Picking the right b20v head gasket is usually the moment where a B-series "Frankenstein" project either becomes a legend or a total nightmare. If you've spent any time on the forums or in the garage, you know that slapping a VTEC head onto a non-VTEC B20 block isn't exactly a factory-spec job. It's a custom setup, and because the oiling passages and coolant ports don't perfectly line up between the block and the head, the gasket has to do some heavy lifting to keep everything from mixing.
I've seen plenty of guys try to rush this part, thinking they can just grab any old B-series gasket and send it. That's a one-way ticket to milky oil and a warped head. When you're building a B20V, you're dealing with different bore sizes and specific alignment needs that standard parts just weren't designed for.
Why the B20V Setup is Picky About Gaskets
The main reason your b20v head gasket choice matters so much is the bore size. A standard B16 or B18 gasket is usually around 81mm, but the B20 block has an 84mm bore. If you try to use a B16 gasket, the fire ring is going to overhang into the combustion chamber. That's going to cause hotspots, pre-ignition, and eventually, the gasket will just disintegrate.
Then there's the issue of the VTEC oiling. Since the B20 block doesn't have the internal oil feed for the VTEC solenoid, you're running an external line. However, you still have to deal with the existing oil control orifice in the block and make sure the gasket doesn't block off vital cooling passages that the VTEC head needs. It's a bit of a balancing act, and getting it wrong means your engine won't last through its first dyno pull.
Modified OEM vs. Aftermarket Specialized Gaskets
This is the big debate. Some old-school builders swear by using a modified OEM B20 gasket. They take a factory Honda gasket, which is high quality and usually made of multi-layer steel (MLS), and they carefully drill out the dowel pin holes to accommodate the B16 or B18C head.
While that works if you're a surgeon with a drill press, most people are better off going with a purpose-built b20v head gasket. Brands like Golden Eagle or Cometic have already done the math for you. These gaskets come pre-drilled for the VTEC dowel pins and are sized correctly for the 84mm (or larger) bore.
The Case for Golden Eagle
Golden Eagle is pretty much the gold standard for B20V parts. Their gaskets are basically modified OEM Honda gaskets that have been precision-machined. You get the reliability of a factory seal with the exact fitment needed for the conversion. It takes the guesswork out of the equation. If you're not looking to reinvent the wheel, this is usually the smartest path.
When to Consider Cometic or JE ProSeal
If you've bored your B20 block out to 84.5mm or 85mm, or if you're running a crazy high-compression setup, you might need a specific thickness or bore diameter that the standard conversion gaskets don't offer. Cometic is great because they offer different thicknesses, which can help you slightly adjust your compression ratio or make up for material that was milled off the head or block. Just keep in mind that Cometic gaskets require a very specific, mirror-like surface finish to seal correctly.
Preparing the Surface (Don't Skip This)
You can buy the most expensive b20v head gasket in the world, but if your block and head surfaces aren't perfect, it's going to leak. This is where most DIY builds go wrong. The B20 block is an open-deck design, which means the cylinders can walk a little bit under high stress, and the mating surface can get uneven over time.
I always recommend taking both the head and the block to a machine shop. Tell them you're running an MLS gasket. They'll need to ensure the Ra (Roughness Average) is low enough—basically, the surfaces need to be smooth enough to look at your reflection in them. If you just hit the block with a scotch-brite pad and call it a day, don't be surprised when you see bubbles in your coolant reservoir.
The Dowel Pin Situation
Alignment is everything. When you're putting a VTEC head on a B20, the dowel pins that align the head to the block don't just drop in. You have to use special conversion dowel pins or modify the head. If the head isn't perfectly centered, your b20v head gasket won't sit right, and your valves could even make contact with the edges of the cylinders if things are really out of whack.
Most conversion kits come with these pins. They are stepped, meaning one end fits the B20 block and the other fits the VTEC head. Make sure these are seated fully before you even think about laying the gasket down. If the gasket is riding up on the shoulder of a pin, you'll never get a seal, and you'll likely crush the gasket when you torque the studs down.
Choosing the Right Head Studs
While we're talking about the gasket, we have to talk about what's holding it down. Don't even bother with OEM head bolts for a B20V. Just go straight for ARP head studs. The extra clamping force is vital for keeping the b20v head gasket compressed evenly, especially since you're likely planning on revving this thing to 8,000+ RPM.
When you torque them down, do it in three steps and follow the factory VTEC head sequence. I usually do 25, 45, and then 60-65 ft-lbs. Some people go higher, but you have to be careful not to distort the threads in the block. Using a high-quality assembly lube on the threads and under the nuts is non-negotiable for getting an accurate torque reading.
Keeping an Eye on the Oil Feed
Since you're likely using a conversion kit with your b20v head gasket, you'll have an external oil line running from the back of the block to the head. Double-check that the gasket isn't interfering with where the oil needs to flow once it reaches the head. Most conversion gaskets have the oil orifice blocked off because you're feeding it externally, but it's always worth a "dry fit" to make sure all the holes for coolant and oil line up with the passages in both the head and the block.
I've seen a few "budget" gaskets where the coolant holes were slightly off-center. It might not cause a failure on day one, but it'll create hot spots in the head that will eventually lead to a cracked casting or a blown seal.
Final Thoughts on the Install
Building a B20V is one of the most rewarding things you can do with a Honda. You get that torque from the 2.0L bottom end combined with the screaming top end of the VTEC head. It's the best of both worlds. But that b20v head gasket is the "glue" holding the whole thing together.
If you're doing this for the first time, take your time. Clean everything twice. Then clean it again. Use a little bit of copper spray if you're nervous about the seal, though many pros suggest installing MLS gaskets dry. Personally, if the machine work is top-notch, I go dry. If there are some minor imperfections, a light dusting of Copper Coat can be a lifesaver.
At the end of the day, don't cheap out. Spend the extra fifty bucks on a reputable gasket and the extra couple hundred on proper machine work. It's a lot cheaper than pulling the engine back out two weeks later because you wanted to save a few dollars on a "no-name" gasket you found online. Build it once, build it right, and enjoy that VTEC crossover.