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DIY pedestal type Hi ratio rocker arms for my MGB

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ozieagle Avatar
ozieagle Gold Member Herb Adler
Geelong Victoria, Australia   AUS
1958 Wolseley 1500 "Wooly"
1966 MG MGB "Bl**dy B"
Double BUGGER!!!!

Herb



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Denis Avatar
Denis Denis Hill
Bearii, Nth Victoria, Australia   AUS
You could not trust the rest of em. Must be a bodgy batch. Your workmanship looked great to me and would have thought they would have been indestructible. Denis



68 B roadster, Daffodil yellow, supercharger, Burgess SC head, SC cam, Mikuni HSR 48 carburetor and engine built for supercharging.

73 BGT V8 conversion starting with a bare shell. Built the engine "3.9L Rover" early in 2016 with high comp pistons and a few other nice bits, plus a T5 ford trans. Started on the body late 2016 and complete late 2017, Did all the work myself, mechanical, body. paint etc.
Finished and going well, great to drive and quick. Now has a nice 3.23 LSD.

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pinkyponk Avatar
pinkyponk Gold Member Adrian Page
Berwick, NS, Canada   CAN
In reply to # 3908356 by fast-MG.com Yes, those are supposed to be press fit. Did you say they came from Rock Auto, not GM? I don't think that rocker has been used by GM for at least 15years. I've seen a few that loosened slightly due to large pushrod side loading from contact in the head hole. Were the bolts still tight? Are any other rockers showing signs of loosening?

They came from a place in Texas http://enginetech.com/ but I bought them through Rock Auto. Lots of places sell them.

The pushrods have plenty of clearance... I removed a lot of metal. All the pushrods spun freely at all lifts. I don't see how pushrod contact would defeat a press fit.

All the rocker hold down bolts were tight. I didn't try to remove any of the other bearings beyond checking them with my fingernails. It was the end of a long day and my enthusiasm was a bit low.

These rockers appear to be very well made. I think they just got a bad batch somehow. Stuff happens. It would be difficult to trust these now. If I can't find any OEM ones I'll be forced to modify these so the bearings can't escape. Centre punching, welding, a screw? I have a couple to run tests on...

Adrian



Home built Eaton M62 Supercharger with 7.6psi boost, 8:1 compression, custom "supercharger" cam from Schneider Cams, Mikuni HSR48 Carburetor, Chevy Cavalier 1.6 rocker arms, Maxspeeding rods with Teflon wrist pin buttons, custom aluminum cold air intake, CB Performance computerized ignition, Fidanza 9 pound flywheel, 1.44 exhaust valves in 48cc chamber head, matched manifolds, 2 1/4" exhaust system.



Edited 1 time(s). Last edit at 2019-03-14 06:28 AM by pinkyponk.

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MGB enlarged pushrod holes 004.JPG    53.2 KB
MGB enlarged pushrod holes 004.JPG

MGB enlarged pushrod holes 003.JPG    31.7 KB
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B-racer Avatar
B-racer Jeff Schlemmer
Shakopee, MN, USA   USA
1950 Willys Jeep Pickup "Ratrod"
1971 MG MGB
2014 Dodge Charger
My guess is that the same problem that destroyed so many of your rocker shafts in the past is doing this. That's why I recommended using the bronze roller bearing upgrade kit a couple months ago (in the Performance post). It also appears as though there are significant metal shavings in your first photo. What cam are you using in this motor? What valve springs?



jeff@advanceddistributors.com

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pinkyponk Avatar
pinkyponk Gold Member Adrian Page
Berwick, NS, Canada   CAN
In reply to # 3908451 by B-racer My guess is that the same problem that destroyed so many of your rocker shafts in the past is doing this. That's why I recommended using the bronze roller bearing upgrade kit a couple months ago (in the Performance post). It also appears as though there are significant metal shavings in your first photo. What cam are you using in this motor? What valve springs?

Seriously? The metal shavings in the first photo are from grinding the pushrod holes out oval for pushrod clearance. Dave was concerned about pushrod clearance so I posted the picture for him. The second photo shows the clearance around my home made checking pushrod.

My old rocker gear has had zero effect on the lack of a press fit on these new rocker arm bearings. If some mysterious force was destroying my old rocker shafts(with bronze bushings) , how would new bronze bushings fix anything?

Adrian



Home built Eaton M62 Supercharger with 7.6psi boost, 8:1 compression, custom "supercharger" cam from Schneider Cams, Mikuni HSR48 Carburetor, Chevy Cavalier 1.6 rocker arms, Maxspeeding rods with Teflon wrist pin buttons, custom aluminum cold air intake, CB Performance computerized ignition, Fidanza 9 pound flywheel, 1.44 exhaust valves in 48cc chamber head, matched manifolds, 2 1/4" exhaust system.

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pinkyponk Avatar
pinkyponk Gold Member Adrian Page
Berwick, NS, Canada   CAN
A few good swats with a hammer and punch fixes the issue.

Adrian



Home built Eaton M62 Supercharger with 7.6psi boost, 8:1 compression, custom "supercharger" cam from Schneider Cams, Mikuni HSR48 Carburetor, Chevy Cavalier 1.6 rocker arms, Maxspeeding rods with Teflon wrist pin buttons, custom aluminum cold air intake, CB Performance computerized ignition, Fidanza 9 pound flywheel, 1.44 exhaust valves in 48cc chamber head, matched manifolds, 2 1/4" exhaust system.


Attachments:
Centre punch rocker 001.JPG    40 KB
Centre punch rocker 001.JPG

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fast-MG.com Avatar
fast-MG.com Gold Member Dave Headley
Cortez, 4 corners, Colorado, USA   USA
Adrian, I suggest checking them all for looseness before staking. Manufacturing Ah-shits seldom affect only an occasional part. Also, look at all your push rods for side rubbing witness marks. When I was using these parts on race heads, I would plunge cut the pushrod hole with an end mill, top to bottom, removing about .060" from the valve side of the hole.

When an OE engine manufacturer is building 100s of engines a day using supplier parts like these rocker arms, the appearance of a quality issue becomes quickly apparent. When a supplier of after market(only) parts has a problem, it could take a long time to be discovered. Statistical sampling of finished product vs in-process verification can allow for many bad parts getting into the system. This being part of the reason I quit using this part after it was no longer available from GM.


Member Services:
Dave Headley, dba FAB-TEK offers full service race car parts and preparation for MGB & MGA race cars, SCCA and Vintage. Dave is a mechanical engineer and has raced MGBs since 1963.
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pinkyponk Avatar
pinkyponk Gold Member Adrian Page
Berwick, NS, Canada   CAN
I'm staking all of them Dave... loose or not! There was no play evident in any of them before I installed them and none now in the ones that didn't fall apart. Actually the one I put back together feels nice and tight too. (no undue play I mean)

The pushrods are all pristine. No rub marks on them anywhere. When I ground out the holes I took about 3/16" out and went down past half way but on an angle. I drew a picture in my CAD program to check out what needed to be removed and where it needed to come off and where it didn't.

I notified Enginetech of the issue but whether they take any notice is yet to be seen. Rock Auto has been quick to respond.

Adrian



Home built Eaton M62 Supercharger with 7.6psi boost, 8:1 compression, custom "supercharger" cam from Schneider Cams, Mikuni HSR48 Carburetor, Chevy Cavalier 1.6 rocker arms, Maxspeeding rods with Teflon wrist pin buttons, custom aluminum cold air intake, CB Performance computerized ignition, Fidanza 9 pound flywheel, 1.44 exhaust valves in 48cc chamber head, matched manifolds, 2 1/4" exhaust system.

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fast-MG.com Avatar
fast-MG.com Gold Member Dave Headley
Cortez, 4 corners, Colorado, USA   USA
Adrian, just to be totally clear, if this is not a part quality issue, then it has to be something to do with the operating environment as I've done dozens of engines and customer heads w/o issue over a twenty year time span. All rockers used were sourced from GM.


Member Services:
Dave Headley, dba FAB-TEK offers full service race car parts and preparation for MGB & MGA race cars, SCCA and Vintage. Dave is a mechanical engineer and has raced MGBs since 1963.
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Gerald O Avatar
Gerald O Gerald O'Docharty
Wake Forest, North Carolina, USA   USA
1978 MG MGB
If the pressed in bearing races saw significant high temperature they would have expanded, possibly enough to loosen the press-fit. Perhaps this happened during early testing before the oiling was sorted out?

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fast-MG.com Avatar
fast-MG.com Gold Member Dave Headley
Cortez, 4 corners, Colorado, USA   USA
Adrian, what position on the head were the failed rocker arms? #1 intake can require a little hand work on the bench grinder to clear the front front rocker cover stud.


Member Services:
Dave Headley, dba FAB-TEK offers full service race car parts and preparation for MGB & MGA race cars, SCCA and Vintage. Dave is a mechanical engineer and has raced MGBs since 1963.
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pinkyponk Avatar
pinkyponk Gold Member Adrian Page
Berwick, NS, Canada   CAN
In reply to # 3908596 by fast-MG.com Adrian, just to be totally clear, if this is not a part quality issue, then it has to be something to do with the operating environment as I've done dozens of engines and customer heads w/o issue over a twenty year time span. All rockers used were sourced from GM.

Dave... in my opinion it is a part quality issue. Somehow the pivots and bearings were not machined to be a press fit.

Adrian



Home built Eaton M62 Supercharger with 7.6psi boost, 8:1 compression, custom "supercharger" cam from Schneider Cams, Mikuni HSR48 Carburetor, Chevy Cavalier 1.6 rocker arms, Maxspeeding rods with Teflon wrist pin buttons, custom aluminum cold air intake, CB Performance computerized ignition, Fidanza 9 pound flywheel, 1.44 exhaust valves in 48cc chamber head, matched manifolds, 2 1/4" exhaust system.

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pinkyponk Avatar
pinkyponk Gold Member Adrian Page
Berwick, NS, Canada   CAN
In reply to # 3908606 by Gerald O If the pressed in bearing races saw significant high temperature they would have expanded, possibly enough to loosen the press-fit. Perhaps this happened during early testing before the oiling was sorted out?

The only time they were running without adequate oil feed was while stationary in my shop with me squirting oil on them from my oil can. No heat involved. They also came packed with grease for start up lube. I'm sure it's a machining error... a sliding fit instead of a press fit.

Adrian



Home built Eaton M62 Supercharger with 7.6psi boost, 8:1 compression, custom "supercharger" cam from Schneider Cams, Mikuni HSR48 Carburetor, Chevy Cavalier 1.6 rocker arms, Maxspeeding rods with Teflon wrist pin buttons, custom aluminum cold air intake, CB Performance computerized ignition, Fidanza 9 pound flywheel, 1.44 exhaust valves in 48cc chamber head, matched manifolds, 2 1/4" exhaust system.

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pinkyponk Avatar
pinkyponk Gold Member Adrian Page
Berwick, NS, Canada   CAN
In reply to # 3908611 by fast-MG.com Adrian, what position on the head were the failed rocker arms? #1 intake can require a little hand work on the bench grinder to clear the front front rocker cover stud.

#1 and #3. No evidence of contact on the rocker cover studs, inside the rocker cover or the on the rockers themselves.

Adrian



Home built Eaton M62 Supercharger with 7.6psi boost, 8:1 compression, custom "supercharger" cam from Schneider Cams, Mikuni HSR48 Carburetor, Chevy Cavalier 1.6 rocker arms, Maxspeeding rods with Teflon wrist pin buttons, custom aluminum cold air intake, CB Performance computerized ignition, Fidanza 9 pound flywheel, 1.44 exhaust valves in 48cc chamber head, matched manifolds, 2 1/4" exhaust system.

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Gerald O Avatar
Gerald O Gerald O'Docharty
Wake Forest, North Carolina, USA   USA
1978 MG MGB
I wouldn't trust that staking to last if there's no press fit. It will worry back and forth and eventually loosen up again. Best to get new ones.

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