MTFCA Forum

As we venture out in the T we are seeing more hilly ground and with four adults inside we slow down to a point for a bird to land on light cross bar and relieved it's self. Current compression hot or cold is around 65 PSI with standard head and is it worth switching over to a high compression head?

Engine had gone through a total rebuild with standard pistons and I have approximately 25 miles on it.

Any input on switching out the head to high compression.

Your compression readings are very good .... I would put a few hundred to a thousand miles on that engine to break in changing oil at least twice and see what results you get. I'm sure the engine will be peppier.

with 14.7 PSI at sea level, with a 4:1 stock head, 65 is not only very good, it is unbelievable.

if that is a true reading, your head is already shaved a considerable amount and is higher compression than stock.

advice to let the engine break in is good advice as regardless of compression, it will be more powerful once it limbers up.

What rear axle ratio do you have? Ruckstell or other auxiliary transmission? Years ago I had a 26 Fordor and ultimately installed 4-1 gears with a Ruckstell as we lived at higher elevation.

Your engine will need to run at least several hundred miles before it will perform its best. Avoid lugging or racing the engine during this period. Keep a close check on oil and water levels. How you handle the spark timing and carburetor adjustment will have an impact on engine power. Be sure the tires are properly inflated and that there are no issues with dragging brakes or anything else that will add to the engine's load. I would drive the car the first 50 miles without passengers and in an area where I could avoid any hard pulls or high speed driving. If you live in a hilly area, you will need to learn to drive the car in such a way as to conserve momentum and use the available power to the best advantage, much like driving a truck. A Model T that is running properly and handled properly can maintain a good average speed with a reasonable load and can make good time in most driving situations. Grades and headwinds will affect performance, but these effects can be minimized by proper handling, and can be taken advantage of, often as not.

Information on "year model", body style, and specifics on the engine rebuild can be helpful to anyone attempting to give you advice on your car. A high compression head might be something to consider, but I'd want to be sure the engine is fully broken in and running its best before taking any further steps.

Driving your 26 Tudor in hilly country, I hope you have GOOD brakes!

Thanks for all of the replies, it's all ways helpful to get feed back.
The ring and pinion is 3 - 1 ratio. This was my fathers car and he had purchased the ring gear years ago before he passed away.

A stock engine in a sedan with 3 to 1 gears is going to be a dog on hills if you don't also have a Ruckstell.

Tudor + hills + 3:1 axle = lots of low pedal

4:1 differential or a Ruckstell is almost mandatory for your car and hills

A Tudor with a new, tight engine and four adults aboard AND a 3:1 axle isn't going to pull significant hills well. I'd consider a Ruxtell setup to take advantage of the 3:1 gearset. A Ruxtell setup and a high compression head would give good overall performance. A high compression head might be expected to increase power by about 15 to 20% I'd do the Ruxtell first with a closed car. A Tudor sedan with battery, starter and generator will weigh around a ton, empty. Adding 4 adults will add another 700 to 800 lbs to that. Throw in a hill, and/or a headwind, and you're asking a lot of a 20 HP engine.

A late tudor in good shape with a 3:1 axle and aluminum pistons might do 50 MPH on level ground. With an overdrive gear, it might do 55 or so.

Thanks for the additional information on gear ratio, will need to investigate Ruckstell or changing out ring and pinion. Will need to review the options.

Thanks again for the additional feed back on gear ratio and what options I need to pursue. Since I'm retired that gives me something to do.

I believe the term "High Compression Head" is somewhat of an exaggeration. A better term would be "Higher Compression than Stock". It should be noted that modifications using a Higher Compression Head have also had other mod's to improve performance. Yes they improve performance but is it all of what you need. And when your done, you'll only need regular gas. --
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https://www.energy.gov/eere/vehicles/ar ... ane-rating

radiatorman wrote: ↑

Fri May 06, 2022 9:09 am

As we venture out in the T we are seeing more hilly ground and with four adults inside we slow down to a point for a bird to land on light cross bar and relieved it's self. Current compression hot or cold is around 65 PSI with standard head and is it worth switching over to a high compression head?

Engine had gone through a total rebuild with standard pistons and I have approximately 25 miles on it.

Any input on switching out the head to high compression.

Finish the break in. Even when appearing good, the motor may tighten up after getting hot. You can tell when cranking hot.

Since we know you are running 3:1 gears with no rux. It will be a real dog. I wouldnt do this with a hot rod T motor.(without a rux) Tough to start from a stop, hard on the clutch, a mizzery to drive & no horse power on the slightest grades.

What are your expectations? sustained speeds above 60? Then 3:1's with a rux, cam, higher compression head & more fuel flow. (Hot motor)
Definitely doable.

3:1's gotta go! Putting These gears in a rux is likely not the answer. The only time you would be in direct(3:1) would be speeding down a long grade with a death wish. A rux will not last long driving in rux all the time. Gear ratios are selected accordingly. Think of a rux as a way to flatten grades when used. Generally the hottest & lightest T's are candidates for 3:1's. Most Tourings cant pull them well.

You should do pretty well to 50 with your stockish motor & 3.77 gears. (Stock 11-40)
A stock to worn motor would do better with a 4:1 gear set in a sedan. With a regular full load of friends & family this is a very good option.

Adding a higher compression head(I recommend Prus) Will give you more power & speed. (as is) No down side. To take full advantage, you will want better carburation & cam, but there is a definite difference just adding the head.

My 26 was very sluggish compared to others and it’s a pick up!
I fitted a Z Head then Electronic ignition and those made no difference. The single item that cured it was fitting a straight thru
Holley Carburettor on the original factory inlet manifold. I’ve been tempted to fit a high flow inlet manifold or try a Holley G but see no need as I’m happy the way it is. My “test Hill” where I had to drop back to low gear prior to fitting the NH I now go up in top and can accelerate. When the Z head dies (now 18 years old) I’ll fit the standard high head back on it.
Alan In Western Australia

That suggests that the carbueretor you replaced had issues of some sort.

Alan, now that you have a Holly ‘straight through’ carburetor, understand you’ve traded good gas mileage for increased performance and poor gas mileage. My ‘26 Tudor sports a ‘straight thru’ on a high volume aluminum intake and a Waukesha Ricardo head. Its peppy as hell but I probably get 12 MPG.

I suspect you might have a stock "low" head.
I have a 22 Roadster, which is a light car compared with a tudor. The previous owner installed 3-1 ring and pinion. It also has Ruckstell. Although that car goes a little faster on level and downhill, it is slower going uphill. we have a 6% grade leading to our town On that grade I can climb in high if I can keep it around 30 mph, but the T's with standard gearing can go about 22-25 mph, and when on a tour, I have to use Ruckstell.
So you will need to keep your speed up and if it begins to lug shift down to low. You would do much better with Ruckstell or other auxiliary transmission.
I don't know what kind of "hills" you have where you live, here even a start from a stop sign going up a small grade, I will need to stay in low or Ruckstell much longer before I can go up in high. Same hills I can climb with standard gearing and rev up in low and go into high.
I would also suggest, if you haven't done so, you need a SKAT crankshaft. Your car is a candidate for a broken crankshaft. If you install a higher compression head it is even more likely to break the crankshaft, because it has more power at low speeds and lug the engine even more.
Anyway, my best suggestion (in my opinion) would be Ruckstell with standard ratio gear and auxiliary brakes.
Norm

I would like to find a source for 6:1 cast iron head. I don't want an aluminum head on my car! Years ago, I purchased a Giant Power head for my car. What a disappointment! From it I got perhaps a 1% improvement. It wasn't worth the effort!

I'd love to have a cast iron HC head with proper script... and a good copper-asbestos gasket to go with it.

George House wrote: ↑

Sat May 07, 2022 10:25 am

Alan, now that you have a Holly ‘straight through’ carburetor, understand you’ve traded good gas mileage for increased performance and poor gas mileage. My ‘26 Tudor sports a ‘straight thru’ on a high volume aluminum intake and a Waukesha Ricardo head. Its peppy as hell but I probably get 12 MPG.

I dont care about gas mileage so much if the tradeoff is better all around performance.
Does it perform well @ idle & hi speed?
Your feedback would be instructive.

I ran one for a while & had to richen it for speed & lean for idle every time. Too much fiddling.
This was a long ways back, before The knowledge of fine tuning the fuel level. I would consider trying one again.

Those T's I tour with that run them typically run too rich & dont perform well.

I believe the design was realized a failure, hence lasting less than 1 year.

Original Smith wrote: ↑

Sat May 07, 2022 10:32 am

I would like to find a source for 6:1 cast iron head. I don't want an aluminum head on my car! Years ago, I purchased a Giant Power head for my car. What a disappointment! From it I got perhaps a 1% improvement. It wasn't worth the effort!

AMEN. There is a market. I got lucky & found a secondhand lizard head. Very happy with its performance, but would rather have a more conventional looking head. Prus tried, but couldnt get good castings. Why is it so hard to produce an iron head?

Pat,
Possibly a general Carburettor issue as it was just a general performance issue and not one specific fault. Dads 27 Tourer
was even worse especially with passengers. We had driven those cars for decades like that. So now both Model T’s run Holly Straight thru’s and perform so much better. Most likely unnecessary, but we also increased the fuel line to 5/16”

George,
For the amount of miles we travel in these T’s the cost of fuel and level of consumption isn’t a issue to me!
When the tank gets low, we fill it up! Sometimes I get asked how many MPG I get and reply “don’t know and don’t care”
We also now run premium unleaded (also unnecessarily)
Regards Alan In Western Australia

Could the 5/16 line be partially compensating for a low flow needle/seat that improved performance?
Which fuel needle/seat are you running in these carbs?

I am curious about the fixation on cast iron as opposed to aluminum cylinder heads. I have run both and like both. Lack of a Ford script is a solvable cosmetic thing. The lack of “magnetism” on the aluminum head is another solvable thing.

Original Smith wrote: ↑

Sat May 07, 2022 10:32 am

I would like to find a source for 6:1 cast iron head. I don't want an aluminum head on my car! Years ago, I purchased a Giant Power head for my car. What a disappointment! From it I got perhaps a 1% improvement. It wasn't worth the effort!

Strange. I have a Giant Power on my '26 Coupe and it makes a big difference. And some sources say power up from 20 to 26hp.

Pat, Kevin prus was making cast iron high compression heads. His castings are more precise than others available in aluminium. You can easily solve the lack of Ford script and made in USA with a tube of Devcon and a Dremel tools you need pictures?

Allan from down under.

A couple of questions: I know there is a way to find out what gear ratio you have without opening up the rear end but I forgot how to do it. I know you jack up one rear wheel and then ...? Also, are all model T heads interchangeable? Should they line up EXACTLY with the engine block or should some heads be smaller in widths? bobt

You can block the front wheels and jack up one rear wheel, then put the car in "neutral. Put put a mark on the tire, such as a piece of tape or a chalk mark, and move the wheel to place the mark exactly straight down. Then place the car in high gear and use the hand crank to revolve the engine until the mark on the tire is again exactly straight down, indicating 1 full turn of the wheel. This should take from 3 to about 3 3/4 turns of the engine crank. It's easier to do this if you remove the spark plugs from the engine. Accuracy will be improved by having a slight drag on the jacked up wheel to take up slack in the drive line. An assistant can be very helpful by watching the mark on the tire and providing drag. The number of turns of the engine in high gear to make the wheel turn exactly once should give a fairly accurate idea of the rear axle ratio. For instance, 3 1/2 full turns of the engine crank to give 1 full turn of the rear wheel indicates 3.5 :1 gears. Most Ts are 3.64 : 1, while some are 3:1 and a few 4:1

Les and Allan. How do you solve the problem of the lack of Ford script?
I have what may be the last cast iron head Prus made on my 26 Tudor.

As far as I know, all T heads will interchange, but they are not all the same. Early model heads have more compression than later ones, and there is a difference in appearance and top to bottom dimensions (?) between early "low" heads and later "high" heads. All heads I have seen match the block fairly closely. Changing from a "low" head to a "high" head might require changing head bolts. Very late heads may not have the Ford script. Gasket listings I have seen show the same gasket used for all years. All use the same spark plug.

Hi John.
In response to your Needle and Seat question.... I use (and love) the Viton tipped style offered by Lang’s.
I’ve been a fan of these since Ford introduced these into the Stromberg Carbys in the Falcons In 1969 / 1970.
Fuel starvation has never been an issue with the T’s plus our landscape is very flat. The increase to 5/16 was purely emotional
thinking that having more fuel available may reduce the threat of vapour lock and all the issues I don’t have. I spoke to Scott Granger
and he didn’t see the need for me to upgrade to his product. I still may get a few of them off Scott as I believe they are a great
item and can’t do any harm, only good. Some have issues with soft seated needles but I find it’s the way they are treated and often forced closed with a Screwdriver while setting the Float Level.
Alan In Western Australia

Dale, here is my alloy Prus head, now complete with Ford script and MADE IN CANADA. I built a little dam with modelling clay for each word. The dams were filled with Devcon. When set, the lettering was marked out and hand carved with an Exacto knife and a Dremel tool. I even added a number and casting marks just like the original it on head from the motor. Allan from down under.

The 3 to 1 gears need to go. A Tudor is far too heavy for such a high ratio. You will only cause unnecessary strain on the engine and transmission and have to go to low on every hill. A car with stock gearing is capable of going faster than a T as ford built it should be driven anyway. My 26 coupe will readily reach 45 mph with stock gears and no performance upgrades.

Stephen

TXGOAT2 wrote: ↑

Sun May 08, 2022 9:15 am

... and jack up one rear wheel, ...

... use the hand crank to revolve the engine until the mark on the tire is again exactly straight down, indicating 1 full turn of the wheel. This should take from 3 to about 3 3/4 turns of the engine crank...

Pat, I think you meant 2 full turns with only one wheel turning.

I prefer t to turn the engine one turn. Set the rear wheel initial mark at 12 oclock,, the left wheel will stop at about 7 o'clock for a stock axle, 8 o'clock for 3 to 1 ratio, and 6 o'clock for 4 to 1 axle ratio.

I used this one my friend's several cars. We discovered he had a 3 to 1 in one of the cars.

Art Mirtes

Thank you Allan. I'll have to try that.

I would never run another 3:1 gearset, not because of the load on various components, but because the Ford brakes are really compromised. The car tends to push you down the road under brakes. Really good accessory brakes may help. When I sold my speedster to a novice T new T owner, I put te standard gears back in the car. It wouldn't go as fast, but it was much safer to drive.

Allan from down under.