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Need help diagnoising engine flutter, misfire & loss of power

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Need help diagnoising engine flutter, misfire & loss of power #1
Jcbass57 Chip B Carrollton, GA, USA Sign in to contact 1946 Chevrolet 3100 1972 MG MGB 1973 MG MGB	Topic Creator (OP) Oct 25, 2014 11:42 AM Joined 11 years ago 185 Posts

Put new plugs in the B yesterday & gave it a compression test; front to back, 135, 125, 140 & 135. Gave the low one a wet test & it only went to 130. Plug from the low compression cylinder was oil fouled. After driving for a while with the engine acting normal, it starts to flutter when I wound the RPMs up pretty high with a lot of misfiring and loss of power. Still runs great below about 3,000 rpm, but consistently acting up with revs. Would you suspect condenser, coil or something else? This car has about 80000 miles & no engine work yet & I know that's coming. Thanks to anyone knowledgeable that can help!

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Re: Need help diagnoising engine flutter, misfire & loss of power #2
dickmoritz Dick Moritz Philly 'burbs, PA, USA Sign in to contact	Oct 25, 2014 11:56 AM Top Contributor Joined 14 years ago 26,263 Posts

Change the condenser and replace the rotor with one of Jeff's premium red rotors...

Dick

Errabundi Saepe, Semper Certi
(Often wrong, but always certain)

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Re: Need help diagnoising engine flutter, misfire & loss of power #3
HiPowerShooter James Booker Lake Winneconne, WI, USA Sign in to contact 1973 MG MGB	Oct 25, 2014 01:23 PM Joined 9 years ago 7,787 Posts

Condenser or points bounce. Either way...replace them with new. Pull the distributor put it in a vice. Pull the points plate off and manually and visually ensure the weights are not frozen or "tight". It's pretty easy to pull, clean, and lightly lube them. Put the new points in, set to .015, reinstall and see what happens.

"One test is worth a thousand expert opinions"--Alvin "Tex" Johnston...Boeing test pilot.

"Who do you think you are? I am."...Pete Weber

73 MGB. Tires: Round, black, hold air. Oil: Sometimes old, sometimes new...always slippery. Oil filter: Yellow, usually full of oil. Carbs: 2 SU HIF. Distributor: Yes. Headlights: Not that bright but bright enough. A bunch of other stuff most cars have but not really important enough to itemize. Oh, wait...it has a cool sounding exhaust with stickers on the chrome tips. Really slays the ladies...

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Re: Need help diagnoising engine flutter, misfire & loss of power #4
Jcbass57 Chip B Carrollton, GA, USA Sign in to contact 1946 Chevrolet 3100 1972 MG MGB 1973 MG MGB	Topic Creator (OP) Oct 27, 2014 01:51 PM Joined 11 years ago 185 Posts

Thanks for the advise. I've got new points, condenser, rotor, cap & wires coming from Basil. Hopefully I'll be driving this weekend in the mid-seventies Georgia weather!

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Re: Need help diagnoising engine flutter, misfire & loss of power #5
balist steve bali Vernon, BC, Canada Sign in to contact 1962 MG MGB	Oct 27, 2014 02:47 PM Top Contributor Joined 13 years ago 645 Posts

If it was my car I would investigate the cylinder with low compression and a fouled spark plug first. By doing a leak down test you can confirm or eliminate worn broken piston rings and worn or burnt valve seats, A simple test of a condenser is if the points are burnt and blue the condenser is the culprit, the points if adjusted correctly can be cleaned up with some fine emery paper,

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Re: Need help diagnoising engine flutter, misfire & loss of power #6
Jcbass57 Chip B Carrollton, GA, USA Sign in to contact 1946 Chevrolet 3100 1972 MG MGB 1973 MG MGB	Topic Creator (OP) Oct 27, 2014 03:14 PM Joined 11 years ago 185 Posts

Steve, I think a leak down test may be above my pay grade. I'll probably need to have a real mechanic do that one. But I'll see if the new ignition parts are the cure. If not, I'll take your advise. I suspect that the valves are a problem in that cylinder since the wet compression test didn't change the outcome much. Thanks!

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Re: Need help diagnoising engine flutter, misfire & loss of power #7
balist steve bali Vernon, BC, Canada Sign in to contact 1962 MG MGB	Oct 27, 2014 04:01 PM Top Contributor Joined 13 years ago 645 Posts

Hi Chip,
I don't like to see any member spending money needlessly, If I replace parts, it's because they are proven defective, good luck, let me know how it turns out

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