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Discussion Starter #1
I’m going through the process currently. I’m using this video as the procedure.



I have basically a stock 289. Cam information is below.

I’m changing to Pro Comp roller tip rockers.

My first issue is which push rod length checker do I need. I need a base line. I know stock push rods are 6.8” would they typically be longer or shorter then stock? Any guesses?



The different checkers I’m looking at have a cut off right around 6.8” so should I get a longer one or shorter one? I hate to buy two of them.


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IMHO, too much "by eye" guessing. Ninety degrees is 90...not 89 or 91... and estimating what is ".1" of a turn? A cheap Torque-Angle gauge is, like, fifteen bucks at NAPA.... convert the fraction into degrees and make it exact, not a guess. And the angle? Magnetic angle gauges are five bucks at Harbor Freight and a bit more at Home Depot. I guess I',m just a bit TOO anal for "abouts".
 

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A little early in the day Woodchuck.......................
 

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What you want is the roller tip on the valve stem to roll from the inside of the tip to the outside of the tip and be centered as much as possible..You ales need to have a solid lifter in there cause the hyd lifter is going to collapse and give you a false reading..
 

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What you want is the roller tip on the valve stem to roll from the inside of the tip to the outside of the tip and be centered as much as possible..You ales need to have a solid lifter in there cause the hyd lifter is going to collapse and give you a false reading..
No, you do not need a solid lifter. With oil in the lifters and the light springs one is fine.

The pattern left where the roller contacts should be centered on the valve. There are pictures on the web.
 

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No, you do not need a solid lifter. With oil in the lifters and the light springs one is fine.

The pattern left where the roller contacts should be centered on the valve. There are pictures on the web.
What ever you say.....but when the motor sits how come all the valves are closed??
 

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I've attached an image of the pattern created by my valve geometry. Slightly offset from center and as narrow as possible is what you are looking for. This was done with the hydraulic lifters installed.
755696
 

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What ever you say.....but when the motor sits how come all the valves are closed??
Sounds like excessive bleed down. Unless my car sits for years I get no valve clatter at startup, even with fairly stiff springs.

Again, with those light springs installed there is little to no pressure pushing the oil out of the hydraulic lifter. I have yet to find an engine building guide that requires a solid lifter to check PR length. I prefer to check my pushrod length with the components I actually use in the car, lifters included.
 

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Discussion Starter #10
My lifters seem to be “pumped” up right now. I put an old push rod in and I can’t push down on them.

I guess my next issue is I don’t have a spring checker. I’m also not sure how to put one in. I had the shop assemble the heads.

I torqued the heads on last night. Monday I will pick up the push rod length checker and try to figure it out.


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Discussion Starter #11
I tried the method in the Scott Foxwell video. It's no good. Trying to draw a line on the rocker arm and then make it perpendicular to the valve is not easy and way too much room for error. Especially with the engine in the car.

So I ordered spring checkers and will mark the valve stem and go about that method to determine correct push rod length.

How much PSI air do I use to hold the valves up when I change to the checker springs?
 

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I tried the method in the Scott Foxwell video. It's no good. Trying to draw a line on the rocker arm and then make it perpendicular to the valve is not easy and way too much room for error. Especially with the engine in the car.

So I ordered spring checkers and will mark the valve stem and go about that method to determine correct push rod length.

How much PSI air do I use to hold the valves up when I change to the checker springs?
It does not take much pressure. 20 psi is ample. Applying 100 psi will try to push the piston to BDC and could cause the car to roll a bit if you have a manual transmission...from experience. :)
 
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