I have been contemplating installing a Z head on my T. The problem that i have is that it runs great and I'm always hesitant to mess with something that is working perfectly fine. So my question to all the great minds that amass here is this,..Is installing a Z head worth the time and money to achieve what they claim is a 7 HP gain, better fuel burn etc? My engine has very little miles on it and i know it has aluminum pistons. Are the performance gains really worth it, or should i just leave well enough alone?..
Great addition to your model t, do you have high compression Pistons? If you do I don't think you can use the Z head. If I am wrong you can promulgate my ignorance.
I don't know what your terrain is like; where I live and drive there are lots of hills. The best things I've done are the high compression head, ruckstell and stromberg OF carburetor. The head and ruckstell are the two most important; I can climb pretty much anything, and in high / high I can keep up speed. It's not that I can go faster on the flat so much as I can keep my speed better overall. The places I notice the head the most are inclines and head winds. You mentioned your engine is fresh, so it doesn't sounds like domed pistons are in order... running domed pistons with a stock head also works very well and is much less expensive if you're already replacing pistons.
John, I'm pretty sure they are just stock aluminum pistons...thanks for the input, appreciate it.
Once you have experienced the Z difference you will never go back! If you regularly tour in a hilly area you will be particularly impressed. As you have a freshly rebuilt engine it will be a good marriage. I highly recommend it.
Thanks Gary, its an older restoration with very few miles so i doubt they installed domed pistons.
I've got some speed parts on my '15; an oversize intake manifold with an NH carburetor and a high-compression head. _Problem is, I'm afraid to put much torque through that notoriously brittle Model T crankshaft. _For me, I guess the extra grunt wasn't all that necessary.
Thanks Warwick, i thought the input would be positive to the Z head...but i wanted to hear from those that actually run them..Thanks again.
Bob, i know exactly what you're talking about, when i first got my T i treated it like it was a museum piece and was afraid to hurt it. Then i realized this was a piece of automotive history that was meant to be driven, and driven hard...And the best part is,..she likes it that way.
John T. is correct; you cannot use a Z head with domed pistons. I think you'll be pleased with either. You can pop out a plug and crank the car and see what type of pistons you have; you need to be sure you don't have domed ones before you pend the money on the head. That said, you'll swear it was the best $$ you've ever spent on your car, once it's in and you've driven it.
Thanks Gary, reading a description of the advantages they describe always leaves you wondering. I appreciate you chiming in..having someone run one gives me greater confidence in the product...thank you
And a Prus head is even better than the Z, better fit to the head gasket, machined combustion chambers/squish area over the pistons etc for $25 more. Same compression, both give about 5:1 compared to original 3.98:1 with a high head, but the Prus has been tested to give 2 more hp than the Z at higher rpms - during hill climbing rpms they're about equal.
If you don't like antifreeze for some reason (it gives rust protection when using an alu head) - then you can buy a cast iron version of the Prus head for $500. Otherwise the same as the alu version.
I'll second Roger's recommendation. I started out with a Z head on my '26 engine after it was rebuilt. It was a good addition, but I had a second '27 engine being rebuilt for another project, so I ordered a Prus head and pulled the Z head on my project engine. Put the Prus head on my driver. Hands down, the Prus head runs better. A little more power than the Z head, climbs hills better in high gear, and even gets a little better fuel economy. Given a choice I would definitely go with the Prus head.
Apart from their lame names (compared to Ricardo, Giant Power, Simmons Super Power) there's no question the Z and P heads are a great addition to any T. I prefer the Z because of the "Ford" script. The P is a good match for a 26-7 engine.
Having said all that, if you don't have a Dubats or Scat crank you may find the Z or P giving you membership of the two-piece crank club.
From my experience I would not buy another Z head. The quality is very poor. Both heads had to be milled before they could be used. One had to be sent back because of poor quality. I will be surprised if I don't have head gasket failure with the one I have now. I bought a Prus head for my current project, the quality is excellent. I took it out of the box without having to do anything but bolt it to the engine. If you want a Ford script on a Prus head, you can actually make a pattern of the Ford script form the steel head, then cast it with JB Weld and epoxy it to the head. I have done this in the past on steel heads and it has worked perfectly.
I used Z heads on two Ts, a freshly rebuilt Tudor and 13 T. On the Tudor, the fresh engine was overheating due to the tight engine. When I put the Z head on, overheating stopped, and I could shift to, and stay in, high gear sooner and longer.
I believe the Z allows the engine to run cooler and more efficiently, not just go faster. I would always use a high compression in the future for these reasons. It works great with our 13 too.
I like the Z head and Ruckstell on my otherwise stock 26 coupe. No top end change but better on hills. Check the piston to head clearance with NO head gasket before you do final assembly. You may need to "massage" the head a bit for clearance. I'd do the same anytime I installed an other than stock head or different style piston.
Thanks guys for all the input, i really appreciate it. I do like the idea of running a cast iron head v.s. an aluminum one for the corrosion issues alone,...can someone give me a link or tell my who sells Prus heads?....Thanks
Kevin Prus PO Box 357 Canfield , OH 44406
PH. (330) 774-7130
You bet! Good luck with your car. You're going to love this head.
I run Z-heads on three of my Model T's.
I live in Florida and ran my 17 Touring in 95 degree temp today with no over heating. I did a top end run with gps before and after I installed the heat. I got 5 mph more speed with Z-head.