valve guide replace ment

[JIMFROMTEXCO]

upon pulling my head off, thinking only a broken valve i realised my valve guide had a 5 hairline craks in it. how hard is it to auctually replace them? i read from doing a search thast you need to heat the head and freeze the new guide. what elses goes along with doing this? should i use a press to put it in place? do i need any machine work, or coud i use valve lapping compound? another thing is should i coat the cam journals with a moly coating or anything? its a 350x engine. also what would the part number be for a 350x valve guide, dont most honda heads use the same ones? i also have some chromoly valve springs for a 250x, 300ex head and they appear to be the same legnth would it be allright to use them? im alsot thinking about cleaning up the ports with a dremal would i benifit to open the ports up some?

[2muchquad]

I knoiw the head needs to be heated first and driven out with a tool.It looks like a punch that fits in the guide itself.Im sure something else can be used though.The valve seat may need to be "worked" on to make sure the valve is centered in the seat with the new guide.Maybe Dork will see this,he knows more about it.How did you break a intake valve?timing off?You may need both replaced:(

[dork]

you can use 300ex guides, the 350x guides supercede to those anyways. be sure to replace the o-rings underneath them. when you order the guides, order the remover/installer from honda, or someplace like goodsons. you can use a drift punch to get them out, but when you install them the installer has a special back cut to prevent mushrooming the top of the guide bore. you will also need to order a reamer to finish size the guides after, again either from honda or goodsons. you use a hammer to install/remove; a honda service manual will help you out if you don't know how to do that or use a reamer. then you need to check that the valves seat properly against the seat, since the guides control their placement. you may be able to get away with just lapping, maybe not. you can vacuum test the port or pour solvent in it with the valves and springs on to see if they leak.

coat the cam and rockers with some moly or assembly grease and fill the oil well in the head up with oil.

if the springs are the same length, you should be ok.

for the ports, you can blend the valve seats to the bowls, don't get carried away. you want 85-90% of valve diameter for the throat diameter. thats where most of the improvement is. you want a rough finish on the intake, 60-80 grit works good. you can match the intake manifold to the intake entry, but don't go crazy. its safer to have a slight "step" down from each transition as you go down the port so there's no oncoming edges that the air stream will hit. don't knife edge the port divider wall, you'll lose flow, leave it rounded. exhaust can be smoother finish, not critical, and leave the port exit so it steps down into the header. that will help stop reversion. also check your header flange welds that they don't overhang in the pipe.

[JIMFROMTEXCO]

Thank you! my step dad works in a tool and die shop and he told me to bring it over and he can get it all with in spec. im hoping the honda shop has them in stock.

also what is exact spec for valves on the 350x engine i was setting them to .04 intake and .06 on exhaust is that correct? i ordered a .20 over 10.5.1 wiseco and a 400ex carb. i would like to get the powerband to change a little to more topend. i dont really have anymore stumps that need uprooted.

[dork]

stock specs are .003 and .004", aftermarket cams are .004-.006".

to raise the powerband, you'll need to go to a bigger carb and cam. the 400 carb will help, also take off your airbox lid if not already.

[TRX-330]

since you guys are talking about valves. what are the valve settings for the 300ex are they the same as 400ex, and i have a web cam so would that make the settings diff. How about a 400ex carb how much do those run since i just bored mine out i think want to get a 400 carb also.

[dork]

megacycle lists .005/.007 with their larger 300ex cams.
i usually go .004-.006/.005-.007.

[TRX-330]

we set it at .004 on intake side nd .005 on the exhaust side, is that a good setting i dont wanna mess anything up

[dork]

thats good.