Valve guide replacement

Side valve, 803, 948, 1098., 1275 and Vizard mods

Valve guide replacement

Postby clivechafer » Sat Jul 01, 2017 8:42 pm

So I took the valves out today and found what I take to have been the main cause of the misfire and smoking I have had since overhauling the engine last year: 2 of the O-ring oil seals I put on the inlet valves had split, so lots of oil had been getting into the chambers. One of these valves had no play in the guide, the other one had a bit of play. All the other valves had a bit of play, and one of the exhaust valves had a bit more than the rest. My dilemma now is: how many guides do I replace? I'm thinking I'll just replace the 3 inlet valve guides that have play in them. I don't imagine the exhaust valves can let in much oil, since the gas flow is outwards. I will of course replace all the O-ring seals. What do you think? Am I cutting corners by only replacing the worn inlet valve guides, or am I being prudent and not doing more work than needs to be done? (I can't find the correct size drift, and after banging away at the guides I can't get them to move, so I think I'm going to find a machine shop to do the job anyway.)
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Re: Valve guide replacement

Postby Custard » Sat Jul 01, 2017 9:36 pm

You have invested the time to get the head off and get gaskets and seals to put it back on, I would do the lot.

I presume you would get an estimate from the machine shop first so as them for the difference between doing 3 and 8.

So especially if keeping the car a while I would do the lot.

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Re: Valve guide replacement

Postby Panky » Sat Jul 01, 2017 9:41 pm

Get the cast iron Mini guides from Minispares, you can then fit the proper top hat seals. Get the seals that were fitted to the later models as they are considered to be a better item, only a couple of pounds each.
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Re: Valve guide replacement

Postby clivechafer » Sun Jul 02, 2017 4:05 pm

Thanks, Panky. Yes, I was thinking it might be worth getting the newer ones with grooves for the top hat seals, but I wasn't sure they were interchangeable. If they are, then I'll definitely put them on. ESM has them for the same price as the older ones. Thanks!
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Re: Valve guide replacement

Postby clivechafer » Sun Jul 02, 2017 4:06 pm

Thanks, Sean. Yes, if the price for 3 and 8 is similar, I'll do the lot.
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Re: Valve guide replacement

Postby MartinB » Sun Jul 02, 2017 9:39 pm

You will need to get the seats recut after replacing the valve guides. Generally production/replacement guides are not concentric enough to just lightly lap the valves in after replacing guides even if they go in nicely.
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