blackeg

so im 99% sure i have bad exhaust valve guides in my 4th cylinder.

i just ordered 2 new oem exhaust valves as my current ones have light vertical lines/scoring on the stems. problem is that majestic or carland acura seem to only sell oversized guides. noob here, but is that oversized the inner diameter or outer diameter?

also i see that bronze guides are pretty affordable, but i dont really want to take the entire head apart as the rest of it is in very good condition. is it bad to pop in some bronze guides in just that #4 cylinder with new oe valves and have it be oem everywhere else in the head? i havent been down this road before and im just trying to get a probable game plan.

Turbo-LS

iTrader: (4)

This wil quickly become a heated debate so ill quickly break it down. they say bronze ones dont last long but for daily driving and not track racing they last 30-50k miles on average for an all out drag car prob 10k miles cause spends lots of time at redline.

Stock dont wear but if you slightly bend a valve it shatters the stock guide and takes out turbo and piston and damages combustion chamber, VS with bronze will bend with the valve and not do that but they wear.

blackeg

well i put between 5000 and 8000 miles a year on the car but only like 20 passes if im lucky. last year i only had 3 passes on it due to other tranny/clutch/lsd issues

rich7777

Personally (& this is coming from someone that knows where your at) i think you should remove the head & get the lot done properly. Look at it this way, if you have 2 bad guides and you only just replace them how long do you think it will be untill the others go bad ? I know its a pain in the *** as you've just assembled the engine again but the truth is it needs to be done properly so your not back here again soon.

As for the guides, i personally like bronze guides, but they won't last as long as OEM. You need to weigh up whether or not you don't mind changing them again in 30k+ against how long OEM would last.

OneBadTurboCRV

It helps to search...

https://honda-tech.com/forums/forced-induction-16/forced-induction-engines-daily-driven-vs-valve-guides-3034752/#post46997590

blackeg

yes, i did search and i did read that thread.

here are my most important questions currently:


1) are there any adverse effects of running a head with mixed guides between oem and bronze aftermarket between cylinders. id most likely replace at least all the exhausts, but im just throwing the idea out there to see if its been done with success

2) referring to the "oversize" listen for the valve guides from honda, what does that entail? can they be swapped in to replace my old ones with relative ease?

honestly i currently have a b16 head at the machine shop for another build ive got going. when i get that back i might just swap springs and retainers and throw that fresh head on my turbo engine, then go back and replace the guides and use that for my other build.

dntbh8n

matt i have a set of supertech guides brand new

blackeg

no ****. i still havent decided if im just gonna swap springs and retainers with another b16 head ive got at walt's right now and throw that on my black coupe or if im going to rebuild the head on it currently. text me we will talk more. thanks adam

PR8urVtec

iTrader: (1)

I have to bring this thread back up b/c I'm in the same boat and don't know what to expect from an over sized guide. I just want to buy stock replacement guides for the exhaust side and Honda / Acura only sells oversized. What does the mean? Do you have to get oversized guides? The head is at the machine shop and the guy called and said the exhaust guides are out of spec. I need to order these asap.

Thanks,
Ryan

wantboost

iTrader: (2)

oversized would refer to the outer diameter of the guide (part that seats in the head) or the inner diameter (valve pass through) you need to ask and get clarification as either can cause you loads of headaches having to return and get the correct parts

I vote bronze guides. simple to replace, more affordable (which makes having to replace them every 50k not that bad compared to just the OEM parts cost)

you would also need new valve stem seals. I recommend the blue viton seals. again very affordable and the viton material can take a lot of abuse and still seal

motoxxxman

if you rebuild your motor regularly, I would go bronze guides. if you don't want to have to rebuilt the head every 50k or less, I would definitely go with steel guides.

as for the oversized guides from Honda, I don't actually know if it refers to ID or OD. but either way, using them would require either custom valves if the guide ID is oversized, or custom machining to the head if the guides are oversized OD, which would make it impossible to use any other factory replacement guide from then on. for steel guides, I strongly recommend Sealed Power guides. I started using them a few years ago and will never use anything else. check rockauto.com for the best prices on sealed power guides.

as for mixing/matching different guides, well, functionally there would be nothing to worry about because all they do is guide the valve and keep it centered. BUT, different brands often use slightly different shapes/sizes for the tips of the guides. sometimes they match oem, sometimes not. and that different in the tip size/shape will affect airflow. and having mixed guides will cause each cylinder to flow different amounts of air at various points, throwing off the overall balance of the motor. it probably wouldn't be a huge difference, but there would be a difference and I personally would not want to do that. so your best bet is to just replace all of them at the same time. that way you also wont have to go back in anytime in the near future to replace any others.

tepid1

It refers to OD and not the OD where it sits in the head. The OD of the guide that's visible when installed. Larger OD will be more heat friendly when making more power and will help keep the valve more stable at high rpms. It also allows a head porting company material to work with when porting a high flowing head.

motoxxxman

valve guides are straight. anything regarding oversized OD would refer to the entire guide as a whole, including the installed surface, not just the visible surface. having only the visible surface be oversized but not the installed surface would be impossible unless they machine it to have a step.

tepid1

Incorrect.

fil2345

Hi, sorry to revive this thread. I've been using the search button (including google) about proper valve guide length. I am currently building my d15 head and will be replacing the valve guides and valves. But my concern is the valve guide I got has a different length. Exhaust is longer than the intake. Is this going to be an issue? do I need to cut it?

please refer to the photo below

. Thanks!