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

[ksa8907]

I never thought about valve lash, ive messed with it on my go cart about 10 years ago. Got more torque with them slightly loose. Good idea...

[t vago]

Originally Posted by ksa8907

please, don't neuter such an amazing engine. if you want more torque, port-match the intake and exhaust and maybe try an intake plenum from a charger/challenger.

I'm not sure such a plenum would fit. I'd have to do... things to the firewall, probably. The reason I'm using a humungous Pacifica manifold is because it's the only one that'd fit the engine without resorting to major car body surgery.

[arcosine]

If you are looking to gain MPG, then disabling all 8 valves on 2 cylinders would increase it about 20%.

[mechman600]

Originally Posted by arcosine

If you are looking to gain MPG, then disabling all 8 valves on 2 cylinders would increase it about 20%.

Really? Where do you get that number from?

[t vago]

That's in line with what can be expected from deactivating 1/2 the cylinders in a given engine.

[mechman600]

Originally Posted by t vago

That's in line with what can be expected from deactivating 1/2 the cylinders in a given engine.

That's what I figured.

I thought DOD engines were really complicated. Turns out, they really do just turn valves and fuel injectors off on deactivated cylinders.

[arcosine]

I got it from my 1977 Honda Accord, which had a carburetor, 40 to 48 mpg. Slower acceleration than a semitruck. You might have to get two injectors from the junk yard to plug in to keep things happy. My car idled twice as fast. The HF engine and transmission would be better.

[Christ]

Originally Posted by arcosine

The HF engine and transmission would be better.

Got 'em.

[Potenza]

To the OP: Just wondering if you have any updates concerning your 8-valve modification. I was thinking of doing something similar, but I have two questions.

1. Where did you find the spacers for the missing rocker arms? I can't seem to find them on any HF parts catalog.

2. Are there any issues with fuel buildup behind the inoperative intake valve? Upon researching, it looks like the VTEC-E setup actually opens the 2nd intake valve a very small amount just for the purpose of keeping fuel from pooling on the valve.

Thanks for any info!

[Gasoline Fumes]

Originally Posted by Potenza

To the OP: Just wondering if you have any updates concerning your 8-valve modification. I was thinking of doing something similar, but I have two questions.

1. Where did you find the spacers for the missing rocker arms? I can't seem to find them on any HF parts catalog.

2. Are there any issues with fuel buildup behind the inoperative intake valve? Upon researching, it looks like the VTEC-E setup actually opens the 2nd intake valve a very small amount just for the purpose of keeping fuel from pooling on the valve.

Thanks for any info!

The spacers are shown here:
http://www.hondaautomotiveparts.com/...E+-+ROCKER+ARM
#8 and #9 in the diagram. It's a little confusing since Honda strangely included 16 rockers in the HF diagram.

Looks like they might not be available anymore. I got mine from a junkyard. The 1992-1995 CX should have them as well. Or find a pipe with the same inside diameter as the rocker shaft diameter and make your own!

If there's fuel building up behind the valves, I haven't noticed it. I've got something like 5000-6000 miles on it like this, no issues. But you'll never see the top half of your tachometer again!