Is this one happy man, or what???

[Marshall V. Daut]

Some of you may recall my friend John, who bought a 1924 Coupe two years ago to match the one in family photos taken during the 1930's. You may also recall a couple weeks ago that I started a thread about the pistons in the engine and the poor compression/performance the engine exhibited. After removing the cylinder head and discovering oil crud on top of the pistons, we decided to do an in-car overhaul of the engine. The odd unidentifiable 0.031" cast iron pistons with FOUR rings have been a pain the rumpus from the git-go: no one makes rings for these oddballs with 1/8" rings grooves. Because the rings were well-worn with over 0.025" end gap (!), following the advice of some Model T people we ordered a set of 0.040" rings for aluminum pistons and began the tedious process of hand-filing the ends to reach the desired 0.016" gap. A lot of work, but the rings now are correct for the wear in these cylinders. But when I tried to install the rings, we discovered to our horror that the oil rings were taller than the two compression rings and wouldn't fit = unusable in these pistons. Seeing no other alternative, we bit the bullet and ordered new 0.030" aluminum pistons. While we are waiting for them to arrive, we lapped in the valves. John had not done this in over 50 years when he lapped in the valves on his 1949 Ford in the basement of his parents' house during the early 1960's. Here is a photo of John "enjoying" this Oh-so-pleasurable task on his Model T with his 76 year-old back. I think he is actually enjoying this rebuilding job! 'Gotta straighten him out on that...
Marshall

[Kerry]

If you had access to a lathe, just a few minutes work each piston to turn the oil ring groove deeper. Hope the new pistons work out for the job.

[Henry K. Lee]

Those aches and pains go away.., part of the therapy!

Hank

[Dan Hatch]

FYI: I have been told.031 piston are from a Ford branch rebuild. I have no proof that is true or false. Dan

[Dallas Landers]

After doing an in car new valves and lifter job on mine this spring, I can say it makes much younger backs ache also. He does look happy tho!

[Scott_Conger]

After investing in a Neway cutter kit, I will never again lap a valve in a Model T. They are simply wonderful. And quick. And precise.

[Altair]

This is just a heads up mention, an original Model T engine is 3.75 cylinder diameter, the cast iron pistons are tapered with a difference of .010 from top to bottom starting at just under .3647 at the top and 3.737 at the bottom, the rings are 3.75 with a .003 taper to scrape oil coming down and passing over it on the up stroke, Ford is stamped on the top of the rings.

When T engines are rebuilt bored with new pistons and rings these original clearances may get modified and or installed incorrectly. There are as many horror stories as success stories with rebuilt T engines.
As with any engine if the proper clearances are followed the engine will start with no binding or excess stiffness. There are many T rebuilt engines that require to be towed to start, this is an indicator of insufficient clearance, some call it just stiff. Like metals do not require the clearances of unlike metals such as aluminum. On a T engine the clearance is applied to the piston and some piston manufacturers may not observe this and some machine shops mat not bore the T engine correctly, a rebuilt T engine is a
50 - 50 gamble today.

[2nighthawks]

To add a bit to what Scott Conger said, the Neway valve seat cutting equipment he mentioned allows a three-angle valve seat, which is far superior to just an old-fashioned "lapping-in" valve job. In my opinion, the narrow and uniform width valve seat provided by a modern three-angle valve job goes a long way toward providing a valve job that will last much longer, and also helps prevent burned exhaust valves. The uniformly narrow seat will not only provide a tighter seal, but will also allow the valve to crush any carbon particles that are momentarily caught between valve & seat which are then blown away, instead of the old-fashioned "lapped-in" and often much too wide valve seat which often allows a carbon particle to become trapped and stuck between valve face and seat, which then allows valve to fail to seat tightly and seal, which then allows fire to leak through and burn the valve. Again,.....just my opinion,......FWIW,.....harold

[Marshall V. Daut]

Scott -
Which Neway kit did you buy? I see several available on-line. Did it have the correct size pilot shaft and stones for a Model T? In other words, is it Model T ready to use or did you have to buy additional tools to make it work for our cars? I'd be VERY interested in purchasing such a kit.

Would we need to take the valves to a machine shop to have them refaced? They are modern non-magnetic valves all the way and the faces are not burned. They look almost new. 'Makes me think the "rebuilder" simply slapped them in without doing the seats.

Marshall

[Scott_Conger]

Marshal

call Neway directly. They will have a guy who knows what you need and will put together the cutters and pilots that you need. They are very knowledgeable and helpful to our hobby. Do NOT spend your money on Ebay getting a generic set.

Warning: You will need to measure your valve guides to get the correct pilots for YOUR engine. I feel the solid pilots are far superior to the adjustable pilots, as they are perfectly repeatable and the adjustable ones are not nearly as repeatable, and I have used both, and continue to invest in the occasional extra pilot to fit the job I'm doing.

You will want to measure the "top" and "bottom" of the valve guide with a ball gauge to find correct range of solid pilot you want/need.

Regarding valves, I ALWAYS let a shop dress valves (even new ones). Nicks, bumps, unseen dents, all sort of stuff will show up on used or even new valves. It's really worth the small $$ spent.

Neway makes a valve facer which is laborious to use on modern valves, even with carbide cutters, and believe me, there are ways to goof up the valves. My opinion is that a professional grind is worth the time and money. The Neway valve seat cutters are a supremely superior tool that I am glad to own...the valve facer, not so much.

[Marshall V. Daut]

Great! Thanks for the information, Scott. I believe the guides are standard, as I tried to "freshen" them up with my oversized guide reamer, thinking since the engine had been rebuilt at one time, the guides had been reamed oversize. Nope. 'Couldn't even get the reamer to start. The factory lifters that we replaced with adjustables are even standard. Both the valves in their guides and the new lifters in their bores are a good fit.
Are the new stainless steel valves not already angled correctly, needing only to be lapped in if the seats are recut at the 30 degrees? Shouldn't just re-doing the seats and then lapping in the valves be sufficient? The valve faces are excellent, as i said, almost new looking: no pitting, burning, warpage. In all my years working on these cars, I have only watched the valve seats being ground with a stone twice, never doing it myself. I have never owned the tools to do so. It's about time I started doing this myself. A partial tool kit for this job does sound more appealing than buying a generic set and hoping the right parts are there.
Marshall

[Scott_Conger]

If you put the valves in a lathe, ensuring zero runout at the stem, and measure TIR on the valve face, you will likely find there is runout, regardless of how pretty they look, especially if they are used.

The Neway cutter kit will cut a face on the block, as well as relieve the bottom of the face angle (raise the seat), and top of the face angle (lower the seat), to provide the correct narrow seat for the valve at the proper location in the block. The seat will be 1 degree different than the valve and within a few seconds of running, the valve will transfer it's angle to the block for a perfect seal. Any lapping done after using the Neway equipment negates much of the good that the seat cutter does and is neither needed nor recommended.

You still need to measure the valve guide diameter like I said, with a ball gauge. Now, myself, I am not rich enough to purchase cheap tools...however, you may never use these again...but you NEED them for this job: https://www.amazon.com/HFS-Full-Ball-Sm ... B00R5E5QBM

Purchase this or similar, expand into the guide's hole and mic the OD of the gauge...THIS is the diameter pilot that you want to buy for the Neway cutters. Go here: https://www.newaymfg.com/pilots read up on pilots, and after reading, ask yourself if you REALLY know which pilot to buy based on just knowing the valve stem diameter (hint: you won't)

Better to have all the facts and make your own choice than have a job get away from you and end up chasing a series of errors all the way to completion. Best wishes for good luck.

[Marshall V. Daut]

Thanks again, Scott, for taking the time to write out your experience and advice. Nothing is simple with these "simple" cars, is it?
Because the car is so far away and I only get a chance to work on it every other week or so, I will test our valve lapping work by plugging the ports in the block with a drilled rubber stopper and blowing in air from the compressor to see if any air gets past the valves at TDC. Perhaps not the best way to go by hand lapping the valves, but I'm curious to see if our efforts have worked at all. 'Gotta be better than where we started! Assuming no air gets past the valves in the closed position, what would expected compression readings now be with new 0.030" aluminum pistons and rings and a "Z" head? I prefer to do this after installing the head before starting the engine, so the engine will not be warmed up. (The head may have to coma back off) They will be cold readings. As I wrote in my original posting about this engine, the readings in the first three cylinder were very low; only #4 approached a decent reading. What psi readings range should we expect to see with the conditions described? I couldn't find anything on-line that answered this question.
Marshall

[Scott_Conger]

Find the actual compression ratio associated with the head. Multiply 14.7 (at seal level) for ambient pressure. Stock Model T's after 1913 have 4:1 compression ratio. The oversize pistons at .030 over, have theoretical impact but no practical impact to compression increase/decrease. Thus, 4:1 compression at sea level is 4 x 14.7, or 58.8 PSI per cylinder. With spark plug leakage, ring leakage and minor other variables, compression readings range down from that. Good balance between cylinders is among the most important for a good running car.

55 would be wonderful if you could achieve it. 35 is about as low as you can go and get the car to start. So long as cylinders are balanced equally, within that range, your car will run smoothly. The higher the number, the greater the power available.

Your high compression head will come with advertised compression ratio. Some you can believe. Some you cannot. Oddly, the one that has a dispute around it, is in my opinion one of the best designed and running heads.

[Marshall V. Daut]

Thanks, Scott. This Z head is supposedly 6:1 CR with stock spark plugs No anticipated psi readings were included in the instructions. I should hope the compression readings are higher than 55 psi after installing this new head! With the stock head, the best cylinder was just under 50psi. I was hoping the new Z head teamed up with re-lapped valves and new rings would be around 75-80psi, if not more. In Iowa, I believe we are pretty close to sea level, so that should not be much of a factor in variance. Am I being too optimistic with this range or under-estimating?
Marshall