small block chevy distributor question

[finest20]

Hello All
I am not sure if I have a problem here, but this has been bugging me for a while so I want to get opinions, or maybe even a solution to this. When I got the SB 355 for my 71 Vega, I documented the condition and setting of the motor with pictures and markings everywhere. One of the markings I made was the position of the distributor in the intake, so that when I put it all back together, that setting for timing purposes would be close. Well when it came time to put the motor back together and start it for the first time, it would not start. When I moved the distributor around it wanted to catch but not quite. So what I did was to get the #1 cylinder at TDC, then take the distributor cap off to see where the rotor was positioned. It turns out that at TDC, I needed to move all the plug wires over one position in the cap to get the #1 position where it needed to be. Once I did this the engine started fine. My question is WHY I needed to do that when I had all the marking in place for an exact reassemble??????? Is there something I am missing???

[Wizeguyrc]

Did the distributor seat all the way down to the intake surface, or did you have to roll the motor around to get it to bump on down?

[mastiff]

In a case where I have to remove the dist. and put back for some reason. I not only mark where the dist. meets intake, but also the rotor position. this way when I put it back together and something doesn't line up, I know to look for a problem somewhere. If I turned the engine even a little bit and put it back and the dist didn't line up. what I'd do is keep the dist. cap off but leave dist. in place. move the crank pulley back and forth to see how much the rotor moves. if you can move the crank pulley and the rotor doesn't move right away. then I'd be checking timing chain. it could also be when you set the dist. on the bench. the gear or rotor touched and moved before it was fully set down on bench.

[rtm]

if you changed distributors (from points to HEI )
the #1 plug position would change from 6:30 to 5:30, thereby changing the others by one position, as the firing order would remain the same.
(sorry the hei diagram is small)

[marco_1978_spyder]

Hello All
I am not sure if I have a problem here, but this has been bugging me for a while so I want to get opinions, or maybe even a solution to this. When I got the SB 355 for my 71 Vega, I documented the condition and setting of the motor with pictures and markings everywhere. One of the markings I made was the position of the distributor in the intake, so that when I put it all back together, that setting for timing purposes would be close. Well when it came time to put the motor back together and start it for the first time, it would not start. When I moved the distributor around it wanted to catch but not quite. So what I did was to get the #1 cylinder at TDC, then take the distributor cap off to see where the rotor was positioned. It turns out that at TDC, I needed to move all the plug wires over one position in the cap to get the #1 position where it needed to be. Once I did this the engine started fine. My question is WHY I needed to do that when I had all the marking in place for an exact reassemble??????? Is there something I am missing???

Because the rotor always moves a tooth or two forward when you remove the distributor housing, which in turn twists the oil pump shaft so the rotor wont reset back exactly to where it was unless you reset the oil pump shaft back about a little bit with a long screw driver.

[duckblaster67]

A lot of good answers here that all need to be taken into concideration. It sounds pretty obvious that you are a tooth or 2 off and need to pull it back out and moved towards the way it wanted to run. My past experience is that it never goes in all the way when it's right. If it drops in flush with the intake without cranking it over a bit to make it drop the rest of the way, then most likely it's off! Also on an HEI distributor, the cap will generally be setting horizontal with the firewall when correct.

[Fasterthansome]

Sounds like as Marco mentioned you were one off on rotor when re installed.

If you marked distributor housing to intake/rotor to dist housing location then lined up those marks when assembled it should have been good to go. If you moved them all one position and that fixed the problem not really a big deal.

[finest20]

yes that was the problem.....when I went to put it back together in the exact position the distributor did not seat all the way down. I had to position it differently and move the wires over one. S you are saying that I can remove it, turn the oil pump shaft a bit and reseat the distributor with the wires back inthe right spots? Or should I just leave it the way it is????

[rtm]

yes that was the problem.....when I went to put it back together in the exact position the distributor did not seat all the way down. I had to position it differently and move the wires over one. S you are saying that I can remove it, turn the oil pump shaft a bit and reseat the distributor with the wires back inthe right spots? Or should I just leave it the way it is????

The engine doesn't "care" where #1 is located, as long as the proper firing order is followed.
If you have a full sweep of the housing for timing adjustments(with no impediments)
then you COULD leave it alone IMO
the only reason I can see, to have a typical setup, is for the next plug wire swap.
as long as you know where #1 is, and you are the only person performing maintenance,
no harm, no foul.
but, It wouldn't hurt to change it either, just for piece of mind.
that way you KNOW it's correct.
I know how it is, I'm kinda funny about stuff like that,
just my two cents

[spencerforhire]

As a couple of others have stated, the engine doesn't care; there is no right place for #1. Different engine builders and tuners have their favorite ways of setting things up. One thing that it does affect is how neatly you can run your plug wires; with #1 at 5:30, you only have #'s 3 an 2 on the wrong side with the wires usually crossing behind the distributor. With #1 at 6:30, you end up with 3 & 6 crossing behind and 1 & 2 crossing in front. Any other arrangement usually ends up looking like a mess with most of the wires on the wrong sides. Of course, a "corrected cap" can solve all this mess and really only fits one way.

[Smiley]

if you took the motor apart you could also be off 180 degrees at the cam, because the crank makes 2 revolutions per every one of the cam.
pull # 1 plug and turn the crank clockwise by hand while your finger is in the # 1 plug hole to make sure you are at top dead center on the compression stroke. when you feel air coming out of the hole, watch the timing mark on the balancer and stop the crank at about 10 degrees before 0
then align the distributor rotor to just before the #1 terminal on the cap.

leave the distributor clamp just loose enough to allow moving the distributor while cranking if it does not fire right up.

[scy135]

It doesn't matter what position the rotor is, being TDC whatever post the rotor is pointing to that's going to be your #1 and you just continue the wiring from there you just have to remember which one is your #1. Most people like it pointing towards the #1 cylinder to make it easier but for me that's too much of a hassle

[SeniorSavage]

My question is WHY I needed to do that when I had all the marking in place for an exact reassemble??????? Is there something I am missing???

maybe because the guy who built the 355 got it wrong when he installed the distributor (one tooth out) and then had the wires on the wrong distributor posts to make it work?

did you notice whether the wires were on the distributor correctly when you disassembled it?

just sayin ..

[Bullet]

You most likely nudged the crank a tiny bit during the process while the distributor was out. Consider the diameter of the cam gear vs. the diameter of the crank pulley, just nudging it a 1/4" could have easily put you a tooth off on the cam gear. If you want to fix it, pull the distributor, use a long screw driver to engage the oil pump drive and turn it opposite the direction you had to move the wires. Turn it about 1 "hour" looking at it as a clock. Then just drop the distributor in and move your wires back. As has been stated, it doesn't matter where it is as long as the firing order is correct but the fewer wires you have crossing one another, the fewer chances there are for crossfiring as the wires age.

Another method that will work without pulling the distributor all the way out is to pull it up until it clears the cam gear, turn the rotor one tooth opposite the direction you moved the wires then let the distributor slide back down and engage the cam gear. It will not drop all the way in, then get someone to bump the engine over while you keep a little pressure on the distributor. It would be a good idea to have the hot wire to the distributor unhooked. As the engine is bumped over, when the drive slot and pin aligns between the distributor and oil pump, the distributor will drop all the way in, then line up your marks and move your wires back to their original location.