Cam sprocket cam timing differences-yes, its true!

[turbovanman²]

Following the massive debate that cam gears don't have different degree's of advance and retard built in, I finally did my own test. I was at the wreckers and picked up a "690" gear off a 2.5 tall deck. I am just doing a headgasket on a stock 89 2.5 so I line it all up with the stock "557" gear, leave the belt a tad loose, slide off the stocker and try to install the "690", no go, it looks to be 2-4 degs off, so I would have to retard or move the cam anti-clockwise to make it fit. Not exactly technical but close enough.

[iTurbo]

I once compared a 690 and 557 sprocket by holding them in my hands with the two next to each other so that the belt teeth were aligned...when looking through the center you could see that the keyway slot was off a little bit between the two. Just a few degrees difference as you said.

[2.216VTurbo]

There is one more gear, can't remember the # right now but it's different still...

[black86glhs]

Isn't that the 2.2 square tooth(????? on the number also)?

[cordes]

I thought the fact that the tall deck gears being different was the on thing people could agree on?

[turbovanman²]

Isn't that the 2.2 square tooth(????? on the number also)?

No, tall deck is a round tooth.

I thought the fact that the tall deck gears being different was the on thing people could agree on?

No, I was arguing someone had posted this info up but I can't find it and he said there is no difference, I think "tryingbe"???

[BadAssPerformance]

Can you line up teh keyways and measure how far they are off with a degree wheel?

Talldeck is 2.5L EFI... weren't those square tooth in '86-87?

[black86glhs]

No, tall deck is a round tooth.



No, I was arguing someone had posted this info up but I can't find it and he said there is no difference, I think "tryingbe"???

Sorry, misunderstanding. I meant the other cam sprocket that Alan was talking about...isn't that one the 2.2 Square tooth?

There is one more gear, can't remember the # right now but it's different still...

[turbovanman²]

Can you line up teh keyways and measure how far they are off with a degree wheel?

Talldeck is 2.5L EFI... weren't those square tooth in '86-87?

I could but don't have the time or energy plus its back together.

No, tall deck is round tooth, sheesh.

[Vigo]

No, tall deck is a round tooth.

no it aint! i just put an 86 tall block in my aries and its square tooth!

[BadAssPerformance]

I could but don't have the time or energy plus its back together.

No, tall deck is round tooth, sheesh.

not the early ones...

Both for 2.5L TBI (K)

'86 & '87


'88


sheesh

[black86glhs]

The # I found on my cam sprocket was 974. Sound right for a 86 sprocket?

[turbovanman²]

not the early ones...

Both for 2.5L TBI (K)

'86 & '87


'88


sheesh

This one came off a 87 Tall deck 2.5L, sheesh.

[black86glhs]

Damnit, stop arguing and read my posts....LOL.

[carmanspd]

86 & 87 tall deck were square tooth. '88 is round (remember Aug. '87 is usually start of '88 production). I did all sorts of "impromptu" research when I couldn't find a lower accessory drive pully for my tall deck turbo. In the process I discovered an '86, '87, and '88 tall deck in the same yard, just feet from each other! I got a history lesson in Chrysler 4 cyl accessory and timing pullys.

[BadAssPerformance]

Damnit, stop arguing and read my posts....LOL.

LOL! you type faster than I look up pics!

btw, Jake and Elwood rule!

[black86glhs]

LOL! you type faster than I look up pics!

btw, Jake and Elwood rule!

LOL!!!
Here ya go.

[GLHNSLHT2]

Of course the gears between a tall deck and and CB are different, the Tall deck is almost .5" taller than a CB. WTF Simon?? Common sense says you'll have to have 2 different timing positions.

[black86glhs]

That was his point. Someone else said they were the same. They can't be.

[puppet]

If you're referring to our discussion ... in another thread ... about cam sprockets, I conceded the differences between these two sprockets (690 and 557) back then (a month+ ago) in that same thread after checking both sprockets myself. Russ also has this very info posted in the KB here.

The debate was/has always been between sqth and rdth (557) ... to which I say there is no timing difference Simon. Do the same test on a head using the arrows to align the sprockets and you'll see what I mean.