BC valve guides, valve wont fit.

[MJTru]

Im wondering if any of you guys using standard nissan valves on a rb26 with BC valve guides. I notice that the exhaust valves fit the exhaust guides but the intake valves are tight on the intake guides and wont fit. Also both intake and exhaust guides are different lengths. The BC guides are way longer than the factory guides.

Im wondering if any of you guys have this problem. I can only imagine once the guides are fitted into the head that it will get even tighter. I have post a photo to give a better idea. I cant get around the thought of the intake valves not fitting the intake guides. Like in the photo. Like the exhaust valves. In the photo its std size but supertech valves, but i have tried the factory vavles as well, and the same intake valves dont fit the bc guides.

[GTSBoy]

It is normal to have to ream new guides to suit the valves that will be running in them.  It is also normal for aftermarket guides to need to be shortened, especially as they often get installed in heads that are getting ported and would need to be shortened even if they were supplied at the factory length.

[HarrisRacing]

^^^ 100% correct.

I had a machine shop install them and ream them to specs. But you are definitely doing the right thing by dumping the stock ones! 2 of mine were chipped off when I tore my engine down!

Good luck. It's not cheap, but worth the upgrade.

[MJTru]

Thanks mate. Seems like im down the path of stacking up on some good tools. Well as for the valve not fitting. I just figured out ill need to hone them. My choice is a flex hone. Also will need a ball gauge to find the inner diameter of the end hone.
Question. Does anyone know of the clearance im looking for when i hone it. For both intake and exhaust?
I really want to try this myself. I have removed all the guides perfectly, i gut the head up to temperature and pressed them out wit no scaring of the aluminum i couldn't be happer.
One thing im confused about though is the length of the guides. Is this normal and where do i put the long side. Or space it out equally.

[MJTru]

It is normal to have to ream new guides to suit the valves that will be running in them.  It is also normal for aftermarket guides to need to be shortened, especially as they often get installed in heads that are getting ported and would need to be shortened even if they were supplied at the factory length.

Opps didnt see this. How have you been mate nice to hear from you. Thanks as usual

[MJTru]

^^^ 100% correct.

I had a machine shop install them and ream them to specs. But you are definitely doing the right thing by dumping the stock ones! 2 of mine were chipped off when I tore my engine down!

Good luck. It's not cheap, but worth the upgrade.

Thanks sir. Intrested in what shop you used. Seeing that we are both from state side.

[HarrisRacing]

Sent my head to RAW Brokerage...right there near you. They have a machinist. Make sure you get ALL of the things you want done to your head in writing first. They did good work, but we did have a miscommunication on what I wanted them to do overall. It did take quite a bit of time as well.

[GTSBoy]

28 minutes ago, MJTru said:

Opps didnt see this. How have you been mate nice to hear from you. Thanks as usual

 

Hi Marcus, I'm good enough.  Don't try to hone the guides.  The correct technique is reaming.  Do your usual youtube research - there's bound to be someone demonstrating valve guide replacement tasks.

[MJTru]

I was thinking of using them. My next choice was port flow design in CA. RAW Brokerage i like because i can travel there personally. This is my, i guess you can say experimental head. My try. For notes the valve to guide clearance is 0.1m (0.004)
Tomorrow ill try to trim the guides to the right length heat the head up again, and using some nitrogen dip the guides and quickly install them. I spent 2 days making a guide jig so that i cant over press it to deep. Once there cut to the right length i.e stock length i hope it goes well. Ill have to wait for my ball gauge to arrive along with my flex hone.
As for now im looking for a reamer tool, and if i get this right the honing comes after i ream it. Choosing the right size reamer is the next hard part. I think they have reamer that can expand. Not to sure. The search is on.
Thanks for all your comments and suggestions very insightful

[HarrisRacing]

The reamers are different sizes FYI. My local machine shop that has built all of my other heads didn't want to mess with this since they would have charged me for the reamers needed to get them done.

I would NOT hone them unless you are 100% sure you are true with the valve seat...hence the reamer to make sure to get the valve guide straight after installation. Then of course machining seats to match valves.

It all can be done no problem, and it's not exactly rocket science, but I sure wanted my valves straight in my head and my machine shop agreed when I told them the motor might spin 9,500 rpms one day!

[MJTru]

I agree that the seats have to show good signs of a proper seating pattern. I have had mixed feels about if it will be out that bad, and would need recutting. If thats the case im screwed. I can do a bit of slap seating old school style, but im interested to see how far out it will be. Lots of guys say it will be off and its best to cut the seat using the guide to center it up. But some guys say they never had to cut the seat. A good slap seating worked just fine. Ill find out sooner than later. Not to long ago i found out the reamer size i needed. About 6mm intake and 7mm exhaust. I plan on measuring the valves up tomorrow then buying the reamers