MTFCA Forum

For the 20 years (to this day) that I've owned my T, it's always had a starting difficulty if the car has been sitting for more than a couple of days, particularly in cold weather. Once started and warmed up there's no further problems - easily starts on a quarter turn of the crank, and once in a while, a free start. Runs great, very smooth, does 75km/h (47mph) down the freeway, and goes up hills in top gear.

During some of its difficult starts, I've established the compression and ignition is good. Reading through a 1925 car magazine brought up something I'd never considered before - leaky intake valve guides. And yes, I've been aware that my valve guides are worn (they're original). But since the engine ran so well, I never thought it mattered. Anyway, my theory is that worn intake valve guides is causing the starting difficulty. When it does 'start' it sometimes runs very roughly on what seems like 2 cylinders, then quickly comes good after about 10 seconds. My guess is the oil is getting into the valve guides by then and providing a seal.

So what are the options? I could ream the guides and put in valves with oversize stems. I see the suppliers can provide both - but what makes sure the reamer stays straight? But then I saw these in one of Murray Fahenstock's books:
It seems that such an accessory was once available to fix this problem. Has anyone tried something like this with success?

I had worn guides and thought about using the seals, but decided to ream the guides. I made a fixture to guide the reamer. It worked very well. It took very little to clean up the valve seats in order to get concentricity with the guides.
Art Mirtes

really doesn't sound like overly worn guides to me...it sounds like a float level situation that rectifies itself after it starts and stays correct for some time until it sits for awhile

worn intake guides so worn as to make harder starting also tend to suck and burn oil at idle

personally I would be loathe to pull the head and ream the guides, fit new valves, wait 9 months for a head gasket and then find the car was still hard to start after sitting a few days

here is info toward your question: http://www.mtfca.com/discus/messages/41 ... 1419223598

Scott_Conger wrote: ↑

Tue Jun 14, 2022 11:00 pm

worn intake guides so worn as to make harder starting also tend to suck and burn oil at idle

That's a good point; it doesn't seem to do that since oil consumption is low and there's no smoke in the exhaust. I hadn't even thought about the float level, so will investigate that too.
I'm loath to ream the valve guides, or do anything to the valves for that matter, which is why the felt seals are so attractive. In fact I'd rather just live with the 'fault' than open a can of worms. Just curious to know what it is more than anything.
If my theory about oil sealing up the valve guides was true, it should be possible to confirm that simply by squirting oil up into them, before starting the car, so will try that also.

When it comes time to ream the valve guides, look for a Stevens Valve Guide reamer set up.

In order to accurately pilot the reamer through the guide, a centering guide is placed in the valve seat. When Ford machined the blocks, the valve guides and seats were machined at the same time. Stevens utilized this when they designed their valve guide reaming set up. See the attached illustrations from the Stevens catalog.

Respectfully submitted,

Trent Boggess

Hi John,
Have you done a compression check both hot & cold ( cold as in having set for the same amount of time that you notice the difference) That may lend some insight to the issue. If not using oil & running well this may not be that bad. I have had many engines display these starting issues even after a rebuild. Could be carb. issues worn throttle shaft or not rich enough to start with. As far as reaming the valve guides the piloted reamers the venders sell give a pretty good and well centered guide and any issues should be corrected when cutting the valve seats. If you have original two piece valves replacing them before one ( only takes one ) comes apart might be a good idea next off season just for piece of mind.
Craig.

Craig,
For a long time I thought it might be a valve sticking open, because it would run exactly like it did on 2 cylinders when a valve retaining pin once broke.
So, on one of the mornings when it was being difficult, and before it came good, I did a compression check - all cylinders more than 35psi. Similarly, I checked for a spark at all cylinders.
As for two piece valves, I had to replace the head some years ago because the #4 exhaust valve broke off. It's had all one piece stainless since.

My 1912 van with Holley H1 carburetor became increasingly hard to start over the years. From being a one pull start after priming, it became a real bear to start, with varying degrees of choke, advance settings etc.

Eventually i fitted Stan Howe beautifully restored spare carburetor and a better alloy intake manifold. Starting problem solved! On inspection, I found the original cork float had shrunk, leaving it loose on hinge, so float levels were all over the place. That and severely worn shafts on the throttle and choke butterflies were the cause of the hard starts.

Allan from down under.

If you determine the valve guides are worn, there is a procedure called knurling. The guides are run thru with a tool that raises a thread, then is burnished back down.(not reamed) This raises & resizes the holes with no metal loss.(displacement) No need to go with over sized valve stems.
You are still running 2 piece valves?

I believe that valve stem seals are primarily intended to prevent excess oil getting past the valve stems, especially in overhead valve engines. The fit of the stem in the guide, plus the oil film, is what primarily controls air leakage. As for the symptoms your car displays, I'd think a roller-type timer could easily cause that. A weak roller spring, excess oil in the timer case, off-center timing cover, and/or general wear of the timer parts might cause the problem you're having. Another thing to consider is an intake tract leak that closes off as the engine warms up. Even a slight amount of moisture in things like the coil box can cause transient issues. If you have composite valves, a valve head that is loose on the stem might leak when cold, then tighten up as the valve head temperature increases.

This discussion brings to mind some issues in a friends engine. Humor me for asking some obviously newbie questions.

Just how difficult (and advisable) is it to install new valves in an engine without removing the engine from the car? The car in question has two part valves in the intakes but not the exhausts. I think it would be wise to install improved valves with all that goes along with that process.

Tim

other than a rebuild, "in the car" is the only way I've done it, myself

my version of the Stevens Tool for Reaming:

John K. We use to knurl valve guides on skinny block Chevy heads back in the 70's and used ford valve stem seals. Always thought of it as a short term repair for there soft castings. Ford casting are much better. And no more than many drive there T's I guess it would be a option. Have you ever successfully done it in a at T?
Tim, I believe it was common practice to do valves, seats & rings in the car. The factory service manual shows it in chapter IV the big draw back is the cost of the seat cutters ( New-way makes a very good set ) & the cost of head gaskets now.
Craig.

Craig Leach wrote: ↑

Wed Jun 15, 2022 10:30 am

John K. We use to knurl valve guides on skinny block Chevy heads back in the 70's and used ford valve stem seals. Always thought of it as a short term repair for there soft castings. Ford casting are much better. And no more than many drive there T's I guess it would be a option. Have you ever successfully done it in a at T?
Tim, I believe it was common practice to do valves, seats & rings in the car. The factory service manual shows it in chapter IV the big draw back is the cost of the seat cutters ( New-way makes a very good set ) & the cost of head gaskets now.
Craig.

I do it all the time, as long as the guides are not too worn. Its the first option instead of going oversized on the valve stems. This is a thing I learned/did when I partnered with a fellow doing motor overhauls/head work. On a T, the only inconvenient thing is the knurler goes in one way, so it must pass thru the lifter holes. Cam & lifters have to be out.

John,
That is a good thing to point out that the knurling tool has to go all the way thru. I picked up a box of knurling tools at a swap meet with that in mind because I have a set of std. valves that I have never been able to use because of worn valve guides.
Craig.

Craig Leach wrote: ↑

Wed Jun 15, 2022 11:31 am

John,
That is a good thing to point out that the knurling tool has to go all the way thru. I picked up a box of knurling tools at a swap meet with that in mind because I have a set of std. valves that I have never been able to use because of worn valve guides.
Craig.

Its also best to finish the hole with the intended burnishing tool.
Some ream & remove metal unnecessarily.

I don't believe your cold starting problem is related to worn valve stem bushings at all. Very possibly fuel/carburetor is more likely. The possible 2 piece business should be checked out though.

Charlie B in N.J. wrote: ↑

Wed Jun 15, 2022 1:00 pm

I don't believe your cold starting problem is related to worn valve stem bushings at all. Very possibly fuel/carburetor is more likely. The possible 2 piece business should be checked out though.

This is a common problem with old harleys. Shovel heads especially. Valve guides get worn & they get hard to start quirky.

Those old Harleys are the best exersize machines.

TXGOAT2 wrote: ↑

Wed Jun 15, 2022 1:34 pm

Those old Harleys are the best exersize machines.

They make for strong leg muscles IF they dont kill you first.

Scott Conger;....thanks for posting the link to Ken Kopskys forum post of years ago that shows his modified drawing of what he labeled "HAROLDS SLICK IDEA". (.....I'm the "HAROLD") Those original home-made intake valve seals that I made from inexpensive standard hardware items (....four little soft springs, four steel washers and four little felt discs with valve stem hole punched in them) are still in my '23 roadster with worn intake valve guides, and have always worked well and have never caused any problems, and I still feel that on a good running but well worn "T" engine, they are very cheap and easy to install "bandaid" solution to a problem, at least until the good running engine eventually gets a total rebuild. I guess it's a good example of a favorite little "dittie" that I subscribe to that I learned from this forum:

"There's nothing more "permanent" than a "temproary fix" that works!" ......harold

Take a bow, Harold...

The opening surface area of a 1-1/2” diameter valve opening 1/4”, is 1.18” sq/in. The annulus of a valve guide with .010” wear is a mere .01” sq/in. If you consider that the efficiency of a pneumatic orifice is proportional to its length, you may want to reduce the .010” sq/in number. Also consider that the oil vapor being drawn in is combustible at some value. My point is that the valve guide air leak is most likely insignificant.

Other side effects of worn valve guides are; poor valve to seat concentricity, irregular valve and seat wear, and delayed valve sealing. All of these conditions cause the valves to seal poorly during engine operation, reducing overall performance.

Hard starting can typically be traced back to poor valve sealing. During startup, low rpm’s provide poor sealing valves lots of time to leak down the essential compression necessary for quick starting, especially if hand cranking. Once the engine is started, the poor sealing valves have less time to leak and so therefore are more efficient.

More than likely, your engine suffers from a commonly overlooked problem, excessive valve seat width. A valves sealing power is a result of valve seat pressure. The valve spring supplies a constant amount of force when the valve is closed. This spring force is divided amongst the surface area of the valve seat contact surface. Larger valve seat contact surface = lower valve sealing potential. With valve springs as weak as a T, the seat width must be watched closely. A minimum of a 3 angle valve grind is required for proper valve operation, resulting in quick starting and reliable performance

Wouldn’t adding a valve seal negatively effect the vacuum produced by the intake valve to draw the oil mist into the valve chamber?

I've taken a video of the problem
https://youtu.be/Kk2GQrSTUoA

Sometimes the rough running is so bad the engine stops within a few revolutions. Today it was a lot better and kept running before smoothing out.
The rough running period can be a lot longer than shown here.
On a warm day it will often start completely smooth.

To answer a couple of questions brought up so far; the valves are one piece stainless. The timer is an E-Timer, and the fault was exactly the same with about 16 years of mechanical timers - roller, Anderson, TW.

Bryant,
What if it sealed the oil out of the valve guide & seized the valve up?
Craig.

Have you though about looking at the engine during startup with a Flir thermal imaging camera? If it's only running on two cylinders for the first couple of minutes it should be pretty obvious on the Flir.

Craig Leach wrote: ↑

Thu Jun 16, 2022 12:47 am

Bryant,
What if it sealed the oil out of the valve guide & seized the valve up?
Craig.

It looks like in the picture the seal is in the intake port. i guess that would allow oil to retain in the guide. But if its correct that the vacuum created by the intake valve draws oil mist into the valve chamber in the first place i guess oil starvation would occur with a seal added. now if you had a pressurized system i could see the advantage of the seal. i like the idea of soaking the guides with oil before start up to see if its actually the problem. probably have to use thick oil though or you would have to work quick.

Re: "On a warm day it will often start completely smooth." ////// This points toward a problem with your carburetor or intake manifold. If you get consistently good compression readings, hot or cold, it strongly indicates your valves are OK. It's unlikley that your valve guides are causing your problem.

The Goat's right. worn valve guides don't affect starting. It's something (fuel) else.

I to believe it’s a carburetor issue. I was just addressing the topic of valve seals.

Bryant

since you've thought it through and asked some good questions, here's some interesting food for thought: early engines had no drain-back holes in the valve chamber...yet they would fill up with oil (considerably!) and leak past the valve cover gaskets with abandon...where could the oil come from? How would the valves get lubricated?

the oil comes up the pushrods, even though the clearances are very small. How much clearance does an intake valve have? Over what length? Is vacuum "sucking up" oil there? Oil will indeed get "sucked" into the combustion chamber on a really worn guide, but is vacuum the sole mechanism to lubricate a new engine's valves? What about exhaust valves where there is no vacuum...how do they get their lubrication?

the reality is that a felt seal will become wet with oil and will continuously and forever, lubricate whatever valve it is installed on (like you mentioned, it would be short-sighted to not thoroughly wet the felt with oil first). The method was very successful and was the primary disbursement mechanism for oil, on nearly every plain-bearing machine there was, in the era that our cars were built (after the cessation of the use of drip oilers).

Perhaps you know all of this already and if so, forgive me...I just saw your post and thought I'd chime in.

I understand a lot of things but your post has me confused. To be clear I don’t think it needs valve seals. The topic of the thread was about valve seals. According to modeltfordfix oil gets in the valve chamber by vacuum. I would think a seal would stunt that vacuum. But hey do whatever works for you. Ok now what could be making this engine start and run like it does? Most say carburetor. I think carburetor. So what’s the man got to do to solve his issues?