Hi Guys
Besides the usual clean clean and more clean and checking clearances
Do u guys do any other work to the Crank Rods and Pistons before u assemble as Im just about to start screwing together.
Trev
Crank Rod and Piston Preperation
Moderator: Team
-
bill jones
- Guru
- Posts: 2651
- Joined: Sun Sep 05, 2004 6:38 pm
- Location: salt lake city, ut
- Contact:
-I have my own shotpeener so I shotpeen the radius' of ALL crankshafts and some freshly machined places on steel rods that I feel need to be shotpeened.
-Pistons may get either top or side gasports.
-I also quite often install the "volume" recesses or grooves on the 2nd ring land and the thin threadlike multigrooves above the top ring on the top ring land.
-Some pistons are real hard to get the spiral locks out of so I might machine an access slot so I can get a small screwdriver tip in there.
--------------------------------------
-When I install the spiral locks I'm real fussy about the exact orientation of the ends so that the end you want to pry out ends up where you can get it out the easiest.
-This usually works best for me to start the first tail of each spiral lock at the very bottom of the snapring groove so that the end you pry out ends up about 1/2 way up either side of the groove.
-----------------------------------------------------------
-I also like to drill one more oil hole from the oil ring groove into the pin oil channel that wets the pin, if there is only one per each side of the wristpin.
--------------------------------------------------
-If the pistons are to be pressfit I also machine the inside and the outside of the pin bosses flat and square so the press pads don't squash that metal either when pressing the pins in or out.
-------------------------------------------------
-If the pistons are used I use big eyeballs and a carbide pointed prick to pick the metal pepper out of the skirts so that metal doesn't act as bore scrapers.
------------------------------------------
-I check ALL used or reconditioned rods and most new rods to make sure they are straight.
-New rods I file or just barely break the edges near the parting line and torque the bolts up to 90% about 5 times before final stretching of the fasteners.
------------------------------------------
-Need to make sure the piston pin bosses don't get bound up with the sides of the pin end of the rods when you use the "trick" pistons like I've seen a set of Ross pistons that I had to machine the inner pin boss to get clearance for the pin end of the rod.
----------------------------------------
-Some people don't pay much attention to the chamfer on the lower skirt edges but depending on what you are doing with oiling systems chamfers may be better on a high vacuum engine and I like sharp edges better on conventional wet sumps to act as scrapers to the oil.
---------------------------------------
-If the crank is new, check the fit of the fasteners to make sure they aren't loose.
-I bought 6 cranks from LA Billet one time and one crank had the flywheel bolts way too loose and I had to tap'm out from 7/16"-20 to 1/2"-20 and ream the flywheel bolt holes.
----------------------------------------
-One other thing is to check the radius's of the crank to the sides of your rods and bearings to make sure they like each other, and check the mains while you are at it.
-It seems a lot of guys get surprises when they go to install the damper so you might want to check the exact fit there as well.
-Another issue I've seen is the timing chain sprockets rear chamfer sometimes interfers with the crank snout radius.
-AND sometimes that sprocket doesn't align with the top sprocket so you have to machine one of the rear sprocket surfaces a few thou.
-------------------------------------------
-If it's stickshift car I file a slight chamfer at the rear half of the thrust bearing, both sides, to get a positive slight oil feed to the rear thrust pads of the bearing.
--------------------------------------------
EDIT:
-Another set of issues I deal with is actually measuring piston dish or dome volumes----and all the rest of the compression ratio components---and then doing the math so that I know positively what the REAL compression ratio is.
-No engine has left my shop for nearly 40 years without the cam being degreed in at the cam lobes----and I also profile the action at the valve/s with the engine race ready----and along with this do whatever it takes to get the rocker geometry in the ball park.
-Wet sump oil systems get the pump housings (like SBC's) sanded to at least .0025" end play---pull the rear main cap dowels on Chev engines and flat sand the mounting surface of the main cap--also flatsand the pump mating surface---because I had witnessed how bad oil was spraying out of there while priming an engine in the late 1960's.
-Most oil pump pickup tubes I modify with a bracket that bolts to the oil pump--I have used a lot of stock oil pump pickup tubes but I peel the crimped edge back on the screen end---install a bolt thru the center hole of the screen--bolt the screen to the bottom metal plate in a manner that the bolt end becomes a positive stop to the oil pan--radius the inlet of the inner suck tube---then reassemble and recrimp the edge.
-Personally I would much rather use a stock pickup tube than the common aftermarket small square box type---just don't like those at all.
-------------------------------------------------------------------------------
-There's tons of stuff like deburring the oil passages, valley screens, setting the cam endplay---most engines I lockwire the cam & oil pumps fasteners.
-Pistons may get either top or side gasports.
-I also quite often install the "volume" recesses or grooves on the 2nd ring land and the thin threadlike multigrooves above the top ring on the top ring land.
-Some pistons are real hard to get the spiral locks out of so I might machine an access slot so I can get a small screwdriver tip in there.
--------------------------------------
-When I install the spiral locks I'm real fussy about the exact orientation of the ends so that the end you want to pry out ends up where you can get it out the easiest.
-This usually works best for me to start the first tail of each spiral lock at the very bottom of the snapring groove so that the end you pry out ends up about 1/2 way up either side of the groove.
-----------------------------------------------------------
-I also like to drill one more oil hole from the oil ring groove into the pin oil channel that wets the pin, if there is only one per each side of the wristpin.
--------------------------------------------------
-If the pistons are to be pressfit I also machine the inside and the outside of the pin bosses flat and square so the press pads don't squash that metal either when pressing the pins in or out.
-------------------------------------------------
-If the pistons are used I use big eyeballs and a carbide pointed prick to pick the metal pepper out of the skirts so that metal doesn't act as bore scrapers.
------------------------------------------
-I check ALL used or reconditioned rods and most new rods to make sure they are straight.
-New rods I file or just barely break the edges near the parting line and torque the bolts up to 90% about 5 times before final stretching of the fasteners.
------------------------------------------
-Need to make sure the piston pin bosses don't get bound up with the sides of the pin end of the rods when you use the "trick" pistons like I've seen a set of Ross pistons that I had to machine the inner pin boss to get clearance for the pin end of the rod.
----------------------------------------
-Some people don't pay much attention to the chamfer on the lower skirt edges but depending on what you are doing with oiling systems chamfers may be better on a high vacuum engine and I like sharp edges better on conventional wet sumps to act as scrapers to the oil.
---------------------------------------
-If the crank is new, check the fit of the fasteners to make sure they aren't loose.
-I bought 6 cranks from LA Billet one time and one crank had the flywheel bolts way too loose and I had to tap'm out from 7/16"-20 to 1/2"-20 and ream the flywheel bolt holes.
----------------------------------------
-One other thing is to check the radius's of the crank to the sides of your rods and bearings to make sure they like each other, and check the mains while you are at it.
-It seems a lot of guys get surprises when they go to install the damper so you might want to check the exact fit there as well.
-Another issue I've seen is the timing chain sprockets rear chamfer sometimes interfers with the crank snout radius.
-AND sometimes that sprocket doesn't align with the top sprocket so you have to machine one of the rear sprocket surfaces a few thou.
-------------------------------------------
-If it's stickshift car I file a slight chamfer at the rear half of the thrust bearing, both sides, to get a positive slight oil feed to the rear thrust pads of the bearing.
--------------------------------------------
EDIT:
-Another set of issues I deal with is actually measuring piston dish or dome volumes----and all the rest of the compression ratio components---and then doing the math so that I know positively what the REAL compression ratio is.
-No engine has left my shop for nearly 40 years without the cam being degreed in at the cam lobes----and I also profile the action at the valve/s with the engine race ready----and along with this do whatever it takes to get the rocker geometry in the ball park.
-Wet sump oil systems get the pump housings (like SBC's) sanded to at least .0025" end play---pull the rear main cap dowels on Chev engines and flat sand the mounting surface of the main cap--also flatsand the pump mating surface---because I had witnessed how bad oil was spraying out of there while priming an engine in the late 1960's.
-Most oil pump pickup tubes I modify with a bracket that bolts to the oil pump--I have used a lot of stock oil pump pickup tubes but I peel the crimped edge back on the screen end---install a bolt thru the center hole of the screen--bolt the screen to the bottom metal plate in a manner that the bolt end becomes a positive stop to the oil pan--radius the inlet of the inner suck tube---then reassemble and recrimp the edge.
-Personally I would much rather use a stock pickup tube than the common aftermarket small square box type---just don't like those at all.
-------------------------------------------------------------------------------
-There's tons of stuff like deburring the oil passages, valley screens, setting the cam endplay---most engines I lockwire the cam & oil pumps fasteners.
Last edited by bill jones on Sat Jul 14, 2007 12:10 am, edited 2 times in total.
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katman
- Member
- Posts: 158
- Joined: Sun Jan 23, 2005 3:57 am
- Location: Overland Park in the Great State of KANSAS
- Contact:
How much smoothing do you do to new pistons? I just got a new set of Diamond pistons and cut my thumb on one just taking it out of the bag! These things have sharp machined edges everywhere.
Kevin A Thornton
KAT Automotive
For Speed Equipment, Nitrous Express
katman@everestkc.net
For AMSOIL products
http://www.lubedealer.com/kat
For Herbs from the Amazon
http://www.168336.amazonherb.net
KAT Automotive
For Speed Equipment, Nitrous Express
katman@everestkc.net
For AMSOIL products
http://www.lubedealer.com/kat
For Herbs from the Amazon
http://www.168336.amazonherb.net
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DavidHarsay
- Pro
- Posts: 242
- Joined: Thu Apr 28, 2005 11:15 pm
- Location: Phoenix
Wow, nice write up Bill!
The only thing I would add... and this may be more than what you were looking for... is the eccentricity of the rods on the big ends... take a measurement with the bearings installed and see where you are... and we've discussed it somewhat in previous threads... here's one (Sstart with Darin's post on page 2)
viewtopic.php?t=3653
Some bearings have this built in by tapering near the split slightly.
Dave
The only thing I would add... and this may be more than what you were looking for... is the eccentricity of the rods on the big ends... take a measurement with the bearings installed and see where you are... and we've discussed it somewhat in previous threads... here's one (Sstart with Darin's post on page 2)
viewtopic.php?t=3653
Some bearings have this built in by tapering near the split slightly.
Dave
-
63longroof
- New Member
- Posts: 35
- Joined: Thu May 18, 2006 1:31 pm
- Location: Southeast Kansas
Great as always Bill, thanks!
I would be curious to find out other peoples methods but FWIW I clamp the piston in a vice and carefully use a cartridge roll to knock off all the real sharp edges and finish them all by hand with foam sanding pads. Starting with fine/medium type grit and finishing with a real smooth pad to somewhat "polish" the piston where the grinding has been done.How much smoothing do you do to new pistons? I just got a new set of Diamond pistons and cut my thumb on one just taking it out of the bag! These things have sharp machined edges everywhere.
-
katman
- Member
- Posts: 158
- Joined: Sun Jan 23, 2005 3:57 am
- Location: Overland Park in the Great State of KANSAS
- Contact:
Back in the early 80s, when I worked on F1 Yamaha's, we used to use rubberized abrasives on aluminum parts. Guess I'll have to try and find some of them, if they still make them.
Kevin A Thornton
KAT Automotive
For Speed Equipment, Nitrous Express
katman@everestkc.net
For AMSOIL products
http://www.lubedealer.com/kat
For Herbs from the Amazon
http://www.168336.amazonherb.net
KAT Automotive
For Speed Equipment, Nitrous Express
katman@everestkc.net
For AMSOIL products
http://www.lubedealer.com/kat
For Herbs from the Amazon
http://www.168336.amazonherb.net
http://www.cratex.com
I spend at least 30 minutes on each dome re-radiusing and blending in the valve relief cuts and spark notches to 1/8" radius where practical. Unless it's an alcohol motor the compression loss is harmless compared to the enhanced flow.
I spend at least 30 minutes on each dome re-radiusing and blending in the valve relief cuts and spark notches to 1/8" radius where practical. Unless it's an alcohol motor the compression loss is harmless compared to the enhanced flow.
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Ed-vancedEngines
Sitting here and reading this and thinking. All of you guys have it going on.
I can not guess at how many engines I have torn down to discover factory box stock pistons with all the problems that come with failure to spend prep time and energy to do it right. Yet we do not get to charge any extra for the countless hours of extra prep time and energy we do to turn out good engines.
Self satisfaction will not allow me to cut corners on anything.
Ed
I can not guess at how many engines I have torn down to discover factory box stock pistons with all the problems that come with failure to spend prep time and energy to do it right. Yet we do not get to charge any extra for the countless hours of extra prep time and energy we do to turn out good engines.
Self satisfaction will not allow me to cut corners on anything.
Ed
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MileHighMan
- Guru
- Posts: 1045
- Joined: Mon Aug 07, 2006 10:31 am
- Location: usa
- Contact:
Quality!!!
Hey Ed. That self satisfaction is "Quality". Don't be afraid to charge for it. I always advise. Your race car is, Your Hobby. Good Luck. Dan.
It's a tough choice. For my own stuff I couldn't sleep unless I did it - you know how that is!
For customers who have blind faith ("if you think it helps, do it and charge me") or who agree after a discussion, it gets done.
For customers who ask why, and then respond "but why... my uncle says... I was told that..." it doesn't.
For customers who have blind faith ("if you think it helps, do it and charge me") or who agree after a discussion, it gets done.
For customers who ask why, and then respond "but why... my uncle says... I was told that..." it doesn't.
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BLACK BART
- Pro
- Posts: 433
- Joined: Tue Feb 20, 2007 7:05 am
- Location: California
One thing I also know to check for on a crank in a stick car is the fit of the pilot bearing/bushing being used. A buddy of mine had an Eagle crank that the hole was too big on and couldn't get any press fit at all. The thing could be put in and taken out with your fingers. He had to knurl the hole and epoxy it in place. This was found after the engine was built. CJ