I finally got my Z head on my 21 chasis - soon to be a Syverson depot hack. What a difference! I had put the old style intake manifold on a few months back that is supposed to increase hp by 2, but I never really noticed any difference. Boy, I sure can tell the difference now with the Z head. I certainly would recommend this to anyone desiring to get a little more umph from your T.
The head makes more power thru the entire RPM range. The manifold will help at the upper end of the RPM range if you combine it with a freer flowing carb. such as a straight thru NH.
I didn't know about another head made with hemi combustion chambers. Does anybody have one? I'm sure it's too much to expect a side-by-side comparision if a guy has one of each on two cars - but I'll ask anyway!
Dan, look on previous posts regarding the Lizard head. I hesitate to mention the name without causing a flood of negative comments. It had some production problems and is out of production. The plugs are above the cylinders instead of above the valves. As such, there is a problem with pre-ignition and pinging with the stock magneto system. Some folks like them for use with distributors. I found a slight bit more accelleration at low rpm's, but mine pinged at anything over 40mph regardless of what I did. I'm running a Z now. The Lizard hangs on the wall.
I didn't realize the hemi-head was the "Lizard". After all the good reports for the "Z", I think that's the one. Years ago I bought a "Jensen" head and it went away with the car when I sold it.
I'll have to call Lang's I guess and get a "Z" head on the way.
I called Chaffins a few minutes ago to order the head and a low '17 style radiator, but Dave was so busy he only had time to tell me how busy he was and that he wasn't very happy.
Maybe the folks at Lang's won't be quite so snappy and sharp about their dissatisfaction with work issues. For years I've used Chaffin as "my" parts supplier, but maybe it doesn't pay to depend on only one parts house. Spread the wealth, you know?
You putting that Z head on your new '17?
Yup, Keith. I've been driving it to work (30 miles each way); I wired the headlights and put some mag bulbs in them and off to work in the dark it went! It's sure smooth and quiet, but it needs more muscle.
I put a set of John Regan coils in it and an Anderson timer from Chaffin's to replace the black New Day, which was all used up. The plastic between the copper contact segments on the New Day was scooped out about 1/4" deep and the brush was bent crooked and worn over to one side - it must have had more than 200 miles on it! The improvements to ignition were great and it sure cleaned up a high-speed falter or miss it had. It is smoooooooooooth. I guess the best may I could describe it though, is that it's very "polite". The driver would be naive thinking he might perceptively speed up when he quickly pulled the gas lever down. Well, to be fair, it DOES speed up, but so softly and gently it's almost like a golf cart with low batteries. It's fun and smooth and quiet (almost silent), but it needs a little more youthful vigor and less rigor mortise.
I haven't put a compression gauge in a hole yet, but by the feel of the crank it has feeble compression. The head that's now on it is a very late non-script high Ford head and it doesn't have even a trace of any lively bounce at the crank.
Still, as slow and weak as it is, I just can't keep my hands off it or my buns out of the seat. The poor thing is NEVER cold.
I've found, too, that on warm California days, the radiator isn't up to the job anymore. As long as the temps were no higher than in the 60s, it was OK. Driving in 70+ degree temp is enough to make it spit and slobber around the threads of the radiator cap. If 70 is enough to make her break a sweat, what will it do when it's 95? So a radiator is at the very top of the list, too. Even above upholstery. The rest of the shopping list is as long as my arm.
I put a set of Bennett small drum outside brakes on (also from Chaffin's), a floor mat (Chaffin's), it had a leaky rear tire - a new tube from another box from Chaffin's fixed that, too.
Dan, you can check if the low compression comes from sticking (or worn out) rings by pouring some (- a teaspoon?) motor oil in each cylinder, remount the spark plugs and try cranking without ignition. If the compression increases significantly, you should check the rings and cylinder bores
- If no change, then the valves may be leaking? (less likely though, that all valves should leak about the same..)
Very silent.. Mouses nests in the muffler?
If it's a reproduction muffler - Take it apart and check if it's correctly assembled?
I think I have heard of mufflers with the insert pipes turned in the wrong direction? Or was it something with the holes?
Oh boy, I can hardly wait. New head and new bolts are coming from Lang's.
Roger, if I had to guess, I would place my money (and I guess I AM! Har!) on both the head and the cam. Cranking the engine doesn't give that lively, satisfyingly springy bounce like a good T has. It just mooshes through the strokes - if I stop cranking, it just stops moving. No eager spring back against compression. There's no wheezing sound through the breather; when it's running, there is no noticeable blow-by. The rings appear to be doing their job competently.
The engine seems to breathe nicely, if I "blip" the gas, it is fairly responsive and the exhaust sounds perfectly normal and there is all of the exhaust volume (puffs of exhaust gasses) I could expect issuing from the muffler. I'm sure the muffler isn't constipated. The car is just feeble. It's quiet because it just doesn't make any noise! when it's going down the street, it glides. No eagerness, no vibration, no struggling. It just glides. Honestly, to drive it, it feels like a steamer. There is no feeling that it's working. In fact, there's no real feeling that it's even running. Open the throttle wide and it begins gaining speed without complaint and without vibration. It tops out at about 32 mph for speed. And a 1917 runabout in good fettle should handle gusts up to 50, at least.
It runs VERY evenly with no soft spots or weak cylinders (low idle gives a slow, distinct "Ka-poc-ket-a-ka-poc-ket-a-ka-poc-ket-a"), so I don't think it's a bad valve. I can easily see each individual fan blade when it's idling.
It can be kind of a jerk to start cold, it has a hard time keeping going long enough until it gains speed. This seems to me to be because it is so weak. Almost wide-open throttle is needed to keep it running long enough to make an over-the-fender diving lunge for the spark. After it's warm, it's better. In warmer weather, it's better.
The engine was, I'm told, rebuilt; new babbit, new SS valves, new aluminum pistons. I don't know what, if anything, was done to the cam. If the cam is heavily worn, the valves might be just bumping open and not giving a deep breath to the intake nor opening wide for exhaust. A flat cam will sure make an engine feeble and "gentle" like this one is.
And, it reminds me of is an engine I had years ago - decades ago - that had modern flat-topped Ford six pistons in it with a stock high head. When they were at TDC, the pistons were dead level with the surface of the block with none of the familiar chamfered pop-up shape. I can't remember for sure what the compression was on a gauge, but I think it was in the 30s. That engine ran absolutely BEAUTIFULLY. And talk about a joy to crank - It was so sweet and practically silent too and weak as a kitten. It would idle so slowly it would almost STOP between individual power strokes. The car would coast along in high gear at a walking pace, the only sound it made was from the carburetor. It was like one long, low intake of human breath - but the stupid thing couldn't pull a hat off your head.
So, we'll see what a Z head does on this one...