I've read all the posts about the performance gains from the Z Head, but is there anything I should be concerned about with the switch? Does it add any stress to the motor that could cause failures or anything like that? Motor runs great now, just looking for a bit more power since I live in an area with lots of steep hills, just don't want to regret it.
The simple answer is that you can't get something for nothing. If you are getting more power out of the engine, it is adding more stress to the engine.
The crankshaft seems to be the weakest link in the T engine and it is very likely that the more stress on it, the more likely it is to fail. It is a trade off, more power and less durability or less power and more durability, you choose.
You get more power on the same amount of fuel.
More compression can also solve overheating problems, as you'll get more work and less heat from the same amount of fuel.
Those who have had bearing problems after changing to Z heads likely had excessive play in the bearings before the change too, the knocking that was about to start was perhaps just coming a little sooner with higher compression? When a rod starts to knock, it bangs itself to ruin fast - the oil film can't cover up for more than a couple of thousands..
So if the rods hasn't been checked for a long time, it's best to check and perhaps pich a shim on each if needed when doing the head exchange. Then it'll run quiet for about as long as with a standard head.
Another important thing to check is clearance for the piston tops - test fit the head without a gasket, crank the engine and listen/look if any piston touches the head. Some grinding in the combustion chamber needed if it does, then the gasket creates the proper distance needed for heat expansion, flexing at speed etc. If the head doesn't cover the crush area in a copper gasket as described in this thread: http://www.mtfca.com/discus/messages/257047/295708.html?1340402616 try get it exchanged for one with a better fit - or try a steel/fiber gasket instead. Very few seems to have any actual problems from this, despite lots of Z heads in use.
The Prus head is another choice: http://www.modeltford.com/item/3001HP-14.aspx It may give a couple of more HP than the Z in top end and no piston interference or gasket problems as far as I know, but pulling the inspection pan and checking the babbitt would be advisable just as with the Z head
With the aluminum head you will HAVE to use coolant, water will cause the Al to corrode. The performance change is noticeable.
I have used the Z head on three cars and have had great success. All times, I had a good bottom end to prevent any potential bearing failures on the crank and rods. I did have aluminum pistons in all three. Good power improvements in all three cars.
Since then, I have been using 7 1/2 degree advanced cam gears with similar power results. And this, in my opinion, does not add extra stress to the crank shaft. But it does improve the power, especially low end torque. And this is without the Z head, instead using a stock head. The Z-head is about $400 and easy to do. The cam gear is $60 and a little more time consuming to install.
We have installed three more cam gears in other cars with similar results.
It is up to you, but I am a big believer in the cam gears, especially if I do not have the best in bearings and don't want to do an overhaul.
Your situation may be different.
I personally didn't like the Z head on my 26 pickup. For some reason there was a lot of cam noise and I had to adjust my clutch because it started to slip under the increased power. I purchased the head off eBay and I wonder if someone had shaved it down for more power. Probably not since the pistons could have hit the head had that been the case, but I've always wondered.
I had better luck with a Waukesha head as far as general driveability, but power was greater with the Z head.
Do you still have the Z head, Richard? I could be interested in buying it ;) (PM sent)
I have a high-compression head which is supposed to yield better gas mileage and of course, the potential for more power. I say "potential" because you only get the additional, theoretical 5-7 horses if you open the throttle wide. If you're like me, you'll never try to draw full power from an engine whose Achilles' heel is its crankshaft.
For that reason, I think of the high-compression head as unnecessary. Does the engine run better or idle smoother because of the high-compression head? Nah. Is the slightly improved gas mileage noticeable? Nah.
If, on the other hand, your engine happens to be equipped with a SCAT crankshaft, not one of which have ever broken, according to what I've read on this forum, then I guess a high-compression head would make sense.
Roger, I sold the head on eBay some time back. If I still had it, I'd sell it to you.
Never did receive your private message.
Bob C. -- I don't like to drive with the engine "wide open" either. But the difference I can tell with higher compression is in the increased torque. That is obvious when climbing hills, not at high rpm's. Whether you get the increased torque using an aftermarket high-comp head, or with pop-up pistons and a shaved stock head, or by increasing the cam timing (or 2 of those 3), more torque at 800-1,200 rpm is what gets you up the hills.
p.s. -- I would like to have an engine with a Scat crankshaft, but I can't afford one. I have used both early and late-type Ford cranks, and I always have them magnafluxed before putting them into an engine. I have yet to break one. (Knock on wood.....)
Ok, Richard. The Scat cranks hasn't broken - yet - since they haven't been in use for as many years and miles as the originals. I think any 4 cylinder crank with 1.25" diameter mains will crack eventually if used, though not necessarily in our lifetime. Scat offers a larger diameter alternative too, but installing them it is a lot more complicated.
I'm having the rebuilders put a SCAT counterbalanced crank in mine. I'll bite the bullet and spend the money now rather than trust a used one. SCAT cranks have an excellent record of reliability and performance across all their products. Could it break in the future sometime? Maybe? But I'm willing to bet it will outlast just about about any other regrind out there in my life time or those of the next few owners.
"Could it break in the future sometime? Maybe? But I'm willing to bet it will outlast just about about any other regrind out there in my life time or those of the next few owners."
I believe Kevin is right on with his thinking. The owner of the Scat crankshaft company (sorry, I've forgotten his name) gave a presentation at the Sunflower Crankers' Winter Clinic a couple of years ago. It was quite impressive. During the Q&A session following, someone asked him directly, "Will your crankshafts break?" He answered, "Yes, eventually."