>I am considering building a Clevor stroker.Dart 9.5 deck block, around 408-418 CI in displacement.
Built a two bolt girdled Windsor 408 (4” by 4”) with A3 heads, and am now building a Dart based 427 that is 4 1/8’ bore by 4” stroke, with a set of Brodix BF301 heads (essentially same head a C302B series of SVO heads with enough meat to port however you’d like).
>Who would the list members reccomend to build >and deliver a turn key, properly broken-in dynoed motor?
There are a bunch that could do this and I’d suggest you merely select reputable builder in close proximity to where you live.
>Who in your opinion could deliver this package with a dialed in EFI package?
I’d suggest Dennis Quella at Pantera Performance in Colorado, especiallly if you want an independent runner EFI. He’s done a bunch of them.
>What issues do I need to be aware of with regards to valve train geometry, durability, >etc?
Valve train geometry and cam selection are a long discussion. Since you're looking to have the engine professionally built, I’d suggest you describe the torque/rpm/power range you desire, select an appropriate set of heads, have them flowed, and let the engine builder choose the appropriate grind and geometry. As for durability....depends upon usage and who built it. Many will tell you a 408 will go through rings. It’s true compared to a stock engine. How many miles a year do you put on your car and how hard do you drive? I’d say for 90% of the street drivers, this isn’t much of a concern unless you put a lot of miles on your car per year and are looking for longevity not necessarily torque/performance. For my money, they’re plenty reliable and pull like a train.
>What issues will I need to be aware of with regards to coolant flow?
More displacement and power = more heat. If you haven’t upgraded your cooling system, I’d figure on doing so. If you never drive in traffic and are always at speed, it may not be necessary depending upon what you have.
>What issues exist with this combination with regards to header/accessory mounting and placement?
The 9.5” deck alone will require custom headers. Most any head you’d want to put on such an engine will have raised ports. Even if you stayed at 9.2, this would again require custom headers, so you may as well figure that into your cost as well. An appropriate intake will be the next issue. There are precious few that don’t require extensive mods and fab work to fit depending upon your head choice. I’m tooling up an IR IDA intake to help with that part, but that’s an even longer story. The coolant tube from the thermostat will need to be fabricated. Depending upon your intake and head combination, you may also have to remove the coolant from the front water jacket of your heads and remotely locate a thermostat before return to the pressure tank. You will also likely have to relocate your coolant tank because the #4 header primary will hit it on a tall deck raised port combination (mine did). If you want to have an air conditioner your old Cleveland bracket won’t work without mods and same with your alternator and idler. By the time you go tall deck and performance intake, don’t count on ever getting an air cleaner to fit under your engine screen. Quella has a low profile EFI that will. The other IR EFI set-ups will require you to notch your deck lid as required with Weber IDAs. Other than all this, no problem. At least the ZF and motor mounts bolt up!
>Please feel free to comment on other issues I have not thought of?
It’s sort of hard to say if a large displacement stroker is a good choice for you without knowing what you want out of it. If it’s a street car, it may be good choice. If it’s a Silver State or open track car where you’re looking for top end, you’re probably better off building an over square higher rpm engine. That is unless you want to spend the bucks to gear your ZF a lot taller, which the open track guys usually find necessary anyway. My car is a street car, has plenty of top end for me, and pulls very hard without having to wind it up tight. How fast do you need to go and where on the street can you make a habit out of living North of 150 mph?
If you are going with the Dart block, they still have a ¼” of wall at 4.185” and can be bored safely to 4.25”. You can get to 408 CI with much less stroke than 4” but this may bias the torque curve up into the rpm range for a given cam selection. Desk top dyno and other simulation software is useful for comparison sake but I wouldn’t necessarily bank on the predicted HP figures. Good luck, and start saving you $ now. -It'll take plenty. Good luck.
-Kelly
