HEI Rotor Orientation

[Buda63]

Hello All

After reviewing many Youtube videos and other forums on HEI distributors I am becoming more confused. I purchased this truck in August and finally had time to work on the idle/timing issues. I wanted to start with the distributor and noticed the rotor is facing to the back of the engine at top dead center. Do I need to rotate the distributor so the rotor points toward #1 cylinder at TDC or should I start the plug wire firing order where the rotor currently sits.

The truck does start and run but does not run smooth.

Sorry the picture is rotated.

[Chevy Fleetside]

If the #1 plug wire is on that post then probably not. If it is where it is supposed to be and it runs then you might be off 180º Now so don't touch the dist. Not running smooth could be a lot of things. low compression or even a cracked dist cap. Maybe a vacuum leak.
Trace where the #1 cylinder wire is on the cap. Should be on the left side up front, if this makes sense.

[geezer#99]

where is #1 plug wire on the cap?
If it’s 180 degrees from where your rotor is pointing then it’s set up right.
There are two tdc’s. tdc compression and tdc exhaust.

[Buda63]

The #1 plug wire is at the 5:30 spot, front right side.

[Chevy Fleetside]

Originally Posted by Buda63

The #1 plug wire is at the 5:30 spot, front right side.

If I understand this right. This would be on the driver side and would be correct. Just to be on the clear the Left side is driver side and right side is passenger no matter where you are standing.

[Buda63]

Sorry for the confusion. The #1 plug is on the front driver side at the 5:30 spot.

[geezer#99]

Originally Posted by Buda63

Sorry for the confusion. The #1 plug is on the front driver side at the 5:30 spot.

That’s where you want it.
While you have the cap off, check shaft wear by lifting up/down on the rotor. Shouldn’t move much. If it does it could be part of your rough running.
When I check for #1 tdc compression I use my compression gauge. That way I’ll see whether it’s on compression or not.

[LVPhotos]

Is the TDC on compression stroke or other? I do the tape over hole rotate till bubble or comes off. If not on compression stroke the rotor will be 180 out. Fyi if your timing is set 15 initial set rotor at 15 and not 0

[SkinnyG]

~Where~ the rotor and #post are don't matter as far as quality of running. If the rotor, where you have it in the first pic, has THAT post going to cylinder #1, then it'll work. If it's running rough, AND THE BASE TIMING IS SET CORRECTLY, it's not because the rotor is pointing somewhere else.

The rotor is supposed to pointing AT cylinder #1 at TDC of compression. #1 wire should be coming off the post just left of front and center on the cap. With the cap off, the rotor is POINTING AT #1. This is just the standard way of doing it; it's easier to troubleshoot if it's set up correctly and "as expected."

As LVPhotos says - you might have the rotor where it is in you photo if you are at Top Dead Center (TDC) of Exhaust, in which case it WILL be pointing to the right location in the next rotation and #1 is at TDC of compression.

BUT: which post you use to fire #1, assuming the rotor is at that post, won't affect how the engine runs, all else being equal. If the timing is correct, your issue lies elsewhere.

[geezer#99]

What make is your hei?
Where’s the vac advance pot?

[Buda63]

I was able to get a helper to turn the ignition while I checked the compression at the #1 plug. Now the truck is at TDC with the rotor pointing directly to cylinder #1. I will put the plugs back on and work on the timing now. Thanks for the help.

geezer - I have a Mallory 8548201 no vac advance

[geezer#99]

You might want to find an hei with vac advance.
It helps with mileage and motor efficiency at all rpm’s above idle.
What’s your initial timing?

[Buda63]

Unfortunately, I don’t have a timing tab so that will be the next step for setting the timing.

[geezer#99]

Perhaps you do have a timing tab. Some were found at the 12 o’clock position. Look right behind the water pump for a tube.

[BOE]

is this true for all engines? strait six and v8

[geezer#99]

Is what true.

[Buda63]

No luck for me. I checked and nothing is there. This is a rebuilt motor with an aftermarket timing cover. If I add the timing marker to the bolts on the timing cover will it be accurate?

[geezer#99]

Maybe!
You want it accurate you’ll need to use a piston stop. Here’s a recent discussion on it.
http://67-72chevytrucks.com/vboard/s...d.php?t=754407
It’s east to make one.
First install your timing tab.
Easy to do, just pull all your plugs, bump the starter until you feel compression on #1, bump it a bit more until the mark on the balancer is at 12 o’clock, insert the piston stop, rotate the motor back until the stop touches the piston, put a mark on your balancer beside the zero on the tab, rotate the motor by hand all the way back around until the stop touches the piston, make another mark like the first. Exactly midpoint between your marks make a better permanent mark on your balancer. You can score the balancer with a hacksaw or lightly with a chisel. That mark lined up with zero on your balancer will be tdc #1.
I use white out to mark with. White out is used to correct mistakes on printed documents.
Some might say you don’t need to be so accurate but if you want consistency in your timing settings, you need it.

[BOE]

my engine has timing gears not a timing chain but the last owner isnstalled hei seems to work but i dont know to adjust

[geezer#99]

Originally Posted by BOE

my engine has timing gears not a timing chain but the last owner isnstalled hei seems to work but i dont know to adjust

Start a new thread Of your own, BOE.
Give lots of info and some pics.

Apologies to buda63 for slightly jackin’ His thread.