HEI Firing order

[ratman90]

My BIL gave me a 72 C10. Looks like someone got 90% done and gave up.

Spark plug wires were atrocious on this engine, I assume 350. Held together by zip ties. And way too long.

Bought a set for a 75 better and they looked to be ok. Now is the weird part.

PO had #1 plug wire In the back at what every other picture calls # 5.
ACCEL HEI Super coil 140003 coil? Ran fine. Just wanted to put correct length wires and rout them nice with some separators. Kind of hard to do. Ram horn manifolds and AC compressor in my way.
So I routes them per the normal diagram that is all over the net with cyl 1 on the cap facing cyl plug. And 6&5 running parallel with the firewall.
18436572 with 7 being on the firewall side of electrical connections and 2 being on radiator side of connections.

Problem is it will not start but backfires through the tailpipe.

Did not turn dist or mess with timing.

Removed accel coil and replaced with parts store coil and dust cover. Still backfires.

I thought # 1 could be anywhere on the dizzy as long as you followed proper firing order? I have double checked. Double checked with my son. And then had him double check. Wires are routed correctly.

Thoughts?

Larry

[BigBird05]

Remove the distributor and place # 1 in the correct spot.

[ratman90]

I have never had to do that before but that basically is just putting a bolt on the crank and turning the engine over to top dead center 4 cylinder one correct and there's two options for the distributor it could be on the intake stroke pointing at cylinder 1 and it could be on the exhaust stroke pointing at cylinder 1 correct?

This is what I was afraid of even though everything I am reading says you can put the number one spark plug anywhere on the distributor that you wanted As Long as You Follow the correct firing order. That seems to not be the case. So I bet you whoever did this originally had the distributor 180 degrees from where it needed to be

[Bigdav160]

If the engine has the correct balancer - timing cover combination you can line up the TDC marks. This is either #1 compression or #1 exhaust.

The biggest difficulty is aligning the oil pump drive shaft on the bottom of the distributor so the distributor sits flush with the intake manifold.

[RustyPile]

Not to sound condescending, but you're very confused on firing orders and plug wire placement.. Let's keep this clean and simple.. Don't mess with the distributor.. Don't change the timing, or remove the distributor.. And never mind the "proper" position (the one listed in the service manual) for #one.. Doing this will probably result in just confusioning you more. Just put the new plug wires in the original position of the old ones.. Follow the firing order, and you should be good to go..

[geezer#99]

That might work rusty!
There is a possibility his new wires might not be long enough though.

And yes you can put #1 plug wire anywhere on the cap. Only if the rotor points at #1 post on the cap and the #1 piston is at tdc on the compression stroke.

[RichardJ]

>> intake stroke pointing at cylinder 1 and it could be on the exhaust stroke pointing at cylinder 1 correct?<<

When you see a reference to pointing to number 1 they are talking about the rotor pointing to the #1 wire tower on the cap. This has nothing to do with the physical location of cylinder number One or its spark plug.
The tower in the cap that is towards the front of the engine is just the normal location for the tower used for #1.

[dmjlambert]

Originally Posted by ratman90

....everything I am reading says you can put the number one spark plug anywhere on the distributor that you wanted As Long as You Follow the correct firing order. That seems to not be the case....

ratman90, I think I understand the mix up about what you read. When installing the distributor you can put the number one spark plug anywhere on the distributor, which your PO did. Once the distributor is installed you can't pick some other post to be your number one, you need to stick with the number one terminal your PO chose. Unless you re-install the distributor and re-orient the rotor.

[siggyfreud]

Step by step:

1. Take of Dist Cap/Coil so you just see the rotor, but keep the cap handy.
2. Take off driver side valve cover
3. Take out #1 spark plug
4. Rotate engine by hand. Wait until you see the INTAKE valve on the head close on the #1 cylinder, then use a feeler to determine when the #1 piston is at top dead center. This is TDC of your intake stroke.
5. Now take note of where the rotor is pointing. Put a piece of tape somewhere on the engine that shows the direction the rotor is pointing.
6. Put the cap on, and wherever that rotor was pointing (or now a piece of tape) is the spot for your #1 spark plug.
7. After that, put the rest of the plug wires on.
8. As you start it, you may have to rotate the cap forward or back or get the proper timing for it to idle, but that's normal. Just get it running.
9. Now go back with a timing gun and do the proper timing.




Hope this helps.

[RichardJ]

>>6. Put the cap on, and wherever that rotor was pointing (or now a piece of tape) is the spot for your #1 spark plug wire.
7. After that, put the rest of the plug wires on.<<

[randy500]

Do what siggy says in post 9, its time consuming but will absolutely work.

Modify his method to simplify things....

Must have a helper or a remote starter switch.

Remove number one plug, front of drivers side.
Hold finger over plug hole
Bump starter until pressure is felt,
Rotate balancer clockwise to line up timing marks.


I do it inside the vehicle with a spark plug adapter on a 6’ air hose, finger over the end of the hose bumping starter.

[randy500]

My method short cuts using a feeler to make sure your At tdc when the timing marks are lined up. This can be a mistake on an unknown engine.
The engine could have a mixture of balancers and timing pointers, if you feel that is possible then verify tdc by inserting a wire in the plug hole while someone moves the balance and you feel tdc woth the wire, now check the timing marks...should be at approx tdc, if not you have mismatched timing marks, re-mark the balancer.

[siggyfreud]

Good tips randy5000!

And thanks for the catch RichardJ

[ratman90]

Ok. I have not removed the dizzy at all. Have not even taken the cap off.

Just removed the accel coil to replace the wires.

Seems crazy I know, but I may put the wires back in original configuration to confirm, or just go ahead and make sure where it is pointing at
T when TDC for plug wire # 1 placement.

[ratman90]

It would not backfire if wires were arcing off each other or on the body would it?

That should just be a mess I thought. That was the reason I even started this as they were zip tied to each other and various components and looked horrible.

[dmjlambert]

Originally Posted by ratman90

Ok. I have not removed the dizzy at all. Have not even taken the cap off.

Just removed the accel coil to replace the wires.

Seems crazy I know, but I may put the wires back in original configuration to confirm, or just go ahead and make sure where it is pointing at
T when TDC for plug wire # 1 placement.

Yes, just put the wires back on in original configuration. If you have not removed and re-oriented the distributor, the PO's original choice for which post on the distributor is for plug #1 applies.

[RustyPile]

Originally Posted by geezer#99

That might work rusty!
There is a possibility his new wires might not be long enough though.

And yes you can put #1 plug wire anywhere on the cap. Only if the rotor points at #1 post on the cap and the #1 piston is at tdc on the compression stroke.

The odds are in Ratman's favor.. I can't count the number of times in my 35 years of building, rebuilding, and just simple servicing engine components almost daily during my professional career. But I can count on half the fingers of one hand the number of times I've had wire length issues that required pulling the distributor and re-clocking it.... Usually all that's needed it to "pivot" the wire at the distributor end to gain length or "shorten" the wire..

[ratman90]

So I am running again.

Rearrange plug wires like previous owner had them.
Was curious to see that my 77 camaro also had the #1 plug wire in the back towards the firewall.

How would a person drop in a dist. to be like what the manuals and internet says? With the #1 cylinder spark plug wire being on the front and to the right. As if the rotor would be pointing at the physical #1 cylinder along with the #1 corresponding plug wire on the dizzy?

Attached is my chicken scratch of what the internet says should be the arrangement, and the 2 diagrams of the c10 and my 77 camaro.

Hypothesis?
Seems when the PO dropped the dizzy in, with #1 cyl ATDC, they did not try to orient the rotor to point at the #1 cylinder.

They just dropped it in and where the rotor pointed at, they made it the #1 spark plug wire location?

Maybe because that was where the oil pump lined up at? Should have turned the oil pump to enable the rotor to orient and point to #1 cylinder?

[truckster]

Generally it only matters where the #1 wire is if the vacuum pot is close to the firewall. In that case, you may need to pull the distributor and re-orient it in order to get enough adjustment room to properly set the timing.

[Steeveedee]

Doing it right makes it easier on the next person (which is you, this time!), and avoids confusion.

[Bigdav160]

How would a person drop in a dist. to be like what the manuals and internet says?

Easy. Did someone rebuild the motor? Or put a cam or timing chain in? Lining the marks up on the timing gears is TDC compression for#6 cylinder and not #1 as most people would assume. They install the distributor and find it will not start. They struggle to find TDC #1 and drop the distributor in any where the oil pump shaft will align. The later happens with intake manifold replacement also.

edit to add: if you have Corvette style wires that go under the manifolds distributor position makes or breaks the wires fitting correctly especially with the corvette wire covers.

[randy500]

Originally Posted by Bigdav160

Easy. Did someone rebuild the motor? Or put a cam or timing chain in? Lining the marks up on the timing gears is TDC compression for#6 cylinder and not #1 as most people would assume. They install the distributor and find it will not start. They struggle to find TDC #1 and drop the distributor in any where the oil pump shaft will align. The later happens with intake manifold replacement also.

edit to add: if you have Corvette style wires that go under the manifolds distributor position makes or breaks the wires fitting correctly especially with the corvette wire covers.

This...
Wired it to 6 tdc position or very close after dropping in the distributor and finding out It wont start because its 180 degrees out, The distributor is already in and wires on when they discover the error. Instead of correcting the distributor they move the wires to make it run.

[AussieinNC]

Do not remove the distributor

The placement of the No 1 plug lead where the number 5 lead is usually found is a very common situation where the distributor was dropped in with cyl No 1 on the overlap TDC position and the oil pump drive not lined up...people bump the ign switch a little to drop the dist down and it ends up with cyl 5 cap location needing to be used for No 1 cylinder. Cylinder No 1 comes to TDC twice during a firing cycle
Once on overlap of exhaust closing and inlet opening
Once on compression stroke where both valves are closed

Firing order for 350 is 1,8,4,3,6,5,7,2
Cylinders on drivers side front to back are 1,3,5,7,
Cylinders on passenger side front to back are 2,4,6,8
Rotation is clockwise looking at top of distributor


Regardless....

Find on compression TDC on cyl 1...
Pull No 1 plug and put your finger over the hole and have an assistant bump the ign switch to slowly bring motor onto compression stroke for Cyl 1.
Align the timing marks on balancer and timing tab.
Replace Cyl 1 spark plug
Look at the rotor tip position is relative to the cap
The cap position lining up with where the rotor is pointing is Cyl 1 fire position,
Starting with that position, go clockwise inserting plug leads in firing order 1,8,4,3,6,5,7,2...

Make sure leads are not touching any exhaust manifolds

Start the engine and set timing

[jocko]

I believe Aussie nailed the root cause - someone installed the distrib 180 out and was too lazy to pull it back out and do it right - so they did the wiring trick.

Yes, it will work to return it back to how the PO wired it, but you can also kiss yer cousin. (i.e. some things just aint right).

Why all the resistance (wiring pun) to just installing it correctly, i.e. the way GM did?

[garyd1961]

The correct place for the #1 on the cap for a HEI is in line with the #1 cylinder. So your rotor button would be pointing straight at the #1 on the cap and the #1 sparkplug at the same time.
The old points distributor the #1 post would be towards the #2 cylinder.
As said it will run anywhere you put it but why not put it in the right place while you are working on it.