# Help with timing pls



## Seol21 (Mar 14, 2011)

So I got my engine back from the machine shop and he installed the timing chain when i picked it up. I am kind of a rookie and this and need help understanding how this works. So the cam gear is at 12 and the crank gear has a R at 12. What's the R? Second, cylinder #2 and #5 are at tdc. Can you guys help me understand or did this dude screw up?
When I set #1 at tdc the marks are lined up at about 2 o clock

Thank You 
Seol


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## freethinker (Nov 14, 2009)

Seol21 said:


> So I got my engine back from the machine shop and he installed the timing chain when i picked it up. I am kind of a rookie and this and need help understanding how this works. So the cam gear is at 12 and the crank gear has a R at 12. What's the R? Second, cylinder #2 and #5 are at tdc. Can you guys help me understand or did this dude screw up?
> When I set #1 at tdc the marks are lined up at about 2 o clock
> 
> Thank You
> Seol


put cam at 6


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## Seol21 (Mar 14, 2011)

If I put cam at 6 , cylinder #2 is at tdc. Is that ok?
Cam is a edelbrock 7157/ ram IV
Pontiac 400. .040 over


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## BearGFR (Aug 25, 2008)

Seol21 said:


> So I got my engine back from the machine shop and he installed the timing chain when i picked it up. I am kind of a rookie and this and need help understanding how this works. So the cam gear is at 12 and the crank gear has a R at 12. What's the R? Second, cylinder #2 and #5 are at tdc. Can you guys help me understand or did this dude screw up?
> When I set #1 at tdc the marks are lined up at about 2 o clock
> 
> Thank You
> Seol


It's ok - relax  Remember that the cam makes one revolution for every two of the crankshaft, so you actually have two choices of how to install it. Imagine two clock faces, one on the front of your crank, the other on the front of your cam. Turn the crank so that the timing mark on the gear is at 12 o'clock (straight up). Turn the cam so that the timing mark on the cam gear is either at 12 o'clock (straight up) or 6 o'clock (straight down). Install the chain, making sure you maintain that alignment. You're done.

(I like doing it with the cam gear at 6 o'clock because it's easier for me to "see" that the marks are in alignment, but either way will work.)

Later in the build, when you're installing the distributor, you'll want to make sure that you have the motor at TDC on the compression stroke and install the distributor so that the rotor is pointing to the #1 terminal on the cap.

Bear


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## Mr. P-Body (Jan 20, 2011)

RED FLAG!!

If there are three keyways in the crank gear, and the "R" keyway is used, the cam will be "retarded" 4 degrees from "straight up". This a cam tming thing, not an ignition timing thing (for clarity). The cam really should be "degreed" when it's installed. It really can make a big difference in performance. Typically, there will be an "0" for "staight up", an "A" for "advanced" and the "R".

What IS the cam?

Jim


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## Seol21 (Mar 14, 2011)

Its a an edelbrock 7157 / RA IV. So clearly it was installed wrong right. When cylinder 1 is a tdc I should have the dots lined up right. Now should I use the 0 in the crank gear. Or do want to retard or advance it. As of now if I put# 1 at tdc, the cam gear marker is at about 2 o clock and so is the R on the crank gear.


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## freethinker (Nov 14, 2009)

Seol21 said:


> Its a an edelbrock 7157 / RA IV. So clearly it was installed wrong right. When cylinder 1 is a tdc I should have the dots lined up right. Now should I use the 0 in the crank gear. Or do want to retard or advance it. As of now if I put# 1 at tdc, the cam gear marker is at about 2 o clock and so is the R on the crank gear.


does your crank gear have more than one slot? even if you use the r crank slot you still use the dot to line up the marks.


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## Seol21 (Mar 14, 2011)

Ok so no matter what slot the crank gear is in the 0 and the dot on the cam gear need to line up while in tdc. So if the R and the dot keep lining up its already wrong correct? Sorry for the rookie questions guys just trying to learn.


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## BearGFR (Aug 25, 2008)

Seol21 said:


> Ok so no matter what slot the crank gear is in the 0 and the dot on the cam gear need to line up while in tdc. So if the R and the dot keep lining up its already wrong correct? Sorry for the rookie questions guys just trying to learn.


Do you happen to know exactly which timing set (gears and chain) you have? That'd help. I missed earlier when you were talking about the 'R' on the gear, glad Mr. P caught that. The "R" and the "A" (if that's what you have) are used if you want to install the cam "retarded" or "advanced". It's not something to do unless you know what you're doing and why --- GENERALLY SPEAKING -- advancing the cam will move the engine's power band lower in the RPM range, retarding it will move it higher --- but those actions also have an effect on dynamic cylinder pressure too and can get you into trouble with detonation - again if you don't know what you're doing. Mr. P-Body also mentioned degreeing the cam --- highly recommend that you do that or have it done, otherwise you'll never really be sure "where it's at". 

Fer example, if you've got a RamAir IV grind on that cam then it's already a "higher than normal" RPM cam, retarding it (which is what it's starting to sound like you've got) is going to make it even more so --- unless the rest of your combination (gears, converter, etc.) are all set up for that you're likely to be pretty disappointed in how it performs on the street - it's going to have very little bottom end power set up that way. With the "wrong" gearing, by the time you get your motor up into the sweet spot the guy in the other lane is going to be long gone. How big's the motor? How many cubic inches? What tranny and rear gear are you running?

Manufacturers of both cams and timing sets sometimes make mistakes - just because a mark lines up with another mark doesn't guarantee that's really TDC - the only way to know for sure is to measure everything yourself, starting with using a piston stop to locate actual TDC. I put a nice and not cheap SFI-rated harmonic balancer on the engine for my 69, and when I measured everything I found out that the "TDC" mark on the balancer was actually "wrong" by a few degrees. Had I not checked it (and corrected it with a timing tape) then everything I did after that with trying to tune that motor would have been off and I wouldn't have even known it.

Bear


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## freethinker (Nov 14, 2009)

Seol21 said:


> Ok so no matter what slot the crank gear is in the 0 and the dot on the cam gear need to line up while in tdc. So if the R and the dot keep lining up its already wrong correct? Sorry for the rookie questions guys just trying to learn.


a picture of the crank gear would sure help. there should be a dot on the colar of the crank gear. that is what you line up with even if you use the a or r slots


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## Seol21 (Mar 14, 2011)

K got it guys. I set the chain with the 0 and the dot lining up and cylinder# 1 is on tdc. I think the machinist screwed up and set it with cylinder# 2 on tdc. He said something about the furthest cylinder being nuumber 1 when I tried calling him , which I take is not correct with pontiacss. My first pontiac by the way 64 lemans. It has a 400 from a 71 that im rebuilding with a th400.


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## BearGFR (Aug 25, 2008)

Seol21 said:


> He said something about the furthest cylinder being nuumber 1 when I tried calling him , which I take is not correct with pontiacss.


(Like Jim says) RED FLAG!! That's a sure sign of a "Chevy guy" who doesn't know anything about Pontiacs and also can't be bothered to double-check his work. 

You are correct sir, #1 cylinder on a Pontiac is the front cylinder on the drivers side, despite the fact that front cylinder on the passenger side (#2) is "closest" to the front face of the block.

Be very careful, Will Robinson. If he got that wrong he might have made other, more serious mistakes also. (Like leaving out the "hidden" oil gallery plug on the rear passenger side of the block in front of the distributor, getting the rod bearing chamfers turned the wrong way, etc.). If'n it wuz me, I'd check "everything" before I tried to fire that motor.

Bear


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## geeteeohguy (Feb 2, 2008)

Really good point on the oil galley plug(s), Bear. The first Pontiac engine I ever did had all three plugs left out: the one at the rear behind the core plug, and both up front behind the timing chain cover. What a _major _hassle that was.


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## Seol21 (Mar 14, 2011)

So far everything else looks good. The plugs are all there. The only thing im not sure about now is the chamfer on the rod bearings now. Which way should the chamfers be. Also what can happen from having the other way. Im assuming bad oil flow but what is the damage because I have a buddy that has a 326 that was machined by the same dude.


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## BearGFR (Aug 25, 2008)

Seol21 said:


> So far everything else looks good. The plugs are all there. The only thing im not sure about now is the chamfer on the rod bearings now. Which way should the chamfers be. Also what can happen from having the other way. Im assuming bad oil flow but what is the damage because I have a buddy that has a 326 that was machined by the same dude.


The chamfers on one side of the rod bearings are there to provide clearance for the fillet on the crank next to the counterweight where it "curves" into the rod journal. If the bearings are backwards, then you'll have the "sharp" edge of the bearing riding on this fillet and it will tend to bind up --- depending on the crank and the bearing and how tight it is there it could lock the motor up completely so that you can't turn it over by hand, or cause abnormal wear once things start to heat up with the motor running, maybe spin a rod bearing. The correct orientation is to have the bearing chamfers on the pair of rods that share the same crank pin pointed to the "outside" next to the face of the crank with the "non-chamfered" edges of the bearing turned to the inside -- so that they "face" each other.

I'll try to "draw" you a picture - don't laugh, ok?

| Rod 1 | Rod 2 |
\-------+-------/ <-- chamfers to the "outside"

Crank Journal

/-------+-------\ <--chamfers to the "outside"
|______|______|
Cap1 -- Cap2

Make sense?

Bear


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## Bensjammin66 (May 12, 2009)

BearGFR said:


> It's ok - relax  Remember that the cam makes one revolution for every two of the crankshaft, so you actually have two choices of how to install it. Imagine two clock faces, one on the front of your crank, the other on the front of your cam. Turn the crank so that the timing mark on the gear is at 12 o'clock (straight up). Turn the cam so that the timing mark on the cam gear is either at 12 o'clock (straight up) or 6 o'clock (straight down). Install the chain, making sure you maintain that alignment. You're done.
> 
> (I like doing it with the cam gear at 6 o'clock because it's easier for me to "see" that the marks are in alignment, but either way will work.)
> 
> ...


I know this is an old post but I have one question. When the crank is at 12:00 and the cam is at 6:00 is that #1 or #6 firing position? I agree that 12/6 is easier to see. I want to install the dizzy so #1 fires upon first start up so 12/6 or 12/12 for that? If 12/12 is #1 firing I can install the timing set and spin the crank once from the 12/6 position. Unless of course 12/6 IS #1 firing... :confused


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## BearGFR (Aug 25, 2008)

Honestly? I don't remember. I could go look it up but there's no reason to go to that much trouble. It's easy to figure out. When the piston is at TDC (remember both #1 and #6 will be at TDC when the timing marks are aligned), just take a look at the rockers/lifters. If both intake and exhaust are shut, then you know that's the compression stroke. If the exhaust valve is open, then that's the exhaust stroke. As long as you installed the chain/gears in the correct orientation, it doesn't hurt anything to turn the engine over to get things situated however you want them.

Bear


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