Disabling intake and exhaust valves (going to 8 valves in a 16-v head)

[Gasoline Fumes]

I should add that I tried the increased valve lash. I just used my thickest feeler gauge on both the intake and exhaust. I think it was 0.035". Or about five times the correct lash! It seemed to help out the low end a little. And I kinda like the ticking sound.

And with only 8 valves, I was able to fully advance the distributor without pinging. That gained me even more on the low end.

[arcosine]

You could probably turn the idle speed down too. Vtech engines only disable one intake valve and leave both exhaust valves operating. You might try that to see what happens.

[Gasmiser]

What about getting your cam ground like a lean burn engine?

[Gasoline Fumes]

Originally Posted by arcosine

You could probably turn the idle speed down too. Vtech engines only disable one intake valve and leave both exhaust valves operating. You might try that to see what happens.

You can't really turn down the idle, it's controlled by the computer. Or was until recently. I'm having issues with the idle control valve right now. With it currently disabled, the engine will sometimes idle at ridiculously low RPM. Or sometimes it will just stall. But I think you're right, it seems like it could idle a lot lower than 750 RPM. At this point, I'd be happy with any idle speed as long as it was consistent. My current choices are a 1000-1500 bounce with the idle valve working or somewhere between 750 and stalling with the idle valve plugged. The only idling I do is coasting at night with the heat and lights on, so I'm not sure I'd gain much with a lower idle speed anyway. Especially if I replace my dying battery with something bigger!

I am curious what would happen if I had all 8 exhaust valves opening. Any predictions? Finding the motivation to play with the oily puzzle might be a challenge! And I built an exhaust system that will outlast the car after doing the valve delete. The tiny single straight-through muffler I used wouldn't be enough with all 8 exhaust valves talking. This engine never had an EGR valve. I'm wondering how much EGR effect I'm getting with less exhaust valves.

[Gasoline Fumes]

Originally Posted by Gasmiser

What about getting your cam ground like a lean burn engine?

What's different about the lean burn cams?

[Gasmiser]

Just that 2 of the 4 valves only open a little as far as I can tell. I don't go over 3000 rpm anyway so I think this is a great idea.

[Potenza]

Wow, thanks for the quick reply. That was the parts diagram I had been looking at, but I found it a bit confusing as well. Looks like the intake spacers are still available, so I'll give those a shot.

My plan is to do the 1 intake valve, 2 exhaust valve setup. This is how it ran on my old SOHC VTEC del Sol with great effect. And by shifting low I never reached the 4-valve changeover.

But my Civic LX has a full-time 4v/cyl setup, and I'm looking to increase both low-end pull and fuel economy. I never shift over about 3100RPM. (It's an auto, so it doesn't always do as I like.) I'm thinking the 3v setup with its swirl effect will do the trick. If I like it, I will consider getting the cam permanently ground into the VTEC setup for the 2nd intake valve, to address the theoretical fuel puddling issue that Honda seemed concerned about. We'll see... cross that bridge when I get there.

[nbleak21]

I can engage vtec as low as 1500rpms with my VAFC, and setting it at 2400 seemed to net me the best highway mpg (cruise between 26-2900rpm) during the summer, but due to this colder bout of weather it's been kicking my ecu into open loop any time I'm at low load longer then a min or two, so im thinking that possibly with the colder charge air (70-80f IAT, 25-35F ambient) that running vtec engagement at 2900 will help keep the ecu from running open loop. I'll post preliminary results aft my return trip home, and do some aba testing over the rest of the week!

[Gasoline Fumes]

Originally Posted by Potenza

Wow, thanks for the quick reply. That was the parts diagram I had been looking at, but I found it a bit confusing as well. Looks like the intake spacers are still available, so I'll give those a shot.

My plan is to do the 1 intake valve, 2 exhaust valve setup. This is how it ran on my old SOHC VTEC del Sol with great effect. And by shifting low I never reached the 4-valve changeover.

But my Civic LX has a full-time 4v/cyl setup, and I'm looking to increase both low-end pull and fuel economy. I never shift over about 3100RPM. (It's an auto, so it doesn't always do as I like.) I'm thinking the 3v setup with its swirl effect will do the trick. If I like it, I will consider getting the cam permanently ground into the VTEC setup for the 2nd intake valve, to address the theoretical fuel puddling issue that Honda seemed concerned about. We'll see... cross that bridge when I get there.

Please post your 3-valve results here when you have them! I'm curious how it compares to my 2 valves.

[ps2fixer]

Subbed

My dad suggested the same concept a few months back, then boom someone is doing it O.o. For me I would be suck with grinding down my cam to disable the valves, direct push from the cam .