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The Wife and the Car
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Discussion Starter #1
There seem to be so many honda engines out there.
From 13 series to 14,15,16,17,18,20,22 engines.

Is it not possible to find valves from withing the hond series which can be little bit larger but which can be used on smaller heads.

Say my y8 head has a 30mm valve is there not an option to move up to a larger valve from a bigger engine.

Sorry if this is the wrong forum to ask.
 

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I am also very curious. I have read guys on this forum mention that the Y7 valves are 1mm bigger but i have a Y8 and Y7 head and the valves are the same diameter.
 

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1988 CRX
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I'm not sure about the sizes between heads, but for the money you'd have to spend to modify the head to make the new, bigger valves seat correctly why not just get some new valves?
 

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Brokedick Millionaire
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There seem to be so many honda engines out there.
From 13 series to 14,15,16,17,18,20,22 engines.

Is it not possible to find valves from withing the hond series which can be little bit larger but which can be used on smaller heads.

Say my y8 head has a 30mm valve is there not an option to move up to a larger valve from a bigger engine.

Sorry if this is the wrong forum to ask.
Stem length will be different.
 

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no need to go oversize on valves unless you happen to have a good cam to push more air, or high compression to draw more air

Doing oversize valves is like doing exhaust. no need unless its supported

I do however, see sense in doing them if you think at some point you eeventually will benefit.


If you are in your lil investigating mode, search for valve specs.

I would imagine the A series and early B series in the 2nd or 3rd gen rpeludes would be worth investigating if you really must know.

But I sure would NEVER put used valves into my motor unless my wallet was rather starved
 

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well not my thread, but my wallet is definitely starved most of the time :p

I love knowing what upgrade paths are the best bang for teh buck

@mattliston

Why not re-use valves?
Ever had a valve fail on you? Was it because teh valve was old, or because of some other factor.

I'm relatively new to Hondas, I had a few Mazdas before and there was never really any fear of reusing valves. When i rebuilt my Mazda head I threw on my old valves after cleaning em, no issues for 100k kms. I don't beat my cars but I'm not afraid of a few runs every now and then.

Nick
 

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Valves do not magically maintain 100% dimensions

over time they get wear and tear on the part that hits the head on every cam rotation

eventually you can lose compression if its not wearing down 100% even
 

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yeah I get that, but you could lap em no, or just have em reground if they were really bad.

Can't you check if they're sealing by using paint or something on the head and seeing if there are any untouched spots?

Nick
 

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I dont think the op was actually discussing using used valves but instead using new valves spec'd for a different engine than his to achieve an oversized valve.
 

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The Wife and the Car
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Discussion Starter #12
I dont think the op was actually discussing using used valves but instead using new valves spec'd for a different engine than his to achieve an oversized valve.
Right on
Length is not an issue if going from too long to short.

I did a little more dinging. And there are stories of using spring retainers and locks from another model for added strength.

The bad news is that our y8 heads allready come with the larger valves i.e. 30vs29 on the intake.

Im thinking of larger valves for when I go turbo.
Though they wont hurt to run something larger with a Bisi or Crower stage 2 cam.
 

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I have not done any flow bench testing, but my understanding is most high performance D series engine valves are already optimum for the std bore. Increasing size leads to shrouding. Of course id you sleeve and bore, bigger valves might then yield improvements in flow.

You can normally cut existing seats for 1mm bigger valves.

Longer valves help if you have a smaller base circle cam or if the lift you are using causes coil bind, so long as you can get springs to suit the longer valve and still have adequate seat pressure.

Also shrouding hurts high lift flow more than low lift, so if for some reason you are severely limited re lift, bigger valves might help.
 

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Most Honda valves have a 5.5mm stem diameter. However, as Bone mentioned, the important thing is that the stem length will be different, especially between VTEC and non-VTEC heads.
I found this out recently. The hard way. I thought all d16 valves were the same. If you look on some sites, they don't even label them vtec or not. Just d16 valves. So I bought vtec valves for my A6 head. Big difference! Vtec valves have a 1mm bigger head and if I remember right the Intake valves have a different length stem.
 

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Yes, due to the VTEC mechanism and how the rock arms are very different. If you run into that situation, you should look for valves for the D15 engines, as it is the same as the A6. (Which you probably know.)

There are some interesting valve options for the DOHC D, but not so many for the SOHC, as far as I know, but, I would like to be proven wrong.
 
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