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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 MGA - Twin Cam engine assembling

Don,

I don't know if you have had much experience in assembling the mga twin cam engine. I have a few notes that I have written out to help avoid the problems that can arise.
Best of luck with that Ebay engine when you get it.
The article is at the link below:

http://www.angelfire.com/amiga/mga/index.html

It is a PDF file requiring the Adobe Acrobat program. If you prefer MS Word or plain text let me know.

Mick
Mick Anderson

Thanks Mick!
This is my first one, so any info is good! I should have the engine next week.
Don
D.M. Black

Mick- I read your assembly instructions for the twin cam and am just curious what kind of head gasket they do use if not copper and why cant you turn the engine over for fear of the the valves fowling if the timing chain is not fitted, the cams are not turning if the chain is not on, then they should not hit right? The chances of me owning a twin cam are about as great as winning a lottery, but then again if I did win the lottery I could have one! Saw a nice black tc coupe a few months ago in a English magazine, told the wife our 1600 coupe needed a playmate - at least I can dream
gary starr

Gary,

The Twin Cam head gasket is copper on the side that faces the iron engine block and thin steel on the side that faces the alloy cylinder head. I will email you photos of both sides.
The reason why you will bend valves if you turn the engine without the timing chain fitted is that in any camshaft positions you will have at least one valve (usually more) that will be hit by a piston, even though it is only partially open. You do not need to turn a camshaft to do that damage.
With the high crown 9.9 CR pistons there is very little clearance.
This is also the case with most (not all) modern cars. If you break a camshaft timing belt the camshafts will stop turning, but the valves will be bent.

Mick
Mick Anderson

Gary,

I suppose that the fact that the Twin Cam engine will always have valves open is shown best by the following.
The inlet camshaft opens at 20 degrees BTDC and closes 50 degrees ABDC. So it is partially open for 250 crankshaft degrees.
Now, talking in camshaft degrees, a valve is partially open for 125 degrees. There are 4 lobes 90 degrees apart. It is obvious that you can never have all the valves closed at the same time.
With the very small piston to valve clearance, even with a valve closed, it is clear that at least one valve will be bent in any camshaft position.

Mick
Mick Anderson

Thanks Mick makes sense now. I knew that on modern engines w/ belts that could happen but I thought it was from the inertia of the cam still turning as the belt broke that caused it. Can you still get those type of head gaskets and do you have any idea if it would fit a 1600? The reason I ask is that I have HRG cross flow head that some day will make it on my car and have wondered what type of gasket to use. Thanks again
gary starr

Gary, the Twincam head gasket only fits the Twincam engine, not a pushrod. Different stud pattern.

You have to be very careful assembling a Twincam. I've measured valve to piston clearance when timing is correct and it is in the range of 0.080" !

Be thankful you have a chain, not a belt, as the belts do break - chains may slop but rarely break.

When you get into the engine I can send you lots of info on building it to last, and eliminating weak points like the chain tensioner (they regularly strip), carb mounts (how not to burn pistons) etc.
Bill Spohn

Don,

I have two doc's that might be worth a read.

Twin Cam Production Changes and a sort of Special Tuning guide, both still draft, but drawn from as many sources as I can find.

Both list changes made to the engines over the years, to help make the engines more reliable.

Email me for the Production Changes.
S/T guide is here.
http://freespace.virgin.net/marka.hester/RaceStuff.htm

Cheers <MARK>
Mark Hester

This thread was discussed between 17/05/2006 and 18/05/2006

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