My "T" is a little gutless!

[JohninKuranda]

Just looking for some suggestions about what I can do to get a little more oomph out of my Model T. The engine is a 1915 Canadian made.

I seem to lose power when the engine is under any strain - like going up a hill. On the flat I am lucky to get 45KPH (28MPH). Down hill is obviously faster!

I have adjusted the transmission bands and inspected for wear. All seem okay.

I have also checked the fuel line - that is clear. I have rebuilt and swapped out, several times, the carburettor. I have checked the coil boxes, they are all fine and producing the correct charge. Changed the wiring loom - the old one was a tad old and somewhat fragile. Changed the spark plugs. I have now tested the compression - one each cylinder it is 40PSI - give or take 1-2 PSI. I am a little unclear as to whether this is an acceptable level of compression.

Does anyone have some ideas, comments or suggestion as to what else I can try?

Many thanks
John

[Sunny the Model A]

that's low compression for a stock T, it should be a bit higher around 55 psi. so that means pressure is being lost. now when you did the test did you fully open the throttle to get the full volume of air? if the throttle is closed it won't give the right reading. now if you did and it still only gives 40 psi, I'm suspect of piston ring and cylinder wall wear. that's what is most common on T and A engines. Got any other symptoms from the T that might explain it? since you say you rebuilt the carburetor several times and the coil boxes I'm thinking it's internal but let's not jump to conclusions. so by your description over a certain point it just bogs down. well if it struggles to get 30 mph that tells me it can't pass peak torque which occurs at approx 950 rpm, with stock tires thats about 25 mph so it's consistant with your description

[39portlander]

John they all seem to lose power with any incline, thankfully my Fordor has a ruckstell and thats not a problem.

yes 40 seems low 50-55 is a good reading for compression, that being said I would pull your valve covers and make sure every thing looks good there. More than likely like mine I had a very worn cam and the lifter or "push rods" worn down and "dished" as well.

Also check that your rear drums are clean and properly adjusted, it's a real pain adjusting those brake rods and getting them just right

[rotorwrench]

It may need a ring job overhaul and/or valve resurface. If the bearings are getting sloppy then it could be full overhaul time. Model Ts respond well to a high compression head but they need to be in fairly good condition to start out in that direction. A Ruckstell conversion will give it the extra ratio but it would likely need Rocky Mountain rear brakes for that kind of go fast.

[Will N]

Originally Posted by rotorwrench

It may need a ring job overhaul and/or valve resurface. If the bearings are getting sloppy then it could be full overhaul time. Model Ts respond well to a high compression head but they need to be in fairly good condition to start out in that direction. A Ruckstell conversion will give it the extra ratio but it would likely need Rocky Mountain rear brakes for that kind of go fast.

I thought that a Ruckstell axle was not an overdrive unit for extra top speed. Isn't it actually an underdrive to give you an intermediate gear? It comes in handy on those uphill roads where it won't make it in high gear and low gear is too low and holding that pedal down is a chore.

[stevests]

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A Ruckstell is an underdrive unit - one can fit a "special" Ruckstell gear set (if you can find a serviceable set) to make a 3.25 to 1 ratio to increase road speed a little but you'll lose your "pulling" ability somewhat.

[Gary loves Fords]

This may be too simple to fix. Before pulling pistons and looking at rings, try finding the sweet spot with the spark advance before diving into the motor. Often, if you are running too rich or too lean, you don't get much power out of a T engine. Adjust the spark advance until you notice a real increase in the RPMs and you may have just fixed your problem with a minimum of effort.

[rotorwrench]

Originally Posted by stevests

A Ruckstell is an underdrive unit - one can fit a "special" Ruckstell gear set (if you can find a serviceable set) to make a 3.25 to 1 ratio to increase road speed a little but you'll lose your "pulling" ability somewhat.

The 40 tooth ring is available and will work with the available 12-tooth pinion for a 3.33. I think there is a 39 tooth ring that will work with the 12 tooth for 3.25. The reduction is a planetary set which has some similarity to the later Columbia. The old 13-tooth pinions may be out there but I've not seen any new ones.

Folks that want to get taller gears generally go with an in line gear box type that has an overdrive ratio. With a model T that is stock, it may not do all that well developing higher road speed. Hop the engine up with a larger fuel delivery system, a cam, a more tuned exhaust, and a high compression head and it will develop more power and higher speed capability. Folks that go this route generally do away with the magneto on the flywheel to try and lighten it up. A distributor usually replaces the old trembler coil set as well.

I sort of prefer the old original set up myself. It takes too much work for make a faster car out of a T when a model A is better suited to hot rodding.

[HDowse]

As Gary said above, try finding the timing sweet spot and then try adjusting the carburetor control under the dash to find the smoothest engine. I do this in low gear so I don't have to be going too fast.

[jimTN]

Sounds to me like its running a little low in timing.

[J Franklin]

I bought a T with these symptoms and found the cam gear was 1 tooth off the crank gear mark.

[A bones]

Two weeks now.

[ronn]

The engine is a 1915 Canadian made.


therein lies the problem........................................... ...!


lol

[JohninKuranda]

Just an update - what with Easter and work commitments over the past few weeks, I have not had a chance to do much - but it is another long weekend here in Australia and I have some free time. I did have though, the opportunity though to retest the compression again with various levels of choke. Sadly, no change so further explorative work. I am thinking of pulling the head to check the condition of the pistons and rings. I know that no work/inspection has been done in the 22 years that I have owned the car, and suspect nothing long before that.

John

*************************************
UPDATE:

Well that was an interesting mornings effort! And I may have found an answer. When I went to pull the head, the first random bolt I chose needed very little effort to reverse it out. After moving with the wrench, a few turns and fingers only were needed to remove the bolt. Same for the second bolt. Before trying a third bolt, I grabbed the torque wrench - only to see less than 10 psi was needed to loosen. All the rest were equally loose. The only one that needed much more effort was the one that had the horn stand attached - and I mounted that. Looking at the gasket after removing the head, it looks as if the lack of torque across all the head bolts meant that in certain areas there was not a sufficient seal between the cylinders. The gasket does show carbon build up in certain areas - the thinnest areas between cylinders as can be seen. I do not profess to be a mechanic, but I would have thought that a leak via the gasket would affect the performance. There was approximately 1/8" of thread sealant on most of the bolts. So I am assuming that whoever did the last overhaul before I purchased the T 25+ years ago simply forgot to torque the head bolts.

The other item of interest was that the valves were all branded "Holden" which was the Australian subsidiary of GM.

I now have on order a new gasket and head bolts (just because) and I shall re-assemble when those parts arrive and see the result. The pistons appear in good condition and there is no wear on the cylinders - so this is probably the most economical solution currently to my original problem. If there is no unwarranted escape of gas on the ignition stroke, then I reckon that will be transferred into increased power and therefore speed.

[ronn]

a higher compression head wouldnt hurt, while youre at it.........

[stevests]

It is imperative that you clean out the block holes that receive the head bolts ! Years of crud & carbon deposits can prevent the new headbolts from doing their job. This is the tool I use and you won't believe the amount of stuff can be hidden down there & prevent the correct torque !

[rotorwrench]

I use the single flute chasers to clean threads. The risk of using taps is that the thread fit class can be tight and actually remove some metal. This is an example.
https://www.autotoolworld.com/Jims-U...RoCE_EQAvD_BwE

A person can use a cut off wheel to cut a flute in an old bolt that will work in a pinch.

[stevests]

The above tool I posted is not a tap.

[rotorwrench]

Spiral flute taps are good for production since they help remove chips better, but they are still taps and are subject to different thread classes just like any other thread tap. As long as it has a thread class that is equal or looser to original such as a class 1B it should be OK. The model Ts were made to use bolts so are likely already a loose fit but studs as used in the model A are a different story. I do know that model A engines already have loose fitting studs but that may also be due to wear from previous disassembly and reassembly with cleaning of threads. Studs are generally made to be a tight fit in engine blocks such as the early Ford V8.