Difficulty timing a 1995 Chevy 454ci

[OutofTime]

I'm helping my brother clean up a 1995 Gulfstream Sunsport that is built on top of a 1994 Chevy P30 Chassis. It comes with a Chevy 454 big block v8. For the life of me I can't get the thing to fire off. I've verified spark, fuel and air. According to the directions on the air cleaner the timing should be set to 4 degrees BTDC on the number 1 wire. I've tried timing to that and I get nothing. I've read that if you use the timing marks at the 5 o'clock position, use cylinder number 5. Tried that too and nothing.

I made the assumption the harmonic balancer has slipped so I tried timing it the old fashioned way by pointing the dizzy at cylinder number 1 while it's on the compression stroke before reaching TDC. Nothing. I'm pretty sure my wire order on the dizzy is correct and that the spark plugs aren't fouled out.

Anyone have any advice?

[Bikeboy57]

I just have to say there is no ill intent on my part. But I am pretty sure this is a different read for the people reading than it is for the poster.

When you hear hoofbeats, think horses not zebras. All signs point to a timing issue. You can continue to throw money at it, but until the timing is addressed, it is just a frustrating exercise. Continuing to throw parts at it only increases the odds of some issue arising with the new parts to compound the problem.

Second. Insanity is doing the same thing over and over, but expecting a different outcome the next time. Point being, you set the timing to 4 BTDC with the timing connector disconnected, and it sort of runs. Then you connect the timing connector, and it falls flat. Meaning there could be something in your application of the setup routine that is causing this, and therefore the symptom keeps repeating itself.

It is popping back through the TBI. Meaning the timing is too early for the position of the valves.

I can think of two possibilities that would explain this.

One, is the correct mark for 4BTDC being used on the harmonic when you set the original timing? There are four marks on that harmonic. Are you using the big indented mark or a mark 3 notches over from that one? This also could be the whole basis of the distributor being off. Are you 100% percent certain the piston is at TCD when putting the distributor in, or are you using that timing mark as the indicator that the engine is at TDC. After all you keep mentioning the harmonic slipping on the crank. That simply does not happen with shearing the key.

Second, the engine has jumped time and the valves are no longer in time with the piston. This very much will cause poor ignition and popping because the valve is opened when the engine fires. As you mentioned earlier, pull the valve cover and watch the valve train actuation as the engine is barred over. Also, a compression test would tell you somewhat if the engine were out of time.

I am not criticizing you, please don’t read it that way. There is benefit in having a third party looking over your shoulder to identify what may be going on.

I think you are in Florida from your profile. Where? If you are close, and I live in Inverness, would you be open to on site help?

[OutofTime]

Updates.

After much research and reading much spirited debate online, I've concluded a TBI dizzy with electronic advance cannot be a tooth off. Not possible. What it can be is wires setup in such a way that you can't rotate the dizzy hat enough to get the engine in time. In that situation you would need to adjust the dizzy a tooth so that things will work out.

There are some early Ford TPI fuel injected engines that need to reference the number 1 cylinder in a certain place or they won't work right. However those engine have the number one stamped on the correct tower to make all that work on the dizzy hat.

The origin of a dizzy being a tooth off goes back to the early days with distributors that still used points. If the dizzy was a tooth off the points would open/close at the wrong time, leading to rough running.

All that out of the way.... I have the engine timed to 4 BTDC. After timing it to that and seeing the engine operation still acting as it was before, I decided to remove the TPS and swap it with another I had from a 350 in another vehicle.

I did check and the TPS are supposed to be the same part... in any case engine would only run with the accelerator fully on the floor with the 350 TPS. After swapping the original TPS back in it wouldn't start at all. I then read that I should have done this with the battery disconnected so the TPS 0 point would reset.

After doing the reset with the original TPS installed I got it running again.

Interestingly enough, now when I rev the engine it actually revs! Still pops through the intake but it will rev now instead of falling flat on it's face. Smoke coming out the exhaust seems to cleaned up a bit too.

Only thing I can think if is the TPS was jammed up somehow and causing issues. I should have some new injectors coming in next week that I hope will make a difference. I can stare at the spray pattern coming out of the current ones and it is not even.

[enblethen]

No not all the way around, lift up about 1/2 ich where it clears the cam gear then turn slightly in the direction. The distributor will not drop all the way in until it aligns with the oil pump.
Odds are you are dropping it back in the same place!

[OutofTime]

enblethen wrote:
Yes, one tooth.
Remember that the oil pump runs off the distributor shaft. The distributor will not drop completely in until engine turns over to align shafts. I like to do this with socket on vibration damper retaining bolt.

Riddle me this then. As I've been moving the dizzy around, I've moved it by lifting up on it just enough to spin the button and then move it clockwise just enough that it will fully seat against the intake. So when I say move one tooth counterclockwise, I mean that I would "walk" the dizzy all the way around then stop one tooth shy of it's current position.

Are you saying that instead I should try to move it one tooth back, then spin the engine counterclockwise to get it to seat?

[udidwht]

Be sure that once you confirmed the dizzy was out of position that you correct reoriented the wires in their correct positions.

[enblethen]

Yes, one tooth.
Remember that the oil pump runs off the distributor shaft. The distributor will not drop completely in until engine turns over to align shafts. I like to do this with socket on vibration damper retaining bolt.

[OutofTime]

Doing some more thinking about it, if I'm a tooth off as you claim, then to fix the advance problem the dizzy needs to move one tooth counterclockwise, correct?

[OutofTime]

enblethen wrote:
I would say no on the vibration damper slipping.
Is popping through intake or exhaust?
Intake would be too far advanced, exhaust is ********. (opposite from advanced)
One tooth off on distributor one way or another!

The popping sound comes from the TBI, so intake.

That would line up with my thought that the engine is too advanced right now.

You've mentioned in several posts you think the dizzy is a tooth off. That doesn't make sense to me. If I can get the dizzy to point at the cylinder 1 terminal on the cap and the balancer is at 4 BTDC while on the compression stroke, how can it be off a tooth?

If I have room to adjust the dizzy by turning it by hand and I can bring it to within factory spec, how is it off?

[enblethen]

I would say no on the vibration damper slipping.
Is popping through intake or exhaust?
Intake would be too far advanced, exhaust is ********. (opposite from advanced)
One tooth off on distributor one way or another!

[OutofTime]

Updates

I did indeed have the distributor 180 out. Using an old compression tester fitting I had laying around I identified compression stroke on cylinder 1 and adjusted the distributor accordingly. After doing so the engine fired right up.

However... still the same issues. Popping, running extremely rich, falls on it's face when you attempt to rev. This is with using all ACDelco ignition basically and ECT.

One thing I noted is when I first got it running it was at around TDC, and no popping from the engine. After adjust the dizzy slightly to get timing to 4 BTDC the engine now pops with little backfires at idle.

Plugged the advance back in and computer advance is working as it should.

There's a fairly sizable difference in how the engine wants to run when it moves from open loop to closed loop. I can't do much more digging until I swap out the water pump and fan clutch as there isn't much coolant in the engine.

Based on what I saw with the engine popping, I'm wondering if the balancer has slipped a little and the engine is too advanced when you set it to 4 BTDC... thoughts?

[enblethen]

That is NOTcorrect!
180 degrees off could be the piston was not in compression stroke, but in exhaust stroke.

[OutofTime]

Bikeboy57 wrote:
There are also two other possibilities that you should diagnose before throwing more money at guesses. One, is it possible the engine has jumped time? As best I remember that engine has a timing chain. Second it is possible to install the distributor 180 out which will produce the results you are getting.

A trick for ensuring tdc is to screw a compression test hose in the spark plug hole, but instead of a gauge run the hose into a cup of water. When you reach tdc it will stop bubbling

If it's 180 out, that means the balancer has slipped 180. I'm going to clean plugs and see what happens. If I still get nothing I'll try flipping the dizzy.

Engine needs a new water pump and fan clutch anyway so when I'm working on that I can take a peek behind the timing cover and see if the chain is super sloppy or has jumped a tooth. I don't think the Mark V 454 had the nylon teeth on the gear, but I could be wrong.

[Bikeboy57]

I think pulling the valve covers is an excellent idea, looking for proper valve actuation is you rotate through the four strokes. You can also video that with the spark tester in the shot

[Bikeboy57]

There are also two other possibilities that you should diagnose before throwing more money at guesses. One, is it possible the engine has jumped time? As best I remember that engine has a timing chain. Second it is possible to install the distributor 180 out which will produce the results you are getting.

A trick for ensuring tdc is to screw a compression test hose in the spark plug hole, but instead of a gauge run the hose into a cup of water. When you reach tdc it will stop bubbling

[enblethen]

I think you should look into a professional to determine and repair your problem!
I doubt removing valve covers will show anything.