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MG TD TF 1500 - In search for another Laystall

The hunt is on for another Laystall head. If any one has a serviceable head laying around with no cracks, repairs or heavy decking, sunken seats etc and most importantly has an installed spring height greater than !.70 I would be interested in talking with you.
W. A. Chasser Jr

Hi Bill,

There must be a reason that your current Laystall spring height does not measure up. Have you compared it side by side with another? Remember they have 45 degree exhaust seats. I have a Laystall on my car and another dismantled if you want any dimensions. Give me your email address if you want to compare photos etc.

If yours is "different" you have probably already considered this option to use the Laystall head you have. I have been thinking about doing it to my own head to reduce valve train weight so I can weaken the springs and have the benefit of less cam / follower wear.

The plan: Use shorter valves (you said in another post that your Laystall has this effect already). Shorten the rocker pedestals and the pushrods by the same amount. Use shorter springs, with less coils per inch to prevent coil bind. If necessary shorten the valve guides or push them slightly deeper.

More "open" springs (less coils per inch) would themselves have less oscillating weight. Theoretically, (with limitations) spring load and length is a straight line graph but a shorter spring with less coils would have a steeper graph. That means the closed seat pressure and initial cam lift could be lighter but the load could increase to the same (or more) when the valve is fully open. Modern valve springs look very different from the XPAG springs! I think finding suitable springs is the only difficult bit of the plan although Nissan springs set to the Nissan height might be about right.

You could also go the other way and fit Nissan (8mm stem, 35mm Ex, 38mm In) valves which are longer, then you might have to use Nissan valve caps and maybe put packing under the springs, rocker pedestals and lengthen pushrods to get the geometry right.

Good luck in your endeavours
Bob Schapel



R L Schapel

Hi Bob. I would be interested in talking with you in re to the valve situation. Send your email and # to salsburyrocketman at yahoo dotcom
W. A. Chasser Jr

I have an original Laystall that is uninstalled. Saving for my YB. Larry
Larry Brown

Contact Jerry Felper at felperg@earthlink,net for a head.
CJ Lusch

Bill and all,
I checked with Ann Arbor Auto Parts Machine Shop on the subject of looking up valves by dimensions and Daryl gave me a super database to log onto to....
SBI-E-CATALOG.com
You can look up all sorts of valve related components by specification- valves, springs, guides, seats, lifters, keepers, head bolts...

With respect to this Laystall head issue- Bill, you can start by looking at all valves that the stems measure precisely, .3150" (as close to 8mm as it gets) and see what length floats your boat. You can also consider valves by length or head diameter and select a stem larger than 8mm. If you still have old guides, you can run a reamer through to oversize and renew guides without replacing them. A good valve grinding machine can cut the diameter and the angle to whatever you want.

Your options just opened up.
JRN JIM

My car has a Laystall head, but from the looks of things, I can't contribute more than that here. I didn't realize there were that many around.
Frank Bice

This thread was discussed between 16/03/2015 and 20/03/2015

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