I have done this, and some choices will make it easier than others. First, the low deck 400 block is the only way to go because it will handle 150 to 200 more hp before it breaks, at about the 850 level after some use. Go with heads that have a stock port location on the exhaust to help with header clearance. fenderwell headers reduce steering turning radius too much for my taste. That is my reason for pushing the low deck/low port head combo, to gain the most clearance for headers. With the first set of headers I built I had to back up every time I got forced into the near lane at one track, couldn't make the turn. My solution was to cut out the floor pan behind the front wheels so I could move the pipes back for clearance, then weld in sheetmetal to box in the area by the tubes. That made for a nice foot rest! Once you get all the light weight parts on a 400 stroker, and move the battery to the back, your front/rear weight distribution will be acceptable, depending on tire size (slicks) and suspension. To help out starting line traction, gear it a little taller than you think it will need. If your expected trap rpm is above the shift point, drop to the next ratio, like from 4.56 down to 4.30 or 4.10. A torqueflite has the 2.45 low gear and with the torque of a big block it is extremely hard to hook if you build some serious torque into the motor. With the cost of strokers being about the same for different sizes, don't mess around, go with a 4.25 stroke and 4.375 bore for 512 cubes and be done with it. build the short block with a gas ported zero deck flat top, and you can run the Indy low exhaust port Max wedge port size EZ heads, and make 700 to 800 hp without breaking a sweat. The heads can be cut enough to make 13/1 compression with the flat tops, just be sure and have at least .040 piston to head clearance. If you want a solid 800 hp recipe, drop me a pm, and I will go over it with you.


Thank you very much for great info!

One thing we thought of for header clearance issues. Totally customized from heads and design so collectors are actually up much higher/sooner than what you would normally see. (So it would be about level of top short block .... snake each tube to there where fender well cuts are). This way we've only got single exhaust tubes running down by tires. Currently have only 24" tires. May go to 26

Of course I imagine there's the argument of flow and ratios of primaries. But .... we're not looking at squeezing every ounce out either.

If our idea sucks or doesn't work ...lol....I like your idea of modifying the floor pan.

I'm a bit impatient lol. We've already got a 383 block at machine shop getting .030 over and work done. The final displacement will only be 421. I forget stroke. (Away on work trip for month so not able visit the shop ). Our buddy/engine builder (racer himself) wanted to keep closer stroke/displacement ratio so we can spin her up 8k he's thinking.

When get home or ahold of him I'll Get build specs on rotating assembly etc

Here's overview of what we spoke of on quick call:
383 stroked to 431, Ross pistons, H beam rods, Scat 4340 crank, Trick Flow heads, Harland rocker arms, custom Bullet cam, solid roller, Melling oil pump, and Edelbrock Pro-Flo XT intake.

To finish off: Meziere relocated (radiator mounted) water pump, 170 amp Mechman alternator, and Fuel Tech 5.0 EFI (rail). Also will take look at trans (refresh prob) and install JW ultra bell SFI on trans.

Battery already in trunk with new fuel cell and I totally rewired her. Using Speedwire relay and switch panels.

Thanks again for help!