Problems with the engine:
Overheats on the highway.
Loses power at about 5000 RPM.
Backfired at about 6000 RPM.
About 11 MPG.

Read through various posts here and replaced the thermostat, radiator hoses, and since the heater was leaking, blocked off the inlet and outlet hoses.

After further reading, decided to check my timing. Disconnected the flat 4 connector behind the distributor to check the bases timing. My Sears timing light indicates that it is about 41 degrees advanced. I'm hoping that this is why it is doing all of this.

Is it possible that this thing was running like this?

I'm thinking that when the distributor was installed, they lined up TDC and the rotor to #1 firing. Since this is a curved tooth gear, I think it is about one tooth off of where it is supposed to be.

I plan to mark where it is pointing now, remove the distributor, line up the rotor to that mark and reinstall the distributor again.

Yes, No, Maybe?

Thanks for any and all help.

Aaron

 

Those symptoms sound more like retarded timing. Are you sure you had the timing light connected to the #1 sparkplug wire?

Being a tooth off only affects the orientation of the distributor, not the timing necessarily. It's only an issue if you can't set the timing properly because the distributor or cap is hitting something.

 

if you are using a haynes manual the pic of the timing tab is labeld backwards
but if your using a dialback light then it doesnt matter

 

I am using a Sears timing light that has a **** to adjust the light. The **** is pointed to 41 degrees advanced. When I increase the RPM of the motor, the timing mark will go towards the passenger side of the car. to about 46 degrees at 2000 RPM (RPM is a guess).
I am using the shop manual.
I am connected to the Driver's side front plug.

Maybe I'll try to adjust the timing before I remove the distributor.

 

The timing, according to the factory, should be at 6° advanced, AT IDLE, with the plug behind the dist disconnected.

Th etiming is supposed to advance farther as the RPMs increase, but will only do so to a very limited extent with the plug disconnected. At idle, the timing should be about 15-18° farther advanced after you re-connect the plug; and it should smoothly advance another 24° or so if you just slowly rev it to 3000 and watch it with the light. If it does that, then it's all working like it's supposed to.

If your timing light shows 41° advanced at idle, it's probably because you have a stock crank damper that's expecting the timing tab to be at about 12:00; but you have an aftermarket bolt-on timing pointer that locates the tab at about 1:30.... about 35° off. Just like what everybody else with this set of problems has.

Sounds like you need to forget about the "number" the light gives you because it's WRONG. Instead, adjust the timing to where the car runs the best, since that's all you can do now that you have no way of knowing what "number" it actually is at, until you re-calibrate the timing mark. Which requires ACCURATELY finding TDC by observing the piston, and putting a new mark on the damper with white paint or something.

Also sounds like you have a bunch of worn-out stock valve springs, and the valves float at higher RPMs; which is why it "loses power" and backfires. With alot of "rebuilder" cams and valve train components, the motor will make NO POWER WHATSEOVER at those RPMs anyway; so it's beyond pointless to run it like that.

Don't bother removing the distributor, it won't do anything for you. We'll just have to endure yet another "I worked on my car and now it won't run" type of post and we'll have to explain how to put it back like it was and convince you to leave it alone.

 

So here is what I understand right now:
Timing pointers are off.
Assume that the 41 degrees is close to where it should be.
Sounds like it is retarded timing vice advanced.
Advance it a little and find where she is happiest. (41 to say 45 degrees and see what happens)
Don't remove the dist and annoy the board.
remove valve covers and perform a visual to make sure nothing looks broken (obviously can't visually determine weak springs)

Engine Info:
Previous owner installed
GM Base Crate 350
Owner unhappy with performance and removed and rebuilt with unknown parts and experience.
Emissions removed and using a stock distributor with ECM controls. I'm starting to think that the ECM is not advancing enough as RPM goes up. I may need a vacuum advance dist. to fix this disaster. I'm trying to figure out what the ECM needs to function properly and control timing advance.

If anyone near the Groton, CT region knows what they are doing and wants to help, I can supply beer.

 

There you go! A reasonable summary.

It always helps to have a little history. People will post stuff on here like for example, "my car won't run". Well OK.... try this try that, change out this other, put in new plugs, try starting fluid, etc. etc. etc. Then about 3 days later, it finally turns out that what REALLY happened, is that they just hacked on the wiring or something; but since they didn't tell us that, it's IMPOSSIBLE for us out here to guess what's REALLY going on. You can save alot of wasted bandwidth and time by telling the complete story, or at least, as much as you happen to know (which we all realize isn't always very complete, when buying a used car).

The stock ECM program usually works OK for a relatively low-performance replacement motor; which sounds kind of like what the PO put in there. I'd try working with it, for at least a little bit, before just yanking it and starting over. If of course, the whole system (ECM, wiring, sensors, carb, distributor, etc.) is all complete, and not rigged or hacked some kind of way. Which unfortunately is all too common.

The little Chilton's booklet you can get at VatoZone and such places, has the correct wiring diagrams for that system in it. There's minor variation from year to year; but the basic diagram is plenty close enough to work with in most cases. Might be worthwhile to get that, and scope out all the wires and sensors and modules and things, and figure out what's there and what's been altered and if anything is screwed up. Then armed with that info, you're alot better prepped to make an intelligent decision about what to do, rather than getting into an expensive and futile episode of "maybe it's this, maybe it's that" or just wholesale hacking and replacing large expensive things like the carb and distributor.

Meanwhile, you're right about the timing; put it back where it was even if the light is horrified; and try tweeeking it from there. And of course, feel free at any time, to ACCURATELY locate TDC, and install a KNOWN ACCURATE timing mark, and then you'll have an ACCURATE reference for any timing measurements you might like to make (did I mention that it should be "accurate"?). But also keep in mind, a modified motor may or may not work best with everything set to factory "specs", since it's a whole different motor from what those "specs" were designed for; you may need to do a little experienting regardless, to find the optimum settings for things. That's what is commonly called "tuning".

 

If your too advanced you should be getting loads of Detonation. Sounds like someone tapping on your exhaust manifold with a small hammer very fast. This can be quite destructive to an engine if left unattended to. On the other hand, if the engine is missing (Slight hesitation in acceleration) Your timing could be retarded.

 

Update:

Installed a new Vacuum advance Distributor, bypassed / deleted the computer portion. Under heavy acceleration it now has mild detonation. Heats up to 260F+ even quicker now. Decided to trust the harmonic balancer and timing marks on the block. Adjusted the timing to 3 degrees advance at 750 RPM.
She now fires right up, idles smooth and sounds / runs alot better. She still gets way to hot, about 250F at 80 MPH, 240F at 75 MPH and cols off to 220F at intown speeds. The airdam is installed. I think I need a new radiator, I can't afford that for a little while though. She is running about 20 to 30F cooler by properly setting the timing.
Thanks for all the help.

 

My experience with timing is with the orientation of the reluctor and the magnet inside the cap. Before going any further...Cut a hole your cap at the #1 post so you can see through to the rotor as it spins by the post. Install it.. and fire up the engine. If you have a dial-back timing light...set it to 0 deg. Aim it at the hole in the cap...the rotor should be dead on the #1 post...if it's not, it needs to be fixed. In this situation the spark has to jump across the gap created by this mialignment and causes the timing to jump around, overheating, and **** poor driveability. I've described how to fix this in other posts a few months ago. Try it..believe me.. it completly fixed all the issues with my engine!!

 

40-something degrees is on the edge of sparking the wrong cylinder ! ( even if the real timing is actually correct, and the dist is just phased wrong )
As already posted, KNOWING the tabs really are TDC would be a good start.
Pull the #1 plug. Roll the engine BY HAND to what says TDC.
Poke a surveyor's flag, or some such through the plug hole, and find the top of the piston.
Rock the engine slightly, about 10 degrees. If the piston appears to be at TDC when the tab indicates TDC, it probably is, by feeling the piston start down the bore.
If it's not, then getting it aligned becomes a chore.
BE CAREFUL ! If you use a screwdriver, you can scratch the bore, gouge the piston, etc. if top isn't top. Tear down time. If you use a wodden stick and accidentally breake it off inside the bore, tear down time.
I like a surveyor's flag, because the wire isn't heavy enough to do any real damage ( unless you pinch it between the piston and something else ) yet stiff enough to present the "feel."
You'd only ever need to do this once. Then you'll know that TDC is TDC. Everything else flows from there.