The Ford Barn

mach0415 · 10-31-2011, 04:42 AM

Hello. Last night, Dad and I took compression readings on a newly acquired 1929 A and found to be low at 25 lbs. Cylinder 3 had none. So, off came the head and we found a stuck valve. We spun it over to get it free, but I am not sure on the others.

It appears that someone may have rebuilt this before because there are markings on the tops of the pistons. there are 4 dots in the #4 pot, 3 dots for #3 pot, and so on. There are no wear ridges. Should we measure bore diameter and attempt to re-ring?

Also, assuming the engine can be re-ringed, when we pull caps and remove pistons, will we have to necessarily re-babbit too? or are the shells going to come out with the cap and rods?

Thanks,
Mark in NC

BRENT in 10-uh-C · 10-31-2011, 05:47 AM

Mark, if it still is a babbitted engine, you are gonna find there will be no "shells". The babbitt metal should be affixed to the rod and cap respectively.

If the lower end of the engine is clean & free of debris, I think I would re-install the head after making sure all valves are working and try to restart the engine As-Is. With the head off, you can get oil down around the rings and on the valve stems which should help get the sticky parts operating correctly again. After it has been running for a bit, many of your present issues may correct themselves.

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Elcastor · 10-31-2011, 07:45 AM

Sounds like good advice from Brent!

Ice man · 10-31-2011, 09:11 PM

No ridge sound like no ware and sounds like you got a good one. Drive it. Iceman

Tom Wesenberg · 11-01-2011, 01:01 AM

I would have tried freeing the valves before pulling the head by using Sea-Foam in the gas and oil. But since you now have the head off you should be able to bring each piston to top dead center then push the piston to the side and look at the gap on the top ring. The gap should be about .012" with new rings. If you have a wide gap then now is the time to install new rings. Let us know what you find.

V4F · 11-01-2011, 02:25 PM

Sponsored Links (Register now to hide all advertisements)

when ready .... compression on a stock motor should be around #55 . but equal is most important .................. steve

mach0415 · 11-01-2011, 06:40 PM

Thanks, guys. We are going to flip her over on a stand, pull the pan to inspect, and reseal it if all is good. We will reinstall the head with a new gasket and attempt to run out of the car. Still have to get a distributor and carb, though.

mach0415 · 11-12-2011, 12:00 PM

Flipped her over about 45 minutes ago and pulled the pan. Seems like I need to clean her out good. Some sludge at the bottom and grit. Inspected crank and rods. Looks to be good. At some point a rebuild was done, because there are remnants of slag splash on the rods and caps from a re-babbit pour. The rods and caps have been marked with punch dots for each associated cylinder number. I pulled #1 and #3 piston and rod to inspect bores and piston rings. Rings are free and bores look ok, but not perfect. No significant scratches, but some very minor rust "bruising" but no pits. Would you guys recommend honing and reringing it? Also, the pistons say "Mcquay-Norris" on them and have a full-length split skirt. Any light to shed on that? I have not checked specs yet, but on the tops of the pistons it says "P15"

10-31-2011, 05:47 AM	#2
BRENT in 10-uh-C Senior Member Join Date: May 2010 Location: Eastern Tennessee Posts: 11,513	Re: Banger Compression Mark, if it still is a babbitted engine, you are gonna find there will be no "shells". The babbitt metal should be affixed to the rod and cap respectively. If the lower end of the engine is clean & free of debris, I think I would re-install the head after making sure all valves are working and try to restart the engine As-Is. With the head off, you can get oil down around the rings and on the valve stems which should help get the sticky parts operating correctly again. After it has been running for a bit, many of your present issues may correct themselves. . . __________________ . BRENT in 10-uh-C . www.model-a-ford.com ...(...Finally Updated!! ) .

11-01-2011, 02:25 PM	#6
V4F Senior Member Join Date: May 2010 Location: ca. Posts: 2,522	Re: Banger Compression Sponsored Links (Register now to hide all advertisements) when ready .... compression on a stock motor should be around #55 . but equal is most important .................. steve __________________ V4f

11-01-2011, 06:40 PM	#7
mach0415 Senior Member Join Date: Jul 2011 Location: Chester, SC Posts: 162	Re: Banger Compression Thanks, guys. We are going to flip her over on a stand, pull the pan to inspect, and reseal it if all is good. We will reinstall the head with a new gasket and attempt to run out of the car. Still have to get a distributor and carb, though.

11-12-2011, 12:00 PM	#8
mach0415 Senior Member Join Date: Jul 2011 Location: Chester, SC Posts: 162	Re: Banger Compression Flipped her over about 45 minutes ago and pulled the pan. Seems like I need to clean her out good. Some sludge at the bottom and grit. Inspected crank and rods. Looks to be good. At some point a rebuild was done, because there are remnants of slag splash on the rods and caps from a re-babbit pour. The rods and caps have been marked with punch dots for each associated cylinder number. I pulled #1 and #3 piston and rod to inspect bores and piston rings. Rings are free and bores look ok, but not perfect. No significant scratches, but some very minor rust "bruising" but no pits. Would you guys recommend honing and reringing it? Also, the pistons say "Mcquay-Norris" on them and have a full-length split skirt. Any light to shed on that? I have not checked specs yet, but on the tops of the pistons it says "P15"

10-31-2011, 04:42 AM	#1
mach0415 Senior Member Join Date: Jul 2011 Location: Chester, SC Posts: 162	Banger Compression Hello. Last night, Dad and I took compression readings on a newly acquired 1929 A and found to be low at 25 lbs. Cylinder 3 had none. So, off came the head and we found a stuck valve. We spun it over to get it free, but I am not sure on the others. It appears that someone may have rebuilt this before because there are markings on the tops of the pistons. there are 4 dots in the #4 pot, 3 dots for #3 pot, and so on. There are no wear ridges. Should we measure bore diameter and attempt to re-ring? Also, assuming the engine can be re-ringed, when we pull caps and remove pistons, will we have to necessarily re-babbit too? or are the shells going to come out with the cap and rods? Thanks, Mark in NC

10-31-2011, 07:45 AM	#3
Elcastor Senior Member Join Date: Oct 2010 Location: Oregon and Baja Mexico Posts: 617	Re: Banger Compression Sounds like good advice from Brent! __________________ Ben Purkey Mexico and the Pacific NW http://www.martin-parry.com/

10-31-2011, 09:11 PM	#4
Ice man Senior Member Join Date: Jun 2010 Location: Southern Pines, N.Carolina Posts: 210	Re: Banger Compression No ridge sound like no ware and sounds like you got a good one. Drive it. Iceman

11-01-2011, 01:01 AM	#5
Tom Wesenberg Senior Member Join Date: May 2010 Location: Mpls, MN Posts: 27,582	Re: Banger Compression I would have tried freeing the valves before pulling the head by using Sea-Foam in the gas and oil. But since you now have the head off you should be able to bring each piston to top dead center then push the piston to the side and look at the gap on the top ring. The gap should be about .012" with new rings. If you have a wide gap then now is the time to install new rings. Let us know what you find.