Misfires and blown babbitt?

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Model T Ford Forum: Forum 2015: Misfires and blown babbitt?
Top of pagePrevious messageNext messageBottom of page Link to this message  By Chris Bamford, Edmonton AB on Thursday, September 10, 2015 - 08:27 am:

Friend Jerry and I have been speculating on possible causes for the failure of the con rod babbitt on the #4 rod a couple days ago: (http://www.mtfca.com/discus/messages/506218/567999.html?1441856384)

Here's one idea. We have had an occasional, random misfire for the past week… occasionally as often as a few times in several seconds, usually not for many miles on end. There didn't seem to be any pattern, i.e. uphill, downhill, humidity, etc.

When it does misfire, one can feel it as a perceptible jerk in the motion of the car. Jerry, as the usual passenger, notices this more than me.

Might this misfire, if at cylinder #4, be enough to stress the rod bearing and perhaps lead to its failure?

And if so, how might we isolate which cylinder is misfiring, particularly here on the road as we are still 300+ miles from home.


Top of pagePrevious messageNext messageBottom of page Link to this message  By John Doolittle on Thursday, September 10, 2015 - 08:33 am:

Fiber timing gear?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Chris Bamford, Edmonton AB on Thursday, September 10, 2015 - 10:39 am:

John -- bronze or aluminum, can't remember for sure. Probably bronze.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jerry VanOoteghem - SE Michigan on Thursday, September 10, 2015 - 11:06 am:

If misfires ruined babbitt, there would hardly be any T's running. No, I don't believe misfires caused that.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jim Eubanks, Powell, TN on Thursday, September 10, 2015 - 05:16 pm:

Looks like the babbit was not stuck well to the rod when tinned. I have one explode a couple of years ago into nothing but tiny specs from the rod and cap. It had to be faulty babbit. There were no pieces larger than the end of a ball pint pen left.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Royce in Georgetown TX on Thursday, September 10, 2015 - 08:05 pm:

Agree with Jim, the babbit should never come loose like that.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Gregush Portland Oregon on Thursday, September 10, 2015 - 08:58 pm:

Might check the other rods too. Could be that the spark timing is wrong for the load and speed and is knocking from that.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Doug Money - Braidwood, IL on Thursday, September 10, 2015 - 11:21 pm:

I had a rod that was Xed spit one quarter of the babbitt. I thought it was the fact that it was x grooved. I was told that it was because it wasn't tinned properly.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Kohnke Rebabbitting, Clare, Iowa on Friday, September 11, 2015 - 01:09 am:

A circle groove should never used in a bearing, unless it is pressure fed.

Herm.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Chris Bamford, Edmonton AB on Friday, September 11, 2015 - 08:30 am:

Thanks to all for your comments. That makes sense to me.

Jim, there were also many many 1/16" and smaller babbitt bits in the sump when I changed the oil.

Is there a way to check for proper tinning/bonding when I check clearance and inspect the other three rods?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Kohnke Rebabbitting, Clare, Iowa on Friday, September 11, 2015 - 03:14 pm:

Yes.


Top of pagePrevious messageNext messageBottom of page Link to this message  By David L Corman on Friday, September 11, 2015 - 07:53 pm:

You would be wise to change out the rods, if you have any doubts about their condition. Good chance you could ruin the cranks if one goes bad.


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