valves appearance

[berger]

if you are going to hammer them out remove as much carbon build up as possible, it makes life easier

[muskrat]

G'day Eugenio.
Sorry I didn't realize you have an alloy head. In which case yes bronze guides. Heat head to 200C and they will push out by hand. Then measure them with a micrometer. They may have been replaced before and you need to know if any or all are oversize already.
Cheers

[eugenius]

Good morning friends, thanks for the advices. I'll do as you suggest.   

[Swarfcut]

  Alloy heads are valuable...and fragile. I'd be thinking along the lines of making sure the existing valves are the correct ones, because earlier pictures looked as if the valve heads were too small for the seats. Also slop in the guides is also down to valve stem wear. In other words a new set of the correct valves may be a better way to go, rather than changing the guides for very little gain.

 It all depends on what you actually have and how much you want to spend. Recutting the seats is indeed the standard practice, to ensure the bore of the new guide is concentric with the seat and the seat angle matches the valve. All fine and dandy, but some practitioners are heavy handed, and as suggested a check with blue and a light "tickle" may be enough....if only to preserve the seats.

 Swarfy.

[eugenius]

Hi Swarfy, thank you for a balanced suggestion that clearly originate from great experience. Indeed I am tempted to check with blue following an already accomplished light 'tickle' as you say and then decide how to proceed. It is a pleasure to receive so many advices from you all     

[chaterlea25]

Hi eugenius,
If you have access to machining facilities the best way to remove the guides is the machine away the top half , then heat the head as suggested and drive the remainders of the guides down into the ports,  the reason being that any car on stuck to the guides will not damage the guide bores,
Otherwise bead blasting the ports around the guides to remove the carbon , be sure there are no beads or carbon left in between head and guide..
Measuring the valve stems for wear may help with diagnosis.. The guides wear at each end Oreos than the centre
Colisbro guides should be honed to size, not everyone has the equipment to do this

John

[eugenius]

thanks John for further details!
Eugenio

[eugenius]

Hi all. I have bought a new set of valves (still waiting the exhaust ones) and removed the inlet valves guides because there was too much play. I now should buy the new guides but which measure should I choose provided my guides measure 0.566 inches?

[sean]

Hi all. I have bought a new set of valves (still waiting the exhaust ones) and removed the inlet valves guides because there was too much play. I now should buy the new guides but which measure should I choose provided my guides measure 0.566 inches?

I replaced my guides with colisbro ones from SRM they were plus .020 and  turned down the OD to fit the interference spec for each hole  as they were all slightly different .

[eugenius]

Thanks Sean for the insights

[CheeserBeezer]

The reason that valves need to be lapped -in after fitting new guides is because a previous owner might have lapped in the old valves whilst the old guides were still fitted. Consequently, the valve seat may have been ground off-centre or crooked because the valve would not be straight in the guide.

[eugenius]

Yes in fact it is hard to understand what was exactly made by previous owners. So far, I will buy new colsibro guides and afterwards get those placed by a specialist to face the new valves and if necessary adjust the valves seats accordingly. Thanks cheeser-beezer 

[sean]

Yes in fact it is hard to understand what was exactly made by previous owners. So far, I will buy new colsibro guides and afterwards get those placed by a specialist to face the new valves and if necessary adjust the valves seats accordingly. Thanks cheeser-beezer

you dont need colisbro you can go with the regular cast iron valve guides and depending on where you live you may have a problem finding the tools to hone the colisbro valve guide id, you need a special material on the hones and you will need a tool [ ball micrometer ] to measure the id of the guide and a 0 to 1 in outside Micrometer ....if I remember right the intake clearance was .001 on intake and exh .0015 ....I ordered my hones from a company in the USA but I believe they are also in UK  " Brush Research "

[eugenius]

Thanks Sean! I have an alloy head with bronze guides so maybe colsibro guides should fit better? As far as  the mounting issues, there are some specialized centres in Rome that may adequately face these problems hopefully but I will ask better. My main problem will be to decide, which size of guides should I buy, standard or oversized? A nice day       

[limeyrob]

0.566 looks quite big already.  I just took mine out and they are 0.5625 which is 9/16"  0.566 would be +4 which is the largest (normal) oversize.  My bores in the head are worn and the +4 guides are out of stock here in the UK (I did a lot of searching) so I have +14 on order from SRM and I'll get them machined to fit.  The SRM +14 are about the same prices as the Dragan +4 but there's the added cost of machining.  I can't be sure my head is not worn so I feel I have little choice now other than to get the new guides honed and the seat cut (just s skim) to line up.  You may end up at the same conclusion.