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DIY pedestal type Hi ratio rocker arms for my MGB

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Gerald O Avatar
Gerald O Gerald O'Docharty
Wake Forest, North Carolina, USA   USA
1978 MG MGB
This could just be a drop in pressure visible at the gauge due to the already restricted size of the fitting that you tapped into. As I recall, the fitting on the block that feeds the braided hose to the T fitting is already a pretty small hole.

Pressure in the main galleries may be higher. You'll need to take a pressure reading off the main gallery to be sure.



Edited 1 time(s). Last edit at 2019-03-12 02:57 PM by Gerald O.

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pinkyponk Avatar
pinkyponk Gold Member Adrian Page
Berwick, NS, Canada   CAN
Thanks Gerald. What would be the easiest way to take a pressure reading of the main oil gallery?

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
You could tap into an oil cooler line by inserting an appropriate T fitting.

Or rig up a modified oil filter with a fitting tapped into it.

in any case, if it turns out that your pressure gauge is giving a false reading due to the 'pressure divider' you've created, you'll need to think about relocating its feed point permanently.



Edited 2 time(s). Last edit at 2019-03-12 04:06 PM by Gerald O.

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fast-MG.com Gold Member Dave Headley
Cortez, 4 corners, Colorado, USA   USA
That's the reason I source my oil from on top of the block boss that mounts the filter.


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
Adrian, I measured the diameter of the hole drilled through the block fitting to be 0.062" (1.575 mm). This works out to a cross-section area of 1.95 mm^2. The four 0.025" holes in your spray bar total 1.27 mm^2.
1.27/1.95 = 0.65. So this means you could be seeing as much as a 65% pressure drop after the fitting and at the gauge. Though probably not quite that much, due to the boundary effect of the small 0.025 holes which will flow less than a single larger hole of the same total area.



Edited 1 time(s). Last edit at 2019-03-12 06:33 PM by Gerald O.

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pinkyponk Avatar
pinkyponk Gold Member Adrian Page
Berwick, NS, Canada   CAN
Well... if I take the 40 psi I have and add 65% I get 66psi. Your assessment seems legit Gerald. thumbs up ...and thank you! I expect it is all fine the way it was but I can't look at the gauge reading 40 psi like that and be happy.

I have cut things up and will plumb the little fella off the oil filter housing some time tomorrow. I was short a fitting and 2 feet of high pressure hose or I would have had it done tonight.

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
So I plumbed the oil feed to the rockers via the oil filter housing... and my oil pressure gauge reads as it should. Four 25 thou holes spewing hot 70psi oil is a LOT of oil. These rocker arms may fail for some reason... but it won't be due to lack of oil!

I didn't want to drill and tap the block where the filter adapter bolts to so I put my fitting on the bottom of the aluminum adapter itself. This would be a better location because you could keep an eye on the fitting easier. It looked a bit awkward to drill and tap with the engine in place so I did the adapter instead.

Super big thank you to Dave Headley for coming up with this idea and then helping me to make my own setup!

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 2019-03-15 10:58 AM by pinkyponk.

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fast-MG.com Avatar
fast-MG.com Gold Member Dave Headley
Cortez, 4 corners, Colorado, USA   USA
You are welcome!smileys with beer


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 # 3907587 by Gerald O You could tap into an oil cooler line by inserting an appropriate T fitting.

Or rig up a modified oil filter with a fitting tapped into it.

in any case, if it turns out that your pressure gauge is giving a false reading due to the 'pressure divider' you've created, you'll need to think about relocating its feed point permanently.

Turns out it was a false reading as we suspected... a modified oil filter would be a cheap way to see what was what. Just no way I would be happy looking at the oil pressure gauge reading 40 pounds.

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
I took the rocker cover off to have a look at how things were looking and found this. So they held up for roughly a mile and a half. * sigh *


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 2019-03-13 07:46 PM by pinkyponk.


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fast-MG.com Avatar
fast-MG.com Gold Member Dave Headley
Cortez, 4 corners, Colorado, USA   USA
Did you check your springs for coil bind? Any valve interference to block? Any sign of pushrod side loading in the head holes?


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
Oh dear! I hope you accounted for all the bits...

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pinkyponk Avatar
pinkyponk Gold Member Adrian Page
Berwick, NS, Canada   CAN
Yes, I checked for coil bind. There is no contact with the valves to the block... my combustion chambers are deeper than the valve lift. The pushrods are 1/8" away from the holes. The little outer sleeves slid out with no effort. They should be a press fit over the pivot shaft.

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 # 3908344 by Gerald O Oh dear! I hope you accounted for all the bits...

Not yet. I can see 3 needles sitting in the #1 tappet. I can't find my magnet on a stick to retrieve them. I didn't search too hard... I just went in and had a beer and watched tv.

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 06:12 AM by pinkyponk.

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fast-MG.com Gold Member Dave Headley
Cortez, 4 corners, Colorado, USA   USA
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?


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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