madhatter

iTrader: (1)

my friend installed a cam in his camaro and now wont start. when he was installing it he lined up the dots at 12 and 12. can this be a problem. i always set them up at 12 o'clock on crank with cylinder one tdc, and the cam at 6 o'clock, thus lining up the dots. he did it at 12 and 12 as i have stated earlier. now for argument sake he was telling me that this is the correct way of doing it, yet that makes no sence to me. have any of you heard or done it this way.

we checked spark, fuel, injectors, injector pulse, along with many other things, yet no start. i think it wont start because the way i think he installed the cam would put it 180 degrees out of mechanical time. if i am wrong please correct me, if he did it wrong please let me know because i really want to help him get his car running.

Apeiron

Line it up at 12 and 12 or line it up at 12 and 6. It doesn't matter, but 12 and 6 is easier.

madhatter

iTrader: (1)

thanks, i had never heard of that before, guess that shoot the theory of cam timing of to hell.

Apeiron

Install it in either position, and then watch the dots while you turn the crank through a full rotation. You'll see something magical happen.

TylerP

I always timed the sbc with the dots together,but they will end up that way with both at 12. The question in my mind is if the distributer was lined up with #1 cylinder with it timed both at 12,would'nt the distributer be off?

madhatter

iTrader: (1)

we timed the car with the timing light and the time was ***** on, i was only wondering if the actual cam timing, would be off to where it would be sparking, giving fuel on exhaust cycle. i was thinking that the exhaust valve would be open when the fuel injector would be firing. but i guess that isn't the case so we will have to do more trouble shooting

rgarcia63

No, it would not be off. Spin it by hand you should feel compression from the #1 spark plug hole as the dots approach the 12 o'clock position.

TylerP

What I'm saying is that with both dots at 12 and the distributer dropped in at the same time,it would be firing on the wrong engine cycle. It will still spark on the timing marks but it would be 180 degrees out on the distributer. Get it on the compression stroke for #1 cylinder and see if the rotor is pointing to the #1 terminal.

Apeiron

No, because you'd install the distributor with the rotor in the correct position.

rgarcia63

As Apeiron said it's correct, if it doesn't start you're missing one or more of these:

1. fuel
2. air (possible but not probable)
3. timing (as you described, it should be correct)
4. spark (to the correct plug)
5. Compression (greater than 80 psi)

We take the time to help, please post the resolution.

TylerP

Ok,so the crank gear dot is at the 12 o'clock position. Then the cam is installed at the 12 o'clock position also, that means the cam is now set for cylinder #6 to be on the compression stroke. If you turned the crank one revolution the dots will line up for #1 to be at TDC. So if you drop the distributer in while both dots are in the 12 o'clock position and time it for #1,it's going to be 180 out. If the engine cam timing is set with both cam and crank gears at the 12 o'clock position it will need to be turned one crank revolution and then drop in the distributer,pointing to the #1 terminal.

Apeiron

But you wouldn't do that, you'd drop the distributor in with the rotor pointing to #6.

If you don't care, it doesn't even matter where the rotor is pointing as long as you put the wires in corresponding positions on the cap.

TylerP

Exactly my point. But if it got dropped in and timed to the #1 cylinder it wont run. Thats what I was trying to get across. Oh well,maybe we will find out what happened.

rgarcia63

Remove the dizzy cap and #1 plug turn crank by hand in the direction of operation when you feel compression continue turning until the dampner mark aligns with zero on the timing tab, (this is the 12/12 positions) the rotor should be pointing at the #1 terminal if it's not then what was said wasn't what was done.

I've never done 12/12 and I've never had anyone say that's how they did it, that is until now. It's definitely not the method GM uses.

From my AllData for replacing chain, and or sprockets. Here the rotor would be pointing at the #6 terminal.
Turn crank until timing marks on sprockets are in alignment, Fig. 18.

gearhead0384

iTrader: (7)

Thanks Dan (madhatter) for asking the question.

I told you I was right. lol

The Comp Cams instructions even say to install it that way. It is just easier to start your timing from cylinder #1 as opposed to cylinder #6 when it is lined up at 12 o'clock, 12 o'clock.

The reason it is not starting is the injectors are not getting any reference pulse. I think the ignition module is at fault there, since I have tried everything else. We will see tomorrow when I check it out.

rgarcia63

Contradicting information; no dizzy refernce signal to ECM = no injector pulse so who did the checking?

gearhead0384

iTrader: (7)

We thought there was but found out there was not. You a cop or something? hahaha