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High compression engine.

Posted by BRAVO-4 
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BRAVO-4 Avatar
CRAIG PURYEAR
norfolk, virginia, USA   usa
1971 MG MGB "The Killer Tomato"
1979 MG MGB "MAURICE"

So i find out my 71B has a high compression engine, What does that mean for me, good bad, special? anything special I need to be aware of?, thanks, I feel stupid know.
My engine number is
18GK-WE-H-631

Ralph 7h Avatar
Ralph Siebenhaar
Viersen, Germany   deu

Nothing to worry about.
I would ask Jeff Schlemer to built me an adequate dizzy for using all the performance this engine can provide.

mac townsend Avatar
Fairfield, CA, USA   usa

In reply to a post by Ralph 7h Nothing to worry about.
I would ask Jeff Schlemer to built me an adequate dizzy for using all the performance this engine can provide.

but be aware that your socks will remain unbothered by said increased performance<G> (i.e. it will not "knock your socks off"winking smiley



1973 Pale Primrose Roadster. A nice 10-footer!
SUs, Datsun 5-speed
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underdog Avatar
Jim Underwood
Pittsburgh, USA   usa
1972 MG MGB
1980 Triumph TR8 "Fabulous Trashwagon"
1999 Chevrolet Corvette "Darth Vader"
1999 Chevrolet S10 "Spare Change"
2003 Jaguar S-Type "Eleanor"

Even the HC engines were only 8.8 to 1. Not exactly high compression by American car standards. I have a 70 Cadillac that came with 10.5 to 1 as did the Muscle Cars before the EPA came along with unleaded fuel in 71-72.

Ralph 7h Avatar
Ralph Siebenhaar
Viersen, Germany   deu

Mac,

you are certainly right, but it might pretend the engine from melting piston tops down to the first compression ring on highway speeds. Just a personal experience...

Ralph

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scotabbott Avatar
Scot Abbott
Pittsburgh, Pa 15216, USA   usa
1974 MG MGB "Bee"

In their prime, the B motors only produced about 85 HP, which by the standards of the day was on the low side of "OK". Most cars of those days were producing a more than 1 HP per cubic inch, and the best years of the B fell short of that. Later years of B with lowered compression ratio, poorer carbs and retarded timing reduced the output to about 50 HP, which is pretty poor by most any standard.
A motorcycle made at the time of the B's (e.g. honda cb 500) of 500 cc dislacement produces 50+ HP. Scaling for displacement, that corresponds to about 180 HP for a 1.8 liter motor. (i.e. 1HP per 10 CC). Many car motors do about as well these days.

Any way you slice it, the B motor does a pretty poor job. In al.l the stock forms, there is little power but lots of air pollution and fairly poor gas mileage. The kinds of improvements for the B (in order of increasing cost, and decreasing bang for the buck) are :

recurve the dizzy and add electroic ignition
replace single carb with twin carb setup
add high compression pistons
replace carbs with fuel injection
add a better cam
head work or replace head

I personally favor the route of a recurved dizzy, hi compression pistons and fuel injection. (never tried the cam)Makes the B run really nice, reliable and clean. It is not as drastic or expesive as an engine swap or adding a supercharger.



Edited 1 time(s). Last edit at 2010-03-09 05:44 PM by scotabbott.

MrMarty51 Avatar
Martin Draper
Miles City,Montana, USA   usa
1978 MG MGB "" Little Red Crapper Car""

In reply to a post by scotabbott In their prime, the B motors only produced about 85 HP, which by the standards of the day was on the low side of "OK". Most cars of those days were producing a more than 1 HP per cubic inch, and the best years of the B fell short of that. Later years of B with lowered compression ratio, poorer carbs and retarded timing reduced the output to about 50 HP, which is pretty poor by most any standard.
A motorcycle made at the time of the B's (e.g. honda cb 500) of 500 cc dislacement produces 50+ HP. Scaling for displacement, that corresponds to about 180 HP for a 1.8 liter motor. (i.e. 1HP per 10 CC). Many car motors do about as well these days.

Any way you slice it, the B motor does a pretty poor job. In al.l the stock forms, there is little power but lots of air pollution and fairly poor gas mileage. The kinds of improvements for the B (in order of increasing cost, and decreasing bang for the buck) are :

recurve the dizzy and add electroic ignition
replace single carb with twin carb setup
add high compression pistons
replace carbs with fuel injection
add a better cam
head work or replace head

I personally favor the route of a recurved dizzy, hi compression pistons and fuel injection. (never tried the cam)Makes the B run really nice, reliable and clean. It is not as drastic or expesive as an engine swap or adding a supercharger.
:thumbsup:

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