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Question for JMG re valve guides 944S2
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Author:  David924S [ Sat Jun 01, 2013 10:56 am ]
Post subject:  Question for JMG re valve guides 944S2
Hi John,
Quick query I am having a replacement head refurbished by my local machine shop and it has passed pressure test but the exhaust valve guides need replacing, I bought a set of 8 944 104 327 01 7mm TRW guides but when the machine shop has removed one of the old ones it seems the replacements are wrong.

I have not picked up the old one to compare with the new but my question is when replacing the guides should I be buying guides which are described as first replacement or first oversize? I did ask the seller of the ones I bought my new ones from and he seemed to think not however something is wrong. Or can you tell me the correct part number or type for replacement.
Thanks
Author:  jmgarage [ Sat Jun 01, 2013 12:07 pm ]
Post subject:  Re: Question for JMG re valve guides 944S2
I am stuck at home being an invalid for the time being until I get my knee operated on, but my hunch would be that someone has sent you lux/turbo valve guides rather than S2 ones.

Did the machine shop say what as wrong with the guides?

I know my machine shop always ream out valve guides to the exact right size when they replace them, because once they are fitted they will distort/deform slightly due to being an interference fit and Porsche also know this, so just because the valve will not slide into the guide, does not mean anything, if that is their problem, they should know it will need reaming out to size once inserted.

Sorry I can't help with the part numbers, but being away from the part system at work it is a bit difficult to double check the part number.
Author:  pauly [ Sat Jun 01, 2013 8:11 pm ]
Post subject:  Re: Question for JMG re valve guides 944S2
jmgarage wrote:

I know my machine shop always ream out valve guides to the exact right size when they replace them, because once they are fitted they will distort/deform slightly due to being an interference fit and Porsche also know this, so just because the valve will not slide into the guide, does not mean anything, if that is their problem, they should know it will need reaming out to size once inserted.

.


Pretty much what I told TTM over on Rennlist when he was chewing up followers and camshafts after fitting new guides without reaming them. Months later a machine shop said exactly what I had.
Author:  David924S [ Sat Jun 01, 2013 10:49 pm ]
Post subject:  Re: Question for JMG re valve guides 944S2
It's not a problem with the valves not fitting the guides but the guides not fitting in the head so I think more likely wrong guides but thanks for the tips on valve fittment and I hope you get better soon John
Author:  N6TCG [ Mon Jun 03, 2013 8:15 am ]
Post subject:  Re: Question for JMG re valve guides 944S2
teaching you for walking in a foregin country Jon!
Author:  David924S [ Tue Jun 04, 2013 7:33 am ]
Post subject:  Re: Question for JMG re valve guides 944S2
I got the valve guide removed from my car from the machine shop last night completely different to those I bought to replace them. I understand if they were just a larger outside diameter they could be machined down and similarly the internal diameter, however they are also too short by around 6mm and completely different around the stem seal area.

So I need to find a standard replacement set (not oversize as bores are perfect) but I am hoping the head I bought has not been altered or modified and the guides are some special one off manufacture.

Has anyone got a standard valve guide to compare size, my original one seems (rough measurements) to be 11.5mmOD (I know this can be turned down to fit head) 44.5mmLength tip to tip and ID not too sure but around 6-7mm.
Author:  David924S [ Thu Jun 06, 2013 7:08 am ]
Post subject:  Re: Question for JMG re valve guides 944S2
Well the good news is the garage I bought the guides from has refunded my money although they swear they were the right ones. Now I have to try and find a set of 8 standard size exhaust guides 944 104 327 01 rather than the oversize ones.
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