How easy should a cam turn?

[Tony D]

Yes, exactly. A shop that works on them all the time would have told you this 40 posts ago.

Now you're out money and can do the Gollum-Suggested #2 option.

 

It is a Gene-Berg "if you don't have the money to do it correctly now, when will you find the money to do it over?"

Sometimes when the machinist says its not repairable (economically is the term they like to use...) they really mean just that!

 

Stick with the Z-Club, find someone with a used head you can bolt on and run.

 

You just learned one of my oldest axioms: "I'd rather run a Nissan-Assembled component with 100,000 miles on it than most stuff people have "overhauled" and are selling for some reason only 10,000 miles later!"

 

Most work is fixing things that aren't broken, or limping things along that should be scrapped!

 

Sucks, sorry about the painful lesson. I'll be in Houston next week, with a truck... Get a lead on a head anywhere from Chicago/Wisconsin to Dallas, I can pick it up and deliver it to you! (Maybe a whole engin!"

 

Get on the Internet and with the local club.... I can take shipping out of the equation if you PM me before I pass wherever your new parts are laying!

[srgunz]

I did finally read what it takes to straighten a head as described in the

'How to Modify' book.

Too much additional labor($)to stick into that head in my view.

Pick up another head at this point as Tony suggested.

Take this head to metal recycler and get some cash back for it.

Cut your losses and move on.

Good luck.

[Ben's Z]

I forget if I found the seller of this head on here.  If I did that makes two items out of three that have been junk.  There should be feedback on sellers on here.

[PMC raceengines]

if it was fixed right the first time it would have been a good head  ,, crap work in the shop  , its not the blokes prob your shop is crap

[Ben's Z]

One final thought on this head.  Would a shop or could I do the following... Use the exhaust/intake gasket for a template and buy some steel flat bar that is about the size of the side of the head  Drill out all of the holes in the steel template where there are threads in the head.  Put all thread in all of the holes in the head, slide over the bar stock heat the head and slowly turn some nuts and washers on the bar stock trying to get that few thousands out of the head to re align it?  Could I ever get it hot enough?  Would it distort the valve seats?  Would I just end up pulling the threads out of the side of the head? Fruitless?

 

Peter, to your argument, why can't a shop do something similar to this now?  As I said looking down at the head now from the cam sprocket the head makes a slight banana shape like this "(" front to back.

[skirkland1980]

There is a video on youtube of the straightening process. The guy has his phone number there so you can call and ask questions.

[NewZed]

 Use the exhaust/intake gasket for a template and buy some steel flat bar that is about the size of the side of the head  Drill out all of the holes in the steel template where there are threads in the head.  Put all thread in all of the holes in the head, slide over the bar stock heat the head and slowly turn some nuts and washers on the bar stock trying to get that few thousands out of the head to re align it? 

 

Peter, to your argument, why can't a shop do something similar to this now?  As I said looking down at the head now from the cam sprocket the head makes a slight banana shape like this "(" front to back.

 

 

Not to jump in front of PMC, if he even intended to reply, but is the head bent top to bottom or side to side?  You seem to describing a side to side bend.  Why would you use the manifold mounting holes otherwise?  The plan doesn't fit the original problem.

 

As far as fixing the "fixed" head - how thick is it now, from bottom surface to top surface?  After all of the trips to the shops it has to be getting thin.  Measure at each corner to get an idea of how parallel the surfaces are, just for fun, to see where you're at.

 

Do you have the "How to Modify..." book or just the "How to Rebuild..." book.  There's two books, and they're different.  The straightening process is in the "How to Modify".  I'll copy the page if you want to try it or show it to one of your shops, although it might be too late.

[PMC raceengines]

start over mate this head is no good now , you have to do it right from the start. 3 steps to make it right if you start at step 2 and 3 , step 1 can not work  , with out step 1, step 2 and 3 are never right 

stress points in the head must be releved  to remove the twist then it gets planed flat . not any other way can it work 

[Ben's Z]

This head is parallel top to bottom. It is curved side to side with the inside curve dead center on the two center exhaust ports.

[PMC raceengines]

What you are missing is the head well not be parallel as soon as you try make it right it will twist as soon as its heated and stress releved  you will need to have it planed again that why its step 1  it will move 10 to 15 th... So that why i said start over .

[skirkland1980]

Call this guy about your head Billy Vaughn 478-745-5000

[zacward]

I had my machine work done in Schertz, by San Antonio. 210-659-2400. Its called city auto machine. Also, this guy has expirience with L-motors http://www.glennsmachine.com/about.html . He's just north of Austin.

[NewZed]

When I put the cam gear on yesterday it seemed to spin but about 20% of the rotation was tighter regardless of cam................... This really has been hell.

 

From Post #9.

 

It seems to me that one of the original problems was that the cam is bent a small amount (as pointed out in another forum also),  since the binding is not consistent across 360 degress of rotation, it's only there for 20 degrees.  That's what I meant to look for, in one of my posts about measuring cam "run-out", although that may not be best word for it.

 

Just trying to help you avoid more pain in the future.  As has been pointed out, there's a certain sequence to follow to end up where you want to be.

[Ben's Z]

For grins I have messing around with this head a little more.  I took some Prussian Blue and wiped it in the cam towers, inserted the cam and spun it.  On the last tower it was taking off more blue at the 2 o clock position looking at it from the back of motor.  Another interesting thing to note is while I believe this head is banana shaped I can take the cam out with the head and towers torqued without loosening.   I can also get the cam back in but I have to lightly tap the nose of the cam to get it to fit in to the rear tower.  I am contemplating running this just to see how long it will last.  I am 90% sure it won't be long.  What kind of carnage might ensue on the shortblock?

 

On another note I am actively looking for a P90 head.  However there are a ton of P79 Heads around here available.  I know this has been discussed with the liners and such, but one of these will work too correct?

[djwarner]

Hi Ben, Been following your efforts. As mentioned on the other site, bearing clearance should be 0.0015 to 0.0026(difference in the diameters) so this indicates the rear tower is at least 0.001 out of position. For grins and giggles, you could try adding a 0.001 piece of shim stock under the drivers side of the tower. Then see if the prussian blue pattern changes.

 

I measured some standard weight aluminum foil from the local supermarket and it was close to 0.001" thick so you wouldn't have to invest in special shim stock for this experiment..

Edited December 25, 2012 by djwarner

[Ben's Z]

Took this bastard to a HIGHLY recommended shop by not only the local Z Club community, but a friend who said they use to send VW cranks and heads over there by the truck load.  Apparently they also do all the warranty work for a vast amount of car dealerships in Houston.  Lead Machinist was working on a DOHC BMW multi valve head when I went in.  Anyhow, he looked at my head and said "run it".  He owned a Z himself back in the day and said he has sent out multiple heads that turn about like mine with no comebacks.  He basically guaranteed I would not have a problem.  He did also say that if you need to remove one set of tower alignment dowels he had done that before to really "make it right".  He didn't recommened this for every tower, but said the fact it is torqued down means it is not going anywhere when all assembled.  I did ask him to remove a bust exhaust stud out of the head.  Fingers crossed.  Like I said multiple Houston Z club people recommended this shop.