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View Full Version : Valve stem seals or double springs?



billspit
04-23-2008, 08:40 AM
I got a call from the head shop yesterday asking me if I wanted to install seals on the valve guides. I know Spitfires do not use them as standard and I was planning on using the double European spring set I got. If you use double springs, no seal will fit. What is the opinion of you guys? Use the seals and drop in the inner spring? Or stay with the double springs? This car won't likely get a lot of mileage since my Mk I hasn't. I felt the valve actually needed and little lube on them for longevity.

Also, with all of the trouble with cams and lifters these days, I've seen a lot posted that you should only use one valve spring until the engine is broken in. Then install the inner spring. This is mainly for high performance engines and mine is only a slightly breathed on 1500. Do you think it is necessary to leave the inner spring off at first?? I really don't want to try and do this on the engine later by myself.

Opa
04-23-2008, 12:32 PM
Bill if it were mine I would put it together with new valves and guides reamed to spec. put in the double springs and go.I personally don't like seals on an engine designed to run without them, however if your putting a head together reusing old valves, guides,then I would look at clearences closely and possibly use seals.
I'm not convinced that hd valve springs are the problem as much as inferior lifters and possibly cams.
If possible I would have lifters checked for rockwell hardness. I have used BPNW lifters on several engine jobs and had them checked for hardness on my own motor and found them to be well within spec.usually at 56- 60 rockwell.Haven't had any cam troubles yet. JMO

Tosh
04-23-2008, 09:36 PM
Billspit,

I installed the double springs on my recent head rebuild. There were two reasons;
1.) The cause for the rebuild was a broken spring which caused a dropped valve (into the cylinder). I figured that the inner spring would help to insure that a future broken spring would not release the keeper and allow the valve to drop.
2.) The advisor at British Parts Northwest said that the increased spring pressure was negligible.

Keep on

billspit
04-24-2008, 07:44 AM
Thanks for the feedback. They have finished the head with double springs. No seals used. BTW, I had brand new valves and guides installed.

Flinkly
04-24-2008, 12:14 PM
so i have a rebuilt head with old valves and new iron guides. should i have my seals removed? they put them there when they built it up, without asking. i should probably at least ask why.

Brosky
04-24-2008, 07:37 PM
I went with seals this time, in the event that I decide to install an oiler again. It may never happen, but if I do, I'm covered this time.