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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 - Twincam Pistons

The machining phase of the rebuild of my Twincam engine is almost complete. All that remains is to rebore the cylinders, but I have yet to obtain a set of pistons. Does anybody out there know of a reasonably modern design piston for the Twincam? I really don't want to go with the antiquated five-ring pistons if I don't have to.
Steve S.

Call Bob West and ask him. Do a google on Bob West Pontefract
dominic clancy

Here is his site-
http://www.bobwestclassiccars.co.uk/index.htm
gary starr

Venolia made a set for a 1600 for me years ago. I believe you can order a set of cast, not forged, 3 ring pistons for your car.
http://www.venolia.com/imports.html#MG
They have a part # listed here.
The ones I bought were cheaper, better, lighter and stronger than the cast AP pistons that were avaiable then. I would choose these over what is normally available for any engine. For a high performance situation I would also consider better rods.
Carrillo sells rods that can improve performance and durability. http://www.carrilloind.com/app.html
The Carrilo rods can eliminate a lot of weight and are much stronger than stock.
R J Brown

Talk to Jim Alcorn in La Jolla , Calif. You shoud find his number in the archives. He rebuilds Twin Cams and has parts.
JEFF BECKER

I have a set of new original Hepolite +010" pistons, they have 3 rings plus oil control, I am told they are better quality than some repro's, obviously quality race spec pistons should be OK


Terry
Terry Drinkwater

There is a set on eBay now.
D.M. Black

Steve- My TC knowlege is limited but that said be careful of those ebay pistons, they look like the hi compression ones. With the .040 over bore and not knowing how many times your head has been skimmed your CR could be too high.
gary starr

Steve, This is not the same subject, but I had earlier enquired about the details of your deluxe seats (made from MGB frames). How did that go? Could you give details of the cutting process? Could you post some pictures? Or better yet e-mail them to me? Or even better, ask Barney to post them? I would like to do this but feel that a little more guidance from someone who has actually done it would be invaluable. Thanks for any help.
James Johanski

1) Steve, do you know of the twin cam and deluxe specific web site hosted by Yahoo groups?

2) Jahn's can make pistons for you as I inquired about a low compression set a few years back. However, there's really no need to go with the low compression as all of that piston holing problem can be easily fixed by flexibly mounting the carbs.

All of that information and more is available from the 200+ list readers at the twin cam-deluxe Yahoo site.

Regards,
Blake
Moderator, twin cam deluxe owners Yahoo group
Bullwinkle

Steve,

You say that your engine machining is complete, but you have not yet bored the cylinders.
What have you machined?
There are a few traps with the Twin Cam engine.
Have you line bored the main bearing housings in the block? This can cause binding of the half speed gears (there is a cure).
Have you machined the top deck of the block or the head gasket surface of the cylinder head?
Have you re-profiled the camshaft lobes?
When the engine was new the valves only cleared the high compression pistons by 0.076" at the closest point. This was with the standard valve clearance of 0.015" and a standard valve lift of 0.375" and a compressed gasket thickness of 0.031".

Mick
Mick Anderson

Gary-
Thanks for the URL. I'll contact Bob West A.S.A.P.

RJ-
I have a set of Carilo connecting rods and JE pistons in my MGC. Expen$ive! Smooth engine, though.

James-
I have been telling the family for three years that I want a good, high resolution digital camera for Christmas, my birthday, etc. Nothing yet. Maybe this Christmas? As for the seats, I simply cut the top and bottom tubes at a 45 degree angle, reamed the interior, then press-fitted a centerless ground piece of tubing, welded it all back together, and then ground the welds smooth. A good coat of gloss black enamel finished the job.

Gary-
I never but anything off of Ebay. Too great a chance of getting ripped off.

Mick-
All machining is complete except for boring the cylinders. That's why I'm looking into what's available in the way of pistons. I'm aware of the clearance hazard. I was unaware of the binding problem of the half speed gears resulting from line boring of the main bearing saddles. Tell me more.
Steve S.

Steve,

Thanks, and I look forward to the pictures as soon as your family gets you that camera.
James Johanski

Steve,

The normal method of line boring the main bearing saddles in the block is to machine some metal off the joint faces of the main bearing caps, fit the caps, then bore the block and caps back to the original diameter, but with a higher centerline.
This is OK with chain driven half speed sprockets, but with the Twin Cam half speed gears it causes binding of the gears.
The gear backlash should be a maximum of 0.002" to 0.003".
If you have a binding set of gears you will need to have them accurately mounted and lap them in with valve grinding paste.

Mick

Mick Anderson

Mick-
I'm aware of the machining technique that you mentioned, but I would never do things in such a slipshod manner. I always aim right down the center axis. If new main bearing caps become necessary, then so be it. Test assembly showed no binding anywhere. Just goes to show that being a mad perfectionist does sometimes pay off!
Steve S.

You have been getting some excellent advice here.

I would have no reservation about using Hepolite replacement pistons. I do not like Jahns cast - they are too heavy. I have some pieces of some around here somewhere.....

If you will be running your engine to red line, forged would be a nice touch. I had some made up by Ross, but that was a custom job. There really isn't anything wrong with the Hepolites, though.
Bill Spohn

I just reread my earlier post Venolia are forged pistons not cast like the cheapies. I stated it backwards.
R J Brown

Slightly off-topic, but I have recently rebuilt the engine in my XK150 DHC.

I used forged Venolia pistons and Arrow Precision Engineering's steel con rods - both were of excellent quality.

The resulting engine is very smooth & powerful, but B....dy expensive.

I can't speak too highly of Bob West for MGAs,

Nigel Steward

This thread was discussed between 19/11/2006 and 27/11/2006

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This thread is from the archive. The Live MG MGA BBS is active now.