Cranks but won't start.

[DeCaff2007]

@Schurkey, I don't know how to multi quote a single post, so I'll answer your questions the best I can.

"It's dead on perfect" - meaning when the harmonic balancer timing mark is at 0° with respect to the marks on the timing cover, the #1 cylinder is exactly at TDC. Sorry if I wasn't clear there.

Why on Earth are you whacking the throttle WFO during break-in?

AHA! Just figured out multi-quote in a single post! It's not necessarily WOT, but 2500+ RPM sure sounds like it. Regardless, it still started backfiring. I think I heard two backfires in 5 minutes. Better, but not perfect.

Refresh my memory about "that same wiring harness". WHERE is it? What does it control? How is it routed? Details matter, and I've read too many posts to remember the back-story on this engine.

How hot was the coolant temp?

Easier to just take a pic:

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This just happened last night. Didn't get a chance today to really look at it and assess the damage. The header pipe from the #7 cylinder turned the 30+ year old heat shielding into dust, then very quickly burned - and caught fire - to the plastic wire loom surrounding the harness. Yet to be seen if any wires are crispy.

Coolant temp gauge never really goes above half, HOWEVER, the one wire CTS in the drivers side head.... I've replaced the wire going to that sender multiple times because it keeps melting.

These fancy shmancy headers were maybe not such a good idea. Too late to turn back now.

What's wrong with the distributor you have? If there's a problem, you need to fix or replace the thing. If not, you're wasting money on an already-over-budget project.

It's chinesium. A cheap Rock Auto special. Oh and the distributor cap is loose due to stripped threads in the distributor housing. My FIL says that the pickup coil in the distributor is a likely contributor to the no start when hot problem. I believe I've also read that here, and probably elsewhere. Why haven't I replaced it by now? Because this is a RIDICULOUS price.

You almost certainly don't need header-wrap. You need to make the damn thing RUN RIGHT.

When it runs right, the headers won't be that hot.

That's fine, and honestly I hope I end up NOT needing it. I can certainly return it if need be.

There's a hundred electrical circuits in the engine compartment. What "wires" are you talking about? Is this regarding spark plug wires?

Spark plug wires. My T/A is the only other vehicle I have with said wires that will fit. Ironically, the Auto Zone here used to sell single spark plug wires for dirt cheap. They have since thrown all that out in favor of full, overpriced sets which are largely universal fit at that. Ask me how I know........

No, that doesn't make sense. Time the engine per spec., and tighten the hold-down clamp properly. Re-check the timing AFTER you've tightened the clamp, to assure you haven't moved the distributor in the process of securing it. If it changes from that point, you need to find out why. Something is WRONG. Clamp not tight enough, clamp is bent, hold-down-clamp bolt is too long, distributor is failing, distributor gears are wearing, timing chain/sprockets wearing, etc. Virtually everything that would wear to cause ignition timing changes, causes the timing to retard (not advance.)

Ignition timing with electronic distributors is almost--not quite--"Set For Life". Get it right when the engine is built, and it should stay in time more-or-less for the life of the engine, if you disregard potential failure of the various gears, chain, and sprockets that drive the distributor, and perhaps needing intake gaskets or some other service work that requires screwing-up the distributor position.

Very well. Please help me understand what I'm doing wrong, then. The distributor rotor is supposed to point at the #1 cylinder when stabbed, correct? I'm sure I've mentioned that mine points either at #3 cylinder or the upper radiator hose - there doesn't seem to be an in between. If I have the rotor point towards the #3 cylinder, I can start the engine no problem, but then the harmonic balancer timing mark will be retarded - and quite a bit so. From that point, I can spin the dist. cap CCW to compensate. Like I said, that will put the #1 cyl wire just about where the #2 cyl wire was before spinning anything.

I've also read that the "one tooth off" concept is a myth, and that rotating the distributor is what adjusts that out. I DISAGREE, because otherwise it would be possible to just spin the dist. cap 180° to compensate if the dist. was "180 out"... WITHOUT having to restab the whole dist. Is this incorrect?


EDIT: I just realized the typo in my previous post, and corrected it, now mentioned above. Should have been #2 cyl, not #8.

 

[Hipster]

I've also read that the "one tooth off" concept is a myth, and that rotating the distributor is what adjusts that out. I DISAGREE, because otherwise it would be possible to just spin the dist. cap 180° to compensate if the dist. was "180 out"... WITHOUT having to restab the whole dist. Is this incorrect?


EDIT: I just realized the typo in my previous post, and corrected it, now mentioned above. Should have been #2 cyl, not #8.

Who ever is telling you that is full of chit and doesn't understand distributor phasing. The trigger, the rotor, and the tower on the cap need to be aligned. The result of the distributor not being phased correctly is high rpm miss fire due to spark scatter when the advance comes in, which you are already describing.

 

[tayto]

Who ever is telling you that is full of chit and doesn't understand distributor phasing. The trigger, the rotor, and the tower on the cap need to be aligned. The result of the distributor not being phased correctly is high rpm miss fire due to spark scatter when the advance comes in, which you are already describing.

yup 1 tooth = ~30*

 

[Hipster]

yup 1 tooth = ~30*

The miss, it could be the diz install, it could be lean, it could be insufficient valve spring pressure, it could be some other part of the tune, etc.

 

[DeCaff2007]

Alright, so where is exactly is the dist. supposed to be? If I get this right and still have the same problem, it's time to check other things.

So here's something to ponder: could the high RPM backfire and hot no starts be caused by the same thing?

 

[tayto]

like any other SBC, #1 @ TDC and the the rotor points to #1 cylinder. do you have a FSM or have you downloaded one? all this stuff is covered in there along with pictures of how the distributor should be installed, plug position etc

 

[Schurkey]

The distributor rotor is supposed to point at the #1 cylinder when stabbed, correct?

NO.

like any other SBC, #1 @ TDC and the the rotor points to #1 cylinder.

NO.

Alright, so where is exactly is the dist. supposed to be?

The distributor rotor does NOT point to #1 cylinder.

The rotor should be pointing more-or-less to the #1 plug wire terminal contact on the inside of the distributor cap. This is especially important on Vortecs, which have the distributor cap terminals for the plug wires arranged in different positions from the actual contact inside the cap. It may not point "exactly" at the #1 plug wire terminal contact, but it'll be very close. What's actually more important is that the teeth on the reluctor align when the timing mark on the damper aligns with the specified timing on the timing pointer, with the rotor position being a second-best way to get the reluctor alignment right. Sometimes you can verify reluctor alignment by feeling for the magnetic "pull" as the distributor housing is turned.

Get your timing correct, if the distributor is mis-positioned, you can then play games with moving the distributor gear in relation to the cam gear so that the timing AND the distributor position are correct.

As said, all this is in the service manual set for your vehicle.

So here's something to ponder: could the high RPM backfire and hot no starts be caused by the same thing?

Sure. Questions are, 1) is that likely, and 2) are there other items that could cause those problems separately?

 

[Keeper]

Lastly: I think I need a better solution for a distributor, cap, and rotor. I'm guessing most of us have the type of distributor cap that is held on with just those two little screws on either side? Well, one of mine has completely stripped out and the cap wiggles freely, even with the other screw as tight as it will go. That can't be good.

is that issue fixed yet?

 

[DeCaff2007]

is that issue fixed yet?

I have a new distributor on order. I'm also short a kidney now, LoL!

 

[DeCaff2007]

@Schurkey, is this what you're referring to?

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