Hello guys, I found this hex plug inside my block on the back left corner. My old block did not have this plug. This is a css b18c1 block that I got used..I had a machine shop look over it and they said it's good. My old block is a jdm b18c but I'm not sure if that makes a difference. Should.i leave the plug in there or remove it? Does anyone know what it is for?

 

this is just my thoughts on it so dont take my word for it, but perhaps that was to plug the vtec oil feed because someone decided to go with an external oil feed for vtec or perhaps they had the cams locked for vtec killer cams and removed the vtec solenoid so oil supply was not needed any more. one other crazy idea is that they had a none vtec head on the block. im not even 100% sure that that is the vtec oil supply port or not.

 

Thanks those are good ideas. I will just remove it because my other block did not have it. Also this block has the oil squirt block off but idk if this has anything to do with that.

 

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Like I said I wasn't sure if I was right just sharing my thoughts, not facts

 

After some research it IS infact the vtec oil supply.
Please do some research yourself if you still don't agree

 

B20 block

GSR block

Vtec head plugged for an ls vtec conversion

 

The main reason why I'm confused is that my current block B18C does not have that plug and it seems the threads were made by someone and it's not factory. They are both Gsr blocks. Maybe the last owner used an external vtec line I guess. If anything I'll just have to pull the head off again. I will just run it how my old block looks. Thanks for the help guys.

 

That is not an original hole/plug. Someone drilled the hole and plugged it. I suggest you leave the plug in the hole. The teardrop shaped hole that you have circled IS the VTEC oil passage that meets the inlet port in the head.

 

The plug was In the tear drop hole. Thanks for confirming that it's for the vtec.

 

Oh, my bad. I thought there was a threaded hole directly under where the plug is sitting on the block surface now. The first pic appears to show the plug sitting flush with the top of the block... optical illusion.

 

Yeah, one might plug this hole on a VTEC block when using a non-VTEC cylinder head on top... otherwise you have a really bad pressurized oil leak.

 

So I can just hope my vtec works and I have normal oil pressure lol. Good thing my other block is still good. Just incase

 

you need oil line to your head if you block this off. with vtec or no vtec, still need oil pressure to the head.

 

That oil passage only exists on vtec blocks and is the reason why you have to run an external like when going LS/b20 vtec

 

Yes OP, as bigjon just stated, the passage that was blocked off in your block is only for the VTEC rocker arm circuit and thus doesn't exist in a non-VTEC block. Oil for lubricating the head comes through the passage directly behind the middle head bolt hole on the Intake side of the block... you can see it above in the GSR block picture... it has an aluminum restrictor with an O-ring on it. It (the restrictor) is missing on the B20 block pictured above.