Go Back  Offshoreonly.com > Technical > Do It Yourself, Boating on a Budget
Cam timing gear tooth damage from link chain >

Cam timing gear tooth damage from link chain

Like Tree4Likes

Cam timing gear tooth damage from link chain

Reply

Old 02-06-2019, 09:17 PM
  #1
Registered
Thread Starter
 
Join Date: Aug 2013
Location: Kemah, Tx
My Boat: Fino 30
Posts: 154
Default Cam timing gear tooth damage from link chain


Stock rebuild 330 bottom end, stock style link bar timing chain, stock cam, upgraded pushrods/springs (done by previous owner), less than 10 hours run time most under 2k rpm.

I had a timing cover leak, so I pulled it off and went ahead and bought a basic cast cam gear Cloyes double roller timing set to replace the stock one. Once apart I noticed more slack than I would like in the timing chain that was installed, and after pulling the gears off I noticed some pretty significant wear on the cam gear teeth, especially with so little run time and tiny cam. My best guess is a cheap/soft gear that maybe missed heat treat? Anybody seen something like this before?



Last edited by sailtexas186548; 02-06-2019 at 09:21 PM.
sailtexas186548 is offline  
Reply With Quote
Old 02-06-2019, 09:19 PM
  #2
Registered
Thread Starter
 
Join Date: Aug 2013
Location: Kemah, Tx
My Boat: Fino 30
Posts: 154
Default


Here is the timing set before I pulled it, slack is split on both sides evenly in this pic

sailtexas186548 is offline  
Reply With Quote
Old 02-07-2019, 09:05 AM
  #3
Platinum Member
Platinum Member
 
flashgordon's Avatar
 
Join Date: Sep 2012
Location: new baltimore mi
My Boat: 1989 scarab 38 excel-1986 scarabIII-1987 nova syder tw-330's-340/277/260 sea ray
Posts: 201
Red face

Originally Posted by sailtexas186548 View Post

Here is the timing set before I pulled it, slack is split on both sides evenly in this pic

i have never or saw wear like that.................
most people advance cam two degrees to make up for the slack in timing chain..
my engine builder also has drilled a .020 hole in the plugs behind the top gear.

flash ............
flashgordon is offline  
Reply With Quote
Old 02-07-2019, 09:33 AM
  #4
Platinum Member
Platinum Member
iTrader: (5)
 
F-2 Speedy's Avatar
 
Join Date: May 2012
Location: Midwest & T-Rock
My Boat: F2 Speed racer
Posts: 5,735
Default

It doesn't look like that chain fits the cam gear very well ?? could be the pic tho.
Griff, Knot 4 Me and VoodooRob like this.
F-2 Speedy is offline  
Reply With Quote
Old 02-07-2019, 12:05 PM
  #5
Registered
 
Join Date: Feb 2018
Location: Paris
My Boat: Baja 250 sport
Posts: 68
Default

or the contrary
Bajaboat77 is offline  
Reply With Quote
Old 02-07-2019, 04:45 PM
  #6
Registered
Thread Starter
 
Join Date: Aug 2013
Location: Kemah, Tx
My Boat: Fino 30
Posts: 154
Default

I have holes drilled in the oil galley plugs.

You make a good point that the chain and gear may be mismatched, glad I had to pull it down otherwise this would have gone unnoticed until it was much worse. I will check the chain and gear compatibly out of the engine when I get a chance.

I have a Cloyes billet cam and crank gear coming with a true double roller chain, and a Torrington bearing for the cam gear.
sailtexas186548 is offline  
Reply With Quote
Old 02-07-2019, 06:43 PM
  #7
Platinum Member
Platinum Member
 
Tinkerer's Avatar
 
Join Date: Jan 2002
Location: ALTO, MI
My Boat: 2001 Daytona 26, 1992 SCARAB 34, 1989 25 Checkmate Convincer, 1977 Glastron Carlson CVX 18
Posts: 4,477
Default

That chain was so loose that it was on the verge of jumping a tooth or two or more.
I would say that you saved your engine.
Did you assemble the engine?
was the crank bore align honed?
Chain tension is IMPORTANT
That wear was caused by the chain riding up on the gear.
I would say that it would have blown within another 10 hours at the most.
WOW - that was a close call.
Tinkerer is offline  
Reply With Quote
Old 02-07-2019, 09:26 PM
  #8
Registered
Thread Starter
 
Join Date: Aug 2013
Location: Kemah, Tx
My Boat: Fino 30
Posts: 154
Default

I did not build the engine, I don’t believe it was line honed but I don’t really know. It has stock main caps so I doubt it. I will find out when I install the new timing set.

I dodged a bullet for sure, hopefully there aren’t any more surprises hiding from me.
sailtexas186548 is offline  
Reply With Quote
Old 02-07-2019, 10:09 PM
  #9
Platinum Member
Platinum Member
 
Tinkerer's Avatar
 
Join Date: Jan 2002
Location: ALTO, MI
My Boat: 2001 Daytona 26, 1992 SCARAB 34, 1989 25 Checkmate Convincer, 1977 Glastron Carlson CVX 18
Posts: 4,477
Default

Line honing has nothing to do with what main caps you have. You cut some off the top of the caps and then re cut the holes by using a line hone.
this causes the crank bores to be slightly closer to the cam bore causing slop in the timing chain.
They make a chain that is shorter for blocks that have been line honed and need it.
Tinkerer is offline  
Reply With Quote
Old 02-07-2019, 11:14 PM
  #10
Registered
 
Join Date: Jan 2005
Location: Pasadena, MD
My Boat: It's Not About Being Noticed, It's About Being Remembered
Posts: 3,416
Default

I would not be surprised when the past owner "rebuilt" the motor they left the gear on the crank. Either it was worn or not the same exact dimension as the replacement gear and it let the chain flop around. On any motor I open up I dump that single crap and put a double roller on it.
Also there is metal missing and it went somewhere.
mike tkach likes this.

Last edited by f_inscreenname; 02-07-2019 at 11:18 PM.
f_inscreenname is offline  
Reply With Quote

OSO Sponsor
OSO Advertiser
OSO Advertiser
OSO Advertiser