MGB & GT Forum

Please Sign In or Register to Search

1977 MGB engine noise

Posted by 1977MGBflip 
1977MGBflip Avatar
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

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

1977MGBflip Avatar
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

. You can hide this ad & support the site by upgrading to a Gold Membership ~ click here for more info
1977MGBflip Avatar
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

. You can hide this ad & support the site by upgrading to a Gold Membership ~ click here for more info
1977MGBflip Avatar
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

. You can hide this ad & support the site by upgrading to a Gold Membership ~ click here for more info
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.)



"It’s not about the size of your garage or how many tools you have…………..it’s about what you do in your garage."

How I repaired my MGB Clock
http://www.mgexp.com/journal/mcstedman/6919
http://www.mgexp.com/journal/mcstedman/6920
http://www.mgexp.com/journal/mcstedman/6921

LBclassics Avatar
Pierre Sutton
Signal Hill, Long Beach, USA   usa

I will try and attach a video of how to solve this tapping of the rockers. In the mean time I will tell you how I do it, taught by an old school mechanic.

1:get out a shorter flat head screw driver and a 13mm open end wrench
2: take off the valve cover
3: Start engine make sure the engine has warmed up first!!!
4:Take a rag and fold it to make a little pad
5: carefully put it over each of the rockers over the springs and listen for the dull rapping sound or tapping to dull out.
6: the suspect rocker ~ turn off engine, loosen nut, turn on engine then with socket over nut, take your flat head and slowly tighten it till the tapp go's away, then turn off engine and with your flat head holding screw in place.... tighten the socket nut
7: Do this again if needed to others that are still tapping but make sure not to over tighten them. (just until tap go's away.

Replace cover and have a nice drive.

The Video will be more easy sorry.

dipstick Avatar
Kenny Snyder
La Center, Washington, USA   usa

I simply use a .005" sacrificial (it will get dented) feeler blade between each valve tip and rocker with the engine at idle, the noisy one will go silent.



Be safe out there.
Kenny

ErnieY Avatar
Ernie Y
Nr Cahors, France   fra

The B engine is a tappety beast and to minimise it I've habitually run hot clearances of 8 inlet & 10 exhaust.

Everybody tells me that it will burn my va!ves out (somebody will now most likely) but after 30 years and hundreds of thousands of miles I'm still waiting for it to happen winking smiley

dipstick Avatar
Kenny Snyder
La Center, Washington, USA   usa

"The B engine is a tappety beast and to minimize it I've habitually run hot clearances of 8 inlet & 10 exhaust."

Valve clearance is exactly that, clearance/space. If the engine has consistent hot running tappet clearance the valves will open and close properly, and oil will get under the heels of the camshaft lobes. Racers and tuners regularly fiddle with tappet clearances to advance or retard the camshaft timing, less intake clearance and the valve opens sooner providing increased low rpm throttle response.

The key is checking any altered tappet clearance with the engine hot.



Be safe out there.
Kenny

1977MGBflip Avatar
Jeff Burgess
Pensacola, Florida, USA   usa
1977 MG MGB

Thanks for all the input guys. I may tackle that tomorrow. I have a sacrificial .005 feeler I can use.

. You can hide this ad & support the site by upgrading to a Gold Membership ~ click here for more info

To add your reply, or post your own questions

Members Sign In   or   Create an Account

Registration is FREE and takes less than a minute!

Having trouble posting or changing forum settings?
Check the Forum Help File (FAQ) or contact the webmaster.


Join The Club

Sign in to ask questions, share photos, and access all website features

MGExp Menu

What's New

Membership

Forums ->

MGB & GT

MG Midget

Buy, Sell & Trade

Vendor Market

MG Engine Swaps

Original MG

MGA

MGC

MG Magnette

1100 & 1300

T-Series & Prewar

Modern MGs

MG Motorsports

Member Meetup

MG 2015 Event

Other Vehicles

Off Topic

Clubs

Forum Search

Random Topic

Latest Posts

Live Chat

Calendar

Journals

Tech Library

Car Registry

Cars For Sale

Model Info

Motorsport

Directory

Member Map

MGExp Store

Search Site

Advertising Info

Smartphone quick link
mgexp.mobi

Adjust Text Size

Larger Smaller
Reset Save