So I got bored rocking my son to sleep last night and remembered the Nailhead crank destroker 455 and thought about making a BBB crank nailhead stroker. Here's what I came up with: '64 425 block bored 0.030in over to 4.323in (can go less if need be, it's just a handy refference), decked 0.020in 400/430/455 Crank with the mains ground down to the Nailhead 2.75in journals Stock 425 6.220in rods and pins Custom hybrid pistons, really a 455 forging with a 28cc dome on it instead of the -14cc valve reliefs That will give me a 457 Nailhead with the only custom work being the mains of the crank and the pistons. The other idea is to use 6.10in 364 rods and shave the domes on the pistons a bit to reduce the compression back down into street gas levels. The pins are the same, the rod journals are the same, and the thrust bearing is the same location. Balancers interchange and the flexplate would still be TH400 compatable assuming the flange is the same thickness as the Nailhead. I guess that could be a complication since the nailhead converter is burried in the block. I've read a lot of the nailhead stroker threads and the stuff about how the heads will only support a 364ci engine why add more... This isn't a race engine, its something that will live on the street and more displacement is more torque and that's cool. More torque means taller rear gears which of course means less dependence on OD for freeway speeds. Considering I've got a 425 complete and getting a 455 crank isn't the hardest thing in the world this might be something to try. The big hickup I can see is the oil pan which barely clears the existing stroke and if the 0.26in longer stroke fits between the pan rails and under the cam.
Wow! Sounds great. You could always make a spacer ring for the oil pan and add a spacer to the oil pickup. The cam would be the big hang up. I don't know how much clearance is left in a standard engine. I should get off my duff and clean the mess off my nailhead in the garage and measure it for ya. I bet someone on here knows the answer though.
Some pics on the spacer, issue will be the oil galley clearance and putting a spacer under the oil pump means extending the oil pump drive shaft and the angle changes because of this, nothing is impossible, external oil pump might be a simpler (but expensive) solution. Also cross member on the vehicle will probably need to be shaved for the increased pan depth.. Been fighting this animal (due to big aluminum rods) for awhile now, all problems solved, but it is amazing how 1 change causes so many engineering challenges. PS I do have a new 455 crank, never used, still in the box from GM. I guess I need to look at it, didn't think it could be cut down that far without structural integrity problems Roger http://www.youtube.com/watch?v=pTCnNNA_02s
I'd never heard of the cranks interchanging, I would of thought the architeture of the engines would be too different. One thing that popped right into my mind is, will the Nailhead ports support the airflow that displacement would want? Aren't they already a bit cramped for a 425? I really don't know jack about Nailheads though.
Yes, I am with you on this one. It would be cool as hell to build a Nailhead stroker, but why? I'd rather spend the thousands you'd have in a stroker setup on heads and some sort of forced induction.
I realized this.... please read below With the 364 rods it looks like I'd be out the cost of grinding the crank and the machine costs of cutting the domes down on the stock replacement pistons (if I don't have my own mill by then). Figure ~$750 in machine work and ~$300 in new parts on top of everything I already need for a stock rebuild. I don't want more RPM and I'm not going for a drag machine, I have a Turbo6 for that type of stuff. If it will only rev to 5500rpm before falling on its face... fine. Riv1964, what's the distance between the rails on a nailhead? Should be about the size of the distance between the rails on your spacer if it's still off the motor. I've not had the pan off of my nailhead so I don't know how the oil pump is mounted (i.e. canted or straight like an SBC) but I'd probably get another pickup and cut and splice the pickup tube vs trying to space the pump out unless its in the way of a counterweight. After that it's just what is the max component diameter on a 455 and what is the crank to cam centerline distance.
I get what your saying, it just seems a little couter-productive to me. Burton Machine (Justa350) was offering single turbo kits for the 350 for $1295 plus shipping. Mark was interested in possibly doing a kit for the 'Nail - I'm sure you'd see more gains in doing something like that (both horsepower and torque wise) even at something mild like 4 or 5 pounds of boost. I'm just saying, but then again I don't even listen to myself :laugh: . Like I said, a stroker 'Nail would be one bad ass motor.
Just do a turbo stroker nailhead :laugh: as for the oil pan...can you just cut the bottom section off and weld in a larger bottom? Ive known people to knotch a pan and weld a piece in to clear frames and what not...why not just cut off the bottom and add more metel to extend it nake slipped my mind reynolds..on here? he extends oil pans for the 350 and i believe for the 455 also
just install turbos or a huffer and a sticker on the rocker arm covers that says 602 cu. in. :Brow: :Brow: :laugh: :laugh:
CTX-SLPR About 8 5/8 at the front, 9" at the rear, and yes, most likely the oil pump would be in the way of the rod in a stroker engine, I set the rails at a constant 8 5/8th " for the oil scraping screen
If you go the whole stroker/turbo route, what say you about getting a reverse patterned cam to swap the intake and exhaust ports? Put the turbo in the lifter valley like an industrial engine! Ok, I'll be quiet now. Where I've seen the idea:
Thought of that before, even had ideas for cheap ways to mount stuff and EFI it. Still thinking of my stroker nailhead though...
i remember that car from back then and it was nothing but trouble,,, couldnt get it to run right and finally gave up on it..... You would be far better off to just put modern stuff on it... like efi or turbos or both.... or even a Jimmy blower... or paxton blower... with a good porting job...less hassel....:Smarty: :Smarty:
