SOHC 16V Head swap?

[hot4dl8ly]

I was looking to get a little more power w/o sacrificing a lot of fuel economy. I found a B3 SOHC 16V head, and was wondering if it could be spliced onto our B3 block? This would only be a temporary fix, until I get enough time and knowledge to install the BJ setup. This may have been covered here B4, but I couldn't find it. Thanks.

[shorestiva]

I don't think anyone has really played with one of those yet. I believe they might've had different bore sizes than the B3 we got here.

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[hot4dl8ly]

I checked it has the same 71mm x 83.6 mm bore & stroke, but gets around 72hp at 5500 rpm - a 14 hp increase.(and that is B4 I clean up the ports and shave it down slightly) I was actually starting work on a B3 head when I discovered a 1.3 sohc 16v exists. The head looks like it has 2 holes our B3 doesn't, maybe oil return. Only thing is by the time you get the head, intake, exhaust and valve cover - you probably could have found a nice B6-ME. I may do it anyway. Just a temporary thing until I can get enough time and knowledge to get the BJ setup up and running. Might be nice to have 25% more power w/o losing very much mpg.

[ricko1966]

Look up pistons for both engines, I was told the b6 16v have different pistons with different valve reliefs.I was trying to get info on doing a 16v on my B6 but was unable to find enough info.I do know when you go 16V on a VW 8v if you don;t swap pistons you end up with a really low compression ratio.On another threadI did read that 16V had a bigger oil pump and under piston oiler but IDK.

[shorestiva]

The 2 oil return holes were on later b and z series blocks. I think if you put a head that has them on a block that doesn't the holes stick out past the edge of the block. iirc someone just tapped them for plugs and blocked them off. Make sure to check piston to valve clearance since the pistons won't have the correct valve reliefs.

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[hot4dl8ly]

Hey, Thanks for the great information. I was planning on getting the head milled anyway, or If I have a tap large enough - It is just aluminum. As far as the valve reliefs - I guess I have some clay and a Dremel tool (and some luck). The compression may be an issue - I could measure combustion chamber volume, with water or light oil.

[bhazard]

Where did you find a 16v B3 head?

[shorestiva]

I think there was one on ebay a couple months back.

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[ricko1966]

Hey, Thanks for the great information. I was planning on getting the head milled anyway, or If I have a tap large enough - It is just aluminum. As far as the valve reliefs - I guess I have some clay and a Dremel tool (and some luck). The compression may be an issue - I could measure combustion chamber volume, with water or light oil.

I have clay checked engines I have built and had pistons made to my specs. but my thoughts on next time I do this is braze cutters to 1 ex. valve, 1 intake valve make a stop collar that fits my valve stem
touch my cutter to my piston set my stop collar spin the valve with a drill,thats why I asked if there was enough meat in the pistons when I was contemplating a 16v swap.d

[hot4dl8ly]

sent bhazard a PM

[hot4dl8ly]

Just got the 16V head. The combustion chamber volume is approximately the same (I got about 34cc). Valve reliefs may be a small issue, but the valves only clear deck height by about 0.072 int. and 0.080 exh. But this will change when I have the head machined down a little - for better compression. I have yet to get the rest of the necessities, intake, exhaust, valve cover and gaskets.

[Dragonhealer]

Even with the head gasket you are already over 10.5:1CR. Don't cut the head, just run it.
I would check those clearances with clay (or play dough) on a dry run. Turn gently by hand, don't want to bend a valve....

[Eviljimchicken]

If you shave the head, wont you need to get an adjustable cam gear too? Do they even make aftermarket cam gears for this motor?

[shorestiva]

Miata ones will work if a centering ring is made. The b3 camshaft is a smaller diameter than the dohc stuff.

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[TWFodor]

Just got the 16V head. The combustion chamber volume is approximately the same (I got about 34cc). Valve reliefs may be a small issue, but the valves only clear deck height by about 0.072 int. and 0.080 exh. But this will change when I have the head machined down a little - for better compression. I have yet to get the rest of the necessities, intake, exhaust, valve cover and gaskets.

Can you post some pictures of the head? I believe I had one of these but I want to make sure. It is in my brother-in-law's go-kart now. What is the part number on the side of the head?