The Ford Barn

PC/SR · 03-14-2013, 01:31 AM

Any recommendations for valve stem clearance? I now have .0025 with modern guides and valves and the cylinders are oily. Rings are good, compression is good. Thank you.

Tom Wesenberg · 03-14-2013, 02:33 AM

I used to do heads at a shop and used .002" to .0025" for exhaust, and .001" to .0015" for the intakes.

Jim Brierley · 03-14-2013, 10:46 AM

I agree with Tom. Sucking oil into the cyls. isn't very likely on the Model A engine but it can happen. Your oily cylinders may just need more driving, for longer periods of time? If it doesn't smoke or use a lot of oil, don't worry about it.

jkeesey · 03-14-2013, 10:49 AM

How oily are we talking? Is it chuffing out smoke or just "a little" oily?

Tom Wesenberg · 03-14-2013, 11:34 AM

How were the rings installed? It's best to use a ring expander, to ensure even expansion. When the 3 piece oil ring is used, it's best to spiral one on clockwise and the next rail counterclockwise with the gaps about 120* to 180* apart. Was the cylinder bored and honed correctly? What are the ring end gaps? And are they staggered.

Excess oil getting past the rings will usually show as a clean outer diameter on the piston tops. Over the years I've seen some modern engines where excess oil getting past the valve stems has turned to carbon and almost blocked the port.

PC/SR · 03-14-2013, 11:45 AM

Sponsored Links (Register now to hide all advertisements)

Its not smoking, but oily around the valves and chamber, not much over on the piston side. I would not take it down just for this, but since its down anyway...and since JB beat me at Auburn last year, maybe this will put me over the top.

Jim Brierley · 03-15-2013, 10:40 AM

I'l be happy to help with the tune-up this May in Auburn! :-)

03-14-2013, 01:31 AM	#1
PC/SR Senior Member Join Date: May 2010 Location: Santa Rosa, CA Posts: 1,279	Valve stem clearance Any recommendations for valve stem clearance? I now have .0025 with modern guides and valves and the cylinders are oily. Rings are good, compression is good. Thank you.

03-14-2013, 02:33 AM	#2
Tom Wesenberg Senior Member Join Date: May 2010 Location: Mpls, MN Posts: 27,582	Re: Valve stem clearance I used to do heads at a shop and used .002" to .0025" for exhaust, and .001" to .0015" for the intakes.

03-14-2013, 10:46 AM	#3
Jim Brierley Senior Member Join Date: Jun 2010 Location: Temecula, CA Posts: 4,087	Re: Valve stem clearance I agree with Tom. Sucking oil into the cyls. isn't very likely on the Model A engine but it can happen. Your oily cylinders may just need more driving, for longer periods of time? If it doesn't smoke or use a lot of oil, don't worry about it.

03-14-2013, 10:49 AM	#4
jkeesey Senior Member Join Date: Apr 2011 Location: Glenmoore Pa Posts: 1,644	Re: Valve stem clearance How oily are we talking? Is it chuffing out smoke or just "a little" oily?

03-14-2013, 11:34 AM	#5
Tom Wesenberg Senior Member Join Date: May 2010 Location: Mpls, MN Posts: 27,582	Re: Valve stem clearance How were the rings installed? It's best to use a ring expander, to ensure even expansion. When the 3 piece oil ring is used, it's best to spiral one on clockwise and the next rail counterclockwise with the gaps about 120* to 180* apart. Was the cylinder bored and honed correctly? What are the ring end gaps? And are they staggered. Excess oil getting past the rings will usually show as a clean outer diameter on the piston tops. Over the years I've seen some modern engines where excess oil getting past the valve stems has turned to carbon and almost blocked the port.

03-14-2013, 11:45 AM	#6
PC/SR Senior Member Join Date: May 2010 Location: Santa Rosa, CA Posts: 1,279	Re: Valve stem clearance Sponsored Links (Register now to hide all advertisements) Its not smoking, but oily around the valves and chamber, not much over on the piston side. I would not take it down just for this, but since its down anyway...and since JB beat me at Auburn last year, maybe this will put me over the top.

03-15-2013, 10:40 AM	#7
Jim Brierley Senior Member Join Date: Jun 2010 Location: Temecula, CA Posts: 4,087	Re: Valve stem clearance I'l be happy to help with the tune-up this May in Auburn! :-)