MG-Cars.info

Welcome to our Site for MG, Triumph and Austin-Healey Car Information.

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG TD TF 1500 - NEW ROCKER ARM SHAFT

Hi all. I have just replaced the rocker arm shaft on my TD. It is 14 7/8 long. I followed all instructions explicitly per Horst Schach and Malcolm Green. I took pictures and marked everything. All the casting numbers are correct for the respective location. The one hole underneath the shaft is lined up with the rear platform. All is correct. My question to you is this: 5 of the rockers have their oil hole lined up with the hole drilled in the new shaft. But 3 of them are off just enough so that I can not pass a wire drill through it and into the shaft like I can on the other 5. Is this a concern? Is there a fix? Do I start drilling???
As always, Thanks, Sandy
smb brainsky

Sandy. Did you perhaps double up on one of the spacer spring washers? Also, there are different length spacer springs. Any potential the are in the wrong spot? If you ordered new springs, check that they are the right length.

Bruce Cunha

Don't the rocker bushes have a butterfly wings groove cut into their bore. Oil flows out of the rocker shaft hole and then around this groove before exiting from the hole in the rocker. It would probably be better for the oil holes not to line up so the oil can flow round the bushes before coming out of the rocker hole. There are also long and short bushes. Are yours the same lemgth as the rocker bore?

Cheers

Jan T
J Targosz

The only part renewed was the shaft. All springs were reused and appear to be correct. The spacer washers are only against the springs and are all accounted for. There are no washers used between support brackets and the rockers. Jan brings up an interesting point. Are the 5 holes that line up with the ones in the shaft the correct ones and the 3 that do not are wrong, or are the those 5 the incorrect ones. Or does it even matter?
My belief is that these holes are the only source of oil to the top of the head and valve train. Seems like and important detail.
Again thanks,
Sandy
smb brainsky

Sandy.
If you still have the old rocker shaft you can check it for a match with the new one.
I have been rebuilding these MG engines for over 35 years and some of them did not have holes in the rockers themselves.
I would accept J Targos explanation and run it and enjoy it as is.
Sandy Sanders
Sandy Saunders

Sandy, At the risk of being terribly embarrassed, I'm going to toss something out. I don't have a rocker shaft available to look at, but ... is there any chance that the shaft is not symmetric and that it could be installed backwards? Bud
Bud Krueger

Bud,

There's an oil hole in the bottom of the shaft at the rear. This allows oil to feed thru the shaft to the rockers. If he's got this hole at the back of the head which it sounds like he has it's installed correctly.

Gene
Gene Gillam

Long time ago I took a lot of photos when I was taking apart the engine that I bought for Lazarus. I just came across one that says "Rocker parts". It shows the top view of the rocker shaft. Doing a few measurements shows me that the top of shaft is symmetric in regards to the oil holes for the rockers - but they are in two sets of 4. The space between the 4th and 5th holes is about 1/3 greater than the nominal spacing between holes. Sandy, if it were me, I'd take the assembly apart and reassemble while looking at page 5 of an Abingdon Spares catalog. Make certain that the parts, especially the rockers, are in the correct order. If you were to set the assembled shaft onto the head, would the rockers align with the pushrods and the valves? Bud

Bud Krueger

One other point I overlooked in my previous response, after fitting a new rocker shaft and properly honed bushes to the TF's engine the oil pressure increased by 5psi. If oil can pass along the rocker shaft and directly out of holes in the rockers you will see a significant drop in oil pressure. Also the thrusts at the side of the rockers will be starved of oil.

Jan T
J Targosz

Bud is correct. Like so many things on T types it's all too easy to refit the shaft backwards. This will prevent any oil from reaching & lubricating the rockers. I know because I have done it. I picked this up prior to tightening down the rocker gear. During re installation check to ensure that the 8 oil holes in the shaft point to approximately 1 o’clock when viewed from the front of the car. Cheers
Peter TD 5801
P Hehir

I got a return call from the technical dept at Moss. He said that the scroll lines in the bushes will get plenty of oil where it belongs and not to be concerned. I may disassemble the whole thing one more time anyway, just to scrutinize the 2 shafts side by side. Thanks for all the good comments. It will give me the opportunity to verify that the shaft is indeed assembled properly, just to be absolutely positive.
Thank you all, Sandy
smb brainsky

Sandy, how come you are not rebushing the rockers as well as replacing the shaft? Did the bushes measure out as new?
Regards, Tom
tm peterson

Honestly Tom, the old bushings are so snug on the new shaft that I thought they were too tight already. The old shaft was definitely worn. The new one should make a substantial improvement. What I would really like is to install the roller kit. But that is going to have to wait. I want to see how my rebuid is going to run. Havn't done this since I was a kid. I may have built the next Chernoble.
Sandy
smb brainsky

This thread was discussed between 01/11/2016 and 04/11/2016

MG TD TF 1500 index

This thread is from the archives. Join the live MG TD TF 1500 BBS now