So when starting to go through the short block I bought I noticed when timing dots are lined up the #1 cylinder is about 3/4" btdc. Cam gear is at 6 o'clock, crank gear is at 12 o'clock. On my last 455 i did chain and gears, top gear was nylon tooth, so I assumed it to be original, when it was at tdc the cam gear was at 12 o'clock and crank gear at 12 o'clock. So I guess my question is, if cylinder 1 is at tdc and crank dot is at 12 o'clock, is the cam gear supposed to be at 6 o'clock or 12 o'clock? I looked online and have seen pics of them installed both ways.

 

The cam turns at half the speed of the crank. If you start with both at 12 o'clock and you rotate the crank one full turn, then the crank will be at 12 and the cam at 6. So long as the crank is at 12, the No. 1 piston is at TDC.

On an Olds motor, with the cam at 6 (dowel pin on the end of the cam up), No. 1 will be on the compression stroke. With the cam at 12, No. 1 will be on the exhaust stroke.

 

Here I found on the bottom end I just bought, you can see the 0 by the keyway, the other 0 on crank gear and the dot on cam gear. This is how it lines up at tdc

 

Might want to correct that.

 

That would be an issue. I can't believe that was even running with it like that.

 

I think so, so if I understand correctly, crank gear O at 12 o'clock, making the keyway at about 1 o'clock. Cam gear at 12 o'clock and I should be good for.puttimg.the distributor

 

[QUOTE=svnt442;942927]That would be an issue. I can't believe that was even running with it like that.[/QUOTE


I don't know if it ran or not, story I got was it ran, andno smoke or rattles, so l took a $300 gamble, I figured I can always use it for parts if I have to

 

Keyway location is irrelevant (though note that the crank gear has three slots for advance, retard, and straight up. It is currently in the straight up location). As I noted above, simply align the dots with the crank at 12 and the cam at 6. This is easy to see and puts the No. 1 cylinder at TDC on the compression stroke. Install the dist and put the No. 1 plug wire on the terminal that the rotor points to.

 

Thanks Joe! Hey, is there anyway to tell what was put in it for a cam? Do they stamp or mark cams anyplace?

 

Other than the timing it seems decent

 

Factory cams have indicators on the front surface, as shown in the Chassis Service Manual. Aftermarket cams all vary depending on the manufacturer. A dial indicator and degree wheel are the only real option.

 

# 30m306406 .030, miles are unknown but still cross hatch in the cyls

 

Those are low compression pistons....ack.

 

Yep, but at this point I dont care, last summer I put 5000 miles on the car, this year it have 300 miles, I just want to drive it

 

Two things:

1. If you look at this picture:



it looks like whoever assembled it lined it up with the cam mark opposite the keyway (and the subordinate keyway zero mark), instead of with the correct zero mark.


2. Joe, don't you mean to say that 12:00 and 12:00 is TDC #1, while 12:00 and 6:00 is TDC #6?

- Eric

 

12:00 on the crank is always TDC on #1.

 

Should have said TDC compression stroke #1 vs TDC compression stroke #6.

- Eric

 

Eric, don't you mean "on the compression stroke"?, since both No.1 and No. 6 are at TDC at the same time?


Actually, I skimmed a diagram in the 68 CSM, and may have misinterpreted it. This is why I just check for compression on No. 1 and route plug wires that way. Memory is the second thing to go, and I can't remember the first.

 

Yeah, that's the thing, the CSM tells you to set it up for TDC compression on #6, without telling you that that is what they're doing, so the casual reader might ASSume (and often does) that they mean #1, which it would be if it were a Ch__y.

There was a thread last month where I gave this advice, and then completely doubted myself for the aforementioned memory whatchamacallit, but then the poster confirmed that I had given him the correct advice, so I feel better about it this time.

- Eric