Z head

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Model T Ford Forum: Forum 2018: Z head
Top of pagePrevious messageNext messageBottom of page Link to this message  By Philip Thompson Graham NC on Wednesday, December 12, 2018 - 09:11 pm:

I have put new valves, push rods,oil dips and an accessory inside oil line in my 24. I have a z head that I bought last spring it caused a vibration or rough running condition so I took it
Off. The bearings seem to be in good shape I adjusted them when I put the oil dips on. Should I try the z head again ? Philip


Top of pagePrevious messageNext messageBottom of page Link to this message  By Tim Juhl - Michigan's Thumb on Wednesday, December 12, 2018 - 09:20 pm:

I have a Z head on my engine - it runs really smooth. Since the Z head is an inert piece of aluminum, I suspect your reason for rough running is due to something in motion that is a bit out of balance.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Gregush Portland Oregon on Wednesday, December 12, 2018 - 09:30 pm:

Have you reinstalled the Ford head and if so how does it run? Could be you are not setting the spark for the RPM/load or spray needle adjustment? Are you running stock pistons? Or it could be what Tim said.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Scott Conger - Wyoming on Wednesday, December 12, 2018 - 09:47 pm:

I read back over your refreshing project. I am going to bet that new valves, fitted properly in their guides will provide you with a much better running engine now. I'd try the z head again if you're really inclined.

Understand that any boosting of the top end will be harder on the bottom end, particularly if you kept the CI pistons.

In any event, you're likely to have more success with a high compression head now...


Top of pagePrevious messageNext messageBottom of page Link to this message  By Noel D. Chicoine, MD, Pierre, SD on Wednesday, December 12, 2018 - 10:12 pm:

Are you sure there was enough clearance between the pistons and the head. If one was touching, it would cause a vibration and rough running. I once had an old Kawasaki 350 with a shaved head and teflon piston. at high rpm, the piston would tap the head. Took me a little while to find the problem.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Terry Woods, Cibolo, Texas on Thursday, December 13, 2018 - 12:34 am:

I read there was a casting problem on some, allowing the piston to hit the head.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Frank van Ekeren (Australia) on Thursday, December 13, 2018 - 01:34 am:

Terry,
the casting is only one of the variables that can contribute to a piston hitting, another is the way and who has rebuilt the rods, a decked block, gasket thickness also.
So a Z head should always be checked for clearance.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Brendan Doughty Central wisconsin on Thursday, December 13, 2018 - 06:12 am:

The older Egge pistons and Z heads were a problem also. The piston hit the head because the distance from the wrist pin to the top of the piston was about .075 greater than other brands.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Philip Thompson Graham NC on Thursday, December 13, 2018 - 08:13 am:

pretty sure it is not the pistons hitting the head.
back when i had the z head on the car had more power
but you could never find an rpm where it just cruised along it is hard to explain. i plan to check out the u joint and 4th main while the weather is
bad. i also have some wheel issues the 21 demountable split rims are not true i have worked on them and balanced the wheels and they are better.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Gregush Portland Oregon on Thursday, December 13, 2018 - 11:45 am:

What carb? Battery or magneto? Re cruising along, you have to learn how to use the spark lever. The Z head is going to have different requirements as to when/where the spark happens. You can't just get in, start the car, pull the ear down and go.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dave Hanlon N.E.Ohio on Thursday, December 13, 2018 - 11:52 am:

I would check the clearance as mentioned before, make sure it's flat and run it...just my opinion.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Philip Thompson Graham NC on Thursday, December 13, 2018 - 01:27 pm:

magneto and nh side drain. is what im running


Top of pagePrevious messageNext messageBottom of page Link to this message  By Neil Kaminar on Thursday, December 13, 2018 - 08:59 pm:

Hi Phil,

The Z head will put more load on your bottom end, as Scott said. Give it a try but order an extra head gasket in case you don't like it.

Neil


Top of pagePrevious messageNext messageBottom of page Link to this message  By Brad Marble - New Hamshire on Friday, December 14, 2018 - 03:14 pm:

If the combustion chamber isn't centered on the cylinder then the piston could hit the edge if the of the head gasket and or head, I don't believe the piston could hit head in the combustion chamber, because there is a lot of space there.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Frank van Ekeren (Australia) on Friday, December 14, 2018 - 03:22 pm:

Trust me Brad, they do!


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mike Bender Tulsa Oklahoma on Friday, December 14, 2018 - 04:46 pm:

I will second Frank's comment. Need to check a Z head for piston clearance and I don't care what brand of piston is used.


Top of pagePrevious messageNext messageBottom of page Link to this message  By John Doolittle on Friday, December 14, 2018 - 04:58 pm:

How about if he removes the Z head. Then removes the head gasket. Then place the head squarely on top of the block so that all bolt holes line up (w/o the head gasket in place). Then hand crank the engine. If the head lifts up, then he needs to look into a fix. If the head stays put, he heeds to find the source of his problem.

(Message edited by 600wt on December 14, 2018)


Top of pagePrevious messageNext messageBottom of page Link to this message  By Gene Carrothers Huntington Beach on Friday, December 14, 2018 - 05:02 pm:

Third YES,
It's a no brainer but more than just us have had to relieve a spot to give a bit of clearance.

So simple to just sit the head on without the gasket and no plugs and hand crank it over.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Bruce Compton on Friday, December 14, 2018 - 06:11 pm:

The initial request was concerning "rough running " and a "vibration" that he thought might be caused by the Z head, and no mention was made about noise that should have been apparent if the piston(s) were hitting the head. I have a Z head on my '25 and it ran perfect for maybe 500 miles until a head gasket blew and then I had a rough running engine with a vibration, and no coolant loss. There is precious little material between the cylinders in the combustion chambers of every Z head I've seen and that's where mine blew. I even took the Z head to Stowe and Don Lang had a real close look at it,and compared it to a Prus head he had brought as a possible replacement but they were almost identical in the area in question. A new gasket didn't help, but I was able to reuse the Z head by soldering the seam on a used copper head gasket with 50/50 soft solder and sanding it down to match the original "used" thickness. I got this tip from a race engine builder that guaranteed it would work (although I didn't believe him). I've been running the head now for two years with no issues. I strongly suspect that Philip had the same problem although he didn't say how long he ran he car with the vibration and rough running condition


Top of pagePrevious messageNext messageBottom of page Link to this message  By Philip Thompson Graham NC on Friday, December 14, 2018 - 06:23 pm:

I did not run it long I was getting ready for my first tour with the tarheel ts. And put the original head back on and have ran it since.
I think my plan is to put the original head back on with a used gasket to get a feel of how my new valves oil dippers and 7.5 advanced alum cam gear
Perform. Then I want to pop the rear end out and check the condition of the 4th main then I will revisit the z head. I would like more hill climbing power but I don't want to tear the bottom end up getting it. Philip


Top of pagePrevious messageNext messageBottom of page Link to this message  By Joss sanderson on Saturday, December 15, 2018 - 12:40 am:

A prior poster mentioned piston hitting the Z head. There was a number of heads at least 5 years ago where the head clearance was short on #2 and #3 from a casting defect. If you measured from the deck to the top of the combustion chamber those cylinders were about .050 to .100 less. Causes all manner of problems.


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