Just wondering what others experiences are with running a high compression head with original coils are. I'm currently running original coils but considering a Z head for a little extra pep. Everything is stock and I really like hearing the coils and they really haven't been troublesome thus far. Would I be wasting money on replacing the head without changing the ignition system?
HC heads work just fine with stock ignition.
More power with higher compression no matter how ya' light the fire!
It becomes more important that the front cover is correctly centered to ensure that the timing is consistently every 90 degrees of the camshaft (180 degrees of the crank). Otherwise should be just fine.
When I went to high compression several years back I developed an intermittent miss. After changing about everything on the car to find it, I gave up. Finally got the help I needed to track it down by one of our forum members. After rechecking everything one by one it was determined that my spark plug gap, set at .0032, was to much for the coils on a high compression engine. After a big long explanation as to why I changed the plug gap to .0025 Problem Solved.
I had a very similar experience to Richard. I would get an intermittent miss but after about 6 miles it would go away. Those T coils wouldn't even out until they warmed up I guess. I was also on 6 volts and the starter struggled a little to get it started with the higher compression.
I have the same set of coils Bret Mize did for me 7 years ago. No problems with my HC head.
Oh, And I run 12 volt all the time.
Bolting on a Z head is like bolting on 5 horsepower.
Mine run fine with original coils. If yours have not been rebuilt, be sure to rebuild them yourself or send them out!
: ^ )
Now that the ignition is pretty well covered and not known your mechanical back ground, I'll just add that bolting a Z head on isn't as simple as remove old replace new.
First the Z head needs to be dropped on with out the head gasket and in turning the engine over making sure that the pistons don't hit. all thread holes in the block need to be cleaned out and run a bottoming tap to clean them up, head gasket can go on 2 ways but only one is right, large water hole to the back. Spray copper seal on gasket.
When re-tightening the head studs after a run, do that on a cold engine with aluminium head.
Now that's the simple part, you might find that your engine still has the original 2 piece valves, that's a whole issue and another job.
I'll probably pick up a lot of critical flak about this, but if it gains me some education, so be it:
I would recommend against bolting high-performance parts onto a Model T engine because when you do, you're flirting with becoming a member of the 2-piece crankshaft club. -The crankshaft is the Achilles Heel of the Model T Ford's drive-train. -It has a long-standing reputation for breakage and anything you do to put more power and torque through that iffy component, the more likely it is to create one heck of an expensive problem for you.
Now, knowing the Model T's reputation for being sluggish and slow, when I purchased my '15 Touring, I had it re-equipped with an NH carburetor, a hi-flow intake manifold and a high-compression head. -Added together, those things really put some zip into the old gal and it was fun to swing the throttle and make that car really get up and go! -Hills? -No problem! -I'd just use as much throttle as it took to lug the car up the incline in high gear.
Then one day, the highly experienced Model T guru who had introduced me to the hobby came over to see my "new" Flivver and go for a ride. -To say he was taken somewhat aback at my aggressive treatment of the throttle would be an understatement. -I was immediately given, in no uncertain terms, a life-changing lesson on how to treat a Brass-Era automobile with the respect it deserves. -Part of that lesson involved impressing upon the primary windings of my cerebral cortex an unambiguous appreciation for the delicate nature of the Model T Ford crankshaft. -Henceforth, I treated the throttle like a vial of nitro-glycerine.
The bottom line is; if you're going to be prudently averse to using the extra power gained through a high-compression head because you don't want to bisect your crankshaft, you might as well just keep your stock Ford head.
not flak, and I don't dispute the need to treat machinery with consideration.
However, with just Henry's 2 gears, there are lots of hills which you approach at 30-35mph, only to see the speed drop....and drop until you are down to about 20mph. You can, of course slow further to about 14 and engage low gear, but most people don't.
With a better head (I have a Giant Power 5.3:1), I find I can hold 30 or close to it on many gradients, and I suspect that the oil film on the bearings and the crank stresses are better than when slogging at 22mph.
On the other hand, I was 'surprised' to read on another thread yesterday the suggestion that any good Model T should cruise at 50mph! My sensitive regions tell me that distress certainly sets in above 40mph.
From what is being stated here, to gain more speed and power from a T engine there should be a total up grade of the power unit. Common sense would direct one to the concept that as metal ages the possibility that at speed and engine loading failure is on the horizon.
It would be best to have all rotating parts tested for mechanical condition. And to remember that the 100 year old plus motor drive train was limited to short burst of speed.
Come to think of it may be a total rebuild or up grad is what is in order for speeds above 50 mph.
I see your point of view and, to an extent, am in agreement with it. -Yes, I do the same thing when it comes to taking a running start at a hill with the intent of performing a "zoom-climb," but as the climb progresses and the engine gradually loads up, I progressively reduce throttle as I near the crest of the hill.
But sometimes, it just can't be done that way. -Sometimes, there's a stop sign or traffic light at a corner where, from a dead stop, I need to make a turn while beginning a climb up a steep hill. -In that case, there's no way to take a running start at it and make a zoom-climb. -When that happens, I turn on the 4-way flashers and crawl up the hill in low gear. -I'm aware that this puts a lot of heat and friction stress on the front main bearing, but I keep my oil level at maximum and have an outside oiler. -While this does the planetary-gear bushings no particular good, nevertheless, I'd rather accumulate some wear and tear on the bearings and bushings over the course of years rather than overstress my crankshaft just one time and thereby break it. -No matter how you look at it, for a Model T Ford, steep hills are a problem.
But because I'm more than a little eccentric, I actually enjoy the challenge of pre-planning and mapping out my routes around steep hills, off-loading unnecessary weight, and have no compunction about telling my passengers to egress and walk up to the top of the hill where the car and I will be magnanimously waiting (and were I not indeed a man of such munificent altruism, I'd also ask them to push).
Now, here I want to tread carefully because we're not all in this hobby for identical reasons. -While I recognize that there's absolutely nothing wrong with wanting to improve the handling and performance of any antique car by means of mods that might include a crate engine, tubular control arms, anti-sway bars and radial tires, it happens that I myself am in it for the historical experience, including its disagreeable challenges. -
Oddball eccentrics like me like to write with leaky fountain pens and, given a choice, would prefer a sailboat to a motorboat. -I make tomato sauce from scratch with my great-grandmother's wooden spoon and pop corn in her cast-iron skillet. -There's a land-line phone with real bells and a curly wire on my kitchen wall and my day starts with slapping the very same wind-up, Westclox alarm clock that woke me up for grade-school.
-Oh. -And I start my car with a crank.
My T has had a Z head on it for as long as I can remember...
Does have other mods, like a distributor. Many many miles, so far.
But back to topic.
Model T coils have plenty of energy to fire a "pumped up" engine. A distributor may be capable of a little higher RPM than a timer. But RPMs are the death sentence of a T bottom end. Bearing wear/alignment and RPM break cranks. IMHO
Looking at the gap measurements above, it's no wonder his spark plugs didn't fire!