Dual timing chain gear orientation : MGB & GT Forum : The MG Experience

Dual timing chain gear orientation #1 This topic is about my 1980 MG MGB Limited Edition (LE)
Kats Bee Jim and Kathy Buckalew Kingsville, TX, USA Sign in to contact 1977 MG MGB "Esmerelda (for Now)" 1978 MG MGB "The Parts Store" 1979 MG MGB "Barbi" 1980 MG MGB Limited Edition (LE) "Elvira"	Topic Creator (OP) Sep 28, 2016 08:08 PM Joined 15 years ago 2,415 Posts

I did the search thing and couldn't find anything, so here goes. I know how the normal single row timing gears go on, but I have heard that the dual sprocket crank gear goes on 180 degrees out from "normal". How far off am I in this thinking? Jim

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Re: Dual timing chain gear orientation #2
ghnl Eric Russell Mebane, NC, USA Sign in to contact 1961 MG MGA "Calvin"	Sep 28, 2016 08:22 PM Top Contributor Joined 12 years ago 12,730 Posts

In reply to # 3363747 by Kats Bee How far off am I in this thinking?

180 degrees?

Where did you hear the dual row gears install differently? The only confusing part of installing the timing chain & gears is that the manual has one align the dots and then turn the crank one revolution (which turns the camshaft 1/2 revolution or 180 degrees) to install the distributor drive gear.

See the bottom of this page: http://mgaguru.com/mgtech/engine/cm105.htm

Eric Russell ~ Mebane, NC
1961 MGA #61, 1981 Alfa Romeo GTV6, 1984 Alfa Romeo Spider, 1991 Honda ST1100

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Re: Dual timing chain gear orientation #3
dickmoritz Dick Moritz Philly 'burbs, PA, USA Sign in to contact	Sep 29, 2016 01:24 AM Top Contributor Joined 14 years ago 26,263 Posts

Eric is exactly right. There is no difference in installation procedures for the duplex chain setup compared with the simplex setup. With both setups, install the sprockets dot-to-dot. Then turn the crankshaft one additional revolution so you can install the distributor drive gear per the illustration in all the manuals.

For the record, the duplex setup changes the camshaft timing ever so slightly, retarding it about four degrees, which moves the power band of the engine up a couple hundred rpm. But this difference is not noticeable during installation...

Dick

In reply to # 3363753 by ghnl

In reply to # 3363747 by Kats Bee How far off am I in this thinking?

180 degrees?

Where did you hear the dual row gears install differently? The only confusing part of installing the timing chain & gears is that the manual has one align the dots and then turn the crank one revolution (which turns the camshaft 1/2 revolution or 180 degrees) to install the distributor drive gear.

See the bottom of this page: http://mgaguru.com/mgtech/engine/cm105.htm

Errabundi Saepe, Semper Certi
(Often wrong, but always certain)

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Re: Dual timing chain gear orientation #4
Speedracer Hap Waldrop Taylors, SC, USA Sign in to contact 1967 MG MGB Racecar "The Biscuit"	Sep 29, 2016 04:50 AM Top Contributor Joined 18 years ago 43,720 Posts

Look at the picture, the end facing upward goes towards the crank, you would figure this out soon enough if you did it wrong, as the two sprockets would be badly misaligned.

Hap Waldrop
Acme Speed Shop
864-370-3000
Website: www.acmespeedshop.com
hapwaldrop@acmespeedshop.com

Acme Speed Shop www.mgexp.com

MG/ Triumph Performance Street Engines - Cylinder Head Porting for street performance and race - DIY Engine Rebuild Kits With Free Tech Advice - VTO alloy wheels for British Sports Cars, and others

MGBcranksprocket.jpg 13.8 KB

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