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Jul 13, 2020 19:09:06 GMT
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ive got a 998 a plus head in working on. I smacked the old valve guides out of the head , and i have bought a 6 ton press. So tonight, i pushed one of them in. I checked with a valve and it moved freely. So i pressed the other 7 in.
1 other valve moves freely. 2 move ok until they get to the top of the guide, and the other 4 are tight at the bottom of the guide.
Have i bent the guides or do they need reaming now ?
thanks
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mk2cossie
Club Retro Rides Member
Posts: 2,948
Club RR Member Number: 77
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valve guides.mk2cossie
@mk2cossie
Club Retro Rides Member 77
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Jul 13, 2020 19:39:40 GMT
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New guides usually need reaming to some extent when fitted, so that there is just enough clearance to not bind, but not soo much that gases/oil get past them
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Jul 13, 2020 19:40:49 GMT
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ah ok, fantastic, i thought i had done something really bad. I need to buy a reaming tool now then!
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Jul 13, 2020 20:35:57 GMT
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I pressed new valve guides in my Rover V8 heads and made a guidance tool from an old valve stem. When posted this on the Rover forum, there were shared opinions on using a press. Some people mentioned you should hammer these in as these could get damaged when it would be too tight. I have a pressure gauge on my press so you can see what the pressure is. For me it worked well with the press. I also have a set of adjustable reamers. These were Chinese made. Not the best quality but suitable for occasional use.
A new technique is too ream the old guide and then fit a special thin sleeve. I got that done on my Ducati motorbike heads as these are prone to crack
Good luck
Peter
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Jul 13, 2020 20:44:35 GMT
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oh i see! i had thought about using an old valve as a tool to get them in, but i just pushed them in with a bolt like i saw ona vid on youtube!
I have bought a reamer for £7.50 from ebay, i wasnt sure if i had distorted them and reaming would make them a funny shape inside.
I'm costing the £65 of the press as not free but not accountable to this job as ill use it for lots of things, and the £7.50 to get them in, it was £2.50 a guide i think at the local machine place, so if it works out ive won lol!
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stealthstylz
Club Retro Rides Member
Posts: 14,834
Club RR Member Number: 174
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valve guides.stealthstylz
@stealthstylz
Club Retro Rides Member 174
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Jul 13, 2020 20:53:23 GMT
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Firstly are you checking them all with the same valve? You should be if not, then do each individual valve to guide. Also have you deburred both ends of the guide after fitting?
However it sounds like its been a bit big on the OD so they've squashed during fitting. It's best to hammer them in but you need a good fitting punch to do it, doesn't make much difference now though. We hone guides out, leaves a much nicer finish than reaming. You can buy small honing brushes fairly cheaply.
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slater
Club Retro Rides Member
Posts: 6,390
Club RR Member Number: 78
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valve guides.slater
@slater
Club Retro Rides Member 78
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Jul 14, 2020 18:43:57 GMT
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Yep, you need a 9/32 reamer. You can hone them but only with a proper hone. A flexhone wont do it properly as they have no ability to 'cut stright' as it were.
You realise you will almost certainly have to cut the seats too now?
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Jul 16, 2020 19:54:53 GMT
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well i had a little go at one today, and then just tried seating the valves with paste. When i pushed the valve hard home it kinda sticks, maybe that is as the centre of the seat is now offset?
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stealthstylz
Club Retro Rides Member
Posts: 14,834
Club RR Member Number: 174
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valve guides.stealthstylz
@stealthstylz
Club Retro Rides Member 174
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Jul 16, 2020 22:50:18 GMT
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Yep, they'll definitely need cutting and the valves refacing if they're being re-used.
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slater
Club Retro Rides Member
Posts: 6,390
Club RR Member Number: 78
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valve guides.slater
@slater
Club Retro Rides Member 78
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Jul 17, 2020 15:00:59 GMT
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Put some blue on the seats, marker pen will do. Give it a quick lap and you will see where the seat is going to seal or not.
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