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MG TD TF 1500 - Laystall expert ???

My engine parts procurement is almost complete for TD4834. I am only awaiting for the pistons to arrive shortly from Arias to begin the final machining. But I've run into a huge problem that I haven't found a solution to. I have a Fanelli roller cam and the upgraded spring kit and roller lifters that will be used. unfortunately the installed height for the springs is 1.750" at 161# seat pressure. No problem there as these should work properly and would if only I had 1.750" to work with.

The problem lies with my Laystall head. When I purchased this it was supposed to be an NOS head that had been on the shelf since new for use as a spare. It certainly looked the part. But on disassembly the valve stems were scored and the guide junk. I bought new MKII valves from Moss and the total length on the valves is nearly the same. My problem is with these valves I only have an installed spring height of !.50' which is .250' short of what I need. The spring pockets cannot be sunk any further as the machine shop says there isn't enough material in the casting to support the spring pressures

So you Laystall experts out there. Is there a longer valve used on the Laystall vs a stock head? Is there a spring that will support my roller cam that will work at !>50 installed height? I don't know if I got some reject of a head or it was bought as bare casting and pieced together but I'm very frustrated at this point. This is not to fault Len in any way and I want to make that clear to every one. This has to do with the Laystalls set up and I'm trying to get a clear picture of how these were meant to be set up. Do I have the wrong valves? Does any one have a head apart of can give me spec's or sources. I have a call into B&G, as well as George Edney but no response as I was too late in the day there. Len is also searching for me as well. Any body who can shed light on this would be greatly appreciated
W. A. Chasser Jr

Bill,

I have an uninstalled Laystall - how can I help?

Gene
E F Gillam

Can you check your installed spring height on your valve? is it 1.50 or 1.750? are you able to pull a valve and check the length? If this is some sort of morphodite I may need to just shelve it. I'm thinking that if I could find a valve that is .250 longer I could solve the problem or find a set of springs at the rating I need that Installs at 1.50 and will operate a cam with .415 lift with out coil bind
W. A. Chasser Jr

Bill,

I'll check tomorrow for you. Email me offlist at anngene @ bellsouth.net

Gene
Gene Gillam

Bill,
There has to be a great variety of valves with 8mm stems; the trick would be in locating someone in the business or some charts with a list.
I swear I hunted down every valve insert on the market for my XPAG head that had been compromised by a previous machinist.
A conventional valve grinder can reduce the OD or the ports/seats machined to accomodate, which is what so many do going with the later/larger valves. Anything slightly longer than stock can be shimmed up, or larger springs used. If they were extremely long, then the end of the stems could be machined exactly to your needs.

Now you have another issue to deal with, the rocker assembly will need to be shimmed significantly to reach longer valves. Not a big deal, but make sure the oil passage is provided. We have to cut the pushrods to fit anyway, so we have to face that geometry issue when the time comes.

God Luck!
JIM
JRN JIM

Jim I was on a long Face time chat with Gene over the weekend. We compared the valves which were the same length, compared the pocket depths, again the same, measured various spots across the head to check the oil valley depths again the same. He has an installed height og 1.820. For the life of us both we can't put a handle on what is going on. I even set my roker assembly on my iron head and then transferred it to the laystall and found no difference in the geometry. Manley Ford even suggested that it could be possible that the wrong seats may be installed thus causing the valve to be lower in the head. IJDK
W. A. Chasser Jr

Hi Guys,

I don't know if any of this will help ..... some random measurements and experience. I run a Laystall on my race car but have another with valves and another bare. They are originals, not modern repros.

The Laystall heads I have all run 45 degree exhaust valve seats and 30 degree inlets. If you put in a valve with the wrong angle maybe it won't reach through as far as it should?

I use Nissan valves 35 and 38mm. OD can be cut down if necessary (Datsun 1600 I think). They have 8mm stems and are just (barely) long enough to cut the Nissan groove off and machine a new XPAG style groove. I also found that BMW bronze guides fit straight in although they are not reduced diameter at the top for the T Type inner spring shroud/guide. I always cut the shroud off (grinder as they are hard) to save weight anyway. BMW guides are also available in a few over-sizes OD in case of worn head holes.

I measured my assembled head and found a measurement of between 1.8" and 1.9" from the top lip of the steel washer against the head to the top of the spring (under the cap). I could get this measurement because my valve cap washers are cut back in diameter for lightness.

The bottom of the spring recess (without steel washer) on my bare head measures about .25" deep at 90 degrees to top head face (slight angle to valve stem). That is in line with where the valve stems enter the head because it is shallower one side and deeper the other.

Isn't it fascinating how the rocker angles etc seem to be ok with both types of head when the Laystall has shallower (but wider) combustion chambers Maybe the Laystall was thinner to start with? My most original is 75mm thick. Standard TC is 76.8 I think

Bob Schapel
R L Schapel

Stock TC/TD thickness is 3.022", i.e., 76.8mm. Bud
Bud Krueger

Bob and Bud Thank you for your comments. Gene Gillam and I had a lengthy Facetime chat last Saturday afternoon where we did a lot of measuring and comparisons. All of our measurements seemed to concur with one another as to length and size of valves, spring pocket depth measured from the valve cover surface, depth of the casting at various point along the valve cover edge etc. We could no come up with any appreciable differences. One thing that was different was the milling of the pedestal base and valve cover flange that left more machining done to the top of my head. Yet the specs all seemed to Jive. My head has a 2 72 stamped on it which I'm presuming was when it was made. Gene has an installed spring height of 1.820 vs my 1.50 and neither of us can figure where the substantial difference lies. I also laid my rocker assembly on my ironhead and then transferred it to the Laystall and the geometry is very nearly identical. In the meantime Len is trying to come up with a solution from his engineer so that I can make this work.

I received my ARP hardware, thermostat housing, core plugs and gaskets from Tom Lange today. High quality stuff and recommend his products to those in need. Check out his site if you haven't done so before...

My Arias pistons where supposed to be in the mail today but haven't heard from them as to whether they got out. if they did they are to be overnighted to me.

Time is of the essence as dads health is diminishing at an alarming rate. Though not in any pain yet he is struggling to maintain his strength and stability. Weight loss is his greatest enemy and the ability to process food. I fear he will not see this through to completion and may very well not see it to start up and a simple test ride around the block sans wings and interior. We are simply running out of time... please keep us in your thoughts and prayers in the coming days

Regards

Bill Chasser Jr
TD4834

Arias Just called in response to my email an hour ago to say they regret that the expedite order was moved and consequently redirected. It will be another week before they arrive but the expedites fees will be removed. Can I not catch a break when its needed most.
W. A. Chasser Jr

Our prayers for your Dad, my Dad left my TD to me to pass on to my daughter, when he passed away.
Len & Andrea
Len Fanelli

Bill,

If it will help I'll send my head to you so you and your machinist can see what, if any, differences there are and make you decision from that. Of course I'll have to get it back from you...it's not for sale!

Gene
Gene Gillam

Gene Thank you for the offer and I may take you up on it at a later time. Len has been working behind the scenes, messaging me on Monday that he will get back with me soon and I am hoping he can come up with a shorter spring solution in the next few days. If not we are going have to rethink this head and either find another Laystall that will accept a taller spring working height or find a modified iron head.

If any one has a good usable Laystall that has a working spring height of 1.750 or greater and is willing to part with it at a reasonable cost...

Thank you Len for your thought. Please PM me offline for an update or call me...
W. A. Chasser Jr

I'm running a single spring, an RR501 from Kelford. I needed it because the standard ones were coil binding with a higher lift cam and breaking rockers at high RPM.

May or may not help, but here it is, anyway. They don't bounce till somewhere over 6,500, and I've got larger valves fitted. It is an iron head, not a Laystall.
D A Provan

This thread was discussed between 27/02/2015 and 06/03/2015

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