Hello!
Iīm in process to exchange the cam and the related parts on my 427 Bigblock. Also the timing chain. I know that the mark at the crank-spoke must be at 12 oīclock and the mark on the cam-spoke must be at 6 oīclock. But there is a problem. On the cam-spoke, the mark is exactly on a tooth. But on the crank-spoke, the mark is between two teeth. So it is not possible, that the both marks line up.

Any ideas????

 

Looks right to me.

 

Looks good to me too. Now degree the cam, that will tell you exactly.

 

That's how the dots are supposed to be.

However, if you want the engine to be at top dead center on the compression stroke so you can install the distributor, you need both dots to be straight up at the 12 o'clock position - not at 6 o'clock and 12. We never assemble engines with the dots pointing together, since it's a bad reference point to work off the exhaust stroke. Put both dots straight up and do your work from that point.

I also noticed that you have installed the crank gear in a position other than "straight up." Have you degreed the cam to determine that it should be installed in that position? I can't remember what the "U"-shaped position is, but you're either 4 degrees retarded or 4 degrees advanced.

Lars

 

Lars,
compression stroke and both dots straight up 12 oīclock is is from 1980-82 if I remember correctly.
I searched in my book form "Chiltons" and that says, Zylinder Nr. 1 at TDC compressioin stroke, both valves closed. 1963-79 timing marks are pointing together.



So how should I do it?

 

Gunther -
Take that Chilton's manual and throw it in the trash can - it's the worst piece of automotive reference material on the planet.

Here's the fact: GM V8 engines, regardless of year, are at top dead center on the compression stroke with both dots straight up. Both dots pointing together is the exhaust stroke. No exceptions. That's the fact. I see people all the time using that Chilton's info and installing their distributor with the cam positioned like that. They then crank and crank to try to start the engine, and in the process, they flatten a couple of cam lobes due to failure to get the engine fired immediately (this is the most common cause of destroyed flat tappet cams that I see).

You can assemble the engine either way. To me, it makes no sense to assemble an engine on the exhaust stroke, but it can be done as long as you drop the distributor in at the #6 firing position. I like to do my engines at TDC compression on #1 for a variety of reasons, none of which justify doing it on the exhaust stroke, as you have done. I'd rotate that crank one revolution if I were you.

Lars

 

Hello Lars!
I really appreciate your help!

Here is what I have done yesterday: 1. Zylinder TDC. Both dots at 12 oīclock straight up. Then installed the distributer, firing positoin Nr. 1. Engine ran like crap.

Today I disassembled the components to change the cam positon to 6 oīclock position because I read this at the book.

Lars, when I have done it correctly at first, why did the engine run like crap???

 

You can take Lars' above information to the bank.
Jim

 

 

Well you're going to adjust the distributor for the proper static timing advance. You can't literally just drop it in and expect the timing to be spot on. There are may other possible reasons as well that your motor runs like crap. Improperly adjusted valves comes to mind, wrong firing order, etc.

 

Yes I know. I tried to set the timing, but still run like crap...

 

No need to disassemble anything. If both dots are at 12 o'clock, and you want the cam dot at 6 o'clock, just turn the crank one full turn - Bingo!

In the latter case, the distributor will, of course, now be pointing at the #6 plug wire instead of the #1 plug wire.

As far as running like crap, if the distributor were 180 out, it won't run at all. Recheck your ignition timing and also spark plug wires going to the correct cylinders.

 

I have to say "AMEN" to the comment about the Chiltons manual. It will get you in more trouble and waste more of your time and $$$. Get rid of it. Old, Outdated, erroneous, incomplete instructions.

 

 

Listen, this is one of few threads where everyone is in agreement, that has to tell you something.
What Lars said about flat tappet cams is 100%spot on.
My neighbor spent alot of money rebuilding his 350/350 vette,could not get it to start. He was lucky and didn't keep cranking. I pulled the distributor got it on the compression stroke and guessed at 14 btdc and she fired instantly.checked it with the light and it was 2 degrees off.you don't always get that lucky but you shouldn't just crank on it.

 

Gunther -
First, let me correct an error in my previous post: I thought I remembered the Cloyes timing gears using the square notch for "straight up" and the "U" shaped notch for retarded. I just checked my notes, and the "U" notch is the "straight up" position and the square notch is retarded, so you have the gear installed in the correct initial position.

Next, for everyone's benefit on the dot position issue, here is a copy of a section from my "How to Replace your Timing Chain" tech paper:

Important NOTE on aligning gear dots:

Aligning the dots on the crank gear and cam gear “dot-to-dot” with the crank gear dot at the 12:00 o’clock position and the cam gear dot at the 6:00 o’clock position will assure that the cam and crank are in the correct position to each other. This is the easiest “visual” way to be confident that the alignment is correct. If you have not removed the distributor from the engine during this process, the “dot-to-dot” method will work perfectly. However, this alignment has the #1 cylinder at Top Dead Center (TDC) on the exhaust stroke – not the compression stroke. If the distributor is not installed in the engine, you cannot install the distributor in the #1 cylinder firing position with the cam and crank aligned in this 12:00 and 6:00 position – it will cause the distributor to be 180 degrees out, and your engine will never start. If you need to install the distributor, you MUST put both gear dots at the 12:00 position (both dots straight up). This position will have the engine configured at TDC on the compression stroke for #1 cylinder. This is a very common mistake, since all the “Chilton’s” and Hayes” manuals use the “12 and 6” alignment positions, and people assume this is the correct configuration for distributor installation. Make sure you’re at 12-and-12 on the dots if you’re dropping the distributor into the engine – it will never start if you chose the 12-and-6 alignment.

As I note in this write-up, and as noted by others posting here, the engine will not run at all if you put the dots in the "dot-to-dot" 6 and 12 position - that's the exhaust stroke, and the distributor must be lined up with the #6 plug wire tower in order to run with the cam in this position. If you drop your distributor into the engine in the 6-12 cam position with the distributor pointing to #1, the engine won't run at all. It won't just run badly. It absolutely won't run.

If the engine is running badly after dropping the distributor in at the 12-12 crank/cam position, you need to work general tuning, such as getting the timing set up correctly and assuring that you are running proper valve lash. There can be several engine issues causing poor running, but it will not have to do with the distributor being installed 180 out.

Lars

 

All of us are saying the same thing. However, I do sometimes install my distributor pointing to the #6 plug wire if I know that the #1 cylinder is on the exhaust (overlap) TDC - the reason is simple - I'm too lazy to rotate the engine another 360 degrees - it's simpler to just install the distributor pointing to #6 in that case. BTW, I should have mentioned that when #1 is at TDC, so is #6 at TDC. One will be at firing, the other at overlap.

Another trick to determine which is which... If the engine is together and the distributor is not installed and it's inconvenient to crank with your finger over the no 1 spark plug hole, just set TDC and then look to see if the #3 intake valve is depressed open (valve cover off). If it is, you're at #1 TDC firing. If it isn't, then you're at #6 firing, so you can set the distributor to point to #6.

Lastly, sometimes I set my timing light to the #6 plug wire if it's more accessible. Since TDC of #1 and #6 occur at the same position on the crank, you can use either for a hookup.

 

Funny I had to learn the "dot to dot" thing the hard way, as most novice builders do. Lots of literature says to install your new chain dot to dot. I guess it is just easier to explain and see the marks.

What they DON'T tell you is that that position is #6 firing TDC!!! Even so, I still prefer to dot to dot, THEN rotate one turn to #1.

When done with the chain install, **very important** verify TDC, and the timing pointer is reading zero degrees!!!

 

I'm impressed you guys can build an engine and never rotate it between installing the timing chain and installing the distributor to fire it up.

I just go dot to dot because I'm lazy and it seems easier to line-up that way. It's gets rotated when I set the valves. I prime it and rotate it again to ensure oil is reaches all the rockers. Then I finally rotate it until it's at TDC with both #1 cylinder valves closed before I drop the distributor and put the valve covers on so I can fire it up.

 

I agree because I would like to know why the heck someone is dropping in the distributor when the timing cover is off anyway? And why? Too many other things to put back together and check before even being close to being ready to drop in the distributor.

And those Haynes and Chilton manuals are not all that bad. Got to remember that is all there really was for people to use for years. Much better documentation available today than there was 20 years ago. No where in either of those manuals have I ever seen mention of dropping in the distributor as the next step right after replacing a timing set. People making too many assumptions and not really knowing what they are doing.