British-Cars.org

Welcome to the DMR Site for British Car Information.

Recommendations

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 MGB Technical - Cam timing

First the background, About 20 years ago I rebuilt the engine on my 76 roadster. I used a stage 2 head and Kent 715 cam, the engineering work was done by a performance engine workshop near me who supplied the head, cam and balanced all parts etc, I assembled the engine.
It went pretty good, I thought, but then lifes problems led me to lay it up until I retired a couple of years ago.
Now with increasing awareness and information gleaned from this forum I realised that I may not of timed the cam correctly, I just set it up with the dimples like it says in the Haynes manual.
So I've finally got round to checking it. It appears to be 25 degrees out. The Kent site says 106 degrees when No 1 valve is fully open, mines just over 80. I used a stop cylinder plug to check the TDC, thats OK. I used a dial guage on the valve. The valve clearances are .4mm ( I've only got metric feelers ) and the compression test gives between 170 and 180.
As I said I think it goes pretty well, I took it out for my first ever track day, and I was able to keep up with like for like on the straights.
What am I doing wrong.
Thanks Chris Cummins
c cummins

OK, I've realised I've made two errors (at least) I thought it was No 1 valve fully open, but it's first inlet, and having made that mistake, the closest 106 on the protractor I glued to the crankshaft pulley was BTDC, so I assumed that was it, but it is 106 ATDC. I'll have another go tomorrow.
c cummins

If your car is running with neck in neck with the others in your class, I would leave well enough alone. When I rebuilt my engine, in the early '90s, I did pretty much the same as you. .040" over pistons, Kent 815 cam, a ported and polished head and a Weber 45 DCOE carb. I've been running a Moss supercharger system, since 2002, and power and low end torque are unbelievable. RAY
rjm RAY

Thanks Ray, I rechecked it and it's near enough with my eyes to 106.
I think it's great when some one really ups the power on a B. There was a GT with a 4.6 V8 that lapped me after about 3 laps; I felt really inadequate untill I checked his youtubes and saw him rinsing Subbies and Ferraris.
c cummins

This thread was discussed between 25/06/2011 and 28/06/2011

MG MGB Technical index

This thread is from the archives. Join this live forum now