cam timing ?'s

mcsman · #1 05-23-2005, 02:00 PM

if we totally disregard the "shiny" link, can we not put the crank with the pointer at the "zero" mark and the cam with the "dimple" at 12 o'clock (actually about 11:45) and get the cam timing correct?

Point here is that the crank pulley fits on the crank only one way, with the zero mark lined up with the pointer and cylinders 1 & 2 at TDC. The cam gear fits the cam only one way so that when the dimple is at about 12 o'clock, the cam should be at TDC for the #1 cylinder. Wrap a chain around the two and should be a "go". Right?

So, how is it that now, when I put the crank at TDC (1&4) and the cam with the dimple at 12, the #1 cylinder exhaust valve is full open?

I DO NOT want to tear into the front of the engine and right now things are lining up this way, even the shiny link is in the right place (very large coincidence).

dave [img]/ubbthreads/images/graemlins/wall.gif[/img]

NEWS FLASH!!!!!!!!!!!

I knew my symptoms indicated cam timing problems, so I released the bolt holding the cam gear to the cam. I could look into the opening and see the end of the cam and the alignment pin but as I slowly slid the cam gear forward, looking down from above I could not see the pin in the end of the camshaft. I pulled the gear off the cam, and, as I did so, heard the pin fall into the oil pan.

So, culprit discovered. no wonder the engine cranks so easily - no compression due to various valves at least partially open at all times.

big mystery is how it worked loose. it didn't shear off, it just came out. the channel that the pin fits into in the cam gear is the same channel that the distributor gear pin fits into, that is, the channel goes all the way through. this left enough room for the pin to "have a place to go."

So, now, do I find a new pin a drive it into the cam? Or do I replace the cam? If I replace the cam, I have to release the head bolts - if I am careful, I don't have to replace the head gasket, do I?

dave [img]/ubbthreads/images/graemlins/wall.gif[/img]

Gnarly4X · #2 05-23-2005, 06:44 PM

[ QUOTE ]
if we totally disregard the "shiny" link, can we not put the crank with the pointer at the "zero" mark and the cam with the "dimple" at 12 o'clock (actually about 11:45) and get the cam timing correct?

[/ QUOTE ]

Yes.

[ QUOTE ]
Point here is that the crank pulley fits on the crank only one way, with the zero mark lined up with the pointer and cylinders 1 & 2 at TDC. The cam gear fits the cam only one way so that when the dimple is at about 12 o'clock, the cam should be at TDC for the #1 cylinder. Wrap a chain around the two and should be a "go". Right?

[/ QUOTE ]

Yes.

[ QUOTE ]
So, now, do I find a new pin a drive it into the cam? Or do I replace the cam?

[/ QUOTE ]

The camshaft keyway and the gear keyway should be within specs. If any of them are worn or damaged, then replace it, both, or all.

[ QUOTE ]
If I replace the cam, I have to release the head bolts - if I am careful, I don't have to replace the head gasket, do I?

[/ QUOTE ]

If I were doing it, I would think I could be careful enough NOT to have to replace the head gasket. That's just my worthless opinion.

Let us know how it turns out.

Gnarls. [img]/ubbthreads/images/graemlins/headspin.gif[/img]

JEFF_S · #3 05-23-2005, 07:31 PM

Make sure you pull the spark plugs out and drain the coolant.
Jeff

Gnarly4X · #4 05-23-2005, 07:45 PM

[ QUOTE ]
Make sure you pull the spark plugs out and drain the coolant.
Jeff

[/ QUOTE ]

THAT is a very hot tip!!
Gnarls. [img]/ubbthreads/images/graemlins/headspin.gif[/img]

RatLabGuy · #5 05-23-2005, 08:59 PM

[ QUOTE ]
So, now, do I find a new pin a drive it into the cam? Or do I replace the cam? If I replace the cam, I have to release the head bolts - if I am careful, I don't have to replace the head gasket, do I?

[/ QUOTE ]

Yer probably okay on the head gasket if yer really careful.

I think this is a good time (excuse) for a new cam, maybe an engbldr mid-range...

mcsman · #6 05-23-2005, 10:13 PM

OK - drained the coolant. did not remove sparkplugs, never occured to me.

when removing the head, the FSM says to remove the bolt under the distributor gear first. don't know why, but it does. but, I didn't remove this bolt figuring it would help hold things stable while the cam is changed.

Went to the Toy store and found the pin in question is available, but had to be ordered for delivery on Wed. Very surprised that it had its own number.

ordered the pin, but then decided I didn't want to wait. the whole point in replacing the pin was to avoid changing the cam. but I wasn't real sure the keyway in the cam hadn't been danaged and didn't know if I had a clear shot at driving a new pin into the hole, so went with plan "B" and replaced the cam.

had a new engnbldr cam on the shelf, so the choice was easy. oddly enough, the cam that lost its pin was another engnbldr cam. originally bought the cam and oversize valves separately, but then bought a complete head with valves and cam as a set. so had the cam left over. any body want some valves?

only moment of horror was when I was trying to get the cam gear onto the cam. was using a punch in the hole on the cam to rotate the cam so the pin would line up. had wone of those odd spastic moments and dropped the punch....wait for it....into the timing cover. it lodged between the tensioner and the face of the block. after many tears and much head scratching was able to retrieve it using a long handled magnet held in a pair of pliers. phew!

so, now I have the cam in place and the valves are adjusted. who knows what tomorrow will bring?

dave

JEFF_S · #7 05-23-2005, 11:02 PM

The reason for removing the plugs is to keep compression from pushing up on the head while the head bolts are removed. You may not of had that problem though with your situation.
Good luck!
By the way how much for the valves?
Jeff
Jeffstoyo@aol.com

#8 05-23-2005, 11:13 PM

I don't know if it matters but!!!

Did you ever remove the original cam pin that dropped into the oil pan? You got a lot of things going on just wanted to make sure you didn't forget it.

Big Al

mcsman · #9 05-23-2005, 11:56 PM

didn't forget - it weighs heavy on my mind. but it will be staying right where it is for now. figure it is big enough and heavy enough not to be sucked through the screen on the oil pickup.

and JEFF_S , make me an offer. hope you aren't in a terrible hurry, though. I know I have them, but putting my hands on them may take a bit of hunting.

dave

Gnarly4X · #10 05-24-2005, 09:01 AM

[ QUOTE ]
didn't forget - it weighs heavy on my mind. but it will be staying right where it is for now. figure it is big enough and heavy enough not to be sucked through the screen on the oil pickup.

and JEFF_S , make me an offer. hope you aren't in a terrible hurry, though. I know I have them, but putting my hands on them may take a bit of hunting.

dave

[/ QUOTE ]

Wow... I'd be freak'n out think'n about that pin in my oil pan! There's no way I'd start the engine until I got it out... but I'm old and anal!! (I used to be young and daring!)
Gnarls. [img]/ubbthreads/images/graemlins/headspin.gif[/img]