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Engine question

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jaybird

jaybird

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Does a '66 MGB have a 3 or 5 bearing engine? I can't find out - either that or I don't know exactly where to look.

We're onto Plan B (literally) since the crochety ol' bag wouldn't take this crazy lady's ridiculous offer on the '71. The answer to this question could make a difference.
 
Would it make a HUGE difference when looking for a car? I know the 5 main has supports on each side of the bearing, that has to be better.
 
5-main bearing engines were first introduced in late 1964 for the 1965 model year. So a '66 model should have a 5-main engine if it is still original. As far as what to look for, the 5-main engines are stronger, have less vibration and will last a bit longer between rebuilds. However, the 3-main units are said to rev faster and more freely which is why many racers love them. I have a 5-main in my '65 which has been bombproof. I also have a 3-main 8100 in my MGA and it really does rev very nicely. Hope this helps!
 
But, I can put an aluminum flywheel on a 5 main and have the best of both worlds right?
/ubbthreads/images/graemlins/devilgrin.gif

I suppose I'm jumping the gun a bit, since we don't have a '66 in our possession yet. But I wanted to make sure it wasn't a deciding factor.
 
I would personally go for the 5-main in a daily driver MGB. If you really want it to rev more easily, lighten the stock flywheel a bit. The aluminum ones are a pain in traffic from what I've been told.
 
Steve wrote:

"I also have a 3-main 8100 in my MGA"

How did you squeeze it in?
 
[ QUOTE ]

"I also have a 3-main 8100 in my MGA"


[/ QUOTE ]

So your pistons are about the size of a 2 litre bottle of diet coke? Sweet!

Did you go for the PTO option so you can split logs after you pull those stumps with it?
 
Take my word for every penny it's going to cost you...

Aluminum flywheels are not intended to be used on the
street in stop and go traffic. Unless you enjoy replacing
clutches. Then go for it, but I can ensure you won't be
pleased doing it 3 or 4 times a year. I got fed up with
replacing a twin disc 5.5" Tilton every 4 months in my
2.0L Capri, I couldn'y imagine doing it in an MG... as
the tranny in the Capri will come out the bottom, good
luck with an MG...
 
In my Competition Preparation Manual it says this about the flywheel. "The standard flywheel is adequate for competition use as supplied. The balance should, of course, be rechecked before assembly on the engine. It is possible to lighten the stock wheel to a minimum of 16 pounds. I do not advise going lighter than 16 lbs for safety reasons. Care should be taken while machining the stock wheel to insure that no section is less than 7/16" thick. When lightening the wheel, a 3/8" minimum radius should be used at all corners. A factory lightened flywheel is available for 18GB engines. Part #AHT 86."

I assume the factory flywheel may not be available unless someone cross references it. Just thought you should know.
 
The flywheel is a major contributor to overcoming inertia... a torque booster of sorts starting from a dead stop. If you only do that once in every 100 miles of driving, no prob! Otherwise stay with the "stock" version. Save the clutch.
 
I have a very light factory flywheel (11#) that was cut on a cnc machine and balaced to 15000 rpm (as I am told). Works well on my street/race prepared car. Yes, it can stall if you do not launch just right. But the motor spins up very fast...It is quite amazing, IMO. The car is my daily driver....I like the way it drives, but wouldn't recommend it for most drivers

Here are some pics of it:
dscn0027.jpg

dscn0030.jpg


Paul
 
Phantomracer, AKA, Paul, yeah, the Capri wound up really
quick, but the scrubbing of the clutch caused massive wear,
so while the car accellerated much quicker, it was a bit
of an annoyance to be changing the clutch disks as often
as I was. So a standard flywheel was found and installed
and all the problems with the clutch solved. I haven't put
a clutch in ti for almost an entire year...

SteveL
 
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