WS6nJAX

iTrader: (207)

looked for a thread but had no luck. can someone point me in the direction where I might find detailed instructions on how to check PTV clearance with the heads off?

MrDude_1

iTrader: (4)

i would be interested in any truly accurate way that doesn't involve clay myself.....

WS6nJAX

iTrader: (207)

anyone? after seeing the damage from the thread i just looked at , i really would like to know as to to avoid any problems like those that are posted.

ThirdGenLS1

iTrader: (11)

I put a checker spring(really weak spring) on one of the valves, put the rocker arm back on with a adjustable push rod so i could get zero lash. Then put a dial indicator on the nose of the rocker so i could measure how car it moved. Then turned the motor using a rachet on the crank pully bolt, brought it to 15 degrees BTDC and took measurements every 2 degrees, till 15 degrees ATDC. With the check spring i was able to push down on the spring and measure how far i was from hiting the piston.

.08 on the intake, and .100 are the the limits for PTV.

Hope that helps and makes sense

Justin

WS6nJAX

iTrader: (207)

thanks Third. you explained that very well. can anyone also explain the clay method in detail? since i am doing the h/c sawp, isnt that the technique i should use?

Xtnct00WS6

iTrader: (8)

The heads need to be on to be able to check PTV clearance. There are two basic ways that I know of. The clay method and using a dial indicator. I used a dial indicator.

http://www.fordmuscle.com/fundamenta...ve/index.shtml

Things I found you need to check PTV clearance w/ a dial indicator:

- Adjustable Pushrod
- 24mm socket to rotate the engine by the crank bolt.
- Comp Cams degree kit (pn 4795) It includes a Piston stop, Degree wheel, checking springs, metal rod use as a indicator on the degree wheel, Dial indicator, and a stand for Dial indicator (you need to make one part of the stand that goes into the valve cover bolt holes because the kit doesn’t use a metric bolt)

This pic is of a stand with the comp cams mount on top and the home made on bottom:



I made my own by getting a 5/8 bolt and cutting the threads off and using JB Weld to attach the right size bolt on the bottom of the 5/8 bolt. I think the right size bolt is a M6. I then got a nut and threaded it on the M6 bolt so you could screw it down on the head to stabilize the whole assembly when taking measurements.

Here’s a pic of the whole assembly on the head (not my pic where I have the nut on the threads):



When/if you have the heads off, plan on keeping the cylinder your going to work with at TDC to make it easier down the road.

I found exact TDC by putting a piston stop in the spark plug hole when both intake and exhaust valves were closed (I could tell is was about TDC too because of how far I could push the valves down and when the piston came up it was pushing air out of the spark plug hole) and then rotated the engine backwards (counterclockwise). I then marked the spot on the degree wheel. I then rotated the engine in the normal rotation (clockwise) and then marked a spot on the degree wheel. The position between those two spots is supposed to be exactly where TDC is. Make sure the metal rod indicator is pointing to TDC when all is said and done. I attached the metal rod to one of the top bolts on the timing cover.

- Install Degree wheel by taking the crank pulley off. I used a 2 arm pulley puller which was A LOT easier than 3 arm pulley puller. In our cars the crank bolt size isn’t the same size as the opening in the degree wheel (where you put the bolt through) so try and get it centered as best you can or you’ll have inconsistent readings when using the dial indicator.
- Install checking springs on both valves. This is definitely easier when the heads are off.
- Install adjustable pushrod on the valve you want to check first. Set as close to zero lash as you can. You’ll probably have to put the rocker on and off a few times to make sure it’s exactly at zero lash. Be sure not to compress the checker spring or lifter plunger
- Install rocker stand and rocker arms and tighten.
- Install dial indicator on top of valve retainer like the pic below. Make sure you have the dial indicator parallel to the valve.



- Rotate engine until you see the exhaust valve open, and then close. After it closes and the intake starts to open, this is the area you need to take your measurements. This is called the "overlap period". At no other point in the four stroke cycle does the valve get closer to the piston.
- Take measurements from 20* Before TDC to 20* After TDC in 2* increments, taking measurements at each increment by opening the valve by hand until it hits the piston and note measurements. Each time you rotate the engine you’ll have to reset the dial indicator back to zero.

According to Tony Mamo from AFR (a very well respected engine builder), you can add about .015 on to the measurements you get when using the dial indicator method because of the lack of pressure you get from the checking springs. Minimum clearance should be .080 on the intake and .100 on the exhaust.

Good luck!

WS6nJAX

iTrader: (207)

wanted to thank X for the detailed info. excellent job on the post.

ShevrolayZ28

iTrader: (4)

Bookmarked! Great post, Xtnct00WS6. Thank you!

WS6FirebirdTA00

iTrader: (33)

exactly what I was looking for, thank you