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Boom #1
Steve64B Steve Opitz Phoenix, AZ, USA 1966 MG MGB	Posted: March 13, 2012 08:01AM Registered: 6 years ago Posts: 8,348

Thats the sound a motor makes when one of the lock bolts from a Rollmaster adjustable cam gear works loose and gets stuck in the space between the crank gear and timing chain.

First time for this type of failure.

Looks like #4 intake kissed a piston but not a lot of other visible damage ( well except for the timing assembly which is now toothless)

What else should I look for, any pieces automatically suspect?

As always thanks in advance.

Steve

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Re: Boom #2
Filth and Greed Motors Paul Gaylo Corning, NY, USA 1959 MG MGA 1500 1970 MG MGB GT	Posted: March 13, 2012 09:55AM Registered: 5 years ago Posts: 1,379

I always wondered how those bolts stayed put. I will be using loctite on mine.

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Re: Boom #3
Steve64B Steve Opitz Phoenix, AZ, USA 1966 MG MGB	Posted: March 13, 2012 10:13AM Registered: 6 years ago Posts: 8,348

In reply to # 2010132 by Filth and Greed Motors I always wondered how those bolts stayed put. I will be using loctite on mine.

That was my thought when I first saw it as well, and I thought I had loctited all of them, but it appears I missed one!

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Re: Boom #4
Bandit Racing Donald Dickey Illinois, USA 1963 MG MGB Racecar "#99 BRG Vintage Racecar" 1965 MG MGB Racecar "#10 Huffaiker/ British Leyland"	Posted: March 13, 2012 11:25AM Registered: 8 years ago Posts: 271

I have used both Rollmaster and Kent. The clamping force is better on the Kent. I allways locktite plus drill and tap for a 10-32 SHCS which I also locktite. This assures me that the timing will not change

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Re: Boom #5
Steve64B Steve Opitz Phoenix, AZ, USA 1966 MG MGB	Posted: March 13, 2012 03:25PM Registered: 6 years ago Posts: 8,348

In reply to # 2010225 by Bandit Racing I have used both Rollmaster and Kent. The clamping force is better on the Kent. I allways locktite plus drill and tap for a 10-32 SHCS which I also locktite. This assures me that the timing will not change

I don't have the parts in front of me, but after taking the motor down and assessing the mess my first thought was to figure out how to safety wire them so this can't happen again.

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Re: Boom #6
Speedracer Hap Waldrop Greenville, SC, USA 1967 MG MGB "The Biscuit"	Posted: March 14, 2012 07:24AM Registered: 7 years ago Posts: 20,337

One thing that could aggravate this, that I don't think alot of folks are aware of. You absolutely must torque the cam retainimg nut before you adjust the cam timing bolts on any of the verniers adjustment bolts, if you don't do it in this sequence, the torque required to get the cam retaining nut tight, will overpower the small vernier adjsutment fastners, change your cam timing and could cause those fastener to loosen. What I do as far as keeping up with what fasteners I have torque/tightened/loctited is use a touch-up paint bottle (I like red), once it gets torques/tighten/loctitied it gets a dab of the red paint on it, that way I know I've done it at a quick glance.

I've never had this type of failure, with any of the verniers, and I use them on lots of engine for decades now, Rollmaster, Kent, and Powertune, but I'm anal as hell when it comes to double checking and using red loctite,and on low torque fastener, I do not loctitie high torque fasteners like rod bolts , main bolts/studs, etc. just the opposite, they are lubricated, but on small stuff, like 1/4" and 5/16" all that stuff get loctitied, and I only use red loctitie.

Don, I also make index marks on the vernier face with a sharpie, and have never saw any indications of the timing changing, a sharpie marking will be there when you go back for refresh. I write all kinds of stuff on my motor internals with sharpie.

Hap Waldrop
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Edited 2 time(s). Last edit at 03/14/2012 07:33AM by Speedracer.

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Re: Boom #7
blackmgb Fred McConnell Hollidaysburg, Pennsylvania, USA 1992 Mazda Miata NA "MAC"	Posted: March 14, 2012 12:05PM Registered: 6 years ago Posts: 5,194

In reply to # 2011060 by Speedracer ... but I'm anal as hell when it comes to double checking and using red loctite,and on low torque fastener, I do not loctitie high torque fasteners like rod bolts , main bolts/studs, etc. just the opposite, they are lubricated, but on small stuff, like 1/4" and 5/16" all that stuff get loctitied, and I only use red loctitie.

I blew a head gasket at the SCCA races at Barber. Hap and I changed it in less than two hours to make the start, but he checked the torque on my head bolts like five times. I didnt see it as anal and much as compulsive winking smiley

...

2012 SCCA FP MARRS Champion

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Re: Boom #8
Speedracer Hap Waldrop Greenville, SC, USA 1967 MG MGB "The Biscuit"	Posted: March 14, 2012 03:09PM Registered: 7 years ago Posts: 20,337

In reply to # 2011323 by blackmgb

In reply to # 2011060 by Speedracer ... but I'm anal as hell when it comes to double checking and using red loctite,and on low torque fastener, I do not loctitie high torque fasteners like rod bolts , main bolts/studs, etc. just the opposite, they are lubricated, but on small stuff, like 1/4" and 5/16" all that stuff get loctitied, and I only use red loctitie.

I blew a head gasket at the SCCA races at Barber. Hap and I changed it in less than two hours to make the start, but he checked the torque on my head bolts like five times. I didnt see it as anal and much as compulsive winking smiley

...

Yep, I think anyone who every watched me torque head bolts, main caps or rod bolts, knows it would be pretty much impossible for me to leave them loose grinning smiley

Fred that was a broken rocker arm wasn't it, that was the "rebuilt" rocker assembly you had bought somewhere before we went to the roller rocker arms. Yep, that and the distributor I had to time by ear, made for a very interesting weekend, but we got what we came for, got thru the weekend in one peice, you got your regional SCCA license, and two throphies to boot thumbs up

I even got cursed out that weekend for just knowing Dick May grinning smiley

Hap Waldrop
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Re: Boom #9
John Hamilton Austin, TX, USA 1965 MG MGB "The Great Pumpkin" 1968 MG MGB GT "Buck" 1970 MG MGB "Dad's Car"	Posted: March 15, 2012 08:06PM Registered: 5 years ago Posts: 1,699

Ya know, that's the same sound an engine makes when your new trick lightened lifter breaks in half and wedges itself between the block and the cam. I got lucky and only wasted the cam and stock timing gear. The gear spun on the end of my new cam and welded itself on permanently. Live and learn, right?

If I can't be fast, I'll just be obnoxious!

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Re: Boom #10
Steve64B Steve Opitz Phoenix, AZ, USA 1966 MG MGB	Posted: March 16, 2012 03:45AM Registered: 6 years ago Posts: 8,348

In reply to # 2012770 by John Hamilton Ya know, that's the same sound an engine makes when your new trick lightened lifter breaks in half and wedges itself between the block and the cam. I got lucky and only wasted the cam and stock timing gear. The gear spun on the end of my new cam and welded itself on permanently. Live and learn, right?

John, that was my first failure that involved a really big noise and an almost instant loss of power.

Both of the timing gears have that toothless grin going on, one of the grade 8 bolt heads holding the tensioner was sheared off and the cover is now "art". The failure happened just as I was shifting gears and the timing chain piled up around the crank gear and stopped the assembly from turning PDQ.

I still need to clean and measure everything to see what else was damaged.

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Re: Boom #11
timfred Tim Frederick Berkeley, CA, USA 1971 MG MGB GT	Posted: March 20, 2012 01:00AM Registered: 1 year ago Posts: 243

Hi Guys,

I just lurk here in the motorsports forum, dreaming about my race build. But I have to ask...why isn't there a non-vernier but still adjustable cam gear available for these engines? One with multiple keyways, each 1 or 2 degrees advanced from each other? If you have the book, check out page 214 of "Four-Stroke Performance Tuning" by A. Graham Bell for an example.

It would take longer to set up, but no screws to loosen or ring to slip. And should be much less expensive?

Back to lurking...

Tim

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Re: Boom #12
Speedracer Hap Waldrop Greenville, SC, USA 1967 MG MGB "The Biscuit"	Posted: March 20, 2012 06:56AM Registered: 7 years ago Posts: 20,337

In reply to # 2016816 by timfred Hi Guys,

I just lurk here in the motorsports forum, dreaming about my race build. But I have to ask...why isn't there a non-vernier but still adjustable cam gear available for these engines? One with multiple keyways, each 1 or 2 degrees advanced from each other? If you have the book, check out page 214 of "Four-Stroke Performance Tuning" by A. Graham Bell for an example.

It would take longer to set up, but no screws to loosen or ring to slip. And should be much less expensive?

Back to lurking...

Tim

Tim, they are, they are multi keyway crank pulley set ups for B series motors, they are a joke and compromise on cam timing, most folks can't even set them up properly, there once was a adjstable dail pin cam gear set up, they were known to fail at the dial pin, and that lead to big time engine failures, there are offset keys and they are compromises. I think you look at a given component, and it number of uses and failure rate, if the failure rate is low, then it's either a assembly problem or possibly just a rare fluke failure, everything in perforamcne and racing fails eventually, I don't care what it is, hell I've seen billet cranks snap in half on guys, ARP rod bolt break, etc. etc.. In this case of vernier cam gears, they have a wonderful overall sucess rate, been used by damn near everyone for millions of race miles, just because one fialed doesn't mean you abandon the idea.

Hap Waldrop
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Re: Boom #13
Speedracer Hap Waldrop Greenville, SC, USA 1967 MG MGB "The Biscuit"	Posted: March 20, 2012 07:20AM Registered: 7 years ago Posts: 20,337

I'll throw this one out there, to it's no where in the instructions and most of the time people seem quite surprised when i tell them about it.

You can NEVER torque the cam retaining nut after you set the cam timing with 1/4"-28 vernier adjustment bolts, because if you do this out of sequence, the torque of the larger cam retaining nut will overpower the much smaller vernier adjustment bolts and change your cam timing and potentially loosen these fasteners, and especially void loctite, if it's set up. Bottom line, you can never do this out of sequence, or you are asking for trouble, and it would be in a lot of folks mind a good thing to do, no tightening the cam retianing nut until the cam timing is nailed, due to the fact they might have to remove the gear and reposition it, but the cam nut alwas has to be torqued first, always.

Hap Waldrop
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Re: Boom #14
fast-MG.com Dave Headley Cortez, 4 corners, Colorado, USA	Posted: March 20, 2012 08:39AM Registered: 4 years ago Posts: 3,244

Tim, I've used the vernier gears for years, two different brands with never an issue. Hope this comment doesn't jinx me! confused smiley

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Re: Boom #15
larrym Larry Moeller California, USA 1963 MG MGB "Racer" 1968 Volkswagen 1600 "Manx" 1970 Porsche 914 "Sixer" 1999 Mazda MX-5	Posted: March 25, 2012 03:55PM Registered: 9 years ago Posts: 299

bump

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