Future build option brainstorming: current combo is a .040 over 400 - 451. Turned factory crank, 6.76 rods & Icon 1.322 ht pistons. CNC’d stealth heads.

Looking at the future with my 400 block, and a 512 kit would be my preference, but my block has been decked slightly and mainline honed, so I believe the deck ht to be 9.960. The 440 source kit puts the piston right at 9.98. So what are the issues with running .020 above deck? Obviously head gasket choice becomes paramount, clear of the bore and thick enough to keep the pistons off the head. What issues are there beside that?

2nd option is the 500 kit, this combo would keep the piston within the hole, but I want longevity, and I’m not crazy about the short piston ht and oil ring support rails in this combo. Weigh in on those issues if you have input.

Lastly, I could get a set of 6.700 BBC rods, use my existing slugs and turn my crank to 3.875 and land at zero deck for approx. 470 cubes. This would perhaps save me a little money that I could put elsewhere, but probably not much. Also, both of the source kits are available @ .042 over, so I could hone to those pistons from where I’m at now. Current bore is in good shape, but I can’t help but think if you’re going to rebuild, you might as well have new slugs and such.

Goal is approx. 650 hp, or whatever I need to put my B-body into the low-mid 10’s. Thanks for your thoughts.

I've done that with open chamber heads.

You do lose a bit of valve-piston clearance.

Machining .020" from the top of the piston is quick and easy.

If you use the proper thickness head, gasket the piston to head remains correct. As does the piston to valve. If it’s .020” out of the block, run a .060” gasket. No machining necessary. A .060” gasket will be pricey. You’ll need Cometics or something similar. If you chose to run a open chamber head the entire chamber has to be equal or greater to the bore size. And in this case piston to valve would be closer. In most cases quench depth would still be to great to be of any help.
Doug

you can get cometic head gaskets as thick as .100 and as thin as .020.

My choice would be a 4.25 stroke, 6.535 rod, piston set up for Max compression you are willing to run. Cubes and compression are very effective in upping the hp potential of your build . .043 top and second rings, gas ports, don't worry about rod length or piston pins height being her n the rings. Check to see if it is possible to cut the closed side of the piston only. That will create a bit more compression and cost about as much as a thick cometic gasket, or less. Watch out for valve to piston clearance, or the need to add some.
If you are going to spend money to build a good motor, why not build it to make an extra 75 to 100 hp by employing all the changes you can that add power? A b body isn't light. Build the 512. Use narrow rings. They work, and live. What heads do you plan to use?

Have you tried the M1 intake yet or consider a bigger cam. Just tossing ideas around to take advantage of the combo you have currently

In addition, check out Line2Line coatings. If you rebuild in the future, you can coat the piston skirts to build them back up to desired size. I had a 550 cube bigblock set of pistons done to take up . 0043 that the bores grew from rehones, scratch cleanup. This was a high end build, made 926 hp. L2L says the coating is applied about . 0025 thicker than needed, and wears in during a breaking procedure they lay out. They can coat pistons to . 020 oversize! Which means you can reuse your current block many times.
The coating cost me $300.

My 440 source 400 512 is .016 out of the hole, I run a .052 head gasket, been that way for over 11k miles

I never did get it installed last year. It’ll be on the car in ‘22 though. I was going to do a quick refresh and add more camshaft; I contacted Hughes to talk about cam selection. Their advice was that I didn’t have enough cylinder pressure to take advantage of more camshaft. Static compression currently sits at 10.7:1, but cylinder pressure is only at 155. Does that seem low to you guys? It is pretty even across the board with a low of 150 and a high of 158. This, along with the reality that it is 12 years old now and was originally built as a street / strip effort has me looking at more race-specific build options for the future.

The heads will continue to be the CNC Stealths for the purpose of this conversation. Carb is an annular 1000-4150.

I like this line of thinking. As said above, my CNC Stealths will have to do for the purposes of this discussion. But the obvious next step could be a set of real race heads at some point.

Regarding compression: I really like being able to run pump gas. I’ve been running non-ethanol 93 from a local street pump. The cost factor of race fuel, especially with the direction the price of gas is going is a reality that is hard to ignore. I think I
could go to 11.25 - maybe 11.5:1 with perhaps at least a mixture of mostly pump fuel. ?? I really don’t want to be roped into $14- / gallon fuel just to go bracket racing.

Since Greg asked about heads, What about option #4: refresh only (rings and bearings); and spend my money on heads instead. Would a good set of Indy SR’s or something similar on a flat-top 451 get me to my goal for a lot less $$? It also would allow me to utiluze my current gearing with less piston speed (??). Just thinking out loud here, I guess.

How much would you have to mill the heads to be able to bump the compression up some?

Maybe try and borrow a dominator carb along with the intake swap might show some results you are wanting.

Good luck on whatever you decide your combo has always been impressive to me

a 3.915 crank and a 6.7 chevy rod gets you a little more compression and you can use a 1.32ch piston (which you probably already have in your motor right?)
only thing with that is i think your piston will be also be above deck a bit since you milled you block already.

I think a 78cc combustion chamber will get you a little over 11:1 compression

How much e85 could a guy add to 93 pure gas comes to mind. If your carb can accept being jetted up 20 percent say, that may be as much as 1/3 e85 to 2/3 93, and would possibly allow a full point or more compression? All this is off the top of my head. You might get away with 40 percent e85. If it interests you as a possible way to go, research thoroughly.

Heavy car, pump gas compression?

Cubes are your friend.