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DIY pedestal type Hi ratio rocker arms for my MGB

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pinkyponk Avatar
pinkyponk Gold Member Adrian Page
Berwick, NS, Canada   CAN
I've never liked the MGB rocker arm setup and have had my eye on something a bit more precise and durable. I figured American V8 type rocker arms looked like a good way to go. Then I stumbled on Dave Headley's Fab-tek rocker arm setup. Dave used Chevy Cavalier rocker arms to do what I wanted. I asked Dave for permission to do a DIY thread on my version of his great idea. Dave said "feel free" so here's where I'm at so far.

I decided to modify Dave's setup to make it fit more with my limited machining abilities. I didn't want to have to drill and tap bolt holes into my head and I'm not sure how Dave does his external oil system to the pedestal rockers so I'm going to try to do mine from the original rocker shaft oil port with some sort of manifold.

So I ordered a set of 8 Chevy Cavalier 1.6 ratio rocker arms and designed my rocker arm base plate to suit. I drew up a base plate in my CAD program based on lots of measurements of my spare head. I have a large laser cutter for making sign letters among other things so I cut out the base plate on the laser from 1/2" acrylic(Plexiglas). This is just a mockup to get all the dimension correct before I make one out of metal. I had to mill a slot using my table saw along the length of the plate to key the rocker pedestals into. Then I threaded all the rocker arm bolt holes.

I had to make 2 plates to finally get all the dimensions correct... but the second attempt bolts right up. One of the valves on this head is 1/16" off to one side which a bit of a surprise. I'll fit it to the head on the engine before I make any adjustments.

Now I have to figure out how to get oil to the rockers. Suggestions/ideas welcome.

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 3 time(s). Last edit at 2019-01-20 04:12 PM by pinkyponk.

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MT-B Avatar
MT-B Matt T
City, NY, USA   USA
Looks great! Could make for a very tidy install. Where are the oiling points you are hoping to lubricate? Both sides of each pedestal?

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pinkyponk Avatar
pinkyponk Gold Member Adrian Page
Berwick, NS, Canada   CAN
In reply to # 3877230 by MT-B Looks great! Could make for a very tidy install. Where are the oiling points you are hoping to lubricate? Both sides of each pedestal?

Not sure... I think if it hit the bolt in the middle it would get pretty much everywhere it was needed. Or else either side of each bolt. I'm worrying about how big a "hole" I can use without upsetting the oil pressure to other vital parts. By "hole" I mean total surface area of all the little holes required to hit 8 rocker arms.

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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MT-B Avatar
MT-B Matt T
City, NY, USA   USA
Good point, that area would add up quickly if you tried to have one oiling port for each side of 8 rockers. I was originally thinking of an oil passage milled into your mounting plate with tiny ports to spray upwards to the sides of the pedestals. If you siameased the ports between rockers to spray in both directions you might only need 9 ports, but I have no idea what type of nozzle or port you could use to generate that kind of spray.

[/quote]

I'm worrying about how big a "hole" I can use without upsetting the oil pressure to other vital parts. By "hole" I mean total surface area of all the little holes required to hit 8 rocker arms.

Adrian
[/quote]

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260mgb Jim Nichols
Sequim,WA, USA   USA
Too bad you can't use lifters that feed hollow pushrods.

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mgblestyle Avatar
mgblestyle Philip Shave
Olympia, WA, USA   USA
Adrian, your projects usually come out very well so I'm looking forward to following this. If your base were to incorporate a channel feeding oil from the factory rocker feed hole in the head, then you could vertically drill for a port to your oiling manifold. looks like oiling is necessary to the pushrod side of the rocker and the valve tip side; perhaps a spurt hole directed at each from a central manifold? I see Dave has begun using LS rockers at 1.7:1; reason you decided to stay with the Cavalier rockers? Phil

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ozieagle Gold Member Herb Adler
Geelong Victoria, Australia   AUS
1958 Wolseley 1500 "Wooly"
1966 MG MGB "Bl**dy B"
Looks great.

One thing that would worry me is fitting the mounting plate under the head bolts. With the "hammering" pressure on them would the base plate distort, leading the possible head gasket, or worse, failure?

IIRC special hardened steel washers go under these stud nuts, to stop that distortion.

Herb



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pinkyponk Avatar
pinkyponk Gold Member Adrian Page
Berwick, NS, Canada   CAN
In reply to # 3877263 by mgblestyle Adrian, your projects usually come out very well so I'm looking forward to following this. If your base were to incorporate a channel feeding oil from the factory rocker feed hole in the head, then you could vertically drill for a port to your oiling manifold. looks like oiling is necessary to the pushrod side of the rocker and the valve tip side; perhaps a spurt hole directed at each from a central manifold? I see Dave has begun using LS rockers at 1.7:1; reason you decided to stay with the Cavalier rockers? Phil

The original oil hole in the back rocker will be used for oil to go up to some sort of oil spray pipe that will go across the top of the rockers. I'm just not sure what size holes I need to use. The smallest drill I have is 1/64" (16 thou). They look extremely fragile. I'm hoping something closer to 25 or 30 thou will be required.

I went with the Cavalier rockers because I don't want the extra lift... I have a cam designed for the supercharger and it was setup for a 1.4 rocker ratio. I also liked that the "key" at the bottom of the pedestal was 90 degrees to the rocker. It makes machining the groove they sit in very easy.

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 2019-01-19 09:59 PM by pinkyponk.

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pinkyponk Avatar
pinkyponk Gold Member Adrian Page
Berwick, NS, Canada   CAN
In reply to # 3877281 by ozieagle Looks great.

One thing that would worry me is fitting the mounting plate under the head bolts. With the "hammering" pressure on them would the base plate distort, leading the possible head gasket, or worse, failure?

IIRC special hardened steel washers go under these stud nuts, to stop that distortion.

Herb

Thanks Herb. The MGA used to use aluminum pedestals so I guess aluminum will work. Apparently they weren't that great but It would also be much taller in the case of an MGA rocker pedestal than my 1/2" plate. I am considering using steel though. There is a company in Halifax with a large metal cutting laser so I figured I would get a quote. I wouldn't be able to mill the slot for the rockers myself though. If I went with aluminum I can use my Plexiglas pattern to cut the plate out with my router and flush trim bit... and mill the slot on the table saw. I'll get a quote for aluminum and steel. It might be a decent day trip to go see a big metal laser in action.

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 2019-01-25 02:08 PM by pinkyponk.

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fast-MG.com Avatar
fast-MG.com Gold Member Dave Headley
Cortez, 4 corners, Colorado, USA   USA
Adrian, I'm still interested in knowing your source for the Cavalier rockers as the supply from GM dried up. This the reason I went to the LS rockers which are now and should be readily available for a long time. Now that I've worked out the engineering of the LS 1.7 rockers I am quite happy with those.smoking smiley


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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Denis Avatar
Denis Denis Hill
Bearii, Nth Victoria, Australia   AUS
Adrian you are definitely a goer. Looks great and has real potential. 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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tvrgeek Avatar
tvrgeek Scott S
Hillsborough, North Carolinia, USA   USA
1965 MG MGB
I think an overhead pipe might be the best bet. You can get cooling oil on the springs that way.



Cogito ergo sum periculoso

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pinkyponk Avatar
pinkyponk Gold Member Adrian Page
Berwick, NS, Canada   CAN
In reply to # 3877304 by fast-MG.com Adrian, I'm still interested in knowing your source for the Cavalier rockers as the supply from GM dried up. This the reason I went to the LS rockers which are now and should be readily available for a long time. Now that I've worked out the engineering of the LS 1.7 rockers I am quite happy with those.smoking smiley

They are not OEM Dave, they are Enginetech ER901. Made in China someplace. Enginetech seems to be a fairly large importer of parts in Texas.

I got them from Rock Auto. https://www.rockauto.com/en/parts/enginetech,ER901,rocker+arm,5656

I would have used the LS1 rockers but I want to keep the lift down closer to the what the cam was designed for.... to limit overlap. Also it's easier to cut one long slot to locate them.

Any suggestions on how many and what size holes I might want to use for my oil spray bar?

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
Let me just say that eight .025" holes in a spray bar tube above the rockers is borderline too much oil, especially if the tappet chest drains are not increased. This with a nearly unlimited oil supply coming from the right side main oil galley, not the rear cam bearing.


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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riley1489 Avatar
riley1489 Gold Member Bruce H
Great White North, QC, Canada   CAN
1953 Jaguar XK120
1959 Riley 1.5 "King George"
1973 MG MGB
Some random thoughts Adrian, and you probably have already considered;

I think the B seines engine relies more on a 'controlled leak' for this top end lubrication rather than a particularly measured release of oil. FWIW a worn rocker shaft will not show up as alarmingly oil pressure drop?

We should remember that the rear camshaft bearing oil supply to the top end is intermittent with every second revolution . Cut a new slot in your camshaft bearing journal and get double the oil supply. cool smiley

The early engines had an oil feed to the tappet adjusting screw, later dispensed with this. Did oil pressure change? winking smiley

Some dimensions that you probably have covered;

Oil feed hole in cylinder head, .215"
holes in rocker shaft .100"
hole to tappet adjuster screw .100"

'spray' hole in rocker arm .070"

Have fun

B



Check your ego Amigo!

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