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 - Vernier cam gears

I am planning the purchase of a vernier camshaft timing gear setup for my XPEG and am looking for input on where best to source one and also any information on the experiences of others who have gone down this track.

One of the MG discussion forums mentions some installation difficulties relating to end float with a unit by Powertune (in that case on a B series motor).

It is not always clear on a seller’s website who is the manufacturer of their units or for that matter what the item being offered actually looks like.

Any thoughts would be welcome.

Michael
M R Calvert

Why? A lot of money for something you can do for the price of a timing wheel and an offset key.

I have one decorating my Wall o' Speed, because I would never bother to use it.

Tom Lange
MT? Repair
t lange

I did purchase one from Manley Ford for my XPAG build. My only suggestion is that once you get it dialed in where you want that you drill and thread the hub and gear to lock it into place. I bought the vernier because I wanted to be able to play with cam timing readily without having to play with pulling the headset on and off to place offset keys. I also tend to question the the sheer strength of offset keys as they get progressively offset. My spring pressures are very stiff with the particular roller am I chose to run. I didn't pin my gear set after it was degree'd and I think it has slipped and the cam timing acts retarded. Now I need to pull the front of the car apart to recheck it and pin it as it was suggested to me by Manley

Is it worth the expense? For an all out race motor maybe if only to facilitate adjustments on an existing cam for tuning purposes. On a stock engine... No way! Degree it with offset keys and save the hassle of extra moving parts and hardware coming loose

JMHO

Bill Chasser jr
TD4834
W. A. Chasser Jr

I agree with Bill. In a race motor where every degree means a fraction of a second lost, I can understand it. But for a street engine, it really seems overkill - especially for the money. Careful work with a degree wheel can get you dialed in within a degree or two, and offset keys (I've never seen any wear on one) can be very helpful to correct any manufacturing error. To me, 99% is good enough for a few laps around the track from time to time, in a street machine.

Even with a roller cam I suspect a degree wheel is more than adequate. As Bill notes, they come with their own problems!

Tom Lange
MGT Repair
t lange

Thank you for your thoughts Bill and Tom.

I have noticed from pictures that some units use four bolts and some use six in the adjustment mechanism. (I will try to attach pictures). The potential for slip in the system is something I have wondered about. Your comment, Bill, is the first time I have heard it actually raised as an issue. I wonder has anybody else any experience in relation to this?

I had to photograph the computer screen to get an image to upload. Hoping it is clear enough.

Michael


M R Calvert

Michael.

The gearset I have is what is in your lower right pic. The one I had expected was the 6 bolt as that was what Manley shows on his site. When I got it Manley told me that he pins all of them once they are dialed in and suggested that I do it also as insurance that it didn't change. The 4 bolt screws are not much more than a SAE #10 screw to set the adjustment wheel. I have spring seat pressures of 150 psi and open pressures nearing 260 if my memory is correct on the latter. That's an awful lot of tension to be held in check by 4 #10 screws, hence the suggestion of pinning. He literally pins them I would prefer to thread and bolt them

Cheers

Bill Chasser jr
TD4834
W. A. Chasser Jr

Thanks for the information Bill. The six bolt one, top right, is what B&G used to offer but they now appear to only have a four bolt unit, top left. It seems like a down grade on the face of it. The price remains the same.
It sounds like you have one of Len's roller cams - so do I, and so share the same concerns.
The concept of pinning as insurance does not suggest confidence in the underlying design. I wonder does the idea come from knowledge of failures of units in use or just general caution.
My level of interest in the adjustable timing gear is not being enhanced from the information to hand thus far.
Cheers,
Michael
M R Calvert

This thread was discussed between 02/11/2015 and 04/11/2015

MG TD TF 1500 index

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