The Ford Barn

oldwoodsman · 07-17-2015, 08:45 AM

Just curious, at what clearances do rod and main bearings start to knock?

Patrick L. · 07-17-2015, 11:16 AM

I've seen [heard] them knock at .003" on other engines. These model A engines seem to be able to handle a little more before they get noisy.

40 Deluxe · 07-17-2015, 05:03 PM

Depends on oil viscosity, too. And oil temperature.

CarlG · 07-17-2015, 05:11 PM

They put up a pretty good knock when the Babbitt in a rod decides to fall to the bottom of the pan in little bitty pieces.

Dave Mc · 07-17-2015, 05:28 PM

RE; 29 Business Coupe -my engine was rebuilt before I bought the project , when I finally got it together and running it had a knock, determined it sounded like it was # 2 cylinder. I pulled the pan rolled the engine over and was able to see the rod was tight against the piston Boss , just had to pull that piston and had the boss machined for clearance , good as new now. might not be your problem , just sharing my results

Kurt in NJ · 07-17-2015, 08:36 PM

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Quote:

Originally Posted by Dave Mc

RE; 29 Business Coupe -my engine was rebuilt before I bought the project , when I finally got it together and running it had a knock, determined it sounded like it was # 2 cylinder. I pulled the pan rolled the engine over and was able to see the rod was tight against the piston Boss , just had to pull that piston and had the boss machined for clearance , good as new now. might not be your problem , just sharing my results

most likely this means the rod is bent, and that the piston is cocked in the cylinder

Floats · 07-17-2015, 08:42 PM

Hi Kurt,
What would cause tods to bend?
Regards
Chris
Cape Town

oldwoodsman · 07-17-2015, 09:43 PM

Quote:

Originally Posted by Dave Mc

RE; 29 Business Coupe -my engine was rebuilt before I bought the project , when I finally got it together and running it had a knock, determined it sounded like it was # 2 cylinder. I pulled the pan rolled the engine over and was able to see the rod was tight against the piston Boss , just had to pull that piston and had the boss machined for clearance , good as new now. might not be your problem , just sharing my results

Dave I don't have a problem with my engine, just curious for future reference.

BILL WILLIAMSON · 07-17-2015, 09:43 PM

I've heard tell uf a "ROD BENDIN' GREMLIN"!--Sum times, he fills one cylinder clean full uf WATER & WHAMO!
Bill W.

oldwoodsman · 07-18-2015, 08:48 AM

Quote:

Originally Posted by BILL WILLIAMSON

I've heard tell uf a "ROD BENDIN' GREMLIN"!--Sum times, he fills one cylinder clean full uf WATER & WHAMO!
Bill W.

Probably dog Pee

Dave Mc · 07-18-2015, 10:28 AM

Rod NOT Bent , machinist inspected , aftermarket piston problem

07-17-2015, 08:45 AM	#1
oldwoodsman Senior Member Join Date: Oct 2013 Location: Duluth, MN Posts: 196	engine knock question Just curious, at what clearances do rod and main bearings start to knock?

07-17-2015, 11:16 AM	#2
Patrick L. Senior Member Join Date: May 2010 Location: Largo Florida Posts: 7,225	Re: engine knock question I've seen [heard] them knock at .003" on other engines. These model A engines seem to be able to handle a little more before they get noisy.

07-17-2015, 05:03 PM	#3
40 Deluxe Senior Member Join Date: May 2010 Location: now Kuna, Idaho Posts: 3,818	Re: engine knock question Depends on oil viscosity, too. And oil temperature.

07-17-2015, 05:11 PM	#4
CarlG Senior Member Join Date: Nov 2010 Location: Anchorage, Alaska Posts: 9,192	Re: engine knock question They put up a pretty good knock when the Babbitt in a rod decides to fall to the bottom of the pan in little bitty pieces. __________________ Alaskan A's Antique Auto Mushers of Alaska Model A Ford Club of America Model A Restorers Club Antique Automobile Club of America Mullins Owner's Club

07-17-2015, 05:28 PM	#5
Dave Mc Senior Member Join Date: Jun 2010 Location: Indian Hills,Nevada Posts: 358	Re: engine knock question RE; 29 Business Coupe -my engine was rebuilt before I bought the project , when I finally got it together and running it had a knock, determined it sounded like it was # 2 cylinder. I pulled the pan rolled the engine over and was able to see the rod was tight against the piston Boss , just had to pull that piston and had the boss machined for clearance , good as new now. might not be your problem , just sharing my results __________________ Any man who thinks he can be happy and prosperous by letting the Government take care of him, better take a closer look at the American Indian!" - Henry Ford

07-17-2015, 08:42 PM	#7
Floats Senior Member Join Date: Dec 2013 Location: Mossel Bay, about 300km from Cape Town Posts: 530	Re: engine knock question Hi Kurt, What would cause tods to bend? Regards Chris Cape Town

07-17-2015, 09:43 PM	#9
BILL WILLIAMSON Senior Member Join Date: Dec 2010 Location: FRESNO, CA Posts: 12,560	Re: engine knock question I've heard tell uf a "ROD BENDIN' GREMLIN"!--Sum times, he fills one cylinder clean full uf WATER & WHAMO! Bill W. __________________ "THE ASSISTANT GURU OF STUFF"

07-18-2015, 10:28 AM	#11
Dave Mc Senior Member Join Date: Jun 2010 Location: Indian Hills,Nevada Posts: 358	Re: engine knock question Rod NOT Bent , machinist inspected , aftermarket piston problem __________________ Any man who thinks he can be happy and prosperous by letting the Government take care of him, better take a closer look at the American Indian!" - Henry Ford