Hello I have a question about my b18c1 block. The other day I had taken my block to the machine shop to have it checked over and they had said my block will need decked .015" to make the top surface flat again. My question is am I going to run into problems with piston to valve clearance, especially down the road if i decide to change to a hotter cam. I plan on running supertech 11.5.1 forged pistons, and eagle rods. I know there are Cometic headgaskets available that can take up the material that would be lost in the milling of the block but again I've researched and they dont always have the best results, I would rather run an OEM. Any advice would be great I am just undecided on what I should do.

 

I think this is the best advice possible:

If it needs to be decked, it is a definite need. No avoiding that unless you have another block that doesn't need it. But here is where the advice starts. When you get it back, clay the block>>head and measure your p2v clearance personally. Write this info down because you will need the p2v clearances later when considering upgrades.

You can use the b-series compression calculator to ESTIMATE the change in p2deck (which is also directly related to p2valve). But nothing is better than using a little clay while you have the motor apart.

 

Thank you for the input i did some calculation and came up with this. If the deck was milled .015" .381mm off and the stock headgasket on a gsr is .026" .6604mm. The stock Gsr block deck height is 212.39 mm or 8.362", I would need a .041" (1.0414mm) headgasket or greater to keep the stock piston to valve clearance. And the stock piston to deck height on a usdm b18c1 is .838MM or .033". So maybe I shall buy a thicker headgasket. I just wanted to hear some input from others. Also I know the rods will stretch under heavy load....9000 rpm, as well as the bearings wearing and lessoning the clearance between valves and pistons these all could pose problems down the road. Also compression ratios are increased as you take material off the block. Correct me if im wrong but these are the numbers i came up with.

 

Just make sure you don't put all your faith in the calculator. After they mill the block, clay the p2v and measure it for yourself (without the headgasket installed). If you still have clearance without the headgasket installed, then you can count on extra clearance with the headgasket installed. As for using different pistons, make sure you keep all this data, and use can estimate clearances (etc) using this data. But again, make sure to clay it before you crank it after the piston upgrades.

 

are you sure he said .015 or .0015"

 

Yeah .015" is a lot. Regardless you can run a thicker cosmetic gasket, they are fine despite the myths.

 

Thank you everyone for the info. I will clay and check the clearance.

 

for a daily driver on pump gas would you guys recommend 12.1 pistons or 11.5.1 pistons?

 

Honda blocks RARELY, need decking. Its a good pratice to resurface the head everytime it is removed, but very..very rarely do honda blocks need to be straighten or decked.