valve guides

Post by **murray33** » Thu Apr 14, 2005 8:17 pm

Hiya, thought my engine was smoking due to split stem seals but my valves have around 1-2mm play in the guides. Is this too much? Would I need to renew the valves as well and are and special tools needed to remove/fit the guides?

Thanks

Post by **Alec** » Fri Apr 15, 2005 7:54 am

Hello Murray,
that clearance is far too much, new guides are very much in order.
The guides may be removed and replaced with a stepped drift, but the biggest obstacle is re-cutting the valve seats as the new guides may be on slightly different centres. You may be lucky and be able to grind them in with paste, but!!. Whether the valves also need renewing will depend on their condition, there is no fixed rule.

Alec

Post by **doobry** » Fri Apr 15, 2005 9:29 am

If you have 1 to 2mm play in the valve guides, I'd expect you need new valves and would recommend that you get the seats re-cut also (not just re-lapped). As the existing valve isn't well constrained, the seats could be worn off centre.

Post by **bmcecosse** » Fri Apr 15, 2005 8:05 pm

1 - 2 mm is 40 to 80 thou !!! Never ever seen play like this in 40 years of A series engines !! You are faced with new guides and valves - totally uneconomic. Better by far to just source another head and bang it on - or take the plunge and get it converted to unleaded. If getting another head - go for an upgraded one for a bit more power - what engine have you got ??

Post by **57traveller** » Sat Apr 16, 2005 11:14 am

That's excessive. When the engine is running the valves may not be initially making full seat contact. There is then a risk of the cone fracturing off the stem (worst case scenario). I've experienced this happening on larger engines - not pleasant!

Post by **bmcecosse** » Sat Apr 16, 2005 4:02 pm

Are you really sure it's 1 to 2 mm ?????????

Post by **Alec** » Sat Apr 16, 2005 4:48 pm

Hello BmcE,

I was assuming the reference was to the amount of play at the end of the valve when waggled, not the actual guide to stem clearance.

Alec

Post by **bmcecosse** » Sun Apr 17, 2005 7:49 pm

Ahhh. Normally it would be the radial clearance in the guide. Still think another head is the answer - they cost almost nothing - loads of them about.

Post by **Alec** » Mon Apr 18, 2005 8:06 am

Hello BmcE,
that may be so but I would never dream of fitting a used head without doing an overhaul. Really 'A' series parts are so cheap it's not worth taking a chance and having to do the job twice.

Alec

Post by **rayofleamington** » Mon Apr 18, 2005 10:45 am

that may be so but I would never dream of fitting a used head without doing an overhaul. Really 'A' series parts are so cheap it's not worth taking a chance and having to do the job twice.

I agree, but it does depend on your budget. When I was in my late teens I would never have dreamed of getting a recon head when £10 would get you a second hand one... and £3.50 for a gasket.

The joys of earning proper money is that now I buy all the parts I 'might' need before starting a repair, rather than trying to work out what the absolute minimum is when it is all stripped down. However, my box of new unused new parts is now starting to overflow

Post by **Pyoor_Kate** » Mon Apr 18, 2005 1:15 pm

However, my box of new unused new parts is now starting to overflow

You can always send 'em to me Ray ;-)

....Well it was worth a shot! *grins*

Post by **rayofleamington** » Mon Apr 18, 2005 1:38 pm

You can always send 'em to me Ray

Well I do remember digging out a leaf spring frount mounting pin and plate for you when you did Niki's car....

Post by **bmcecosse** » Mon Apr 18, 2005 9:09 pm

Most of the heads on ebay will be fine if given a quick valve grind. Unless you are building a competition motor - a used head will be perfectly good, after a valve grind !