How can I turn the crank and cam so the timing marks line up right?
 

71 C-10 402. Not a rebuild, just a new oil pump and timing gear.

Just pulled the timing chain and gears off, and something escapes me for installing a new chain and gears.

Each gear has a timing mark. As long as those marks face forward the gears only insert one way. That's because there's just one key way on each snout.

As I understand it, assuming the engine is straight (which it's not in the picture), when you install a timing chain the cam gear mark should be at 6-O-clock, and that lines up to crank gear mark at 12 O-clock. In other terms, the timing marks line-up vertically.................I assume the cam and crank turn independently without a chain (clockwise). As it sits the marks on the gears did not meet per the description. How do you safely rotate the crank and cam so the marks line up correctly for installing a chain?


I realize the spark plugs should be removed beforehand. Can't use the flex plate to turn the crank, because the block is on a stand. No I'm not going to use the crank bolt.........or a pipe wrench (yikes). Thank you.....

Re: How can I turn the crank and cam so the timing marks line up right?
 

Use the harmonic balancer. Place it on the crank snout enough that it engages the key. Put two long bolts in it and use a long screwdriver to turn it. You can do the same with the cam. DO NOT put any kind of pipe wrench, vise grips, etc. on the crankshaft. You will regret it.

Also, when the dots on the crank and cam gear meet you are at TDC on the #6 cylinder. To be at TDC on #1 you need to have both dots at the 12 o'clock position.

Re: How can I turn the crank and cam so the timing marks line up right?
 

Man, great idea on those bolts, I'll do that, thank you.

I was looking at this video. Dana - calls the mark on the cam "12 O-clock". You ask me that looks 6 O-clock, but what do I know. Is he top dead center at the #1 cylindar? https://www.youtube.com/watch?v=58ksIFmX-wk&t=66s

Re: How can I turn the crank and cam so the timing marks line up right?
 

A Crank socket (just has a slot for the keyway) is a good investment, not vey expensive. But in a pinch, and for 0$, the balancer is a great idea also.

Yes, the guy says 12 o'clock in the video, but installs it at 6 o'clock (correctly).

Re: How can I turn the crank and cam so the timing marks line up right?
 

You can use the crank bolt if the plugs are out, it should turn over easily and not cause any issues. As stated, both timing marks at 12 o’clock with #1 on TDC is corrrect.

Re: How can I turn the crank and cam so the timing marks line up right?
 

oy vey

Re: How can I turn the crank and cam so the timing marks line up right?
 

Yikes............I'm confused. Does the video show TDC on 1 or 6? You want to be on 1 right?

Re: How can I turn the crank and cam so the timing marks line up right?
 

1 and 6 hit tdc at the same time
When 1 is on TDC compression, 6 will be on Tdc exhaust

1&6 come up together
8&5 come up together
4&7 come up together
3&2 come up together

Re: How can I turn the crank and cam so the timing marks line up right?
 

Good timing on this, pardon the pun. Long story short water seeped through the intake into a cylinder or so. I was told to oil the cylinders and spin the crank.

I put the harmonic balancer on as stated, but no bolts. No chain no spark plugs, I'm able to turn the crank by hand with minimal effort.

Re: How can I turn the crank and cam so the timing marks line up right?
 

Do you still need to know how to align and install the chain properly?

https://forums.iboats.com/forum/engi...amshaft-change

http://www.chevytalk.org/fusionbb/sh...hp?tid/262803/

Re: How can I turn the crank and cam so the timing marks line up right?
 

Great information, thank you. On a side, I was stumped how a oil pump operates. I see it's to the distributor, but that can't be it. I still don't know how it operates, but I see it's rotated by the cam somehow. I'll look it up.

Re: How can I turn the crank and cam so the timing marks line up right?
 

oil pump drive shaft tang engages roll pin in the bottom of the distributor shaft..

there are also tools available to prelube the engine with the distributor removed..

good luck on your engine project!

http://www.grumpysperformance.com/jan18/sbcoilh5b.jpg

http://www.grumpysperformance.com/pumpdrivw.png

http://www.grumpysperformance.com/148_0506_how_09_z.jpg

http://www.grumpysperformance.com/jan18/sbcoilpj.jpg

http://www.grumpysperformance.com/PrimeTool800.JPG

Re: How can I turn the crank and cam so the timing marks line up right?
 

To install Timing Chain (which will set valve timing):
1.With no chain yet installed, rotate Crank sprocket so dot is at 12 o'clock high.
2. Rotate Cam sprocket so dot is at 6 o'clock low.
3. Carefully remove cam sprocket without rotating the cam, loop new chain over cam sprocket, keep the dot at 6 o'clock, droop chain down below the crank sprocket to engage the chain on the crank sprocket teeth, then gently slide the cam sprocket back onto the cam face without rotating the cam or crank.
4. Re-confirm that the crank sprocket dot is at 12 o'clock and aligned with the cam sprocket dot at 6 o'clock.
5. Install cam sprocket bolts.

To set up Ignition timing after the chain has been installed (i.e. when it's time to install the distributor, etc):
1) Rotate crank until crank sprocket dot is again at 12 o'clock, and via chain which rotates the cam 1/2 as much, the cam sprocket dot is now at 12 o'clock straight up. (if you haven't rotated the engine at all since you installed the timing chain, this will be one full crank revolution, which will result in the cam sprocket dot rotating from 6 o'clock to 12 o'clock).
2) Engine is now set at approx. TDC on #1 Cylinder firing position.
3) Install distributor with rotor pointing roughly at #1 cylinder - front driver's side cylinder. You'll have to rotate the rotor to engage the oil pump tang, so plan on this when you stick it in there. It will make more sense when you do it - but note how much the rotor spins when you try to slide the distributor body straight down into the block - the rotor rotates when the distributor helical gear engages the cam's distributor drive gear) and start with that much offset so that it rotates to pointing at the #1 cylinder distributor cap tower just as the distributor is fully seated against the block (and pointing roughly at the #1 cylinder itself). May take a couple tries.

You are now in the ballpark to start the engine.

You can also set approx. initial timing advance by rotating the crank slightly so the damper timing line is lined up under the desired initial timing setting on the timing tab, ~8 deg BTDC is a good 1st guess, and then rotate the distributor housing slightly (rotor will remain stationary because it's now engaged to the drive gear on the came) so the points are just about to break open pointing at the #1 cylinder distributor tower. Or, on an HEI, just as the rotor is about to engage the #1 cylinder distributor tower, i.e. no points.

I had to re-learn this a few months ago, has been quite a while since I'd done it, and flat out forgot about the difference between the valve and ignition timing being two separate, distinct "things". What's old is new again.

Re: How can I turn the crank and cam so the timing marks line up right?
 

Some GREAT information here, thank you, I have a much clearer picture. At the moment I'm stumped at the intermediate shaft clearance, but I haven't tried putting one in yet, so pending.

I purchased a replacement pump and screen, and an intermediate shaft with the steel coupler as opposed plastic. I'm working on a 402. Not a single instruction with the parts outside using a spring for a HP Corvette. The pump included a small rolling pin as well, which has something to do with the spring. I received this information from Melling.


You will want to check and make sure that there is some end play in the I-Shaft when it is installed. The I-Shaft is not adjustable, I only tell you to check that because something that old may have had the heads or block surfaced.

No need to take the pump apart they are tested before they are shipped.

You do want to oil the inside of the pump, pour oil in the hole that the pickup tube goes into while spinning the pump drive you can also put the pump in a tube of oil and spin the pump drive until it pushes oil out the top.

Mounting bolt torque is 66 foot pounds.

There are no additional parts needed to assemble the pump, make sure you pan to screen clearance is correct, we have a video on our website explaining how to do this. In other terms, for a 402 anyway, the only parts required are the pump, screen, shaft and a bolt. That's assuming you're not using a plastic coupler (aka collar).


On a side, sure a lot of variances in methods to install a pump (youtube). I wouldn't have guessed.

Re: How can I turn the crank and cam so the timing marks line up right?
 

Sure took me a while to get here. Apparently "I'm not in a hurry" anyway, powder coat and paint are backed up. I see most people use lock-tite if anything at all for the cam sprocket bolts, and torque to 20 ft. lbs.

ARP suggests their high pressure lube instead of lock-tite, and torque to 25 ft. lbs., and it was suggested elsewhere I use a lock plate too.........So that's what I did. After the chain was installed I spun the crank a turn and set ignition timing as suggested (shown).

On a side, I saw elsewhere someone suggested to find TDC with a dial before installing the gears. Not sure why that is. Seems to me if you do per post #13 for example, which I did, once done you're at TDC.

Re: How can I turn the crank and cam so the timing marks line up right?
 

My opinion here is that approximate TDC is good enough for installing a standard timing set straight up ( dot to dot ). Don't think on a BBC the "slop" at TDC ( where the rod sort of rides the slope at the top of the journal arc ) would be enough to cause the chain to skip a tooth. If it were, you'd probably see that in the dot alignment anyway, right?

-klb

Re: How can I turn the crank and cam so the timing marks line up right?
 

Unless I missed something. That pic shows the cam 180 out. If 1 or 6 is TDC the cam and crank gears should be dot to dot. Cam dot at 6 o clock and crank dot at 12.

Finding TDC with a dial indicator is not needed for regular builds.

Re: How can I turn the crank and cam so the timing marks line up right?
 

as op mentioned, it's been rotated 180 (with the chain on after setting it up dot-to-dot to set valve timing) so he can now drop the distributor in and set approx initial ignition timing. 4-stroke engine, 1 and 6 are TDC twice in one revolution of the cam - picture shows TDC for 1 and 6, just prior to #1 power stroke, i.e. ignition.

as for finding TDC with a dial indicator, isn't too awful necessary - can be done with a dial indicator or just a cam degree wheel/piston stop combo. GM didn't do it when this rolled down the line, no need for you to either, unless you're goin racin. If you were running high compression pistons/high lift cam combo, you may want to go thru the whole enchilada and find true TDC and verify cam specs with the degree wheel - and check for valve to piston clearance. Just not necessary w/stock stuff though.

Re: How can I turn the crank and cam so the timing marks line up right?
 

Figured I missed something. I guess comprehension is not high up on my list. LOL

Re: How can I turn the crank and cam so the timing marks line up right?
 

I've missed the exact same thing, and so have many others, ha.

Re: How can I turn the crank and cam so the timing marks line up right?
 

I can't say I know much about engines (such as "where the rod sort of rides the slope at the top of the journal arc"), but I think I get your meaning. What's straight up and down to one guy might differ from another (i.e., slop).

When I turned the cam and crank separately, seemed I could feel the engine assembly, for lack of better term. In other words, using the crank as example, as I rotated near TDC, clockwise or counterwise, there's a fine(ish) line where a little nudge offers more rotation. To me that means the other valves are opening/closing, which would be off TDC. There's a happy place somewhere in the middle. That make sense? Not that I put much stock into a level for this, my torpedo level seemed to confirm my vision the marks are lined up.

Speak of slop, I was sure the block was level side-to-side first....HA!. Discovered early this stand only holds the block level if I rotate it to do so. Any movement it's off center again. My guess is that's common.


Not sure how to use any of those tools yet, but should I have had done any of this before installing the chain? I'd rather waste a lock plate now than do everything over again later (yikes). For what it's worth, I didn't go through the engine or remove the cam. It was rebuilt some time ago, with stock HP heads off a 396 Corvette, for example, with a high RPM "RV" cam. If memory serves me punched out = 412-419 something like, 350 HP. Sounds stockish to me. Let me ask, other than dropping the distributor and setting timing, any thing else you'd do on this block from a timing perspective?

I still have a pump to install yet HA!......The painter is taking his time with the oil pan. Can't even install the timing cover, pending a powder coated timing plate. SLOW moving man.

Flip-side might be worse. Try taking everything literally:lol: It's confusing.

Re: How can I turn the crank and cam so the timing marks line up right?
 

Ran into an old friend today, he's a mechanic and has built many hot rods. Verbal has it's advantages over messages, he confirmed what you guys were trying to tell me. Being this is a basic engine, he says finding true TDC isn't worth the effort. Timing marks straight up and down and good to go.

Re: How can I turn the crank and cam so the timing marks line up right?
 

Just so you know, these can be interference engines meaning the pistons can hit the valves. Even a collision turning by hand will make the valve not seal.

I would have loosened the rocker arms.

The picture in #15 is number 1 compression. I usually turn the crank back 8-10 degrees and set the distributor straight up and lock it down.

Re: How can I turn the crank and cam so the timing marks line up right?
 

Nope, not necessary to use a degree wheel, dial indicator, or piston stop (was only mentioning it as something a high compression/high lift cam racing sorta guy might do) - you're good.

Re: How can I turn the crank and cam so the timing marks line up right?
 

Didn't know that, good info. In hindsight I'd have lined up the gears with the old chain on beforehand, and now I see there's a better reason to have done that. I spun the crank and cam individually at least a full turn. With luck no damage. No luck I'll be pulling the engine AFTER the rebuild. Wouldn't that be a *(^)^, the only thing I didn't restore would now require it:metal: