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Re: Valve seats
Posted:
Fri Mar 17, 2017 5:51 pmby alan.barker
hi Phil,
I just had a thought, have you tried fitting a new Exhaust Valve. Assemble with new Valve and compare clearance to clearance before with old Valve. Sometimes the Valves have been recut several times and the head of the recut Valve becomes smaller reducing the clearance. Because it sinks further into the seat.
I think it's worth assembling with new Valve to compare + you will be fitting new Valves anyhow
Alan
Re: Valve seats
Posted:
Fri Mar 17, 2017 6:31 pmby Mazzini
jono wrote:...I almost qualified my post to say others will disagree!
No interest, just the work he did for me was good... perhaps I've just been very lucky.
The only issue I did have was poor communication.
Jon
I thought the work he did on one engine was good, till I pulled it apart. Another member of this forum pulled one his engines apart and found a piston in the wrong way round.
On one of the engines he built for me the oil gallery plugs were finger tight (block and cams)
I like Paul, I'd definitely use him for machine work, but not for an engine build.
Re: Valve seats
Posted:
Fri Mar 17, 2017 6:54 pmby p.faurie
Hi Alan, thanks for your input, I have fitted new valves to the exhaust, refitted both cams to the exhaust side and have zero clearance, I believe the seats have been cut maybe too much, hence the valve stems been ground down, I have to put the old valves back in and fit the inlet cam to the exhaust side to see if I have some sort of clearance,if I have I could assume that the unmarked cam has a similar lift as the inlet,if that's the case the seats have been over cut that's my thinking,
Re: Valve seats
Posted:
Fri Mar 17, 2017 10:12 pmby steveh
p.faurie wrote:Hi Alan, thanks for your input, I have fitted new valves to the <a class="vglnk" target="_blank" href="http://www.ebay.com/sch/i.html?_nkw=exhaust" rel="nofollow"><span>exhaust</span></a>, refitted both cams to the <a class="vglnk" target="_blank" href="http://www.ebay.com/sch/i.html?_nkw=exhaust" rel="nofollow"><span>exhaust</span></a> side and have zero clearance, I believe the seats have been cut maybe too much, hence the valve stems been ground down, I have to put the old valves back in and fit the inlet cam to the exhaust side to see if I have some sort of clearance,if I have I could assume that the unmarked cam has a similar lift as the inlet,if that's the case the seats have been over cut that's my thinking,
If you have standard cam followers @ 0.218" pad thickness you can use thinner cam followers with 0.160" pad thickness and gain 0.058" in shim size / valve length , thus maybe avoiding the need to replace the seats .
Re: Valve seats
Posted:
Fri Mar 17, 2017 10:29 pmby Hawksfield
Phil
Try QED in Quorn, Leicestershire
They rebuilt my head back in 1993, new valves seats and guides still running fine today
Check them out in case they don't do machining now
Good luck
Re: Valve seats
Posted:
Fri Mar 17, 2017 10:32 pmby p.faurie
Thanks Brian type 26/36 and Steveh that's the way I'm going to go,will speak to Qed Monday, thanks to every one great forum.
Regards phil
Re: Valve seats
Posted:
Fri Mar 17, 2017 10:46 pmby rgh0
While fitting the thinner pad followers will help in this sort of situation you need to be careful that you still have a thick enough shim so that the top of the retainer does not contact the bottom face of the follower and the follower pad rests on the shim.
cheers
Rohan
Re: Valve seats
Posted:
Fri Mar 17, 2017 11:27 pmby Craven
They are longer but shouldn?t be a problem, worth checking they don?t bottom out though if you have high lift cam.
Ron.
Re: Valve seats
Posted:
Fri Mar 17, 2017 11:33 pmby billwill
I seem to recall reading that grinding the tip of the valve stem is NOT a sensible thing to do as it is hardened there and you will grind away the hard bit.
But I don't know if this is true.
Re: Valve seats
Posted:
Sat Mar 18, 2017 3:43 pmby Davidb
On the Aston Martin DB2 engines-1949-1957-the only way to adjust the valves is by grinding the valve tips! As long as the valves and seats are in good condition this means that they should not need need adjusting before about every 50,000 miles at least. Which is just as well since the Aston engine is all cast iron and the head is a heavy lump!
