Hot Rod Forum banner

1 - 8 of 8 Posts

·
Registered
Joined
·
293 Posts
Discussion Starter #1
On a hydraulic roller 351W I want to determine proper push rod length and piston to valve clearance. I was thinking about using checking springs but I'm concerned the force required to compress the clay could be sufficient to compress the spring in the lifter resulting in an inaccurate measurement. I could eliminate this possibility if I pumped up a couple of lifters for the test. I've read a lot of differing opinions on potential problems that could arise when starting a new engine with pumped up lifters so I'd like to avoid that. I could just use a dial indicator but I'd like to determine radial clearance between the piston and valve at the same time. If I did pump up a couple of lifters is it worth bothering with the checking springs or should I just go with the actual springs? I realize I can't use the dial indicator if I use the actual springs. Also, I don't have any old lifters to modify for this.
 

·
Registered
Joined
·
13,463 Posts
On a hydraulic roller 351W I want to determine proper push rod length and piston to valve clearance. I was thinking about using checking springs but I'm concerned the force required to compress the clay could be sufficient to compress the spring in the lifter resulting in an inaccurate measurement. I could eliminate this possibility if I pumped up a couple of lifters for the test. I've read a lot of differing opinions on potential problems that could arise when starting a new engine with pumped up lifters so I'd like to avoid that. I could just use a dial indicator but I'd like to determine radial clearance between the piston and valve at the same time. If I did pump up a couple of lifters is it worth bothering with the checking springs or should I just go with the actual springs? I realize I can't use the dial indicator if I use the actual springs. Also, I don't have any old lifters to modify for this.
Your concern is well placed.

To overcome this the test is done with a solid lifter as a substitute for the hydraulic. Or a hudraulic lifter is dissassembled and a stack of washers is placed inside for the pushrod cup to rest upon in its postition against its retainer.

Pumping up a lifter takes some time, isn't always dependable that it is truly filled with oil, and can suffer from leak down so is not typically a rocemmended proceedure.

There are lifter substitute tools sold for this process as well.

Bogie
 

·
Registered
Joined
·
293 Posts
Discussion Starter #4
You're two of the guys that can always be depended on to give solid advice. Thanks!

Is it safe to use two of my new lifters to fill with washers or does that endanger the lifter for future use? Would it be a no-no with the actual valve springs?
 

·
More for Less Racer
Joined
·
19,345 Posts
Just washer stack on lifter, check intake and exhaust clearance separately will minimize messing with two lifters disassembly's. Lifter you can wash and just reassemble it. You can do it with the actual valvesprings, you'll just have less "feel" for the valve actually hitting if clearance isn't enough though.
 

·
Registered
Joined
·
293 Posts
Discussion Starter #6
I've removed the two valve springs on #5 cylinder and replaced them with light weight springs from the hardware store. I put the head on the left side of the block without a gasket and just snugged it up. I installed #1 and #5 pistons. I'll use a dial indicator and get an accurate TDC off #1 and also get an accurate P to V clearance number from #5. Then I plan to clay the head to check radial clearance and confirm my DI number. One lifter will be disassembled and the spring replaced with washers with the plunger back on top.

Won't get to this until Monday. I'm taking one of my granddaughters to a car show tomorrow. Best of both worlds.

I'll let you know how I make out. Thanks again guys.
 

·
Registered
Joined
·
293 Posts
Discussion Starter #7
The intake valve has the least clearance getting to within .156" to the piston (dial indicator). The intake also has the least radial clearance at about .075". Is that radial clearance a little tight?
 

·
Registered
Joined
·
4,203 Posts
The pushrod seat in hydraulic lifters are designed to be set at half travel or .060” deeper than zero preload. Most lifters have .120” total travel. Keep this in mind if you have hydraulic lifters when determining pushrod length.

Solid lifters have no preload setting. However, Limited travel hydraulic lifters have .002” -.004” preload setting and .050” total travel. The preload setting of limited travel hydraulic lifters is just like setting the lash on solid lifters with a feeler gauge. If you don’t want to use a feeler gauge, it is just a twitch of the wrist to get .002”-.004” preload. That small amount of preload is to prevent the pushrod seat from beating on the pushrod seat circ-clip retainer.
 
1 - 8 of 8 Posts
Top