Gearhead68z

I figure it's time to switch to a bbc. I'd like about 10:1, Dart 9.8 Big M,brodix 2xtra heads, and so on. My first question is how many ci can you get out of the 9.8 deck dart. I'd like a 598 4.5x4.6 with a 6.535+ rod, and flat top pistons, is that possible with the 9.8 deck?

Pwmax

588 is about the biggest from a 9.8 deck. Thats a 4.375 crank, and a 4.625 bore.

Frank
Advanced performance
www.get-ap.com

russ67chevelle

if i was u,id keep in mind that with a lot of chevy crossmembers,getting a tall deck in is a pain in da rear!!!if not impossible.if you have a tube chassis car then crossmember doesnt apply!!!BONUS!!! but lots of 540 shot block kits out there if your on a budget!short block 540 start at about 3300 unassembled and go up from there.

OneBadGMC

Can you explain this a little better? The block, to my knowledge, only changes ABOVE the water pump inlet.

Frame cross members below the motor are unaffected to my knowledge.

Maybe I'm missing something?

curtisreed

I think he means you can't drop the motor to provide clearance above.

Curtis

hammertime

If you want to go big build a 582 4.375 x 4.600 Either way you dont have enough head IMO so a smaller motor might be a better option 4.25 x4.560 to make a 555.

russ67chevelle

4.375 is probably about the biggest arm youd wann put in a short deck.thats why the next size larger(4.5 inch stroke)is used in tall decks.ive heard that 4.5"oil pan fitments in stock bodied cars can be a pain.friend has 66 chevelle and he said his 572 tall deck was a beiotch to install with oil pan to crossmember issues.thats all.i agree 540 is a good combo.

joe sherman put a pump gas 540 together and got 752 torque and 829 horsepower at 6500 rpms with the 315 cnc afr heads.

sc3314

For a larger C/I motor in a 9.80 deck the stroke and rod are the problem. 4.375 on the crank and 4.385 on the rod. The bore doesn't matter, but why would you MAX the bore out in a new block. If you have a problem, you will not only be buying parts. But also a new block, or you will be putting sleeves in. As hammer said, the heads will be a problem above a 572 C/I

The problem is in the oil pan with larger C/I motors in a stock front stub. With the larger stroke and rod, you can no longer run a standard rear sump pan. If you are taking that step up to a larger C/I BBC Have the front stub done by a good chassis builder.

The front cross member has to be done, plate it, and change the steering box over to a rack. You may also be changing the front springs. Then the next issue you will have is headers if you go with a T/D So, YES C/I does cost $$$$ in more ways than just building a motor!

Good luck