valve guide dimensions

[Don]

Good morning...........
Can anyone tell me the OD of a standard VW 1200 valve guied? One of mine is "almost loose", pushed out with not much force. It measures 12.05mm OD. CPI lists + oversize guides, but no actual OD dimension, so I dont know which one to order. Also what is the reccomended interference fit (.002"?).
thanks, don

[brian]

the OD of a std guide is .475, yours sounds small. Guides are available in + .005 and + .010 over sizes. Not really sure what the crush should be but I always preheat the head prior to installation and use a press lubricant. Never install or remove the guides from the port side. I prefer an impact gun for removal. Always machine the exposed head on the spring side before pressing out. Leaving the head on the guide will split your head. The valve seats will have to be remachined after new guides. Make sure you have material on the seats left or you will require new seats. Guides are pretty tricky on these old heads and with "ported" heads the seats are generally hogged out.

[Dietmar]

Just to expand on what Brian said, I carry guides in .002, ,005, and .008 oversize.

If your guide in question was falling out, you might be looking at an oval hole and it may have to be drilled before installing the new guide- at least .002 or .005

Dietmar
http://www.quixoteracing.com

[smsazzy]

I send my heads to BRM Engineering if it needs this kind of work. Brian can be reached at 916-712-5742.

[brian]

Another thought, if you do use an oversize guide and the crush is a bit tighter, you will have to ream the guides to size. Reaming the bronze is not an easy proposition, I have over $500 in cutters for this job alone. Unless you're equipped, I'd suggest going to a shop that is. I appreciate the plug, but any competent automachine shop can do this. The valves are approx .312 go to at least .314 on the guide.