How to Build a B20 VTEC Part 6: Head Prep
Let’s shift focus to the head now that the block’s ready to go. Like mentioned earlier, I’m using a GSR head and it’s fully stock but has had some work done to it by the previous owner including milling it flat.
How to Check If The Head Is Warped
My head had already been machined and came from a trusty-worthy seller so I had no reason to doubt that it wasn’t flat but I still opted to check it out of curiosity.
Page 6-74 of the 94-01 Integra factory service manual has the full instructions on how to check for warpage but at a high level it boils down to resting a straight edge on the head in multiple different positions and seeing if there’s any gaps under the straight edge that you can fit a feeler gauge in.
My cylinder head pass as expected.
Checking If the Valves Are Sealing
The proper way to check if the valves are sealing is via a pressure test but I don’t have any equipment for that laying around so I went with a more basic approach of flipping the head over and seeing if any mineral spirits would leak past the valves.
I let the mineral spirits sit for about 5 minutes and then checked inside each of the cylinder head ports to look for wetness. To my surprise, I had 3 leaky valves.
The leaks weren’t super bad and I’m pretty certain I’ve ran leakier heads before but I figured it’d be worth lapping the valves as an experiment to see if that’d fix things.
The first step was to remove all the valves. It’s super important each one goes back where it came from so I took the time to label them.
I was surprised to find that several of the valve seats had rust on them. This head had been sitting for a few years so I’m not sure if the rust was from that, or just from age.
Using one of those cheap valve lapping tools from Oreilly’s I lapped all 16 of the valves by hand. This took about 2 hours and left my hands fairly sore.
I was able to remove almost all of the pitting and rust from the valve seats minus a few deeper spots. (The deeper spots looked too deep to try and get out via lapping and I was worried if I did go after them I’d ruin the factory 3 angle grind from taking off too much material so I felt better leaving them.)
Once I cleaned all of the lapping material out of the head I gave the valves another leak test with some more mineral spirits and can happily report that all of the ports stayed dry and none of the valves leaked.
B20V Conversion Steps
In order to run a VTEC head on a non-VTEC block there’s two modifications you need to make to the head. The first is blocking off the oil port that a VTEC block uses to supply oil to the VTEC solenoid on the head, and second another port needs to be opened so it can be used as an alternative oil source.
I’m using a Golden Eagle VTEC conversion kit because it makes things as simple as possible.
Tap and Plug The Original VTEC Oil Supply Port
The oil port that needs to be blocked off is on the bottom of the head in the back corner behind cylinder 4. Since it’s not a threaded hole it’ll need to be tapped in order to be plugged.
To reduce the chance of any debris getting into the head I covered up everything except for the hole to tap.
Then I slowly worked the 1/8 NPT tap that came with the kit into the hole until it was all done and gave it a good cleaning.
After that I screwed in the provided plug. With the plug tightened down I noticed that the edges around the hole had lifted by about .002" which was a little concerning but I’m not overly worried since the plug mostly hangs off the block and shouldn’t prevent the head gasket from properly sealing.
The main thing to be careful about is ensuring that the plug sits recessed in the head.
For reference, here’s how much of it hangs off the block.
Remove Another Plug for the New VTEC Oil Supply Port
The second and final conversion step for the head is to remove the plug blocking the port on the back of the head by the exhaust port of cylinder 4. I forgot to take a before picture but all you have to do is remove it and swap in the AN fitting.
It’s super straightforward. Just make sure not to overtighten the new fitting.
Swapping Valve Springs
The OEM GSR springs needed to be swapped out because I’m going to be running stage 2 cams and the OEM springs won’t be able to keep up with them.
I bought a cheap valve tool off Amazon and was surprised to find it actually worked quite well. I did have to swap out the bolts it came with for longer ones because the original ones were too short but for the price I can’t complain.
I also made sure to replace the valve stem seals as a precaution while all the springs were out of the head.
Now is a Good Time To Fix Any Damage
With how old B-series parts are nowadays there’s a good chance anything you get your hands on will have some damage. My GSR head was no exception as several of the exhaust header studs were missing and the threaded holes for them were stripped out.
Some of them were completely missing threads or had so much thread missing they were unusable.
I’ve had very good luck with helicoils in the past so I decided to drill out the holes and install m8x1.25 helicoils.
Each of the holes except for the top left was helicoiled using a m8x1.25x16mm insert. The top left stud hole is shorter than others so it needed a m8x1.25x12mm insert.
I bought all the helicoil supplies from McMaster.
**I already had a m8x1.25 helicoil kit on hand but it had a through hole tap that couldn’t get deep enough into the stud holes so I had to buy the bottoming chamfer tap to finish the job.
Besides that my head was missing an intake stud on the other side but the threads were fine so it was just a matter of putting a new stud in.