Cam won't move
- Thread starter karhawk
- Start date
Dang!
I missed it.
Hey Chris, are you and/or Mayu going to Ore'11?
I missed it.
Hey Chris, are you and/or Mayu going to Ore'11?
fiatmonkey
Tim Hoover
Didn't hear what was wrong but glad its ok now
karhawk
True Classic
It's still not good yet!!
I just got our BV head back and I'm trying to adjust the valves, it is very difficult to rotate the cam, this head has Isky springs with an inner flat spring to hold the smaller springs in place at high revs I assume. So you have the outers, the flat middle and small inners could these springs be so stiff as to cause difficulty rotating the cam with a 18 breaker bar? I took the cam box off and the cam rotates just fine, all the tappets move freely, granted is more difficult to get leverage with the cam off the engine but it seems too stiff to me.
We're not sure about Oregon this year, Mayuko will be 7 1/2 months pregnant so she may not be up for it.
Chris
Oakland, Ca.
I just got our BV head back and I'm trying to adjust the valves, it is very difficult to rotate the cam, this head has Isky springs with an inner flat spring to hold the smaller springs in place at high revs I assume. So you have the outers, the flat middle and small inners could these springs be so stiff as to cause difficulty rotating the cam with a 18 breaker bar? I took the cam box off and the cam rotates just fine, all the tappets move freely, granted is more difficult to get leverage with the cam off the engine but it seems too stiff to me.
We're not sure about Oregon this year, Mayuko will be 7 1/2 months pregnant so she may not be up for it.
Chris
Oakland, Ca.
fiatmonkey
Tim Hoover
Shims are and not too big?
fiatmonkey
Tim Hoover
I asked because when I was fitting my cam and decked cam box I realized I was didn't swap out shims to smaller size and the ones in the tappets were large due to a regrind I had in earlier as well. The cam was much easier to turn after I reduced the shim size. I went below stock size (due to decked cam box).
Jeff Stich
True Classic
I think Tim is on the right track here...you can't just swap in a different cam & use the same shims. The shim thicknesses need to be set up for the particular cam being used, custom-sized to each particular cam lobe. If even one of the shims are too thick, you will get "cam bind" as you've described.
I'm not 100% sure of the Alquati A16's required clearances, but most of the PBS cams use a cold valve lash measurement of .010" intake & .012" exhaust for reference. You might try .012"i/.014"e for starters?
Old Fiat Driver
Old Fiat Driver
check warpage
If the cam is working aginst the valves and springs it will be hard to rotate. I there are no valves in the head the cam should rotate freely, however if the cam box is warped it will be be very tight the same holds true for the head where the cam box mounts to the head. Try loosing the cam box bolts and see if that makes a difference.
Charlie
If the cam is working aginst the valves and springs it will be hard to rotate. I there are no valves in the head the cam should rotate freely, however if the cam box is warped it will be be very tight the same holds true for the head where the cam box mounts to the head. Try loosing the cam box bolts and see if that makes a difference.
Charlie
karhawk
True Classic
the cam is hitting a wall like spring bind on a couple of valves, the spring height on these isky springs is not set up right, plus the guy that set up this BV head did not set the height of the intakes to approx the same as the exhaust valves.. they are approx 1-1.5mm longer
anybody running isky springs that would know the installed height? I'm going to take this to a Fiat expert to get this sorted out. The only way out of this mess is to cut the head where the springs sit to get the right height.
chris
Oakland, Ca.
anybody running isky springs that would know the installed height? I'm going to take this to a Fiat expert to get this sorted out. The only way out of this mess is to cut the head where the springs sit to get the right height.
chris
Oakland, Ca.
TonyK
True Classic
Had the same problem.
With a Faza high lift cam. The springs run out of room and have nothing Left to compress. You must either change the camshaft or remove all washers below the springs or machine a recess where the spring seats to over come this.
TonyK.
Grimsby Ontario Canada.
With a Faza high lift cam. The springs run out of room and have nothing Left to compress. You must either change the camshaft or remove all washers below the springs or machine a recess where the spring seats to over come this.
TonyK.
Grimsby Ontario Canada.
bikesandcars
True Classic
have you tried removing the cam box?
Matt Brannon - Midwest Bayless
Mad.Matt
Isky specs
1.417 Installed height or larger. 114 lbs seat pressure at specified installed height.
Bind height: .960. Spring rate: 240 lbs/inch.
You can see that these springs will handle a .460 lift cam (nearly 11.7mm) which is a pretty big lift. Because your intake valves are short though, then yes, you are running into coil bind.
On a street car, running the valve springs at a looser installed height is no problem, so milling the head to give the valves extra height is a potential solution.
-Matt
-M
1.417 Installed height or larger. 114 lbs seat pressure at specified installed height.
Bind height: .960. Spring rate: 240 lbs/inch.
You can see that these springs will handle a .460 lift cam (nearly 11.7mm) which is a pretty big lift. Because your intake valves are short though, then yes, you are running into coil bind.
On a street car, running the valve springs at a looser installed height is no problem, so milling the head to give the valves extra height is a potential solution.
-Matt
-M
TonyK
True Classic
Milling head
The valve guides could stay in providing the miller has a tool that has a hollow bore that will clear the valve guide.
That being said to find a Shop that has the correct tooling may be an issue. This is for hand set up. It is possible to do this with a straight end mill and CNC program. I would suggest taking the head to a few shops and show them what you want. Some may say no problem while others will want the guides pressed down to clear the amount of relief you need machined in the top of the head.
TonyK.
Grimsby Ontario Canada.
The valve guides could stay in providing the miller has a tool that has a hollow bore that will clear the valve guide.
That being said to find a Shop that has the correct tooling may be an issue. This is for hand set up. It is possible to do this with a straight end mill and CNC program. I would suggest taking the head to a few shops and show them what you want. Some may say no problem while others will want the guides pressed down to clear the amount of relief you need machined in the top of the head.
TonyK.
Grimsby Ontario Canada.