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1977 MGB engine noise

Posted by 1977MGBflip 
Jeff Burgess
Pensacola, Florida, USA   usa
1977 MG MGB

Hello,
Just curious about the way an MGB should sound. Mine seems to run pretty well. Only had it a month but notice a rather loud tapping from the top of the engine. Sounds like number one is lounder than the rest. I have listened to many youtube videos of engines running and they seem loud as well but I think mine may be a little louder. Just hard to tell standing in front of the car and then listening to a video. Very similar sound but suprised at just how loud these little engines are! If it is normal, okay then. I did adjust my valves to try and get rid of the tapping but to no avail.
Any suggestions?
Thanks,
Jeff
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Lee Avatar
Lee
Lee Miller
Mburg, PA, USA   usa
1966 MG MGB
1967 MG MGB
1971 MG MGB
1971 MG Midget

I believe what you are hearing is normal push rods tapping the rockers.



Lee Miller

Experience - hobbyist, rotisserie restoration 1967 MGB, welding, bodywork, painting, wiring, interior, suspension, clutch, engine, SU HS4 carburetors, windshield, and installing convertible top.

Website www.myclassicmg.com

1971 MG MGB
1971 MG Midget
1967 MG MGB
1966 MG MGB restoration project
Jeff Burgess
Pensacola, Florida, USA   usa
1977 MG MGB

Thanks, I suspect that your are correct. I wouldn't mind finding a way to quiet them a bit. Think dynamat inside the valve cover would help? LOL
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Jeff Burgess
Pensacola, Florida, USA   usa
1977 MG MGB

May try a compression test as suggested by another just to be sure. Also have a stethoscope just for this purpose. Too lazy to get it out and listen. guess I'd better do that. I really don't expect to find anything wrong though.
Thanks again.
dipstick Avatar
Kenny Snyder
La Center, Washington, USA   usa

If it is one valve you could have a bent push rod. With the valve in the adjustment position rotate the pushrod with your finger and watch for wobble.

The rocker arm surfaces to valve stem tips may have dents in them do to repeatedly hitting the stem tips. With the engine at hot idle insert a sacrificial .004" to .008" feeler gauge under every rocker. If the offending noise quiets down, adjust that rocker tighter to compensate for the dent in the rocker face. Doing this is problematic as microscopic oil droplets will be flying all over the engine compartment; suggest fender covers and safety glasses.



Be safe out there.
Kenny
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Jeff Burgess
Pensacola, Florida, USA   usa
1977 MG MGB

Adjusted the valves befroe reading your post, Kenny. Found one too loose. But no impact on the noise. May go back in and check the rocker clearances and pushrods.
By the way, a Private message suggested I do a compression test and I found all four cylinders even. The test showed 150 psi at each cylinder. I am wondering if my engine has been rebuilt. That seems high? My Bentley manual says my car should have 130 psi?
What do you think?

Jeff
dipstick Avatar
Kenny Snyder
La Center, Washington, USA   usa

150 psi even is not a bad thing (actually really good), may be higher than spec as a result of increased cylinder bore diameter; i.e. larger swept displacement squished into the combustion chamber. Even compression indicates that all of the valves are sealing correctly, as well as the piston rings sealing correctly, a very good thing.

If all of the tappets are equal in the strength of the sound you are probably Ok, these solid lifter engines do have a distinctive audible "tick" for every valve, and if you are not hearing the "tick" the valve clearances are too tight. If one is louder than the others there is some wear somewhere on that specific valve system, and may be compensated by tightening that clearance.

I don't think that you have a serious problem.



Be safe out there.
Kenny
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mcstedman Avatar
Michael Stedman
Athens, Ohio, USA   usa
1972 MG MGB GT
1977 MG MGB ""Bert" - "The Get Away Car""

During a discussion I had one time with an old Triumph guy, he advised that I could quiet my valves by substituting 8 OZ of my engine oil with synthetic oil during my next oil change. I trust the guys advice with regard to LBCs as he has owned and worked on them for years. After adjusting the valve clearance, mine had remained somewhat louder than expected so I tried it with my next oil change and was surprised how much the valves quieted.

(My apologies to the original poster if this triggers a huge oil debate.)



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How I repaired my MGB Clock
http://www.mgexp.com/journal/mcstedman/6919
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http://www.mgexp.com/journal/mcstedman/6921
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