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MG MGA - roller rockers

does anyone have any feedback on using roller rocker arms on a mk11 "A",valve clearance, timing,etc.
PETE CERKA

No idea why anyone would bother - lots of expense for very little or no real benefit.
Bill Spohn

bill
a company out of upstate n.y. make a rocker the runs a bushing similar to the stock bush,has a roller on the tip for the stem and runs a ratio of 1-1.5 which should improve breathing and the cost is in line with new stock arms bushs and honing
pete
PETE CERKA

You see these "roller rockers" on E-Bay all the time, but also see them as "not allowed" for SCCA vintage racing. What's the deal ? Can you explain, Bill or Pete ?

Thanks
Chuck
Chuck Mosher

chuck
i'm not looking to vintage race just looking for some streetable power
pete
PETE CERKA

Roller rockers do not add power unless they increase valve lift. If you increase valve lift you may need to add eyebrows to top of block for valve head clearance. See here: http://mgaguru.com/mgtech/power/cm202a.htm
Barney Gaylord

Better to fit a hotter cam, lighten the flywheel and port the head. Will bring much more benefit than the roller rockers.

Or go the macho way and fit a supercharger.
dominic clancy

barney
i'm installing a 12h1326 head on the motor so it needs the eye brows anyway and wouldn't a alum. flywheel be a hindrence on the street
PETE CERKA

Pete, I don't think you need the eyebrows with this head, with standard valve lift.
A Pearse

Pete

You don't need eyebrows with that head. I have one on a 1622 high compression engine, ported to stage 2, and it works just great


dominic clancy

ON A 1600 MOTOR
PETE CERKA

Pete, its the same thing. In both cases, the MGA and MGB valves overlap the bores a bit (plan view) but do not open enough to clip the block. There is one later MGB head which is shallower, where you need the recesses. Or if you install a high lift cam, or if you have shaved the head too much. A bit of measurement with the head off will confirm this. Measure the depth to the valves and compare with the valve lift, plus .050 for luck.
Art
A Pearse

ART
MY MK11 1622 MOTOR IS THE SAME VALVE DIMENSION AS THE EARLY B HEAD I'M INSTALLING ON THE 1600 MOTOR AND THE 1622 HAS EYEBROWS
PETE CERKA

Someone cut those eyebrows in your 1622 at some point. The only blocks that were "eyebrowed" at the factory were the '72-'74 18V blocks. These engines used heads that had "18L" cast into them. If your head says 18L then you definitely need the eyebrows, UNLESS as Art says someone skimmed that head at some point. Of course it's your engine and you're free to add eyebrows, moustaches, toupes, whatever you want. We're just saying you don't necessarily need to.
Mark J Michalak

"Of course it's your engine and you're free to add eyebrows, moustaches, toupes, whatever you want."

LOL!
Bill Spohn

This thread was discussed between 16/02/2009 and 22/02/2009

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