Wiseco Spirolox

[GVR-4]

I've searched and couldn't find anything useful. Does anybody have any insight on how to install these in a set of Wiseco pistons? Do you need them? The literature that came with the pistons is pretty vague. I've got the wrist pins pressed in, but now I have to center them in the rod. Can I use the Spiroloc as a stop when I center the wrist pin?

 

You mean "pressed in" as slid in, correct? With the spiralocks, just get an edge started and slowly work to the end. You have to press hard but they squeeze in there.

 

[GVR-4]

Maybe I'm calling these things Spirolox and they're not. Maybe they're just snap rings. Here are some pics to help:



Here you can see the groove the snap ring, Spirolox or whatever they are fit into:


And this shows how the wrist pin presses into the small end of the rod, but floats within the bore of the piston.


My issue is how to center the wrist pin in the rod. Any suggestions? Has anyone done this before?

 

[Brianawd]

Here is a idea. GO buy a set of rods. Say Eagle or manley.

 

[GVR-4]

How 'bout... NO.

 

[Muskrat]

Why not?

You already spent how much on pistons? Why not do it right and get the appropriate rods?

 

[GVR-4]

We all have different goals and the stock rods will be fine for mine. What can they handle? >500 whp? I won't be close to that. Using the stock rods is not a "wrong" choice.

Now can we stick to the original point please?

 

[Muskrat]

Ok:

Those are snap rings. They install like any other (aka, compress, get an end seated and work your way around), but are for retaining a full floating piston and rod.

If you're set on using the stock rods make sure you have the appropriate wrist pins and have a machine shop press them in. The snap rings will not be necessary.

 

[Brianawd]

Quote:
We all have different goals and the stock rods will be fine for mine. What can they handle? >500 whp? I won't be close to that. Using the stock rods is not a "wrong" choice.




The 2g pistons would have been more than enough in your case then, as the 1g rod is still the weak link in a 1g/2g combo.

 

[prove_it]

I might be wrong, but don't you need to have the small end of the the rod machined to accept Eagle wrist pins? I always thought that it was a full floating set-up.

 

[GVR-4]

Brianawd: You're right. If I were building a 2.0, I would have used 2g pistons. But as you can see in the 2nd photo, these are stroker pistons.

prove_it: I'm not sure if that was directed at me, but I have Wiseco pistons and they came with wrist pins. They fit into the stock rods properly and I have already pressed them in. I just need to take the time to center each one now. This setup will be just like the stock setup with the wrist pin pressing into the rod and floating within the piston.

This is a low budget build, but don't think it isn't being done properly. For example, I had a friend of mine measure the pistons on a Zeiss CMM for roundness and diameter. He took 500 data points on the skirts. Then I took the largest diameter and added the piston-to-wall clearance and told the machinist what size to machine the block bores (3.36633"). Next week I'll have a bore gage set up to confirm the bores are the correct diameter. I did not come up with my plan for the engine build hastily. My choices are perfectly adequate for my goals.

 

[Barnes]

I would think that if the wrist pin is pressed in evenly, that is all you need to do. The crank will center the rod on the piston anyways.

 

[GVR-4]

It is true that the crank will position the rod where it needs to be. But the issue is not the location of the rod in relationship to the piston; that will take care of itself. The issue is the wrist pin in relationship to the rod. If you look at the 3rd photo above it may help. I want the same length of the wrist pin sticking out from each side of the rod. It will be a trial and error process because you can't see anything when it's set up in the press.

 

[Barnes]

Gotcha. Yeah, just gotta keep measuring and pressing a little until you get it where you want.

 

[Muskrat]

Have you considered making a jig with a hard stop for the press?

 

[GVR-4]

No, but that's a good idea. I'll think about what the best way to do that would be. I should have measured the length of the wrist pins before I pressed them in. Thanks for the idea.

 

[toybreaker]

Most machine shops have a little oven that we use to heat the little end of the rod.

The piston is put in a fixture with an adjustable stop for the pin. The rod is heated, laid into postition against the bottom of the pin opening of the piston. The pin is dipped in oil and then the it goes in with a light push untill it bottoms against the stop..

Doing it this way ensures the pin is centered and the piston won't be subjected to the force of pressing the pin into the rod.

The press fit is pretty tight, and substantial force can be required to install the pin.

Doing it cold can result in distorting or even cracking the piston.

In addition, the pin can get scratched/gouged as it passes thru the rod bore. Those scratches/gouges will chew up the pin bore in the piston once the engine is fired up, resulting in all sorts of problems.

We also have another fixture the pistons are laid in to press the pins out at the beginning of the machining operations. It cradles the piston, spreading the load out to minumise flattening the backside of the piston pin bore, which will increase the amount of force required to drive the pin out.

That's why it's best to let the machine shop to install/remove the pins when using press fit style pistons.

I realise that doesn't help you now, but, Muskrat has a pretty solid idea.

Quoting Muskrat:
Have you considered making a jig with a hard stop for the press?



That's good thinking right there. /ubbthreads/images/graemlins/smile.gif

Combined with a curved fixture to lay the piston in, you should be able to reposition things slightly without any major carnage.

 

[Muskrat]

To measure the length of the pin, use large caliper. Insert some large pin gauges (or something similar that will have the ends cut parallel) on each end of the wrist pin. Measure from end to end, then measure the length of the pins and subtract.

 

[donniekak]

Quoting Muskrat:
Have you considered making a jig with a hard stop for the press?


The dimensions for this are in the 4g63 rebuild manual.

Do not use the clips with a press fit rod. If you actually pressed the pins into the rods, instead of heating the small end of the rod, you probably damaged the pistons.

 

[grocery_getter]

Don't use the snap ring to retain the wrist pin when using the a non floating wrist pin setup.

On a full floating wrist pin setup, the distance between the 2 snap ring grooves is exactly the length of the wrist pin itself, the rod will adjust to the center of the wrist pin as the engine is running.

In a press fit assembly where the rod is press fit onto the wrist pin, it may be impossible to find the perfect center. When a press fit assembly is running during service, the rod will try to move on the crank and will be the variable that will put the small end of the rod where it want to sit, fore and aft, when the wrist pin is pressed fit into the small end of the rod then this will move the wrist pin forward or backward depending the rod final position on the crank. If you have the snap rings installed in this scenario, this fore and aft movement of the wrist pin might be enough to dislodge the snap ring from its groove and walk it towards the wall.