The V8 Owners Forum -

Hi all,as it says in title, is there away i can take out the guides myself without a press. i thought there was a post on here already but i cant find it, all advice welcome rich

May be worth warming up the heads in the oven before you do Rich, the ally should expand more than the iron guides. So long as you make sure everything is perfectly aligned it should be ok

TC

I made a tool on a lathe that slotted in the valve guide with a shoulder on it and wellied it with an hammer. The thing I made stopped the hammer damaging the guide. It worked ok lol

i dont need the guides, they are the old sd1 items, just need to remove them, Ive using an old oil pump gear with the end narrowed to fit down the centre of guide, so is using a hammer ok, and from what side is easier to remove,top of head or bottom, ive about 5 pairs to do rich

Getting the iron out for the scrap man rich?!

i need more than scrap mate, well 1st guide came out not to bad 2nd one not so good, swing with the hammer, removing tool slips i hit knuckle (some choice words used, like damn and bother) and half the spring seat collar has snapped off, more choice words used. half the collar missing would still be ok to use would,nt it??

As I think you are discovering you need to use a press and a suitable tool made to be a good fit in the guide and some way of securing the head. . . Hitting with a hammer normally results in cracking the head (usually between the valves) and in the seat inserts dropping out. The guides should be bronze, stick the whole lot in the fridge should make it a little easier, but not the freezer or you risk making the ally brittle.
Best regards
Mike

no room in the fridge for a pint of milk let alone 2 rover heads, unless i take the beers out .some have said heat them and you say the fridge, is that because they are bronzed??. Would a 1/2 ton or 1 ton arbor press from machine mart do the job?, or maybe i should take them somewhere and have them do it rich

Mike, I thought the guides were iron, and if so would the ally heads not contract more than the guides when chilled making them a tighter fit?

Hi Folks...
The old piston in a cylinder thing but in reverse, a ring/cylinder shape inside diamiter inceases at Pi -1 times its linear thermal expansion modulas thingy, its outside diamiter increases at Pi +1 a hole in a solid large object (head) increases/ decreases linearly (but in the other direction (ie as you heat up a large object with a hole in it the hole gets smaller a ring/cylinder gets bigger as described) hence you can stick a solid ally piston in an iron cylinder liner and although the expansion modulus of the ally is about 2.4 times the iron the thing doesn't sieze. likewise you can heat an ally head with a bronze guide in it by about 100 degrees and the guide doesn't drop out. cool the head and the hole gets bigger (just the geomitry is a bit tricky) cool the guide and the outside diamiter falls rapidly (take the valve out !! ) by the way the thermal expansion rates of bronze and ally are more similar than ally than iron.
Best regards
Mike

ok this is turning into a cooking class, how long should i leave the head in the fridge for, dont think people would like to come home and find a head in the fridge rich

I wouldn't worry too much about the "head in the fridge" just use a 1 ton press and don't do it on a hot day. If you do wan't to chill it, chill it for about 15 to20 min should be enough for ally. It is well worth sticking the new guides in the freezer (sintered bronze does not go brittle until very low temperatures) but don't cool the head, it is a complex shape that is intended to be stable from room temp to 120 deg C or so, try not to load it outside this range.
Best regards
Mike

kiwicar wrote:Hi Folks...
The old piston in a cylinder thing but in reverse, a ring/cylinder shape inside diamiter inceases at Pi -1 times its linear thermal expansion modulas thingy, its outside diamiter increases at Pi +1 a hole in a solid large object (head) increases/ decreases linearly (but in the other direction (ie as you heat up a large object with a hole in it the hole gets smaller a ring/cylinder gets bigger as described) hence you can stick a solid ally piston in an iron cylinder liner and although the expansion modulus of the ally is about 2.4 times the iron the thing doesn't sieze. likewise you can heat an ally head with a bronze guide in it by about 100 degrees and the guide doesn't drop out. cool the head and the hole gets bigger (just the geomitry is a bit tricky) cool the guide and the outside diamiter falls rapidly (take the valve out !! ) by the way the thermal expansion rates of bronze and ally are more similar than ally than iron.
Best regards
Mike

I always used to think that a hole in a huge lump of material would shrink when warmed up (due to being squashed because of the material expanding (I'm in "basic terms" Mike )) but I have been told otherwise since then so my knowledge has been tampered with!
So what about blocks- they heat them up to insert liners! Is it because there is (basically) more hole than material and they are bigger? If so where do you draw the line on when a hole shrinks and when it expands when you heat or cool the surrounding material?

Sorry about your simple answer/wishful thinking Rich, always liked science lessons though!!!

The standard guides are not bronze they are a steel. - Well the rate at which they rust when left outside would indicate that this is the case.

I think you will find that most shops just press them out at room temp although I was of the opinion that a bit of heat on the heads was the way.

Andrew

Hi Tom
Heat the block chill the liner, the deck surface tends to complicate things a bit as it starts to behave like a plate with hole in it, if you look at more modern blocks they tend be of an open deck design so you get uniform stresses along the whole liner.
Mike