What are wrist pins and spiralocks?
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Joined: Feb 2001
Posts: 3,068
From: Cincinnati, Ohio
What are wrist pins and spiralocks?
Im putting together a 383 and grabbing parts from here and there.
Question, what are wrist pins and spira locks? Do all pistons have them or need them?
I see some pistons have them included, some are not mentioned, some say accept XX part.
If needed and not included, what can i expect to pay for these?
Im looking at these pistons:
http://www.cnc-motorsports.com/produ...204&CtgID=7128
It says they are "Full Floating Wrist Pin Design" but doesnt say if they are included or not. Anyone know if probe includes these?
Another issue is P/V clearance. My heads are 2.08/1.6 valves and choice of chambers (AFR) I dont want to be buying pistons and then have to notch them also. Any experience with big valves and Probe pistons, or another decent forged brand which did/didnt clear with oversized valves?
Question, what are wrist pins and spira locks? Do all pistons have them or need them?
I see some pistons have them included, some are not mentioned, some say accept XX part.
If needed and not included, what can i expect to pay for these?
Im looking at these pistons:
http://www.cnc-motorsports.com/produ...204&CtgID=7128
It says they are "Full Floating Wrist Pin Design" but doesnt say if they are included or not. Anyone know if probe includes these?
Another issue is P/V clearance. My heads are 2.08/1.6 valves and choice of chambers (AFR) I dont want to be buying pistons and then have to notch them also. Any experience with big valves and Probe pistons, or another decent forged brand which did/didnt clear with oversized valves?
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Joined: Nov 2003
Posts: 102
Wrist pins are the steel pins that connect the conecting rods to the pistons.
Spira locks are the nasty little clips that hold the wrist pins in. Usually 4 per piston. These take a lot of practice to get in without hurting your fingers.
Full floating pistons will use the wrist pins and the spira locks where the non floating pins will press into the connecting rods. The stock rods use the pressed in pins and most floating pistons can be used with either floating or non floating. But you need to check this with the manufacturer. I know the Kieth blacks can go either way.
Most pistons sets will come with wrist pins. Not sure about the Probes though.
As for the piston to valve clearance, that's going to have to be done in a dry assembly of the engine. You could also call the manufaturer and check with them to see if they believe the valves will clear. But there is more to checking the clearance than if the valve reliefs are big enough. you also have to take into account quench height and valve lift/duration of the cam.
Spira locks are the nasty little clips that hold the wrist pins in. Usually 4 per piston. These take a lot of practice to get in without hurting your fingers.
Full floating pistons will use the wrist pins and the spira locks where the non floating pins will press into the connecting rods. The stock rods use the pressed in pins and most floating pistons can be used with either floating or non floating. But you need to check this with the manufacturer. I know the Kieth blacks can go either way.
Most pistons sets will come with wrist pins. Not sure about the Probes though.
As for the piston to valve clearance, that's going to have to be done in a dry assembly of the engine. You could also call the manufaturer and check with them to see if they believe the valves will clear. But there is more to checking the clearance than if the valve reliefs are big enough. you also have to take into account quench height and valve lift/duration of the cam.
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Joined: Apr 2003
Posts: 2,628
From: Pgh, PA
Spira Locks SUCK ... I repeat SUCK to install the first time you do it. Untill you get a feel for it, youll feel like grabbing the rotating assembly and burning it piece by piece with an oxy acet. torch ...
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Joined: Dec 1969
Posts: 10,745
From: Buffalo, New York
They are the best method for securing the wrist pins, but I end up with sore, bleeding fingers after fooling with them!
This is not any kind of put down, you are asking very reasonable questions. But if you need this kind of basic question answered, maybe you should be talking with the person who is going to build the motor about what parts to get. There is more to this than meets the eye.
Rich Krause
This is not any kind of put down, you are asking very reasonable questions. But if you need this kind of basic question answered, maybe you should be talking with the person who is going to build the motor about what parts to get. There is more to this than meets the eye.
Rich Krause
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Joined: Feb 2001
Posts: 3,068
From: Cincinnati, Ohio
Originally posted by rskrause
They are the best method for securing the wrist pins, but I end up with sore, bleeding fingers after fooling with them!
This is not any kind of put down, you are asking very reasonable questions. But if you need this kind of basic question answered, maybe you should be talking with the person who is going to build the motor about what parts to get. There is more to this than meets the eye.
Rich Krause
They are the best method for securing the wrist pins, but I end up with sore, bleeding fingers after fooling with them!
This is not any kind of put down, you are asking very reasonable questions. But if you need this kind of basic question answered, maybe you should be talking with the person who is going to build the motor about what parts to get. There is more to this than meets the eye.
Rich Krause
The builder i chose is a supplier for eagle and ross, so they push their stuff. IMO, i can get some parts comparable in quality and save some cash if i order them myself.
im fairly confident i have the rest of it covered from the machine work, to parts, to balancing. I wasnt sure however on floating/pressed pins/spira locks etc. Basically the piston/rod connection things were pretty sketchy. Its all comming
Thank you everyone for your responses, looks like i will have to contact probe and see what is included with the pistons, and also ask their experience with oversized valves.
Last edited by atljar; Jun 30, 2004 at 12:59 AM.
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Joined: Nov 2001
Posts: 2,985
From: In a house by the bay
Call Probe and tell them what you're doing... cam specs, valve sizes, deck height etc and they should be able to give you a general "yes or no" on the PV clearance. Regardless what they say... check it.
Good luck.
-Mindgame
Good luck.
-Mindgame
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Joined: Oct 2001
Posts: 368
From: Cincinnati, Ohio
You could have asked me, Jared...I have a set of Probe pistons sitting in my car.
Pistons with pressed in pins don't require any sort of retainer...they're just pressed in. Floating pins require spira locks...they look like little split washers. There is a groove on either side of the wrist pin bore on the piston where they sit...they keep the wrist pin inside the piston. Probe includes these, so you'll be good to go. If you buy from CNC Motorsports, they'll give you a decent set of piston rings too.
If you want to physically see what you'll be getting and how it'll all fit together, head down to Dave's and go through my car...the pistons are either in the back seat or in the trunk.
Pistons with pressed in pins don't require any sort of retainer...they're just pressed in. Floating pins require spira locks...they look like little split washers. There is a groove on either side of the wrist pin bore on the piston where they sit...they keep the wrist pin inside the piston. Probe includes these, so you'll be good to go. If you buy from CNC Motorsports, they'll give you a decent set of piston rings too.
If you want to physically see what you'll be getting and how it'll all fit together, head down to Dave's and go through my car...the pistons are either in the back seat or in the trunk.
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